In cooperation with the Houston-Galveston Area Council and the 

Galveston Bay Estuary Program under the authority of the 

Texas Commission on Environmental Quality 

Variation in Biotic Assemblages and 

Stream-Habitat Data with Sampling 

Strategy and Method in Tidal Segments 

of Highland and Marchand Bayous, 

Galveston County, Texas, 2007 

Scientific Investigations Report 2008–5151 

U.S. Department of the Interior 

U.S. Geological Survey 
Cover: Red Drum (Sciaenops ocellatus) caught near Fairwood Road on Highland Bayou near Hitchcock, 

Texas, on July 10, 2007 (photograph by Erin Sewell, U.S. Geological Survey). 
Variation in Biotic Assemblages and 

Stream-Habitat Data with Sampling 

Strategy and Method in Tidal Segments 

of Highland and Marchand Bayous, 

Galveston County, Texas, 2007

By Jeffrey A. Mabe and J. Bruce Moring

In cooperation with the Houston-Galveston Area Council and the 

Galveston Bay Estuary Program under the authority of the 

Texas Commission on Environmental Quality

Scientific Investigations Report 2008–5151

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2008

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Mabe, J.A., and Moring, J.B., 2008, Variation in biotic assemblages and stream-habitat data with sampling strategy 

and method in tidal segments of Highland and Marchand Bayous, Galveston County, Texas, 2007: U.S. Geological 

Survey Scientific Investigations Report 2008–5151, 41 p. 
iii

Contents

Abstract ..........................................................................................................................................................1

Introduction ....................................................................................................................................................1

Purpose and Scope .............................................................................................................................2

Description of Study Area ..................................................................................................................2

Sampling Strategies and Methods ............................................................................................................3

Benthic Macroinvertebrate Sampling ..............................................................................................4

Fish Sampling ........................................................................................................................................4

Stream-Habitat Measurement ...........................................................................................................6

Data Analysis .................................................................................................................................................6

Data Treatment .....................................................................................................................................6

Statistical Analysis ..............................................................................................................................7

Biotic Assemblages ......................................................................................................................................8

Benthic Macroinvertebrates .............................................................................................................8

Influence of Seasons and Reaches .........................................................................................8

Influence of Sampling Locations ............................................................................................10

Fish .......................................................................................................................................................12

Influence of Seasons and Reaches .......................................................................................12

Influence of Sampling Intensity ..............................................................................................14

Stream-Habitat Data ...................................................................................................................................16

Physical Characteristics ...................................................................................................................16

Riparian/Bank Vegetation .................................................................................................................16

Habitat Quality Index .........................................................................................................................21

Summary .......................................................................................................................................................21

References Cited .........................................................................................................................................22

Appendixes ..................................................................................................................................................25

1. Benthic macroinvertebrate taxa (number of individuals) in standard (midchannel) and additional (deepwater and nearshore) samples, Highland and 

Marchand Bayous, Galveston County, Texas, spring and summer 2007 ..........................27

2. Fish taxa (number of individuals) collected in standard samples by electrofishing 

and seining, Highland and Marchand Bayous, Galveston County, Texas, spring 

and summer 2007 .......................................................................................................................30

3. Fish taxa (number of individuals) collected by electrofishing in multisample 

reaches, Highland Bayou, Galveston County, Texas, summer 2007 ..................................31

4. Fish taxa (number of individuals) collected by seining in multisample reaches, 

Highland Bayou, Galveston County, Texas, summer 2007 ...................................................32

5. Stream-habitat (transect) data collected from reaches on Highland and 

Marchand Bayous, Galveston County, Texas, summer 2007 ..............................................34

6. Habitat quality index data calculated for reaches on Highland and Marchand 

Bayous, Galveston County, Texas, summer 2007 ..................................................................39
iv

Figures

1. Map showing Highland and Marchand Bayou watershed and locations of 

Highland and Marchand Bayou sampling sites (reaches), Galveston County, 

Texas ..............................................................................................................................................3

2. Multidimensional scaling plot of benthic macroinvertebrate community data for 

Highland and Marchand Bayous, Galveston County, Texas, spring and summer 

2007 ................................................................................................................................................9

3. Multidimensional scaling plot of fish-community data for Highland and Marchand 

Bayous, Galveston County, Texas, spring and summer 2007 ..............................................13

4. Boxplots of stream-habitat variables by reach for Highland and Marchand Bayous, 

Galveston County, Texas, summer 2007 .................................................................................17

Tables

1. Sampling sites (reaches) on Highland and Marchand Bayous, Galveston County, 

Texas, spring and summer 2007 .................................................................................................4

2. Description of spring and summer standard samples and division of summer 

sampling in multisample reaches for evaluation of variation associated with 

sampling location and intensity, for fish sampling, Highland and Marchand 

Bayous, Galveston County, Texas, spring and summer 2007 ................................................5

3. Summary of benthic macroinvertebrate sampling from Highland and Marchand 

Bayous, Galveston County, Texas, spring and summer 2007 ..............................................10

4. Summary of richness and diversity metrics for benthic macroinvertebrate 

samples from Highland and Marchand Bayous, Galveston County, Texas, spring 

and summer 2007 .......................................................................................................................11

5. Global and pairwise results for Analysis of Similarities (ANOSIM) tests comparing 

the taxonomic structure of benthic macroinvertebrate communities at three 

different within-reach sampling locations in three separate reaches on Highland 

Bayou, Galveston County, Texas, summer 2007 ...................................................................12

6. Summary of fish-community sampling from Highland and Marchand Bayous, 

Galveston County, Texas, spring and summer 2007 .............................................................14

7. Global results for Analysis of Similarities (ANOSIM) tests comparing the 

taxonomic structure of fish communities collected with different levels of seining 

intensity at three different within-reach locations in two separate reaches on 

Highland Bayou, Galveston County, Texas, summer 2007 ..................................................14

8. Summary of taxa richness and community diversity metrics for fish samples 

from Highland and Marchand Bayous, Galveston County, Texas, spring and 

summer 2007 ...............................................................................................................................15

9. Summary statistics for stream-habitat variables from reaches on Highland and 

Marchand Bayous, Galveston County, Texas, summer 2007 ..............................................19

10. Medians for stream-habitat variables based on different transect sample sizes at 

multisample reaches on Highland Bayou, Galveston County, Texas, summer 2007 .......20
v

Conversion Factors and Datum

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Datum

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).
Blank Page
Abstract

The U.S. Geological Survey, in cooperation with the 

Houston-Galveston Area Council and the Galveston Bay 

Estuary Program under the authority of the Texas Commission on Environmental Quality, did a study in 2007 to assess 

the variation in biotic assemblages (benthic macroinvertebrate 

and fish communities) and stream-habitat data with sampling 

strategy and method in tidal segments of Highland Bayou and 

Marchand Bayou in Galveston County. Data were collected 

once in spring and once in summer 2007 from four stream 

sites (reaches) (short names Hitchcock, Fairwood, Bayou Dr, 

and Texas City) of Highland Bayou and from one reach (short 

name Marchand) in Marchand Bayou. Only stream-habitat 

data from summer 2007 samples were used for this report. 

Additional samples were collected at the Hitchcock, Fairwood, 

and Bayou Dr reaches (multisample reaches) during summer 

2007 to evaluate variation resulting from sampling intensity 

and location. Graphical analysis of benthic macroinvertebrate 

community data using a multidimensional scaling technique 

indicates there are taxonomic differences between the spring 

and summer samples. Seasonal differences in communities primarily were related to decreases in the abundance of 

chironomids and polychaetes in summer samples. Multivariate Analysis of Similarities tests of additional summer 2007 

benthic macroinvertebrate samples from Hitchcock, Fairwood, 

and Bayou Dr indicated significant taxonomic differences 

between the sampling locations at all three reaches. In general, 

the deepwater samples had the smallest numbers for benthic 

macroinvertebrate taxa richness and abundance. Graphical 

analysis of species-level fish data indicates no consistent 

seasonal difference in fish taxa across reaches. Increased 

seining intensity at the multisample reaches did not result 

in a statistically significant difference in fish communities. 

Increased seining resulted in some changes in taxa richness 

and community diversity metrics. Diversity increases associated with increased electrofishing intensity were relatively 

consistent across the two multisample electrofishing reaches 

(Hitchcock and Fairwood). Differences in the physical 

characteristics of the Highland and Marchand Bayou reaches 

are largely the result of the differences in channel gradient 

and position in the drainage network or watershed of each 

reach. No trees were observed on the bank adjacent to the 

five transects at either the Bayou Dr or Texas City reaches. 

Riparian vegetation at the more downstream Fairwood, Bayou 

Dr, and Texas City reaches was dominated by less-woody 

and more-herbaceous shrubs, and grasses and forbs, than at 

the more upstream Hitchcock and Marchand reaches. The 

width of the vegetation buffer was variable among all reaches 

and appeared to be more related to the extent of anthropogenic 

development in the riparian zone rather than to natural changes 

in the riparian buffer. Four additional transects per reach 

were sampled for habitat variables at Hitchcock, Fairwood, 

and Bayou Dr. Medians of most stream-habitat variables 

changed with increased sampling intensity (addition of two 

and four transects to the standard five transects), although 

none of the differences in medians were statistically significant. All habitat quality index values for the five reaches 

scored in the intermediate category. Increasing sampling 

intensity did not change the habitat quality index score for any 

of the reaches.

Introduction

The tidal zones of rivers and streams are unique environments where freshwater rivers transition into brackish 

estuarine ecosystems. These areas help to regulate flows of 

water, nutrients, sediment, and organisms to and from the 

land, rivers, and the sea. They function as critical habitat that 

provides nursery grounds for juvenile fish and shellfish and 

feeding grounds for resident and migratory birds. Economically, coastal ecosystems in Texas provide more than $2 billion in economic benefits annually through recreational fishing 

and another $260 million from commercial fishing (Houston 

Advanced Research Center, 2006).

Variation in Biotic Assemblages and 

Stream-Habitat Data with Sampling 

Strategy and Method in Tidal Segments 

of Highland and Marchand Bayous, 

Galveston County, Texas, 2007

By Jeffrey A. Mabe and J. Bruce Moring
2 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Many of the conditions that threaten tidally influenced 

ecosystems such as sedimentation, habitat alteration, and 

altered freshwater inflow patterns are not strictly water-quality 

issues. Chemical analysis of water samples might not detect 

these types of alterations to ecosystems, and assessments of 

biological communities often are necessary to detect ecosystem changes. Biological communities are effective assessment 

tools because they commonly reflect the cumulative effects 

of multiple stressors over an extended period of time, and 

careful consideration of the structure of biological communities can help identify probable causes of impairment (Gibson 

and others, 2000). However, tidally influenced ecosystems are 

complex and dynamic environments where the physical and 

chemical conditions that affect biological communities can 

vary both spatially and temporally (Odum, 1988; Bulger and 

others, 1993). Consequently, biological communities in tidal 

zones generally display a high degree of natural variation in 

taxa numbers, density, and biomass (McErlean and others, 

1972; LaSalle and Bishop, 1987; Montagna and Kalke, 1992; 

Gelwick and others, 2001). Field sampling methods also can 

introduce variation or bias into biological assessments in tidal 

environments (Livingston, 1987). 

Changes in tidal-zone biological communities associated 

with anthropogenic effects can be difficult to detect against 

background variation. Presently (2008) the Texas Commission 

on Environmental Quality (TCEQ), the agency responsible for 

setting environmental standards for the State of Texas, does 

not have established criteria for evaluating biological data collected from tidal stream segments. Developing suitable criteria 

for describing anthropogenic changes in tidal streams requires 

a clear understanding of the natural variation associated 

with sampling in different locations, at different times of the 

year, and with different methods or levels of intensity. (Level 

of intensity in this report generally refer to the number of 

samples.) Accordingly, the U.S. Geological Survey (USGS), 

in cooperation with the Houston-Galveston Area Council and 

the Galveston Bay Estuary Program under the authority of 

the Texas Commission on Environmental Quality, did a study 

in 2007 to assess the variation in biotic assemblages (benthic 

macroinvertebrate and fish communities) and stream-habitat 

data with sampling strategy and method in tidal segments of 

Highland Bayou and Marchand Bayou (fig. 1).

Purpose and Scope

This report documents and compares the variation in 

biotic assemblages (benthic macroinvertebrate and fish communities) and stream-habitat data with sampling strategy 

and method in tidal segments of Highland Bayou (four sites 

[reaches]) and Marchand Bayou (one reach) in 2007. Sampling strategies and methods are described. Changes in the 

structure of benthic macroinvertebrate and fish communities 

between spring and summer sampling events are assessed 

using multivariate statistical techniques that compare biotic 

assemblages between samples. Taxa changes associated with 

sample variation are described and quantified using diversity 

and richness metrics. Three of four reaches in Highland Bayou 

(multisample reaches) were selected for additional sampling 

to evaluate variation resulting from sampling intensity and 

location. For those reaches, more than the standard sampling 

called for in TCEQ protocols (Texas Commission on Environmental Quality, 2007) was done. For those reaches, benthic 

macroinvertebrate samples collected from three within-reach 

locations are compared and the between-sample variation 

is assessed and described taxonomically; variation in fishcommunity and stream-habitat data associated with sampling 

intensity is evaluated.

Description of Study Area

Highland Bayou is a tidally influenced stream draining an 

approximately 100-square-kilometer area in Galveston County 

on the Texas Gulf Coast (fig. 1). The water course rises near 

the town of Santa Fe and runs east-southeastward 20 kilometers to Jones Bay. The two upper reaches of Highland Bayou, 

Highland Bayou at Hitchcock (Hitchcock) and Highland 

Bayou at Fairwood Road (Fairwood), are riverine in nature 

with relatively narrow channels, steeply sloping channel sides, 

and low banks. Private residences line much of each reach, and 

bank vegetation primarily consists of grasses, trees, and shrubs 

or maintained lawns. During the study period, salinity (dissolved solids concentration) in the upper reaches ranged from 

0.12 to 5.34 parts per thousand (‰) at Hitchcock and 0.19 to 

7.35 ‰ at Fairwood (table 1). 

The two lower reaches of Highland Bayou, Highland 

Bayou at Bayou Drive (Bayou Dr) and Highland Bayou at 

Texas City (Texas City), are more estuarine in nature with 

relatively broad channels, a sinuate shoreline, and gently 

sloping channel sides that grade into shallow banks. Channel 

margins in the lower reaches are less developed and generally are lined with cordgrass that typically extended offshore 

into shallow water at the time of sampling. During the study 

period, salinity in the lower reaches of Highland Bayou ranged 

from 0.50 to 14.25 ‰ at Bayou Dr, and 0.86 to 21.27 ‰ at 

Texas City (table 1). 

Marchand Bayou is a smaller, shallower tributary that 

joins Highland Bayou near its mid-point (fig. 1) and resembles 

the upper reaches of Highland Bayou in adjacent land cover 

and channel form. The Marchand Bayou reach, Marchand 

Bayou at FM 519 (Marchand), is about 0.4 kilometer upstream 

from its confluence with Highland Bayou. Salinity at Marchand ranged from 0.07 to 9.48 ‰ (table 1) during the study 

period. 

Climatic conditions in the study area are classified as 

humid subtropical (Larkin and Bomar, 1983) and characterized by cool temperate winters, long hot summers, and high 

relative humidity. A National Weather Service station on 

Galveston Island (Scholes Field, Galveston Island, WBAN 

12923) was used to summarize weather conditions during the 

study period (National Oceanic and Atmospheric Administration, 2007). The overall mean temperature during the 2007 

study period was 25.2 degrees Celsius (°C) and monthly mean 
Sampling Strategies and Methods 3

temperatures ranged from a low of 19.8 °C in March to a high 

of 29.8 °C in August. Rainfall during the study period totaled 

725.2 millimeters with slightly more than 60 percent of the 

rainfall occurring in March and July. A storm that delivered 

118.9 millimeters over 3 days ended 11 days before the March 

sampling, and another storm that delivered 157.0 millimeters 

over 6 days ended 2 days before the July sampling. 

Sampling Strategies and Methods

Benthic macroinvertebrate, fish, and habitat data were 

collected from four stream reaches distributed down the length 

of tidally influenced Highland Bayou (table 1). Data also were 

collected from a single reach on tidally influenced Marchand 

Bayou. All five stream reaches were sampled for benthic macroinvertebrates, fish, and stream-habitat data once in spring 

and once in summer 2007. Only stream-habitat data from summer 2007 samples were used for this report because the summer 2007 habitat dataset was the most complete. Additional 

benthic macroinvertebrate, fish, and habitat samples were 

collected at the Hitchcock, Fairwood, and Bayou Dr reaches 

of Highland Bayou (multisample reaches) during summer 

2007 to evaluate variation resulting from sampling intensity 

and location. The spring sampling occurred March 26–30, and 

the summer sampling occurred July 9–10 and August 13–14; 

the gap in summer sampling was because of delays caused by 

thunderstorms. Sampling methods at individual reaches were 

consistent across sampling events. 

Figure 1. Highland and Marchand Bayou watershed and locations of Highland and Marchand Bayou sampling sites (reaches), 

Galveston County, Texas. 

J ones Ba y

G alvesto n

B a y

Dollar

B a y

GALVESTON COUNTY

BRAZORIA

Fai wr ood Rd.

Bayou Dr

M o s e s L a k e Highland Bayou

Marchand

FM

Texas City

Hitchcock

Santa Fe

La Marque

08077780 08077738

08077725

08077720

08077700

95°5' 95° 94°55'

29°25'

29°20'

Base from 

Roads: U.S. Department of Transportation, 1999 1:24,000

Counties: Texas General Land Office, 1999, 1:24,000

Cities: Texas Natural Resource Information 

System digital data, 1995

Projection:

Texas Centric Mapping System - Albers Equal Area

Datum: NAD83

EXPLANATION

Study area

Sampling site (reach) number 

and name (table 1) TEXAS

08077700—Highland Bayou at Hitchcock, Tex. (Hitchcock)

08077720—Marchand Bayou at FM 519, Hitchcock, Tex. 

 (Marchand)

08077725—Highland Bayou at Fairwood Rd., La Marque, 

 Tex. (Fairwood)

08077738—Highland Bayou at Bayou Dr. near La Marque, 

 Tex. (Bayou Dr)

08077780—Highland Bayou near Texas City, Tex. (Texas City)

0 3 6 Kilometers

0 3 6 Miles
4 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Benthic Macroinvertebrate Sampling

A 22.9- by 22.9-centimeter (9- by 9-inch) Ekman dredge 

on a pole was used to sample benthic macroinvertebrates at all 

reaches. The Ekman dredge works by placing the sampler on 

the streambed and releasing the spring-loaded jaws to collect 

a sediment sample. An advantage of the Ekman dredge on a 

pole is that it can be placed precisely to target specific depositional habitats. The Ekman dredge was operated from a boat 

in all reaches except Marchand Bayou, where it was operated 

while wading in shallow water. After the jaws were closed to 

collect a sample, the dredge was brought slowly to the surface 

where the sample was transferred to a container for transport 

to shore and eventual processing. All dredge hauls were first 

washed through a 0.64-centimeter sieve to separate the benthic 

macroinvertebrates from any large organic debris present in 

the sample. The general amount of large organic debris in each 

sample was noted, and the material was discarded after it was 

inspected for any remaining benthic macroinvertebrates. Samples were then processed through a 0.05-centimeter mesh sieve 

to separate the benthic macroinvertebrates from the remaining 

sediment. Processed benthic macroinvertebrate samples were 

preserved in 80-percent ethanol and submitted to EcoAnalysts, Inc., in Moscow, Idaho, for taxonomic identification and 

enumeration. Each dredge sample underwent complete sorting 

and enumeration, and all benthic macroinvertebrates collected 

were identified to the lowest taxonomic level possible. 

TCEQ protocols for a standard Ekman dredge sample in 

a tidal stream call for four separate dredge hauls (four replicates) from undisturbed soft sediment near mid-channel (Texas 

Commission on Environmental Quality, 2007). One standard 

sample following TCEQ protocols was collected from each 

study reach (table 1) in spring 2007 and one in summer 2007. 

Two additional samples (four dredge hauls, or replicates, each) 

were collected in summer 2007 at Hitchcock, Fairwood, and 

Bayou Dr for evaluation of variation in benthic macroinvertebrate communities associated with sampling location. At each 

of those three reaches, one sample was collected from soft 

bottom sediment at a deepwater mid-channel location and one 

sample at a shallow nearshore location. 

Fish Sampling 

Two sampling methods, electrofishing and seining, were 

used to collect fish-community data. Electrofishing methods 

were used where applicable; however, relatively high salinity 

common in estuarine environments can make electrofishing 

ineffective. Seining was used where relatively high salinity precluded effective electrofishing. Because of relatively 

high salinity, the two downstream reaches of Highland Bayou 

(Bayou Dr and Texas City) were sampled only by seining. In 

the upstream reaches where salinity was lower (Marchand and 

Fairwood), a combination of electrofishing and seining was 

used. In the uppermost reach of Highland Bayou (Hitchcock), 

seining was not practical because of steep banks and abundant 

woody debris that disrupted effective net hauling; therefore 

only electrofishing was used for fish sampling in this reach.

Electrofishing was done with a Smith-Root 5.0 Generator Powered Pulsator electrofishing system with a maximum 

power output of 5,000 watts. The electrofishing system was 

deployed from a boat in the Highland Bayou reaches and from 

a barge wading unit in the smaller and shallower Marchand 

Bayou reach. Electrofishing was done over the entire reach 

and included mid-channel habitat and channel margins. 

Stunned fish were collected with a net and placed in an aerated holding tank for recovery and transport to the processing 

station for identification. Captured fish were identified and 

enumerated on-site and returned to the water. 

Seining was done with a 4.6-meter flat-panel seine with 

a 0.64-centimeter mesh. Seines were deployed about 4 to 6 

meters offshore and parallel to the shoreline. Seines were then 

pulled inland to the shoreline where the lead-line was lifted 

Table 1. Sampling sites (reaches) on Highland and Marchand Bayous, Galveston County, Texas, spring and summer 2007.

[USGS, U.S. Geological Survey; DD, decimal degrees; ‰, parts per thousand; E, electrofishing; S, seine]

Reach name

USGS site 

number 

(fig. 1)

Reach 

short 

name

Location Salinity

range1

(‰)

Invertebrate 

capture

method

Fish 

capture 

method

Latitude 

(DD)

Longitude 

(DD)

Highland Bayou at Hitchcock, Tex.2 08077700 Hitchcock 29.35361 -95.03028 0.12–5.34 Dredge E

Marchand Bayou at FM 519, Hitchcock, 

Tex. 08077720 Marchand 29.35778 -95.00361 .07–9.48 Dredge S/E

Highland Bayou at Fairwood Rd., 

La Marque, Tex.2 08077725 Fairwood 29.35194 -94.99306 .19–7.35 Dredge S/E

Highland Bayou at Bayou Dr., near 

La Marque, Tex.2 08077738 Bayou Dr 29.33844 -94.97103 .50–14.25 Dredge S

Highland Bayou near Texas City, Tex. 08077780 Texas City 29.33222 -94.94500 .86–21.27 Dredge S

1

Range of salinities recorded during study.

2

Reach where additional sampling was done to evaluate variation resulting from sampling location and intensity. 
Sampling Strategies and Methods 5

and the seine pulled onshore. Seine hauls were considered 

effective only if the lead-line remained on or close to the bottom, and no obstacles were encountered that snagged or otherwise interfered with the smooth progression of the net through 

the water. On Highland Bayou, where reaches were larger 

than the Marchand reach, seining was distributed among at 

least three broadly spaced locations. On the Marchand reach, 

seining was distributed across the entire reach. In all reaches, 

seining covered as many nearshore habitat types as possible. 

Captured fish were removed from the nets, transferred to a 

container, and transported to shore where they were identified 

and enumerated on-site and then returned to the water. 

Captured fish were identified to the lowest possible taxonomic category (generally species). Individuals of unknown 

species were preserved in 10-percent buffered formalin and 

sent to Dr. Dean Hendrickson, Memorial Museum, The University of Texas at Austin, for identification. Voucher specimens (specimens retained for reference) were collected for all 

taxa at each site. Small taxa were vouchered by preserving a 

representative specimen in 10-percent buffered formalin, and 

large taxa were vouchered by photographing a representative 

specimen.

Fish sampling in the summer had two goals: (1) to collect 

representative fish-community samples (standard samples) 

consistent with TCEQ protocols and previous sampling and 

(2) to evaluate the effects of increased sampling intensity on 

the structure of the representative fish community captured. 

Accordingly, sampling intensity varied between spring and 

summer at the multisample reaches (Hitchcock, Fairwood, and 

Bayou Dr), and some partitioning of data was necessary to 

make valid statistical comparisons between spring and summer 

(table 2). 

TCEQ’s protocol for electrofishing calls for a minimum 

of 900 seconds (15 minutes) of shocking time covering as 

many habitat types in a reach as possible for a standard sample 

(Texas Commission on Environmental Quality, 2007). Shocking (collection) times at the three reaches where electrofishing 

was done (Hitchcock, Fairwood, and Marchand) averaged 

20.6 minutes per reach during spring sampling (table 2). Summer shocking time at the Marchand reach was similar to that 

for spring, but electrofishing at the Hitchcock and Fairwood 

reaches involved additional shocking time. Summer electrofishing at the Hitchcock and Fairwood reaches was partitioned 

into one pass of 15 minutes covering the entire reach and three 

Table 2. Description of spring and summer standard samples and the division of summer sampling for evaluation of variation 

associated with sampling location and intensity, for fish sampling, Highland and Marchand Bayous, Galveston County, Texas, spring and 

summer 2007.

[--, not applicable] 

Reach 

short 

name 

(table 1)

Electrofishing time Seining

Spring standard samples

Hitchcock 21.2 minutes --

Marchand 22.4 minutes First 6 effective hauls (entire reach)

Fairwood 18.3 minutes First 6 effective hauls (2 hauls/3 locations)

Bayou Dr -- First 10 effective hauls (3 hauls/2 locations and 4 hauls/1 location)

Texas City -- First 10 effective hauls (3 hauls/2 locations and 4 hauls/1 location)

Summer standard samples

Hitchcock 20 minutes (15-minute period and first extra 5-minute period) --

Marchand 21.7 minutes First 6 effective hauls (entire reach)

Fairwood 20 minutes (15-minute period and first extra 5-minute period) First 6 effective hauls (2 hauls/3 locations)

Bayou Dr -- First 10 effective hauls (3 hauls/2 locations and 4 hauls/1 location)

Texas City -- First 10 effective hauls (3 hauls/2 locations and 4 hauls/1 location)

Division of summer sampling in multisample reaches for evaluation of variation

Hitchcock One 15-minute period and three 5-minute periods --

Marchand -- --

Fairwood One 15-minute period and three 5-minute periods 18 effective seine hauls distributed among three locations

Bayou Dr -- 18 effective seine hauls distributed among three locations

Texas City -- --
6 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

additional 300-second (5-minute) shocking periods for selective resampling of important fish habitat in the reach. Fish 

captured during the individual shocking periods were kept 

separate to allow for assessment of variation with increased 

sampling intensity. However, to be consistent with spring 

sampling for statistical comparisons between seasons, summer standard samples for the Hitchcock and Fairwood reaches 

include only the first 20 minutes (15-minute sample plus the 

first 5-minute sample) of shocking time.

TCEQ protocol for seining calls for a minimum of six 

effective seine hauls (six replicates) for a standard sample 

(Texas Commission on Environmental Quality, 2007). However, there is no limit on the number of seine hauls that can be 

used for a given research objective. Fish sampling in the two 

downstream reaches of Highland Bayou, where seining was 

the only capture method, comprised 10 effective seine hauls 

for the standard sample. In contrast, in the upstream reaches 

where electrofishing was used with seining, only six effective 

seine hauls were done for the standard sample. 

Additional seining was done at Fairwood and Bayou 

Dr to assess variation associated with increased sampling 

intensity. Eighteen effective seine hauls were done in each of 

the two reaches during the summer sampling event. At each 

reach seining was distributed among three broadly spaced 

within-reach sampling locations (six hauls each), and the data 

were partitioned to reflect the fish catch as if the seine hauls 

were done in blocks of two at each location. The result is such 

that, for each reach, the dataset of six seine hauls consists of 

the first two seine hauls from each of the three within-reach 

locations; the dataset of 12 seine hauls consists of the first four 

seine hauls from each of the three within-reach locations; and 

the dataset of 18 seine hauls consists of the entire six seine 

hauls from each of the three within-reach locations. Thus, the 

analysis of increased sampling intensity reflects the difference between two, four, or six seine hauls at each of the three 

within-reach locations.

Stream-Habitat Measurement

TCEQ has not developed protocols for assessing physical habitat conditions in tidally influenced streams. Therefore 

stream-habitat assessment procedures in the Highland Bayou 

reaches, which were generally not wadeable, were modified 

from TCEQ protocols for non-wadeable streams (Texas 

Commission on Environmental Quality, 2007), and reach 

lengths were computed to include at least one river bend. 

Stream-habitat conditions in the Marchand reach, which was 

wadeable, were assessed using TCEQ protocols for wadable 

streams, and the reach length was computed as 40 times the 

mean channel width. Measurements of stream-habitat variables were recorded along five uniformly spaced transects 

perpendicular to the channel at all reaches. The stream-habitat 

variables for this report are

•	 Stream width

•	 Stream depth

•	 Bank slope

•	 Bank erosion

•	 Dominant substrate

•	 Instream cover

•	 Tree canopy

•	 Riparian trees

•	 Riparian shrubs

•	 Riparian grasses and forbs

•	 Width of vegetation buffer

•	 Habitat quality index (HQI)

These variables are described in “Surface Water Quality Monitoring Procedures,” volume 2 (Texas Commission on Environmental Quality, 2007).

TCEQ protocols for assessing stream-habitat conditions 

call for data collection from a minimum of five transects in 

wadeable streams and a minimum of six transects in nonwadeable streams. However, the standard sample for the nonwadeable Highland Bayou reaches was modified to reflect the 

general physical homogeneity of tidally influenced environments (Diaz, 1994) and involved data collection from only 

five transects. Stream-habitat data collection at the Hitchcock, 

Fairwood, and Bayou Dr reaches included four additional 

transects, distributed among the five standard transects, to 

evaluate the effects of increased sampling intensity on streamhabitat data. Additional transects were treated in the same 

manner as the standard transects, and the same stream-habitat 

variables were measured. 

Data Analysis

Benthic macroinvertebrate and fish data were analyzed 

to evaluate differences in community composition among 

reaches, sampling seasons, and within-reach sampling locations. Changes in community composition with increased 

sampling intensity also were assessed. The analysis of 

stream-habitat data emphasized a comparison among reaches 

of transect-derived habitat data to help understand the basic 

differences in physical channel features and aquatic-habitat 

conditions and the effects of increased sampling intensity, 

particularly on the HQI. 

Data Treatment

Benthic macroinvertebrate data from the four separate 

dredge hauls at each benthic macroinvertebrate sampling 

location were combined to form one composite sample (total 

of five samples in March and 11 samples in July/August). In 

some cases, the separate dredge hauls (replicates) were analyzed independently to provide sufficient data replication for 

statistical analysis. 
Data Analysis 7

Results from analysis of benthic macroinvertebrate data 

can be misleading if the taxonomic resolution of samples is 

inconsistent. Therefore, benthic macroinvertebrate data were 

analyzed at the genus level. Individuals identified to a lesser 

degree of resolution (family or lower) were distributed among 

their corresponding children (higher taxonomic resolution 

such as genus) according to their proportions in the samples. 

Individuals identified at a lesser taxonomic resolution with no 

corresponding children were left at their respective taxonomic 

level. Fish-community data from electrofishing and seining 

standard samples were combined into one standard sample for 

reaches where both capture methods were used (Marchand and 

Fairwood). 

Species identification is less problematic with fish than 

with benthic macroinvertebrates, and all individuals except 

juveniles of the genus Brevoortia were identified to the species 

level. Therefore the fish data were analyzed at the species 

level except for juvenile Brevoortia, which was analyzed at the 

genus level (Brevoortia sp.).

Statistical Analysis

Benthic macroinvertebrate and fish data were formatted 

and imported into the statistical software package Plymouth 

Routines In Multivariate Ecological Research (PRIMER) 

version 6 for summation and analysis (Clarke and Warwick, 

2001). PRIMER is designed to use data on community structure (abundance data for a set of taxa) to perform a wide array 

of univariate, graphical, and multivariate statistical procedures 

on sets of samples.

Multidimensional Scaling (MDS) was used to compare 

taxa assemblages between reaches and samples. MDS is an 

ordination technique that uses multidimensional taxa abundance information to construct a two-dimensional plot reflecting the similarities between samples (Clarke and Warwick, 

2001). Samples close to one another on the plot are more 

similar in taxonomic composition than samples farther away 

from one another. Similarities between each pair of samples 

are calculated using the Bray-Curtis similarity coefficient 

(Bray and Curtis, 1957). The Bray-Curtis similarity coefficient 

(S) between the jth and kth samples is defined as

S y y

y y

jk

ij ik i

p

ij ik i

p = − −

( ) +





















−

−

∑

∑

100 1 1

1

, (1)

where 

yij = the abundance of the ith taxa in the jth sample, and 

yik = the abundance of the ith taxa in the kth sample. 

The Bray-Curtis coefficient ranges from 1 if samples are 

exactly similar (same taxa in same abundance) to 0 if samples 

are completely dissimilar (no taxa in common). 

Ordinations such as MDS attempt to fit distances between 

samples in the ordination to match corresponding dissimilarities in community structure. However, because the data are 

multidimensional there is no single unique arrangement of 

samples, and MDS ordinations should be considered exploratory rather than definitive. The average dissimilarity between 

samples or sets of samples that appear to be dissimilar in 

the MDS can be tested with an Analysis of Similarities 

(ANOSIM) test (Clarke and Warwick, 2001). The ANOSIM 

test is based on the Bray-Curtis similarity matrix underlying 

the MDS ordination. Bray-Curtis similarities between samples 

are ranked and then used to compute a test statistic (R) defined 

as 

R

r r

M

B W = ( ) −

1

2

, (2)

where 

M = n(n-1)/2; n is the total number of samples; 

r

W = the average of rank similarities among replicates 

within sites; and 

rB = the average of rank similarities among replicates 

between sites. 

The value of R will be close to 1 if all within-reach replicates 

are more similar to each other than to any replicates from 

other reaches. R will be close to zero if all within-reach replicates are more similar to replicates from other reaches than to 

each other. The test statistic R can be calculated in the global 

sense (Global R) where similarities between all sites are compared, or, if enough data replication exists at individual sites, 

R can be calculated between individual sites (Pairwise R). The 

statistical significance of R is then evaluated against a null 

distribution of potential values for R developed from a random 

sampling of all possible sample groupings. If the actual value 

of R is outside the calculated null distribution of R values, it is 

likely not a result of chance variation and statistically significant at a level defined by the number of possible simulated 

sample groupings, which is computed as

( ) t T +1 1 /( ) + , (3)

where 

T = the number of simulated values of R, and 

t = the number of simulated values greater than the 

actual value of R. 

The Bray-Curtis dissimilarity coefficient (d) can be used 

to identify taxa that account for the dissimilarity between 

groups of samples with the PRIMER SIMilarity PERcentages 

(SIMPER) routine (Clarke and Warwick, 2001). Bray-Curtis 

dissimilarity is the reciprocal of Bray-Curtis similarity: 

( ) d = − 100 S . (4)

The SIMPER routine averages djk (i) for individual taxa (i) 

across all pairs of samples (j,k) to calculate the individual 
8 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

contribution of the ith taxa to the dissimilarity between groups 

of samples. 

Several commonly used measures of taxa richness and 

diversity were calculated to assist in comparing changes in 

biological assemblages with an increase in sampling intensity 

or between different sampling methods. Total individuals collected and total taxa collected were computed for each sample. 

Margalef’s richness index (d), defined as

d S = − ( ) 1 ln N , (5)

where 

S = the number of taxa, and 

N = the number of individuals, 

standardizes the number of taxa collected against the total 

number of individuals collected to give a relative measure 

of taxa richness (Zar, 1998). Shannon’s diversity index (H'), 

defined as 

′ = − =

H p ∑ p i

i

S

e i

1

log , (6)

where 

S = the number of taxa, and 

pi = the proportion of observations in taxa i, 

is based on information theory and provides information 

on the degree of heterogeneity in a community (Zar, 1998). 

Peilou’s evenness index (J'), defined as

J H ′ = ′ ′ / Hmax , (7)

where 

H′

max = the maximum possible value of Shannon’s 

diversity index, 

provides an indication of how evenly the individuals in the 

community are distributed among the different taxa (Zar, 

1998). 

Nonparametric summary statistics (medians and 25th and 

75th percentiles) were used to describe differences in streamhabitat variables among reaches. Kruskal-Wallis multiple comparison tests were used to compare medians of stream-habitat 

variables among reaches to indicate significant differences. 

All statistical analyses of stream-habitat data were done using 

Statistica Version 7 (StatSoft, 2006). 

Biotic Assemblages

Benthic Macroinvertebrates

Sixteen benthic macroinvertebrate samples were collected 

in Highland Bayou and Marchand Bayou in spring and summer 2007 (table 3). Mean depths for standard Ekman samples 

ranged from 0.67 to 1.14 meters; depths for the deepwater 

and the nearshore locations ranged from 1.37 to 1.68 meters 

and 0.30 to 0.53 meter, respectively. The amount of organic 

debris collected in dredge samples generally was higher in the 

upper reaches of Highland Bayou (Hitchcock and Fairwood), 

although the Marchand Bayou samples contained little organic 

debris. The deepwater samples consistently contained relatively little organic debris, and the nearshore samples generally contained relatively medium-to-high amounts of organic 

debris. 

Influence of Seasons and Reaches

The separation between spring and summer standard 

samples in the MDS plot of the combined genus level benthic 

macroinvertebrate data indicates that there are taxonomic 

differences between the spring and summer samples (fig. 2). 

The apparent differences are confirmed by an ANOSIM test 

comparing the replicates from the spring and summer standard 

samples (Global R = .436, p-value = .0001). The distribution 

of samples on the plot indicates that the similarity between 

reaches in the spring was (1) much higher than the similarity in the summer and (2) generally higher than the similarity 

between different sampling locations within the same reach in 

the summer. 

In the standard samples, benthic macroinvertebrate taxa 

richness and abundance were considerably larger in the spring 

than in the summer (table 4). The single exception was Bayou 

Dr; there, although abundance was much higher in the spring, 

taxa richness was slightly smaller in the spring. 

The major taxonomic groups that account for the 

dissimilarity between spring and summer samples, identified by the SIMPER analysis, are the Dipteran insect family 

Chironomidae (non-biting midges), and the annelid worm 

class Polychaeta (polychaete worms). Chironomids of the 

genera Chironomus and Tanypus were found in 100 percent of 

the spring samples and averaged 303 and 116 individuals per 

sample, respectively (appendix 1). In the summer samples, the 

genus Chironomus was found in 18 percent of samples and 

averaged four individuals per sample, whereas the genus 

Tanypus was found in 64 percent of samples and averaged 

five individuals per sample. Another chironimid genus, 

Dicrotendipes, was relatively abundant in the uppermost reach 

of Highland Bayou (Hitchcock) and Marchand in the spring 

samples (average of 44 individuals per sample) and greatly 

reduced in the summer samples (average of 1.5 individuals per 

sample). Two species of polychaetes, Streblospio benedicti

and Amphicteis floridus, also were found in 100 percent of 

the spring samples with an average number of individuals per 

sample of 93 and 62, respectively. Summer sampling yielded 

Streblospio benedicti and Amphicteis floridus in only 64 

percent of samples with an average number of individuals per 

sample of 11 and six, respectively. Although the chironomids 

and polychaetes were the dominate contributors to dissimilarity, other organisms were important at specific reaches. The 
Biotic Assemblages 9

largest contributor to dissimilarity between seasons at the 

Texas City reach was the amphipod genus Ampelisca, which 

composed 54 percent of the spring sample and only 6 percent 

of the summer sample. At Marchand, a species of bivalve 

Mytilopsis leucophaeata composed 23 percent of the spring 

sample but was absent from the summer sample. Also at 

Marchand, the mayfly genus Caenis composed only 2 percent 

of the spring sample but 30 percent of the summer sample. 

Although the spring and summer datasets are taxonomically dissimilar, both datasets indicate a gradient in the benthic 

macroinvertebrate community associated with reaches (fig. 2) 

that is likely caused by increases in salinity with downstream 

distance toward Jones Bay (fig. 1). The lowermost reaches, 

Texas City and Bayou Dr, where salinity generally is highest, 

are on the left side of the plot and have benthic macroinvertebrate communities dominated by highly tolerant freshwater 

organisms such as the chironomids Chironomus and Tanypus

as well as common estuarine organisms such as amphipods, 

isopods, Nemertea (ribbon worms), and polychaetes. The 

uppermost reaches, Hitchcock and Marchand, where salinity generally is lower, are on the right side of the plot and are 

characterized by more diverse chironomid communities, a 

Figure 2. Multidimensional scaling plot of benthic macroinvertebrate community data for Highland and Marchand Bayous, Galveston 

County, Texas, spring and summer 2007. 

Dimensions and units are arbitrary. Samples close to one another

are more similar in taxonomic composition than samples farther

away from one another. 

EXPLANATION

TC

BD

FR

MB

Hk

08077780 (Highland Bayou nr Texas City)

08077738 (Highland Bayou at Bayou Drive)

08077725 (Highland Bayou at Fairwood Road)

08077720 (Marchand Bayou at FM 519)

08077700 (Highland Bayou at Hitchcock)

Sample

Summer deep water sample (SuDW)

Summer nearshore sample (SuNS)

Spring standard sample (SpS)

Summer standard sample (SuS) 

Reach

TC

TC

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DIMENSION 1

Increasing

DIMENSION 2

Increasing

Spring samples
10 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

general absence of amphipods, isopods, and Nemertea, and 

the presence of freshwater organisms such as Oribatei (water 

mites) and Caenis mayflies. The middle reach, Fairwood, is in 

the middle of the plot and contained a mixture of taxa from the 

upper and lower reaches. 

The taxa identified in this report are similar to taxa in 

other tidal freshwater systems. Odum (1988) reports that 

benthic invertebrate communities in tidal freshwater marshes 

(salinities less than 0.5 ‰) on the East Coast generally are 

dominated by chironomid larvae, oligocheate worms, freshwater snails, and some amphipods. The more saline zones 

(salinities between 18.0 and 35.0 ‰) generally are dominated 

by polychaetes, crustaceans (for example, isopods, amphipods, 

and crabs), and bivalves (Odum, 1988). 

The seasonal variation in the benthic macroinvertebrate 

community documented in this report (decreases in taxa richness and individual taxa abundance from spring to summer) 

is similar to seasonal variation reported by other researchers 

(LaSalle and Bishop, 1987; Livingston, 1987; Crumb, 1997). 

LaSalle and Bishop (1987) reported that benthic macroinvertebrates in tidal marshes in Mississippi peaked in abundance in 

the spring and declined to seasonal lows in the summer after 

the metamorphosis and emergence of adults. Crumb (1997), 

on the basis of work in the tidal segment of the Delaware 

River, reported a similar seasonal pattern in oligocheate 

worms (Tubificidae) that do not undergo metamorphosis and 

attributed the pattern to a temperature-mediated reproductive 

pattern where large numbers of juveniles were present in the 

spring. In contrast, researchers studying Guadalupe Bay on 

the Texas Coast in Calhoun County (about 200 kilometers 

southwest of the study area) found a sharp decrease in benthic 

macroinvertebrate densities at a tidal freshwater station in July, 

but they attributed the decrease to a large inflow event rather 

than a seasonal pattern (Montagna and Kalke, 1992). 

Rainfall occurred before the summer sampling event in 

the study reported here, which likely increased streamflow 

in Highland and Marchand Bayous. However, data collected 

for this report are not sufficient for determining whether the 

observed variation in the benthic macroinvertebrate community is the result of high flows, seasonal factors, or other 

factors.

Influence of Sampling Locations

Benthic macroinvertebrate communities in the three 

reaches at which multiple samples were collected (Hitchcock, 

Fairwood, and Bayou Dr) differed among the three withinreach sampling locations (standard, deepwater, and nearshore). 

Table 3. Summary of benthic macroinvertebrate sampling from Highland and Marchand Bayous, Galveston County, Texas, spring and 

summer 2007.

[SpS, spring standard; SuS, summer standard; SuDW, summer deepwater; SuNS, summer nearshore]

Reach 

short name 

(table 1)

Date Sample type Sample location Mean depth 

(meters)

Spring

Hitchcock 03/27/2007 SpS Mid-channel 0.91

Marchand 03/27/2007 SpS Mid-channel .76

Fairwood 03/27/2007 SpS Mid-channel .91

Bayou Dr 03/26/2007 SpS Mid-channel 1.14

Texas City 03/26/2007 SpS Mid-channel .67

Summer

Hitchcock 07/09/2007 SuS Mid-channel .84

Hitchcock 07/09/2007 SuDW Deepwater 1.37

Hitchcock 07/09/2007 SuNS Nearshore .30

Marchand 08/14/2007 SuS Mid-channel 1.07

Fairwood 07/10/2007 SuS Mid-channel 1.14

Fairwood 07/10/2007 SuDW Deepwater 1.68

Fairwood 07/10/2007 SuNS Nearshore .53

Bayou Dr 07/10/2007 SuS Mid-channel .99

Bayou Dr 07/10/2007 SuDW Deepwater 1.37

Bayou Dr 07/10/2007 SuNS Nearshore .37

Texas City 08/13/2007 SuS Mid-channel .76
Biotic Assemblages 11

Global ANOSIM tests indicated that taxonomic differences 

among the three sampling locations were statistically significant at the .05 level at all reaches (table 5). Pairwise results, 

however, were not consistent across all reaches. All three 

sampling locations were significantly different from each 

other only at the most downstream multisample reach (Bayou 

Dr). The Bayou Dr reach also yielded the highest Global R 

value (.847), indicating that many of the replicates from each 

sampling location (for example, nearshore) are more similar to each other than to any replicates from other sampling 

locations. Standard samples and deepwater samples from 

the Hitchcock reach were not significantly different largely 

because of the very low numbers of benthic macroinvertebrates collected in these samples.

The summer benthic macroinvertebrate samples from 

different locations showed strong differences in taxa richness, 

abundance, and diversity (table 4). Values for taxa richness 

and abundance were smallest in the deepwater samples. In 

contrast, two of the three multisample reaches (Hitchcock 

and Fairwood) had the largest values for these variables in the 

nearshore samples. Values for taxa richness and abundance 

were largest in the standard sampling location only at the most 

downstream of the three multisample reaches (Bayou Dr). 

Values for Margalef’s richness and Shannon’s diversity 

(table 4) varied as those of taxa richness and were largest for 

the reaches where taxa richness was largest—that is, at the 

nearshore sampling locations at Hitchcock and Fairwood and 

at the standard sampling location at Bayou Dr. Values for 

Pielou’s evenness for the Bayou Dr reach also varied similar 

to values of taxa richness and were largest for the standard 

sampling location. The deepwater samples from the two upper 

reaches, however, contained few taxa with most represented by 

a single individual (appendix 1). As a result, Pielou’s evenness at these reaches was largest for the deepwater samples 

(table 4). 

Patterns in taxa distribution were evident between summer sampling locations. The nearshore sites tended to have a 

larger diversity of chironomids and larger numbers of annelid 

worms (polychaetes and oligocheates) (appendix 1). Arthropods showed no clear pattern but were the most diverse and 

abundant at the primary sampling location at the most downstream multisample reach (Bayou Dr).

Although determining the reasons for observed differences in community composition among sampling locations 

was beyond the scope of this study, noting the differences 

among sampling locations might provide insight into the 

observed community patterns: The nearshore sampling locations were (1) close to emergent vegetation and woody debris, 

(2) close to the surface where water movement and diffusion 

likely increase dissolved oxygen, and (3) characterized by 

Table 4. Summary of richness and diversity metrics for benthic macroinvertebrate samples from Highland and Marchand Bayous, 

Galveston County, Texas, spring and summer 2007.

[SpS, spring standard; SuS, summer standard; SuDW, summer deepwater; SuNS, summer nearshore] 

Reach short 

name

(table 1)

Sample 

type

Taxa 

richness Abundance Margalef’s richness

Pielou’s 

evenness

Shannon’s 

diversity

Spring

Hitchcock SpS 20 703 2.90 0.401 1.200

Marchand SpS 25 598 3.75 .728 2.344

Fairwood SpS 20 928 2.78 .584 1.750

Bayou Dr SpS 11 968 1.45 .394 .944

Texas City SpS 18 1,068 2.44 .528 1.525

Summer

Hitchcock SuS 5 16 1.44 .865 1.392

Hitchcock SuDW 6 7 2.57 .976 1.748

Hitchcock SuNS 15 140 2.83 .764 2.068

Marchand SuS 23 201 4.15 .736 2.309

Fairwood SuS 11 123 2.08 .757 1.816

Fairwood SuDW 6 7 2.57 .976 1.748

Fairwood SuNS 16 298 2.63 .658 1.824

Bayou Dr SuS 13 73 2.80 .866 2.222

Bayou Dr SuDW 5 24 1.26 .490 .789

Bayou Dr SuNS 12 66 2.63 .844 2.096

Texas City SuS 10 33 2.57 .845 1.946
12 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

a firmer and less anoxic mud substrate compared to that of 

the deepwater and standard sampling locations. Greater taxa 

diversity in the nearshore samples might be a result of one or 

all of those factors, or other factors. 

Fish

Fish-community samples were collected at the four 

Highland Bayou reaches and the Marchand Bayou reach in 

spring and summer 2007 (table 6). In standard samples, 4,980 

individuals representing 29 taxa were collected (appendix 2). 

In standard and nonstandard samples, electrofishing accounted 

for 1,991 individuals and 21 taxa (appendix 3), and seining 

accounted for 3,928 individuals and 21 taxa (appendix 4). 

Influence of Seasons and Reaches

The grouping of standard samples in the MDS plot 

of species-level fish data indicates no consistent seasonal 

difference in fish taxa across reaches (fig. 3). Results of an 

ANOSIM test comparing the standard spring catch with the 

standard summer catch (Global R = .13, p-value = .168) supports this conclusion. The MDS plot does, however, indicate 

that the spring standard samples in the two upper reaches 

(Hitchcock and Marchand) are more similar to each other than 

to their corresponding summer standard samples. The summer 

dissimilarity between these two reaches, as indicated by the 

SIMPER analysis, primarily is because of the abundance of 

juvenile Brevoortia sp. collected at Hitchcock in the summer 

and the absence of this genus from the Marchand collection. 

The SIMPER analysis also indicated that the springto-summer changes in abundance of one species, Leiostomus 

xanthurus, were consistent across standard samples. 

Leiostomus xanthurus accounted for 17.9 percent of the standard fish collection across all reaches in the spring, but only 

0.35 percent of the summer standard collection (appendix 2). 

Spring-to-summer changes in the upper reaches generally 

involved an increase in the abundance of freshwater taxa such 

as Micropterus salmoides and most sunfish species (Lepomis 

macrochirus, Lepomis megalotis, and Lepomis gulosus) and 

a decrease in the abundance of some euryhaline taxa such as 

Menidia beryllina, Mugil cephalus, and Brevoortia sp. The 

Hitchcock reach was a notable exception where juveniles of 

the euryhaline genus Brevoortia sp. accounted for 86 percent of the total fish catch in the summer. Spring-to-summer 

changes in the lower reaches involved a general decrease in 

abundance of most of the common euryhaline species with 

the exception of Menidia beryllina, which increased by 127 

percent at the Bayou Dr reach and 1,625 percent at the Texas 

City reach. 

The lack of fish-sample replication within a given 

sampling period did not allow statistically valid ANOSIM 

tests to be done on the fish communities at individual reaches 

between seasons. However, the amount of separation between 

spring and summer standard samples in the MDS plot (fig. 3) 

at some reaches indicates that some seasonal taxa differences 

were locally important. The amount of separation between the 

Marchand standard samples is caused by spring-to-summer 

decreases in abundance of 92 percent of the euryhaline taxa 

and increases in abundance of 100 percent of the freshwater 

taxa (appendix 2). In the Fairwood reach, the abundance of 

three tolerant euryhaline taxa, Poecilia latipinna, Gambusia 

affinis, and Cyprinodon variegatus, increased from spring to 

summer by 3,117, 6,100, and 600 percent, respectively. Five 

taxa not found at Fairwood in the spring were captured there 

in the summer; these taxa comprised three other euryhaline 

taxa (Lucania parva, Fundulus pulvereus, and Microgobius 

gulosus) and two freshwater taxa (Micropterus salmoides and 

Lepomis macrochirus). Salinities in the upper reaches of Highland Bayou measured during the study were lowest in July and 

might account for the increased presence of freshwater taxa in 

the July samples. 

The MDS plot of the species-level fish data (fig. 3) indicates a fish-community gradient in Highland Bayou. The two 

lower reaches of Highland Bayou (Bayou Dr and Texas City) 

are in the lower middle of the plot, whereas the higher reaches 

(Hitchcock and Marchand) grade into the upper right of the 

Table 5. Global and pairwise results for Analysis of Similarities (ANOSIM) tests comparing the taxonomic structure of benthic 

macroinvertebrate communities from three different within-reach sampling locations in three separate reaches on Highland Bayou,

Galveston County, Texas, summer 2007. 

[R, ANOSIM test statistic; p, p-value; S, standard sample; DW, deepwater sample; NS, nearshore sample] 

Highland Bayou at 

Hitchcock

Highland Bayou at 

Fairwood

Highland Bayou at 

Bayou Dr

Statistical test R p Statistical test R p Statistical test R p

Global test .299 .003 Global test .316 .002 Global test .847 .001

Pairwise tests Pairwise tests Pairwise tests

S, DW .26 .114 S, DW .375 .029 S, DW .969 .029

S, NS .552 .029 S, NS .198 .171 S, NS .781 .029

DW, NS .281 .029 DW, NS .339 .057 DW, NS .948 .029
Biotic Assemblages 13

plot. The ANOSIM test comparing fish catch in the standard 

samples supports the conclusion that the fish communities at 

the different reaches of Highland Bayou are different from one 

another (Global R = .53, p-value = .007). The gradient in the 

MDS plot primarily is related to the lack of freshwater taxa 

in the lower reaches of Highland Bayou and a mix of euryhaline and freshwater taxa in the upper reaches of Highland and 

Marchand Bayous. Samples from the middle reach (Fairwood) 

are above this gradient, to the left, on the MDS plot. The 

SIMPER analysis indicated that the separation of the Fairwood 

samples is because of a decreased abundance in the Fairwood 

samples of some euryhaline taxa found in the lower reaches 

Figure 3. Multidimensional scaling plot of fish-community data for Highland and Marchand Bayous, Galveston County, Texas, spring 

and summer 2007. 

Dimensions and units are arbitrary. Samples close to one another

are more similar in taxonomic composition than samples farther

away from one another. 

EXPLANATION

TC

BD

FR

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Hk

08077780 (Highland Bayou nr Texas City)

08077738 (Highland Bayou at Bayou Drive)

08077725 (Highland Bayou at Fairwood Road)

08077720 (Marchand Bayou at FM 519)

08077700 (Highland Bayou at Hitchcock)

Reach

1

 Su20e at Hitchcock is considered summer standard sample.

Sample

Summer seine sample—6 hauls (Su6s)

Summer seine sample—12 hauls (Su12s)

Summer seine sample—18 hauls (Su18s)

Summer electrofishing sample—15 minutes (Su15e)

Summer electrofishing sample—20 minutes (Su20e)

Summer electrofishing sample—25 minutes (Su25e)

Summer electrofishing sample—30 minutes (Su30e)

Spring standard sample (SpS)

Summer standard sample1

 (SuS) 

TC

TC

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FR

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DIMENSION 1

Increasing

DIMENSION 2

Increasing
14 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

(Menidia beryllina, Anchoa mitchilli, and Brevoortia sp.) and 

a decreased abundance or absence in the Fairwood samples 

of some of the freshwater taxa found in the upper reaches 

(Lepomis macrochirus, Lepomis megalotis, and Lepomis 

gulosus). In addition, the summer sample at the Fairwood 

reach contained an abundance of several tolerant euryhaline 

taxa such as Poecilia latipinna, Cyprinodon variegatus, and 

Gambusia affinis that are only found in low numbers at the 

other reaches. Although comparison of community assemblages to environmental variables was not done for this report, 

the gradient in the fish community likely is caused by changes 

in salinity. Fish communities structured by salinity levels are 

common in estuarine environments (Hackney and others, 

1976; Bulger and others, 1993) and have been documented on 

the Texas coast (Gelwick and others, 2001). 

Apparent differences in fish communities might be 

related to the different methods of fish capture used in the 

reaches. The lower reaches of Highland Bayou were sampled 

by seining, and the upper reaches were sampled by electrofishing or a combination of electrofishing and seining. Samples 

collected using different capture methods are not strictly 

comparable. Although it seems intuitive that the salinity gradient in Highland Bayou would produce a concurrent gradient in 

the fish community based on salinity tolerance, confounding 

effects of different capture methods on results is a possibility. 

Influence of Sampling Intensity

Increased seining intensity at the multisample reaches 

(Hitchcock, Fairwood, and Bayou Dr) did not result in a 

statistically significant difference in fish communities. The 

ANOSIM analysis indicated no significant differences in fish 

communities between samples of 6, 12, and 18 seine hauls at 

either Fairwood (Global R = -.02, p-value = .566) or Bayou Dr 

(Global R = -.03, p-value = .639) (table 7). 

Increased seining for fish resulted in some changes in 

taxa richness and community diversity metrics (table 8). The 

largest changes were at the Bayou Dr reach where an increase 

from six seine hauls to 12 seine hauls added an additional 

eight taxa and increased taxa richness by 114 percent and 

Margalef’s richness by 111 percent. Community diversity 

as measured by Shannon’s diversity index was minimally 

affected by this taxa increase, but Pielou’s evenness decreased 

by 28 percent. Shannon’s diversity index was stable because 

none of the new taxa were collected in great numbers, and the 

numerically dominate taxa continued to be collected in abundance. The decrease in Pielou’s evenness can be attributed 

to the increased collection of juvenile Brevoortia sp., which 

constituted the majority of the catch at one sampling location. 

An increase in the seining intensity at Bayou Dr from 12 seine 

Table 6. Summary of fish-community sampling from Highland 

and Marchand Bayous, Galveston County, Texas, spring and 

summer 2007. 

[SpS, spring standard; E, electrofishing; S, seining; Suxe, summer nonstandard and x minutes of electrofishing; SuS, summer standard; Suxs, summer 

nonstandard and x seine hauls]

Reach 

short 

name 

(table 1)

Date Sample type Method Sample 

intensity

Spring

Hitchcock 03/27/2007 SpS E Standard

Marchand 03/28/2007 SpS S/E Standard

Fairwood 03/27/2007 SpS S/E Standard

Bayou Dr 03/26/2007 SpS S Standard

Texas City 03/26/2007 SpS S Standard

Summer

Hitchcock 07/11/2007 Su15e E 15 minutes

Hitchcock 07/11/2007 Su20e/SuS1 E 20 minutes

Hitchcock 07/11/2007 Su25e E 25 minutes

Hitchcock 07/11/2007 Su30e E 30 minutes

Marchand 08/13/2007 SuS S/E Standard

Fairwood 07/12/2007 SuS S/E Standard

Fairwood 07/12/2007 Su6s S 6 hauls

Fairwood 07/12/2007 Su12s S 12 hauls

Fairwood 07/12/2007 Su18s S 18 hauls

Fairwood 07/12/2007 Su15e E 15 minutes

Fairwood 07/12/2007 Su20e E 20 minutes

Fairwood 07/12/2007 Su25e E 25 minutes

Fairwood 07/12/2007 Su30e E 30 minutes

Bayou Dr 07/11/2007 SuS S Standard

Bayou Dr 07/11/2007 Su6s S 6 hauls

Bayou Dr 07/11/2007 Su12s S 12 hauls

Bayou Dr 07/11/2007 Su18s S 18 hauls

Texas City 08/13/2007 SuS S Standard

1

Summer standard sample consists of first 20 minutes of electrofishing.

Table 7. Global results for Analysis of Similarities (ANOSIM) 

tests comparing the taxonomic structure of fish communities 

collected with different levels of seining intensity at three different 

within-reach locations in two separate reaches on Highland 

Bayou, Galveston County, Texas, summer 2007. 

[R, ANOSIM test statistic; p, p-value] 

Highland Bayou at 

Fairwood

Highland Bayou at 

Bayou Dr

Statistical test R p Statistical test R p

Seining intensity

Global test -.02 .566 Global test -.03 .639

Seining location

Global test .46 .001 Global test .26 .007
Biotic Assemblages 15

hauls to 18 seine hauls added one additional taxon but only 

resulted in marginal changes to the calculated metrics. 

Increased seining intensity at the Fairwood reach generally resulted in increased values for calculated metrics but 

changes were marginal. The first set of six seine hauls collected 12 of the 13 taxa found at the reach. Shannon’s diversity 

index for six seine hauls increased 15 percent for 18 seine 

hauls (table 8). Margalef’s richness for six seine hauls actually 

decreased 5.8 percent for 12 seine hauls because the additional 

seining increased taxa abundance without adding additional 

taxa. The increased taxa abundance associated with the additional seine hauls at the Fairwood reach decreased the cumulative dominance of the two most abundant taxa.

ANOSIM tests indicated significant differences in fish 

communities among the three within-reach sampling locations at Fairwood (Global R = .46, p-value = .001) and Bayou 

Dr (Global R = .26, p-value = .007) (table 7). The SIMPER 

analysis indicated most of the dissimilarity among sampling 

locations at both reaches was accounted for by differences in 

the abundance of common taxa. For example, at the Bayou 

Dr reach, Brevoortia sp. was either sparse or not found at the 

first and second sampling locations but composed 67 percent 

of the catch at the third sampling location (appendix 4). Taxa 

accounting for dissimilarities among sampling locations at 

Fairwood included Poecilia latipinna, Cyprinodon variegatus, 

and Gambusia affinis. 

The lack of valid replicates within the different levels 

of electrofishing intensity make ANOSIM tests invalid; 

therefore changes in fish-community data between levels 

of electrofishing intensity were analyzed only by comparing the values of metrics. Diversity increases associated with 

increased electrofishing intensity were relatively consistent 

across the two multisample electrofishing reaches (Hitchcock 

and Fairwood). Total taxa richness, Margalef’s richness, and 

Shannon’s diversity index for both reaches increased with an 

increase in electrofishing time from 15 minutes to 20 minutes. 

The 5-minute increase in electrofishing time at the Hitchcock 

reach increased taxa richness by 22 percent (table 8) and 

added one sunfish (Lepomis microlophus) and one livebearer 

(Poecilia latipinna) (appendix 3). Taxa richness at the 

Table 8. Summary of taxa richness and community diversity metrics for fish samples from Highland and Marchand Bayous, Galveston 

County, Texas, spring and summer 2007.

[SpS, spring standard; Suxe, summer nonstandard and x minutes of electrofishing; SuS, summer standard; Suxs, summer nonstandard and x seine hauls] 

Reach short name 

(table 1) Sample type Taxa richness Abundance Margalef’s richness

Pielou’s 

evenness

Shannon’s 

diversity index

Spring

Hitchcock SpS 15 666 2.15 0.39 1.06

Marchand SpS 12 430 1.81 .50 1.24

Fairwood Rd SpS 10 244 1.64 .43 .99

Bayou Dr SpS 6 1,286 .70 .53 .96

Texas City SpS 9 285 1.42 .66 1.45

Summer

Hitchcock Su15e 9 789 1.20 .20 .45

Hitchcock Su20e/SuS1 11 833 1.49 .26 .62

Hitchcock Su25e 11 862 1.48 .28 .68

Hitchcock Su30e 11 905 1.47 .31 .74

Marchand SuS 12 88 2.46 .80 1.98

Fairwood SuS 14 419 2.15 .69 1.82

Fairwood Su6s 12 326 1.90 .55 1.38

Fairwood Su12s 12 467 1.79 .61 1.51

Fairwood Su18s 13 642 1.86 .62 1.59

Fairwood Su15e 6 52 1.27 .70 1.26

Fairwood Su20e 9 66 1.91 .70 1.53

Fairwood Su25e 9 80 1.83 .67 1.47

Fairwood Su30e 9 93 1.77 .67 1.48

Bayou Dr SuS 13 572 1.89 .48 1.24

Bayou Dr Su6s 7 354 1.02 .64 1.25

Bayou Dr Su12s 15 683 2.15 .46 1.26

Bayou Dr Su18s 16 1,097 2.14 .47 1.30

Texas City SuS 6 184 .96 .47 .84

1

 Summer standard sample consists of first 20 minutes of electrofishing.
16 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Fairwood reach was increased 50 percent and contributed two 

important game species (Micropterus salmoides and Sciaenops 

ocellatus) to the taxa list. The 5-minute increase in electrofishing time increased Shannon’s diversity index 38 percent 

at the Hitchcock reach and 21 percent at the Fairwood reach. 

Pielou’s evenness was increased 30 percent at the Hitchcock 

reach but was unchanged at the Fairwood reach. Additional 

electrofishing at Hitchcock tended to increase the abundance 

of all taxa, whereas additional electrofishing at Fairwood 

tended to increase the abundance of only the most abundant 

taxa. Additional sampling beyond 20 minutes added no new 

taxa and produced only small changes in diversity metrics, 

which were related to changes in taxa abundance.

Stream-Habitat Data

The analysis of stream-habitat data from summer 2007 

emphasized a comparison among reaches of transect-derived 

habitat data and the effects of increased sampling intensity on 

the stream-habitat variables, particularly on the HQI. Streamhabitat data collected for this report are in appendix 5, and 

HQI data calculated for this report are in appendix 6.

Physical Characteristics

The Marchand reach is the smallest in terms of length 

and stream width, and the Texas City reach is the largest 

(table 9). Median stream width of the Marchand reach was 

significantly smaller than that of the downstream Bayou Dr 

and Texas City reaches (fig. 4). Median stream depth was 

relatively uniform among the five reaches, ranging from 0.87 

meter at the Texas City reach to 2.22 meters at the Fairwood 

reach (table 9). Median bank slope of the Marchand reach 

was several times larger than that of the Hitchcock, Bayou Dr, 

and Texas City reaches, and median percentage bank erosion 

at the Marchand reach was higher than that at the Hitchcock 

and Texas City reaches. Surficial streambed substrate was 

dominated by silt or clay at all reaches (table 9). Clay was the 

dominant bed material at the Marchand Bayou reach, and silt 

was dominant at the other four reaches. Instream cover was 

low (quartile values 0–10 percent) at all reaches and generally 

higher at the upstream reaches, which were characterized by 

more woody debris, emergent and submergent vegetation, and 

other instream structure.

Differences in the physical characteristics of the Highland and Marchand Bayou reaches are largely the result 

of the differences in channel gradient and position in the 

drainage network or watershed of each reach. The relatively 

high-gradient upstream reaches (Hitchcock and Marchand), 

characterized by narrower channels, steeper banks, and greater 

bank erosion than the downstream Bayou Dr and Texas City 

reaches are relatively more riverine; the relatively low-gradient 

downstream reaches, characterized by wider channels, more 

gently sloping banks, and smaller bank erosion, are relatively 

more estuarine. 

Riparian/Bank Vegetation

Tree canopy over a stream channel can moderate or lower 

water temperature and reduce primary productivity (Platts 

and others, 1987). At the Marchand reach, tree canopy was 

greater than 50 percent; at all other reaches, it was less than 20 

percent (fig. 4, table 9). The large difference between Marchand and the other reaches likely is primarily related to the 

relatively narrow Marchand Bayou channel width. No riparian trees were observed adjacent to the five transects at either 

the Bayou Dr or Texas City reaches. The median percentage 

of riparian trees was significantly different only between the 

Hitchcock and Bayou Dr reaches. The median percentage 

of riparian trees was 10 and 15 percent at the Hitchcock and 

Marchand reaches, respectively.

Riparian vegetation at the more downstream Fairwood, 

Bayou Dr, and Texas City reaches was dominated by lesswoody and more-herbaceous shrubs, and grasses and forbs, 

than at the more upstream Hitchcock and Marchand reaches. 

Grasses and forbs accounted for 35 and 93 percent of riparian vegetation at the Bayou Dr and Texas City reaches, 

respectively. The median percentage of grasses and forbs was 

significantly different only between the Marchand and Texas 

City reaches (fig. 4). 

The width and composition of the natural buffer of riparian vegetation adjacent to a stream channel can influence the 

rate, volume, and quality of runoff that reaches the channel 

during a rain event. Carbon in the form of throughfall such as 

leaves and small, particulate organics, and overhanging and 

in-channel vegetation can influence stream temperature and 

provide habitat for aquatic biota (Wente, 2000). The median 

width of the natural buffer of riparian vegetation varied from 

3.4 meters at the Texas City reach to 91.4 meters at the Bayou 

Dr reach (table 9). The width of the vegetation buffer was 

variable among all reaches, particularly the more upstream 

Hitchcock, Marchand, and Fairwood reaches, and the median 

was significantly different only between the Bayou Dr and 

Texas City reaches (fig. 4). The variability in buffer width 

appeared to be more related to the extent of anthropogenic 

development in the riparian zone rather than to natural changes 

in the riparian buffer.

Four additional transects per reach were sampled for habitat variables at multisample reaches Hitchcock, Fairwood, and 

Bayou Dr, the same reaches where additional benthic macroinvertebrate and fish samples were collected. Habitat variable 

medians were computed for sample sizes of seven and nine 

transects per reach, in addition to the standard five transects 

per reach (table 10). Medians changed for the majority of 

habitat variables with the addition of two and four transects, 

although none of the differences in medians were statistically 

significant based on results of Kruskal-Wallis tests. The variables most affected by a change in transect sample size were 

those associated with riparian vegetation. The medians of 

percentages of trees, shrubs, and grasses and forbs for each 

of the three reaches varied considerably with transect sample 

size.
Stream-Habitat Data 17

Figure 4. Stream-habitat variables by reach for Highland and Marchand Bayous, Galveston County, Texas, summer 2007. 

 

HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY

HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY

HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY

STREAM WIDTH, IN METERS

800

600

400

200

100

80

60

40

10

8

6

STREAM DEPTH, IN METERS

4

3.5

3

2.5

2

1.5

1

0.5

0

BANK SLOPE, IN DEGREES

100

90

80

70

60

50

40

30

20

10

0

BANK EROSION, IN PERCENT

60

50

40

30

20

10

0

INSTREAM COVER, IN PERCENT

16

14

12

10

8

6

4

2

0

20

Insufficient data

EXPLANATION

Maximum

Minimum

25th percentile

75th percentile

Median

Medians of variables for reaches with same letter

above box are not significantly different at the .05 level

(10) Number of samples

(5) (5) (5) (5) (5)

(5) (5) (5) (5) (5)

(10) (10) (10) (10) (10) (10) (10) (10) (10) (10)

(50) (50) (50) (50) (50)

ab a b abc c c a ab a c b

a ab ab ab b

ab b a b a a b ab a
18 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Figure 4.—Continued. 

HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY

HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY

HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY HITCHCOCK MARCHAND FAIRWOOD BAYOU DR TEXAS CITY

TREE CANOPY, IN PERCENT

100

80

60

40

20

0

RIPARIAN TREES, IN PERCENT

90

80

70

60

50

40

30

20

10

0

RIPARIAN SHRUBS, IN PERCENT

100

90

80

70

60

50

40

30

20

10

0

RIPARIAN GRASS AND FORBS, IN PERCENT

100

80

60

40

20

0

WIDTH OF NATURAL VEGETATION BUFFER, IN METERS100

90

80

70

60

50

40

30

20

10

0

EXPLANATION

Maximum

Minimum

25th percentile

75th percentile

Median

Medians of variables for reaches with same letter

above box are not significantly different at the .05 level

ab b a a a a ab b ab ab

ab ab ab b a

ab a b a a ab b a ab ab

(10) Number of samples

(10) (10) (10) (10) (10)

(10) (10) (10) (10) (10) (10) (10) (10) (10) (10)

(5) (5) (5) (5) (5)

(5) (5) (5) (5) (5)
Stream-Habitat Data 19

Table 9. Summary statistics for stream-habitat variables from reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 2007.[M, median (50 percent); 25, lower quartile (25 percent); 75, upper quartile (75 percent); dominant substrate category (1, clay; 2, silt; 8, other); --, insufficient data]

Reach 

short 

name

(table 1)

Reach length 

(meters)

Quartile

Stream 

width

(meters)

Stream 

depth

(meters)

Bank

slope

(degrees)

Bank 

erosion

(percent)

Dominant 

substrate 

category

Instream 

cover

(percent)

Tree 

canopy

(percent)

Riparian 

trees

(percent)

Riparian 

shrubs

(percent)

Riparian 

grasses 

and forbs

(percent)

Width of 

vegetation

buffer

(meters)

Habitat 

quality 

index

(HQI)

Hitchcock 490 M 13.7 1.19 17 10 2 10 10 10 40 25 32.8 19

25 12.5 .78 15 5.0 2 10 10 5.0 0 10 0

75 15.2 1.52 20 10 2 10 10 20 60 95 91.4

Marchand 220 M 9.1 .79 54 25 1 5.0 97 15 0 30 53.3 15

25 8.2 .58 30 20 1 5.0 65 0 0 20 62.9

75 9.3 1.02 72 40 1 10 100 20 30 50 91.4

Fairwood 470 M 25.3 2.22 48 10 2 5.0 0 2.5 15 78 16.0 15

25 25.3 1.52 35 5.0 2 5.0 0 0 0 0 1.5

75 25.3 2.87 63 30 2 10 0 10 25 100 91.4

Bayou Dr 540 M 105.5 1.19 5.0 -- 2 0 0 0 65 35 91.4 19

25 73.8 .79 5.0 -- 2 0 0 0 40 20 91.4

75 118.9 1.49 5.0 -- 8 0 0 0 80 60 91.4

Texas City 640 M 354.2 .87 10 10 2 0 0 0 7.5 93 3.4 15

25 280.4 .72 5.0 0 2 0 0 0 5.0 90 0

75 523.3 .93 12 10 8 0 0 0 10 95 9.1
20 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas Table 10. Medians for stream-habitat variables based on different transect sample sizes at multisample reaches on Highland Bayou, Galveston County, Texas, summer 2007. [Variable medians for number of transects (sample size n = 5, 7, 9) per reach; mean ranks associated with sample sizes of 5, 7, and 9 were not significantly different at the .05 level; dominant substrate category (2, silt, 5, cobble, 8, other); --, insufficient data] Reach short name (table 1) Sample size Stream width (meters) Stream depth (meters) Bank slope (degrees) Bank erosion (percent) Dominant substrate category Instream cover (percent) Tree canopy (percent) Riparian trees (percent) Riparian shrubs (percent) Riparian grasses and forbs (percent) Width of vegetation buffer (meters) Habitat quality index (HQI) Hitchcock 5 13.7 1.19 17 10 2 10 10 40 25 25 32.8 19

7 13.7 1.18 15 10 2 10 10 10 50 20 107.5 199 13.7 1.22 17 10 2 10 10 10 50 20 37.5 19

Fairwood 5 25.3 2.22 48 5.0 2 5.0 0 2.5 15 78 16.0 15

7 25.3 2.23 50 18 2 10 0 5.0 23 60 12.5 159 25.3 1.87 41 18 2 10 0 5.0 23 60 12.5 15

Bayou Dr 5 105.5 1.19 5.0 -- 8 0 0 0 35 35 91.4 19

7 105.5 1.24 5.0 -- 2 0 0 0 70 25 300.0 199 105.5 1.01 5.0 -- 5 0 0 0 60 40 300.0 19
Summary 21

Habitat Quality Index

The HQI is a dimensionless measure of stream-habitat 

quality that is based on scoring values for bank and instream 

habitat variables between 1 and 3 and summing the individual 

values to yield an HQI score for the reach (Texas Commission 

on Environmental Quality, 2007). The HQI scores are grouped 

into four quality categories: limited, intermediate, high, and 

exceptional based on ranges of scores assigned by TCEQ to 

each category.

All HQI values for the five reaches (table 9) scored in the 

intermediate category (scores ranging from 14 through 19). 

The Hitchcock and Bayou Dr reaches scored 19, and the other 

three reaches each scored 15. The higher HQI values for the 

Hitchcock and Bayou Dr reaches resulted from larger scores 

for bank stability and riparian vegetation that can be attributed 

to little or no anthropogenic development along these reaches.

In addition to habitat-variable medians, HQIs were 

computed for sample sizes of seven and nine transects per 

reach for Hitchcock, Fairwood, and Bayou Dr, as well as the 

standard five transects per reach (table 10). The addition of 

two and four transects did not change the HQI score for any of 

the reaches.

Summary

The tidal zones of rivers and streams are unique environments where freshwater rivers transition into brackish estuarine ecosystems. Many of the conditions that threaten tidally 

influenced ecosystems such as sedimentation, habitat alteration, and altered freshwater inflow patterns are not strictly 

water-quality issues. Biological communities are effective 

assessment tools to help identify probable causes of impairment. However, biological communities in tidal zones generally display a high degree of natural variation, and changes 

in tidal-zone biological communities associated with anthropogenic effects can be difficult to detect against background 

variation. Developing suitable criteria for describing anthropogenic changes in tidal streams requires a clear understanding 

of the natural variation associated with sampling in different 

locations, at different times of the year, and with different 

methods or levels of intensity (level of intensity generally 

refers to number of samples). Accordingly, the U.S. Geological Survey (USGS), in cooperation with the Houston-Galveston Area Council and the Galveston Bay Estuary Program 

under the authority of the Texas Commission on Environmental Quality (the agency responsible for setting environmental 

standards for the State of Texas), did a study in 2007 to assess 

the variation in biotic assemblages (benthic macroinvertebrate 

and fish communities) and stream-habitat data with sampling 

strategy and method in tidal segments of Highland Bayou and 

Marchand Bayou in Galveston County. 

Highland and Marchand Bayous flow east-southeastward 

to the Texas Coast and drain an approximately 100-squarekilometer area. Marchand Bayou is a smaller, shallower 

tributary that joins Highland Bayou near its mid-point. Benthic 

macroinvertebrate, fish, and stream-habitat data were collected 

from four stream sites (reaches) (short names Hitchcock, 

Fairwood, Bayou Dr, and Texas City) distributed down the 

length of Highland Bayou and from one reach (short name 

Marchand) in Marchand Bayou. All five stream reaches were 

sampled once in spring and once in summer 2007. Additional 

samples were collected at the Hitchcock, Fairwood, and 

Bayou Dr reaches during summer 2007 to evaluate variation 

resulting from sampling intensity and location. Only streamhabitat data from summer 2007 samples were used for this 

report because the summer 2007 habitat dataset was the most 

complete.

A 22.9- by 22.9-centimeter (9- by 9-inch) Ekman dredge 

on a pole was used to sample benthic macroinvertebrates at 

all reaches. One standard sample following TCEQ protocols 

was collected from each study reach in spring 2007 and one in 

summer 2007. Two additional samples were collected in summer 2007 at Hitchcock, Fairwood, and Bayou Dr for evaluation of variation in benthic macroinvertebrate communities 

associated with sampling location. 

Two sampling methods, electrofishing and seining, were 

used to collect fish-community data. All reaches that were 

electrofished (Hitchcock, Marchand, Fairwood) were sampled 

following TCEQ protocols regarding shocking time to obtain 

standard samples, one in spring 2007 and one in summer 

2007. Additional electrofishing was done in summer 2007 at 

the Hitchcock and Fairwood reaches to assess variation associated with increased sampling intensity. All reaches that were 

seined (Marchand, Fairwood, Bayou Dr, Texas City) were 

done following TCEQ protocols regarding number of seine 

hauls to obtain standard samples, one in spring 2007 and one 

in summer 2007. Additional seining was done at Fairwood 

and Bayou Dr to assess variation associated with increased 

sampling intensity.

Measurements of stream-habitat variables were recorded 

along five uniformly spaced transects perpendicular to the 

channel at all reaches, which generally follows TCEQ protocols for the Highland Bayou (non-wadeable) reaches and 

follows TCEQ protocols for the Marchand (wadeable) reach. 

Stream-habitat data collection at the Hitchcock, Fairwood, 

and Bayou Dr reaches included four additional transects, 

distributed between the five standard transects, to evaluate 

the potential for changes in computed habitat quality with 

additional data. 

Changes in benthic macroinvertebrate and fish-community structure between seasons, within-reach locations, 

and sampling intensity were analyzed with a multivariate 

ordination technique (multidimensional scaling [MDS]) and 

univariate diversity metrics. Nonparametric summary statistics (medians and 25th and 75th percentiles) were used 

to describe differences in stream-habitat variables among 

reaches. Kruskal-Wallis multiple comparison tests were used 

to compare medians of stream-habitat variables among reaches 

to indicate significant differences. 
22 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

The separation between spring and summer standard 

samples in the MDS plot of the combined genus level benthic 

macroinvertebrate data indicates that there are taxonomic differences between the spring and summer samples. Seasonal 

differences in benthic macroinvertebrate communities primarily were related to decreases in the abundance of chironomids 

and polychaetes in summer samples. Although the spring and 

summer datasets are dissimilar, both datasets indicate a gradient in the benthic macroinvertebrate community associated 

with reaches that is likely caused by increases in salinity with 

downstream distance toward Jones Bay. 

Multivariate Analysis of Similarities (ANOSIM) tests of 

additional summer 2007 benthic macroinvertebrate samples 

from Hitchcock, Fairwood, and Bayou Dr indicated significant taxonomic differences between the sampling locations at 

all three reaches. In general, the deepwater samples had the 

smallest numbers for benthic macroinvertebrate taxa richness 

and abundance. The nearshore samples had the largest numbers for all sites except Bayou Dr.

The grouping of standard samples in the MDS plot of 

species-level fish data indicates no consistent seasonal difference in fish taxa across reaches. Increased seining intensity 

at the multisample reaches (Hitchcock, Fairwood, and Bayou 

Dr) did not result in a statistically significant difference in fish 

communities. Increased seining resulted in some changes in 

taxa richness and community diversity metrics. The largest 

changes were at the Bayou Dr reach where an increase from 

six seine hauls to 12 seine hauls added an additional 8 taxa 

and increased taxa richness by 114 percent and Margalef’s 

richness by 111 percent.

Diversity increases associated with increased electrofishing intensity were relatively consistent across the two multisample electrofishing reaches (Hitchcock and Fairwood). Total 

taxa richness, Margalef’s richness, and Shannon’s diversity 

index for both reaches increased with an increase in electrofishing time from 15 minutes to 20 minutes.

The Marchand reach is the smallest in terms of length and 

stream width, and the Texas City reach is the largest. Median 

stream depth was relatively uniform among the five reaches. 

Median bank slope of the Marchand reach was several times 

larger than that of the Hitchcock, Bayou Dr, and Texas City 

reaches, and median percentage bank erosion at the Marchand reach was higher than that at the Hitchcock and Texas 

City reaches. Surficial streambed substrate was dominated 

by silt or clay at all reaches. Instream cover was low (quartile 

values 0–10 percent) at all reaches. Differences in the physical 

characteristics of the Highland and Marchand Bayou reaches 

are largely the result of the differences in channel gradient and 

position in the drainage network or watershed of each reach.

The large difference in tree canopy between Marchand 

(greater than 50 percent) and the other reaches (all less than 

20 percent) likely is primarily related to the relatively narrow Marchand Bayou channel width. No trees were observed 

on the bank adjacent to the five transects at either the Bayou 

Dr or Texas City reaches. Riparian vegetation at the more 

downstream Fairwood, Bayou Dr, and Texas City reaches was 

dominated by less-woody and more-herbaceous shrubs, and 

grasses and forbs, than at the more upstream Hitchcock and 

Marchand reaches. The width of the vegetation buffer was 

variable among all reaches, particularly the more upstream 

Hitchcock, Marchand, and Fairwood reaches. The variability 

in buffer width appeared to be more related to the extent of 

anthropogenic development in the riparian zone rather than to 

natural changes in the riparian buffer.

Four additional transects per reach were sampled for 

habitat variables at Hitchcock, Fairwood, and Bayou Dr. Medians changed for the majority of habitat variables with the addition of two and four transects to the standard five transects, 

although none of the differences in medians were statistically 

significant.

All habitat quality index (HQI) values for the five reaches 

scored in the intermediate category. In addition to habitatvariable medians, HQIs were computed for sample sizes of 

seven and nine transects per reach, as well as the standard five 

transects per reach. The addition of two and four transects did 

not change the HQI score for any of the reaches.

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Chesapeake Science, v. 17, p. 271–280.
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Houston Advanced Research Center, 2006, Valuing freshwater 

inflows initiative: accessed December 19, 2007, at http://

www.harc.edu/Projects/Nature/Projects/FreshwaterInflows

Larkin, T.J., and Bomar, G.W., 1983, Climatic atlas of Texas: 

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151 p. 

LaSalle, M.W., and Bishop, T.D., 1987, Seasonal abundance 

of aquatic diptera in two oligohaline tidal marshes in 

Mississippi: Estuaries, v. 10, p. 303–315.

Livingston, R.J., 1987, Field sampling in estuaries—The 

relationship of scale to variability: Estuaries, v. 10, 

p. 194–207.

McErlean, A.J., Kerby, C., and Swartz, R.C., 1972, Discussion of status of knowledge concerning sampling variation, physiologic tolerances, and possible change criteria 

for bay organisms: Chesapeake Science, v. 13 supplement, 

p. S42–S54.

Montagna, P.A., and Kalke, R.D., 1992, The effect of freshwater inflow on meiofaunal and macrofaunal populations in 

the Guadalupe and Nueces estuaries, Texas: Estuaries, v. 15, 

p. 307–326.

National Oceanic and Atmospheric Administration, 2007, 

National Climatic Data Center (NCDC) data available on 

the World Wide Web, accessed December 19, 2007, at 

http://cdo.ncdc.noaa.gov/qclcd/QCLCD

Odum, W.E., 1988, Comparative ecology of tidal freshwater 

and salt marshes: Annual Review of Ecology and Systematics, v. 19, p. 147–176. 

Platts, W.S., Armour, Carl, Booth, G.D., Bryant, Mason, Bufforsd, J.L., Cuplin, Paul, Jensen, Sherman, Lienkaemper, 

G.W., Minshall, G.W., Monsen, S.B., Nelson, R.L., Sedell, 

J.R., and Tuhy, J.S., 1987, Methods for evaluating riparian 

habitats with applications to management: Ogden, Utah, 

U.S. Forest Service, General Technical Report INT–221, 

177 p.

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(version 7): Tulsa, Okla., Statsoft, Inc.

Texas Commission on Environmental Quality, 2007, Surface 

water quality monitoring procedures—Volume 2. Methods 

for collecting and analyzing biological assemblage and 

habitat data: Texas Commission on Environmental Quality, 

Regulatory Guidance RG–416, 202 p.

Wente, S.P., 2000, Proximity-based measure of land use 

impacts to aquatic ecosystem integrity: Environmental Toxicology and Chemistry, v. 19, p. 1,148–1,152.

Zar, J.H., 1998, Biostatistical analysis (4th ed.): Upper Saddle 

River, N.J., Prentice Hall, 989 p. 
Blank Page
Appendixes 1–6 
Blank Page
Appendix 1 27

Appendix 1. Benthic macroinvertebrate taxa (number of individuals) in standard (mid-channel) and additional (deepwater and nearshore) samples, Highland and Marchand Bayous, Galveston County, Texas, spring and summer 2007.[SpS, spring standard sample; SuS, summer standard sample; SuDW, summar deepwater sample; SuNS, summar nearshore sample]

Taxon

Hitchcock Marchand Fairwood Bayou Dr Texas City

SpS SuS SuDW SuNS SpS SuS SpS SuS SuDW SuNS SpS SuS SuDW SuNS SpS SuS

Callibaetis sp. 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0

Caenis latipennis 0 0 0 0 0 60 0 0 0 0 0 0 0 0 0 0

Caenis sp. 1 0 0 0 13 0 0 0 0 0 0 0 0 0 0 0

Aphylla sp. 1 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0

Berosus sp. 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Coenagrionidae 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0

Corixidae 11 0 0 0 2 0 1 0 0 0 0 0 0 0 0 0

Ablabesmyia mallochi 0 0 0 0 10 0 0 0 1 0 0 0 0 0 0 0

Chironomini 4 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0

Chironomus sp. 503 5 0 40 125 0 263 0 0 0 599 0 0 0 23 0

Cladotanytarsus sp. 1 0 0 0 43 9 2 0 0 0 0 0 0 0 0 0

Cryptochironomus sp. 2 0 0 0 3 2 1 0 0 0 0 0 0 0 0 0

Cryptotendipes sp. 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Dicrotendipes modestus 28 0 0 0 41 0 0 0 0 0 0 0 0 0 0 0

Dicrotendipes lobus 0 0 0 0 0 0 0 0 0 6 0 0 0 0 0 0

Dicrotendipes lucifer 0 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0Dicrotendipes sp. 8 0 0 1 9 1 0 0 0 0 0 0 0 0 0 0Dicrotendipes tritomus 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Goeldichironomus sp. 0 0 0 28 8 0 0 0 1 2 0 0 0 0 0 0Parachironomus sp. 3 6 0 11 1 0 1 0 0 0 0 0 0 0 0 0Orthocladius Complex 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0Pentaneurini 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0

Phaenopsectra sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0Natarsia sp. 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Polypedilum halterale gr. 11 0 0 6 1 12 18 15 1 5 0 3 0 0 0 0Polypedilum scalaenum gr. 0 0 0 0 0 0 0 0 0 0 0 10 0 2 0 0

Polypedilum tritum 1 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0

Appendix 1
28 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas Appendix 1. Benthic macroinvertebrate taxa (number of individuals) in standard (mid-channel) and additional (deepwater and nearshore) samples, Highland and Marchand Bayous, Galveston County, Texas, spring and summer 2007—Continued. Taxon Hitchcock Marchand Fairwood Bayou Dr Texas City SpS SuS SuDW SuNS SpS SuS SpS SuS SuDW SuNS SpS SuS SuDW SuNS SpS SuS Tanypus sp. 44 0 0 2 26 2 34 1 0 0 295 3 19 20 181 9 Tanytarsus sp. 2 0 0 0 1 3 1 0 0 0 0 0 0 0 2 0 Bezzia/Palpomyia sp. 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 Ceratopogoninae 1 0 0 2 7 41 0 1 0 2 0 0 0 0 0 0 Chaoborus sp. 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Probezzia sp. 0 0 0 0 0 0 0 0 0 5 0 0 0 0 0 0 Gastropoda 0 0 0 0 0 0 0 0 0 0 0 5 0 0 0 0 Mulinia lateralis 0 0 0 0 20 2 54 12 0 10 4 0 2 3 1 0 Aulodrilus pigueti 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 Physa sp. 3 0 1 0 1 0 1 0 0 0 0 0 0 0 1 0 Bivalvia 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Mytilopsis leucophaeata 0 0 0 0 139 0 0 0 0 3 0 0 0 0 0 0 Capitella sp. 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 Dero borellii 0 0 0 1 0 4 0 0 0 0 0 0 0 0 0 0 Dero sp. 0 0 0 0 0 3 2 0 0 0 0 0 0 0 0 0 Enchytraeidae 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 Amphicteis florida 41 0 1 5 63 20 200 7 1 32 1 0 0 4 6 0 Limnodrilus cervix 0 0 0 13 0 0 0 0 0 0 0 0 0 0 0 0 Leitoscoloplos sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 25 0 Nereididae 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Naididae 2 0 0 0 3 5 1 0 0 0 0 0 0 0 0 0 Nais sp. 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 Polychaeta 0 0 0 0 0 6 12 0 0 0 0 0 0 0 16 0 Polydora cornuta 0 0 0 0 0 0 4 0 0 0 0 0 0 1 0 0 Spionidae 2 0 0 0 4 0 37 1 0 5 3 3 0 0 19 0 Spirosperma sp. 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Steninonereis martini 0 0 0 0 16 1 0 0 0 22 0 1 1 2 4 2
Appendix 1 29

Appendix 1. Benthic macroinvertebrate taxa (number of individuals) in standard (mid-channel) and additional (deepwater and nearshore) samples, Highland and Marchand Bayous, Galveston County, Texas, spring and summer 2007—Continued.

Taxon

Hitchcock Marchand Fairwood Bayou Dr Texas City

SpS SuS SuDW SuNS SpS SuS SpS SuS SuDW SuNS SpS SuS SuDW SuNS SpS SuS

Streblospio benedicti 26 0 0 0 49 6 236 33 0 79 50 2 1 1 106 1Tubificidae 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0

Tubificidae w/o cap setae 0 1 1 23 2 10 0 1 0 0 0 3 0 2 9 2

Tubificidae w/ cap setae 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Tubificoides heterochaetus 0 0 0 0 0 0 0 35 0 110 0 0 0 0 0 0

Oribatei 4 0 2 0 0 0 0 1 0 0 0 0 0 0 0 0

Ampelisca sp. 0 0 0 0 1 0 0 0 0 0 3 0 0 0 576 2

Amphipoda 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0Americamysis almyra 0 0 0 0 0 0 0 10 0 0 0 12 0 10 0 5Apocorophium louisianum 0 0 0 0 0 0 44 0 0 7 5 0 0 0 55 0Corophiidae 0 0 0 0 0 0 0 0 2 3 0 8 0 0 0 1Edotea montosa 0 0 0 0 0 0 1 0 0 0 3 0 0 0 2 0Edotea sp. 0 0 0 0 0 0 0 0 0 0 0 2 0 5 0 0Grandidierella bonnieroides 0 0 0 0 0 0 0 0 0 1 1 16 0 0 32 0Hyalella sp. 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0

Leptocheliidae 0 0 0 0 0 0 3 0 0 0 0 1 0 6 0 0Mysidae 0 0 0 0 0 1 0 0 0 0 0 0 0 2 0 2Penaeidae 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1Mucrogammarus mucronatus 0 0 0 0 0 0 4 0 0 0 2 0 0 0 0 0Ostracoda 0 0 1 1 2 0 0 0 0 1 0 0 0 0 1 0Taphromysis bowmani 0 3 0 1 0 1 0 0 0 2 0 0 0 0 0 0Foraminiferida 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0Nematoda 1 0 1 1 1 1 0 0 0 2 0 0 0 0 0 0

Nemertea 0 0 0 0 0 0 6 3 0 0 2 2 1 8 6 7

Total 703 16 7 140 598 201 928 123 7 298 968 73 24 66 1,069 33
30 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Appendix 2

Appendix 2. Fish taxa (number of individuals) collected in standard samples by electrofishing and seining, Highland and Marchand 

Bayous, Galveston County, Texas, spring and summer 2007.

[SpS, spring standard sample; SuS, summer standard sample]

Species

Hitchcock Marchand Fairwood Bayou Dr Texas City

SpS SuS1 SpS SuS SpS SuS2 SpS SuS3 SpS SuS

Euryhaline species

Menidia beryllina 17 0 41 3 3 9 79 179 8 138

Anchoa mitchilli 2 0 3 12 1 6 143 102 62 10

Lagodon rhomboides 0 0 0 1 5 13 2 7 40 27

Brevoortia sp. 484 719 285 0 24 19 922 267 48 0

Poecilia latipinna 2 1 0 4 6 193 0 2 0 0

Leiostomus xanthurus 67 0 38 0 182 0 110 6 123 1

Oligoplites saurus 0 0 0 0 0 0 0 1 0 2

Mugil cephalus 55 49 28 7 17 32 30 2 0 6

Fundulus grandis 0 0 0 0 0 0 0 1 1 0

Lucania parva 0 0 1 0 0 5 0 2 0 0

Fundulus pulvereus 0 0 0 0 0 12 0 1 0 0

Fundulus chrysotus 0 0 0 1 0 0 0 0 0 0

Gobiosoma robustum 0 0 0 0 0 0 0 1 0 0

Microgobius gulosus 0 0 0 0 0 6 0 0 0 0

Syngnathus louisianae 0 0 0 0 0 0 0 1 0 0

Paralichthys lethostigma 0 0 1 0 0 0 0 0 0 0

Sciaenops ocellatus 0 0 0 0 1 1 0 0 0 0

Pogonias cromis 0 0 0 0 0 0 0 0 1 0

Cyprinodon variegatus 1 0 0 0 4 28 0 0 1 0

Gambusia affinis 2 0 5 4 1 62 0 0 0 0

Leptocephalus larvae 0 0 0 0 0 0 0 0 1 0

Total euryhaline individuals 630 769 402 32 244 386 1,286 572 285 184

Freshwater species

Lepisosteus oculatus 3 5 1 0 0 0 0 0 0 0

Pomoxis annularis 0 1 0 0 0 0 0 0 0 0

Micropterus salmoides 3 13 0 7 0 3 0 0 0 0

Lepomis macrochirus 21 27 12 23 0 3 0 0 0 0

Lepomis cyanellus 2 1 0 1 0 0 0 0 0 0

Lepomis gulosus 4 11 1 1 0 0 0 0 0 0

Lepomis megalotis 2 4 14 24 0 0 0 0 0 0

Lepomis microlophus 1 2 0 0 0 0 0 0 0 0

Total freshwater individuals 36 64 28 56 0 6 0 0 0 190

Total Individuals 666 833 430 88 244 392 1,286 572 285 184

1

 Sample consists of first 20 minutes of electrofishing.

2

 Sample consists of first 20 minutes of electrofishing and first six seine hauls distributed across three within-reach locations.

3

 Sample consists of first 10 seine hauls distributed across three within-reach locations.
Appendix 3 31

Appendix 3

Appendix 3. Fish taxa (number of individuals) collected by electrofishing, Highland and Marchand Bayous, Galveston County, Texas, 

spring and summer 2007. 

Species

Hitchcock Marchand Fairwood

Spring

standard

Summer

(minutes of electrofishing) Spring

standard

Summerstandard

Spring

standard

Summer

(minutes of electrofishing)

15 5 5 5 15 5 5 5

Euryhaline species

Menidia beryllina 17 0 0 0 0 14 0 2 0 0 0 0

Anchoa mitchilli 2 0 0 0 0 0 0 1 0 0 0 0

Lagodon rhomboides 0 0 0 0 0 0 1 5 9 3 2 0

Brevoortia sp. 484 719 0 9 21 8 0 23 18 0 0 7

Poecilia latipinna 2 0 1 0 0 0 0 6 1 0 0 0

Leiostomus xanthurus 67 0 0 0 0 8 0 114 0 0 0 0

Oligoplites saurus 0 0 0 0 0 0 0 0 0 0 0 0

Mugil cephalus 55 23 26 8 6 28 7 17 22 5 11 4

Fundulus grandis 0 0 0 0 0 0 0 0 0 0 0 0

Lucania parva 0 0 0 0 0 1 0 0 0 0 0 0

Fundulus pulvereus 0 0 0 0 0 0 0 0 0 1 1 0

Fundulus chrysotus 0 0 0 0 0 0 0 0 0 0 0 0

Gobiosoma robustum 0 0 0 0 0 0 0 0 0 0 0 0

Microgobius gulosus 0 0 0 0 0 0 0 0 0 0 0 0

Syngnathus louisianae 0 0 0 0 0 0 0 0 0 0 0 0

Paralichthys lethostigma 0 0 0 0 0 1 0 0 0 0 0 0

Sciaenops ocellatus 0 0 0 0 0 0 0 1 0 1 0 0

Pogonias cromis 0 0 0 0 0 0 0 0 0 0 0 0

Cyprinodon variegatus 1 0 0 0 0 0 0 4 1 0 0 2

Gambusia affinis 2 0 0 0 0 5 1 1 0 0 0 0

Leptocephalus larvae 0 0 0 0 0 0 0 0 0 0 0 0

Total euryhaline individuals 630 742 27 17 27 65 9 244 51 10 14 13

Freshwater species

Lepisosteus oculatus 3 4 1 0 1 1 0 0 0 0 0 0

Pomoxis annularis 0 1 0 0 0 0 0 0 0 0 0 0

Micropterus salmoides 3 8 5 2 3 0 7 0 0 2 0 0

Lepomis macrochirus 21 21 6 8 7 11 19 0 1 2 0 0

Lepomis cyanellus 2 1 0 0 0 0 1 0 0 0 0 0

Lepomis gulosus 4 8 3 0 0 1 1 0 0 0 0 0

Lepomis megalotis 2 4 0 2 3 14 24 0 0 0 0 0

Lepomis microlophus 1 0 2 0 2 0 0 0 0 0 0 0

Total freshwater individuals 36 47 17 12 16 27 52 0 1 4 0 0

Total individuals 666 789 44 29 43 92 61 174 52 14 14 13
32 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Appendix 4 Appendix 4. Fish taxa (number of individuals) collected by seining, Highland and Marchand Bayous, Galveston County, Texas, spring and summer 2007. Species Marchand Fairwood Spring standard1 (table 2) Summer standard1 (table 2) Spring standard1 (table 2) Summer Location 1 seine hauls Location 2 seine hauls Location 3 seine hauls

1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6

Euryhaline species

Menidia beryllina 27 3 1 2 2 0 2 12 10 0 3 15 8 20 16 2 0 4 1 1 3

Anchoa mitchilli 3 12 0 2 1 0 0 0 0 0 0 0 0 1 0 3 0 1 0 0 0

Lagodon rhomboides 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 1 0 0 1 0 0

Brevoortia sp. 277 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Poecilia latipinna 0 4 0 162 7 9 29 23 23 5 2 4 2 1 3 14 2 3 0 0 0

Leiostomus xanthurus 30 0 68 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Oligoplites saurus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mugil cephalus 0 0 0 0 3 1 1 0 0 0 0 0 0 0 0 1 1 0 0 0 0

Fundulus grandis 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0

Lucania parva 0 0 0 5 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Fundulus pulvereus 0 0 0 10 1 2 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0

Fundulus chrysotus 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Gobiosoma robustum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Microgobius gulosus 0 0 0 2 3 2 1 1 0 0 1 0 1 1 0 0 0 0 0 0 0

Syngnathus louisianae 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Paralichthys lethostigma 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Sciaenops ocellatus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Pogonias cromis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cyprinodon variegatus 0 0 0 6 20 10 5 11 17 1 0 0 0 0 1 0 0 0 0 0 0

Gambusia affinis 0 3 0 48 4 5 10 12 10 0 0 7 3 1 0 10 0 13 0 2 0

Leptocephalus larvae 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Freshwater species

Lepisosteus oculatus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Pomoxis annularis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Micropterus salmoides 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0

Lepomis macrochirus 1 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis cyanellus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis gulosus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis megalotis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis microlophus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Total individuals 338 27 70 237 42 30 48 61 63 6 6 26 14 25 20 31 4 21 2 3 3
Appendix 4 33

Appendix 4. Fish taxa (number of individuals) collected by seining, Highland and Marchand Bayous, Galveston County, Texas, spring and summer 2007—Continued.

Species

Bayou Dr Texas City

Spring

standard1

(table 2)

Summer Spring

standard1

(table 2)

Summer

standard1

(table 2)

Location 1 seine hauls Location 2 seine hauls Location 3 seine hauls

1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6

Euryhaline species

Menidia beryllina 79 32 62 17 5 11 3 0 10 11 14 39 21 5 3 34 62 60 3 8 138

Anchoa mitchilli 143 5 3 3 0 9 44 26 1 1 21 25 10 2 8 8 14 11 62 10

Lagodon rhomboides 2 0 2 0 1 2 1 2 1 1 1 0 0 0 0 0 1 0 0 40 27

Brevoortia sp. 922 0 1 0 0 4 0 0 0 0 0 0 0 0 138 128 20 0 168 48 0

Poecilia latipinna 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Leiostomus xanthurus 110 0 0 0 0 1 0 5 0 1 1 0 0 0 0 0 0 0 0 123 1

Oligoplites saurus 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 1 0 0 0 0 2

Mugil cephalus 30 0 0 0 0 2 2 0 0 2 0 0 2 0 0 0 0 2 1 0 6

Fundulus grandis 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0

Lucania parva 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0

Fundulus pulvereus 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0

Fundulus chrysotus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Gobiosoma robustum 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0

Microgobius gulosus 0 0 0 0 0 0 0 0 0 0 2 3 0 0 0 0 0 0 0 0 0

Syngnathus louisianae 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0

Paralichthys lethostigma 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Sciaenops ocellatus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Pogonias cromis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0

Cyprinodon variegatus 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 1 0

Gambusia affinis 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0

Leptocephalus larvae 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0

Freshwater species

Lepisosteus oculatus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Pomoxis annularis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Micropterus salmoides 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis macrochirus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis cyanellus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis gulosus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis megalotis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lepomis microlophus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Total Individuals 1,286 37 70 21 7 20 15 52 37 19 20 67 51 15 143 171 91 77 183 285 184

1 Standard samples not partitioned by seine hauls (Marchand) or by location and seine hauls (Fairwood, Bayou Dr, Texas City).
34 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Appendix 5 Appendix 5. Stream-habitat (transect) data collected from reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 2007. [--, not available] Habitat data Upstream Downstream Transect 1 Transect 1.5 Transect 2 Transect 2.5 Transect 3 Transect 3.5 Transect 4 Transect 4.5 Transect 5 Hitchcock

Stream type (RI=Riffle,Ru=Run,G=Glide,P=Pool)

G

G

G

G

G

G

G

G

G

Stream width (feet) 40 42 45 48 54 42 50 52 41

Left bank slope (degrees) 15 15 18 18 20 28 30 25 30

Left bank erosion (percent) 5 5 10 10 10 30 5 25 10

Left bank width of natural buffer vegetation (feet) 300 300 300 300 200 60 200 300 300

Right bank slope (degrees) 15 15 15 15 18 15 15 28 10

Right bank erosion (percent) 5 5 20 5 5 15 5 40 5

Right bank width of natural buffer vegetation (feet) 15 15 0 0 0 5 0 0 0

Tree canopy (percent) 10 10 18 10 1 32 10 15 10

Dominant substrate type (1=clay,2=silt,3=sand, 2 2 2 2 2 2 2 2 2

 4=gravel,5=cobble,6=boulder,7=bedrock,8=other)Stream depth at point 1 (feet, right edge water) 1.61 1.52 1.91 1.82 1.87 2.00 1.75 1.61 2.50

Stream depth at point 2 2.65 2.54 3.22 2.71 3.04 3.19 2.50 2.56 4.00

Stream depth at point 3 3.55 3.05 4.40 3.48 4.16 4.40 3.00 3.25 5.14

Stream depth at point 4 4.81 4.32 5.32 3.92 4.57 5.00 4.25 4.24 5.25

Stream depth at point 5 4.85 5.03 5.75 4.24 5.73 5.50 5.00 5.25 4.99

Stream depth at point 6 4.91 5.05 5.82 4.06 5.57 5.14 5.59 5.53 4.91

Stream depth at point 7 3.85 4.33 5.05 3.87 5.22 4.40 5.50 4.84 4.47

Stream depth at point 8 2.91 2.36 3.69 3.34 4.26 3.45 4.99 4.00 3.75

Stream depth at point 9 2.55 2.61 2.43 2.55 3.35 2.50 3.50 3.10 2.81

Stream depth at point 10 (feet, left edge water) 1.74 1.84 1.72 1.94 2.00 1.70 2.21 2.06 2.46

Substrate gravel or larger (percent) 0 0 0 0 0 0 0 0 0

Instream cover (percent) 10 10 10 10 10 10 10 10 5

Left bank trees (percent) 15 15 30 20 60 20 20 15 20

Left bank shrubs (percent) 80 80 50 60 30 70 60 80 50

Left bank grasses, forbs (percent) 0 0 20 20 10 10 20 5 30

Left bank cultivated fields (percent) 0 0 0 0 0 0 0 0 0

Left bank other (percent) 5 5 0 0 0 0 0 0 0

Right bank trees (percent) 5 5 5 5 5 0 0 0 0

Right bank shrubs (percent) 90 90 0 0 0 0 0 0 0

Right bank grasses, forbs (percent) 0 0 95 95 95 100 100 100 100

Right bank cultivated fields (percent) 0 0 0 0 0 0 0 0 0

Right bank other (percent) 5 5 0 0 0 0 0 0 0

Instream cover types rootmass

limbs intochannel at left bank

rootmass rootmass rootmass

snag

overhang vegetationsnag

logsoverhang vegetation

light debrisrootmassoverhang vegetation

rootmasswoody debriscutbank

rootmassbulkhead piling

>
Appendix 5 35

Appendix 5. Stream-habitat (transect) data collected from reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 2007—Continued.

Habitat data

Upstream Downstream

Transect 1 Transect 2 Transect 3 Transect 4 Transect 5

Marchand

Stream Type (RI=Riffle,Ru=Run,G=Glide,P=Pool) G G G G GStream width (feet) 24 27 30.5 33 30Left bank slope (degrees) 80 40 62 15 72Left bank erosion (percent) 50 15 30 10 25Left bank width of natural buffer vegetation (feet) 25 30 5 50 5Right bank slope (degrees) 72 45 30 87 19Right bank erosion (percent) 20 40 40 25 25Right bank width of natural buffer vegetation (feet) 300 300 300 300 300Tree canopy (percent) 65 54 100 100 97Dominant substrate type (1=clay,2=silt,3=sand, 1 1 1 2 1 4=gravel,5=cobble,6=boulder,7=bedrock,8=other)Stream depth at point 1 (feet, right edge water) 4.25 4.78 0.70 0.65 1.69Stream depth at point 2 4.66 4.23 1.60 1.13 2.42Stream depth at point 3 4.15 4.00 1.88 2.05 3.17Stream depth at point 4 4.78 3.45 2.25 1.75 3.28Stream depth at point 5 3.97 3.10 2.39 2.50 3.22Stream depth at point 6 3.76 2.60 2.50 2.60 3.43Stream depth at point 7 3.34 1.82 2.79 2.68 3.53Stream depth at point 8 2.96 1.75 2.64 2.78 3.13Stream depth at point 9 2.60 1.63 2.35 2.15 2.93Stream depth at point 10 (feet, left edge water) 2.35 1.00 1.90 1.59 2.53Substrate gravel or larger (percent) 0 0 5 5 10

Instream cover (percent) 25 0 15 5 10Left bank trees (percent) 80 10 40 0 0Left bank shrubs (percent) 0 0 0 30 0Left bank grasses, forbs (percent) 20 30 60 0 30Left bank cultivated fields (percent) 0 0 0 0 0Left bank other (percent) 0 60 0 70 70Right bank trees (percent) 20 0 20 20 0Right bank shrubs (percent) 0 0 60 60 0Right bank grasses, forbs (percent) 80 50 20 20 30Right bank cultivated fields (percent) 0 0 0 0 0Right bank other (percent) 0 50 0 0 70Instream cover types submerge

woody debris

cutbanklight debris

overhang vegetationlight woody debris cutbank

light woody overhang vegetation

cutbank

>
36 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas Appendix 5. Stream-habitat (transect) data collected from reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 2007—Continued. Habitat data Upstream Downstream Transect 1 Transect 1.5 Transect 2 Transect 2.5 Transect 3 Transect 3.5 Transect 4 Transect 4.5 Transect 5 Fairwood Stream Type (RI=Riffle,Ru=Run,G=Glide,P=Pool)

G

G

G

G

G

G

G

G

G

Stream width (feet) 83 85 83 88 83 79 83 92 83

Left bank slope (degrees) 72 25 16 52 63 52 43 20 35

Left bank erosion (percent) 40 10 5 50 40 70 30 10 10

Left bank width of natural buffer vegetation (feet) 70 1 2 15 0 2 5 0 70

Right bank slope (degrees) 57 48 68 55 20 10 52 28 40

Right bank erosion (percent) 25 50 10 30 5 10 10 60 5

Right bank width of natural buffer vegetation (feet) 300 1 6 10 35 60 300 50 300

Tree canopy (percent) 0 0 0 0 0 0 0 0 0

Dominant substrate type (1=clay,2=silt,3=sand, 2 2 2 2 2 2 2 2 2

 4=gravel,5=cobble,6=boulder,7=bedrock,8=other)Stream depth at point 1 (feet, right edge water) 3.13 2.00 2.72 2.90 1.75 6.00 2.00 2.55 1.50

Stream depth at point 2 4.81 3.60 6.21 4.65 3.50 8.11 5.02 4.36 4.00

Stream depth at point 3 5.73 6.10 8.27 9.50 5.00 8.86 7.10 5.75 5.01

Stream depth at point 4 8.44 8.00 8.81 10.81 8.39 9.06 8.65 6.99 7.52

Stream depth at point 5 10.10 9.91 10.25 9.91 9.63 8.85 10.00 7.57 11.50

Stream depth at point 6 11.41 10.96 9.88 8.87 9.41 7.49 11.50 8.35 1.10

Stream depth at point 7 11.71 10.11 8.75 7.00 8.70 7.12 11.10 10.00 9.44

Stream depth at point 8 10.99 6.64 7.00 5.41 7.49 6.50 9.84 7.50 8.12

Stream depth at point 9 8.96 2.50 4.38 4.00 6.56 5.00 7.00 3.86 6.50

Stream depth at point 10 (feet, left edge water) 5.81 1.95 2.63 1.73 5.00 2.00 5.46 2.26 5.00

Substrate gravel or larger (percent) 0 0 0 0 5 0 5 0 5

Instream cover (percent) 10 10 5 10 10 10 5 10 5

Left bank trees (percent) 5 15 0 20 0 20 0 15 10

Left bank shrubs (percent) 25 80 0 60 0 70 0 80 25

Left bank grasses, forbs (percent) 0 0 100 20 100 10 100 5 0

Left bank cultivated fields (percent) 0 0 0 0 0 0 0 0 0

Left bank other (percent) 70 5 0 0 0 0 0 0 65

Right bank trees (percent) 20 5 0 5 0 0 5 0 10

Right bank shrubs (percent) 50 90 0 0 50 0 10 0 20

Right bank grasses, forbs (percent) 0 0 100 95 50 100 85 100 70

Right bank cultivated fields (percent) 0 0 0 0 0 0 0 0 0

Right bank other (percent) 30 5 0 0 0 0 20 0 0

Instream cover types light debris

riprap

rootmass riprap

grass

rootmasssnag

overhangbrushgrass

logs overhang vegetation

light woodydebris cutbank

rootmass woody debris cutbank

light brush

>
Appendix 5 37

Appendix 5. Stream-habitat (transect) data collected from reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 2007—Continued.

Habitat data

Upstream Downstream

Transect 1 Transect 1.5 Transect 2 Transect 2.5 Transect 3 Transect 3.5 Transect 4 Transect 4.5 Transect 5

Bayou Dr

Stream Type (RI=Riffle,Ru=Run,G=Glide,P=Pool) G G G G G G G G G

Stream width (feet) 207 -- 415 -- 242 -- 346 -- 390

Left bank slope (degrees) 5 40 5 5 5 50 5 5 56

Left bank erosion (percent) -- -- -- -- -- -- -- -- --

Left bank width of natural buffer vegetation (feet) 300 300 300 300 300 300 300 300 115

Right bank slope (degrees) 5 5 5 5 5 75 5 5 5

Right bank erosion (percent) -- -- -- -- -- -- -- -- --

Right bank width of natural buffer vegetation (feet) 300 300 300 300 300 300 300 300 300

Tree canopy (percent) 0 0 0 0 0 0 0 0 0

Dominant substrate type (1=clay,2=silt,3=sand, 2 2 2 2 8 2 8 2 8

 4=gravel,5=cobble,6=boulder,7=bedrock,8=other)Stream depth at point 1 (feet, right edge water) 2.06 1.75 4.50 1.30 1.75 2.45 1.91 1.40 1.50

Stream depth at point 2 2.61 2.35 5.52 2.55 2.60 3.55 2.78 1.85 2.60

Stream depth at point 3 3.11 3.65 6.24 3.85 4.11 4.79 4.01 2.50 3.05

Stream depth at point 4 3.71 5.25 6.45 5.01 4.90 4.91 4.75 2.55 3.00

Stream depth at point 5 5.00 5.86 4.75 5.82 5.24 5.19 5.10 3.80 3.86

Stream depth at point 6 6.50 6.00 2.55 4.46 5.55 4.75 5.16 4.00 4.25

Stream depth at point 7 6.80 6.12 1.75 2.50 4.85 4.11 4.81 4.52 4.55

Stream depth at point 8 6.00 5.39 1.99 1.79 4.30 2.85 4.25 4.43 4.22

Stream depth at point 9 5.50 3.75 2.11 1.61 3.26 2.66 3.80 3.60 3.75

Stream depth at point 10 (feet, left edge water) 3.25 1.80 1.80 1.45 2.20 1.75 2.15 2.29 2.25

Substrate gravel or larger (percent) 10 0 10 0 0 0 0 0 0

Instream cover (percent) 5 0 0 0 0 0 0 0 0

Left bank trees (percent) 0 0 0 10 0 25 0 0 0

Left bank shrubs (percent) 30 70 80 70 70 25 20 60 85

Left bank grasses, forbs (percent) 70 30 20 20 30 20 80 40 15

Left bank cultivated fields (percent) 0 0 0 0 0 0 0 0 0

Left bank other (percent) 0 0 0 0 0 30 0 0 0

Right bank trees (percent) 2 0 0 0 0 0 0 0 0

Right bank shrubs (percent) 90 80 80 80 60 60 40 60 50

Right bank grasses, forbs (percent) 8 20 20 20 40 40 60 40 50

Right bank cultivated fields (percent) 0 0 0 0 0 0 0 0 0

Right bank other (percent) 0 0 0 0 0 0 0 0 0

Instream cover types macrophyte macrophyte macrophyte macrophyte macrophyte macrophyte macrophyte macrophyte macrophyte

>
38 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas Appendix 5. Stream-habitat (transect) data collected from reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 2007—Continued. Habitat data Upstream Downstream Transect 1 Transect 2 Transect 3 Transect 4 Transect 5 Texas City Stream Type (RI=Riffle,Ru=Run,G=Glide,P=Pool)

G

G

G

G

G

Stream width (feet) 2,005 1,717 1,162 920 621Left bank slope (degrees) 10 10 5 12 5

Left bank erosion (percent) 0 10 10 25 10

Left bank width of natural buffer vegetation (feet) 0 30 115 15 12

Right bank slope (degrees) 5 20 3 30 10

Right bank erosion (percent) 50 0 0 10 5

Right bank width of natural buffer vegetation (feet) 300 10 0 5 0

Tree canopy (percent) 0 0 0 0 0

Dominant substrate type (1=clay,2=silt,3=sand, 1 8 2 8 2

 4=gravel,5=cobble,6=boulder,7=bedrock,8=other)Stream depth at point 1 (feet, right edge water) 1.90 2.00 1.85 1.75 1.70

Stream depth at point 2 2.41 2.71 2.31 3.00 1.90

Stream depth at point 3 2.85 2.76 2.50 4.62 2.06

Stream depth at point 4 2.81 3.28 2.68 5.63 2.10

Stream depth at point 5 2.90 3.00 3.00 5.48 1.94

Stream depth at point 6 2.89 3.11 2.81 3.41 4.10

Stream depth at point 7 2.77 3.16 2.74 3.37 7.00

Stream depth at point 8 2.96 3.18 2.99 3.29 6.60

Stream depth at point 9 2.94 3.44 2.80 2.80 4.75

Stream depth at point 10 (feet, left edge water) 2.00 3.25 2.87 2.05 3.75

Substrate gravel or larger (percent) 0 0 0 0 0Instream cover (percent) 0 0 0 0 0

Left bank trees (percent) 0 0 0 0 0

Left bank shrubs (percent) 10 5 10 10 10

Left bank grasses, forbs (percent) 90 95 90 90 90

Left bank cultivated fields (percent) 0 0 0 0 0

Left bank other (percent) 0 0 0 0 0

Right bank trees (percent) 0 10 0 0 0Right bank shrubs (percent) 5 20 5 5 5

Right bank grasses, forbs (percent) 95 70 95 95 95

Right bank cultivated fields (percent) 0 0 0 0 0

Right bank other (percent) 0 0 0 0 0

Instream cover types mud crushed brick mud bulkhead mud riprap mud mud

>
Appendix 6 39

Appendix 6

Appendix 6. Habitat quality index data calculated for reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 

2007. 

[n, sample size] 

Metric Value Score (n=5) Score (n=7) Score (n=9)

Hitchcock

Instream cover 9 percent 1 1 1

Riffles 0 1 1 1

Pools 0 1 1 1

Bank stability

 Slope component stable 3 3 3

 Erosion component moderately stable 2 2 2

Ripariean buffer vegetation extensive 3 3 3

Channel flow status high 3 3 3

Channel sinuosity high 3 3 3

Bottom substrate unstable 1 1 1

Aesthetics common 1 1 1

Aquatic life use score1 19 19 19

1

 Statewide scoring criteria:

 Exceptional 26–31

 High 20–25

 Intermediate 14–19

 Limited <14

Metric Value Score (n=5)

Marchand

Instream cover 11 percent 2

Riffles 0 1

Pools 0 1

Bank stability

 Slope component moderately unstable 1

 Erosion component moderately stable 2

Ripariean buffer vegetation extensive 3

Channel flow status moderate 2

Channel sinuosity low 1

Bottom substrate unstable 1

Aesthetics common 1

Aquatic life use score1 15

1

 Statewide scoring criteria:

 Exceptional 26–31

 High 20–25

 Intermediate 14–19

 Limited <14
40 Variation in Biotic Assemblages and Stream-Habitat Data, Highland and Marchand Bayous, Galveston County, Texas

Appendix 6. Habitat quality index data calculated for reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 

2007—Continued. 

Metric Value Score (n=5) Score (n=7) Score (n=9)

Fairwood

Instream cover 8 percent 1 1 1

Riffles 0 1 1 1

Pools 0 1 1 1

Bank stability

 Slope component moderately unstable 1 1 1

 Erosion component moderately stable 2 2 2

Ripariean buffer vegetation extensive 3 3 3

Channel flow status high 3 3 3

Channel sinuosity low 1 1 1

Bottom substrate unstable 1 1 1

Aesthetics common 1 1 1

Aquatic life use score1 15 15 15

1

 Statewide scoring criteria:

 Exceptional 26–31

 High 20–25

 Intermediate 14–19

 Limited <14

Metric Value Score (n=5) Score (n=7) Score (n=9)

Bayou Dr

Instream cover 1 percent 1 1 1

Riffles 0 1 1 1

Pools 0 1 1 1

Bank stability

 Slope component stable 3 3 3

 Erosion component stable 3 3 3

Ripariean buffer vegetation extensive 3 3 3

Channel flow status high 3 3 3

Channel sinuosity moderate 2 2 2

Bottom substrate unstable 1 1 1

Aesthetics common 1 1 1

Aquatic life use score1 19 19 19

1

 Statewide scoring criteria:

 Exceptional 26–31

 High 20–25

 Intermediate 14–19

 Limited <14
Appendix 6 41

Appendix 6. Habitat quality index data calculated for reaches on Highland and Marchand Bayous, Galveston County, Texas, summer 

2007—Continued. 

Metric Value Score (n=5)

Texas City

Instream cover 0 percent 1

Riffles 0 1

Pools 0 1

Bank stability

 Slope component stable 3

 Erosion component moderately stable 2

Ripariean buffer vegetation wide 2

Channel flow status high 3

Channel sinuosity none 0

Bottom substrate unstable 1

Aesthetics common 1

Aquatic life use score1 15

1

 Statewide scoring criteria:

 Exceptional 26–31

 High 20–25

 Intermediate 14–19

 Limited <14

Publishing support provided by

Lafayette Publishing Service Center

Information regarding water resources in Texas is available at 

http://tx.usgs.gov/