I 

Estuar~ Program 

Tampa Bay National Estuary Program 

Technical Publication #03-93 

PHYSICAL IMPACTS TO 

HABITATS IN TAMPA BAY 

FINAL REPORT 

MAY 1994 
92-444-03 

PHYSICAL IMPACTS 

TO 

HABITATS 

IN TAMPA BAY 

Prepared for: 

Tampa Bay National Estuary Program 

111 7th A venue South 

St. Petersburg, FL 33701 

Prepared by: 

Coastal Environmental, Inc. 

9721 Executive Center Drive North 

Suite 104 

St. Petersburg, FL 33702 

May 1994 

Printed on Recycled Paper 

#03-93 
TABLE OF CONTENTS 

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii 

EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv 

1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

1.1 BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

1.2 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

2. METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

2.·1 STUDY AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

2.2 HABITAT ......................................... 3 

2.2.1 Salinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

2.2.2 Bathymetry .................................. 10 

2.2.3 Sediment Texture .............................. 10 

2.2.4 Seagrass .................. _ .................. 12 

2.3 PHYSICAL IMPACTS ................................. 12 

2.4 SEAGRASS BED PROP SCAR INTENSITY ................... 14 

3. RESULTS ............................................... 16 

3.1 BENTHIC HABITAT CLASSIFICATION ...................... 16 

3.2 PHYSICAL IMPACTS ................................. 35 

3.2.1 Filled Areas .................................. 35 

3.2.2 Channels and Dredge Spoil Areas ................... 66 

3.2.3 Modified Shoreline ............................. 82 
3.2.4 Prop Scar and Boat Traffic Surveys . . . . . . . . . . . . . . . . 102 

3.2.5 Commercial Fisheries . . . . . . . . . . . . . . . . . . . . . . . . . 110 

3.2.6 Water Quality and Sediment Quality Impacts . . . . . . . . . 113 

3.3 DATA GAPS ..................................... 125 

4. DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 

5. LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 

6. DATA SOURCES FOR GIS COVERAGES . . . . . . . . . . . . . . . . . . . . . . . . 134 

ii 
ACKNOWLEDGMENTS 

This report was authored by David Wade and Anthony Janicki of Coastal 

Environmental, Inc. The authors gratefully acknowledge all of those whose 

assistance contributed to the completion of this project. Technical review and 

recommendation were provided by the members of the Tampa Bay National 

Estuary Program (TBNEP) staff and the members of the Living Resources 

Subcommittee of the TBNEP Technical Advisory Committee, in particular, Roger 

Johansson (City of Tampa), Tom Cuba (Pinellas County Department of 

Environmental Management), Robin Lewis (Lewis Environmental Services), Jim 

Culter (Mote Marine Laboratory), and David Tomasko (Sarasota Bay National 

Estuary Program). The aerial surveys were conducted by a group of volunteers 

which included Richard Eckenrod, Missy Eckenrod, Holly Greening, and Gerold 

Morrison. Technical assistance was provided by John Ascosi, Neeta Mehrotra, and 

Andrew Squires of Coastal Environmental, Inc. Principle data sources and 

documentation were provided by the following agencies and staff: Tom Ries, Leah 

Polomchak, Lela Clark, and Steve Dicks of the Southwest Florida Water 

Management District; Ken Haddad, Gail MacAuly, Frank Sargent of the Florida 

Department of Natural Resources; Ron Schmied, Rosalie Shaffer, John Witzig, and 

Lt. Lee Cohen of the National Oceanographic and Atmospheric Administration; Ken 

Hartley of the TBNEP Citizens Advisory Committee; and James Cassedy of the 

National Archives. This is Technical Publication # 03-93 of the Tampa Bay 

National Estuary Program. 

iii 
EXECUTIVE SUMMARY 

The objective of this project was to identify, quantify, and map the physical impacts to the 

habitats of the Tampa Bay estuary. Many human activities have reduced or degraded a 

variety of bay habitats. The activities causing physical impacts include dredging of 

navigational channels, marinas and port facilities; dredge spoil disposal; filling of bay 

bottom for urban development; and the construction of seawalls and finger canals. As in 

other shallow estuaries that are heavily used by both commercial and recreational boaters, 

habitat damage due to prop scarring has occurred. 

The Tampa Bay National Estuary Program (TBNEP) is defining management targets for the 

restoration, protection and enhancement of bottom habitat, and the physical impacts 

mapped in this project are a key component of the target setting process. The physically 

impacted areas were related to current and historical resource distributions using a 

geographic information system (GIS), and areas which were deemed nonrestorable or 

potentially restorable have been identified. 

About 50% of the existing shoreline is ~odified. In some areas, such as Boca Ciega Bay, 

as much as 73% of the shoreline is modified. Besides the direct loss of habitat due to 

shoreline modification, indirect effects may also be important. Much of the original 

benefits of the non-hardened shoreline such as shoreline stabilization, reduction of 

suspended solids loads, and diverse estuarine habitats have been lost. 

Much of the original mangrove shorelines and shallow seagrass beds of Tampa Bay have 

been filled for residential and commercial development. Over 13,000 acres have been 

filled since the early 1900's, and nearly all (91 %) of these filled areas are in the shallow 

shelf portion of the Bay~ With the exception of the causeways and several fill islands, the 

majority of these filled areas (approximately 1 2,000 acres) have occurred in shallow 

waters which formerly supported seagrass beds. An estimate of approximately half of 

these filled areas exist adjacent to areas which continue to support seagrass today. 

Navigational channels for commercial shipping activities were constructed primarily in the 

naturally deeper areas of the bay. Of the estimated 14,381 acres of channel and spoil 

areas, 87% have been constructed· in the deep portions of the study area where it is likely 

that seagrasses never occurred. The principal channels extend along a naturally occurring 

trough extending from the bay mouth to both Old Tampa and Hillsborough bays. 

An aerial survey was conducted to estimate the levels of prop scar damage in various 

areas of the bay. The results from this survey, conducted in early March 1992 indicate 

that the greatest degree of prop scar damage exists in Mullet Key and the Fort DeSoto 

Park area, Bishop Harbor, Weedon Island, and the northeastern portion of Old Tampa Bay 

near Double Branch and Rocky creeks. No estimate of the prop scar damage within 

Cockroach Bay was made. Approximately 35% of the total seagrass area in Tampa Bay 

falls within the heavy damage and moderately heavy damage categories. More than 40% 

of the seagrass areas were estimated to fall within the areas categorized as having sparse 

or no scar damage. 

iv 
1. INTRODUCTION 

1.1 BACKGROUND 

This report quantifies and maps the physical impacts which have occurred within the 

Tampa Bay Estuary. Many anthropogenic activities have reduced or degraded a 

variety of habitats in estuarine ecosystems such as Tampa Bay. Land use alterations, 

discharge of domestic and industrial wastes, and agricultural runoff are some of the 

activities that have received a great deal of attention recently. Other activities have 

a more direct effect on habitat extent and quality. Notably, these activities include 

dredging and associated fill operations and shoreline modification. In Tampa Bay, as 

in other shallow estuaries that are heavily used by both commercial and recreational 

boaters, damage due to prop scarring can also significantly impact bottom habitats. 

As urban development continues, the need for continued maintenance of existing 

channels and, in some cases the need for new channels, also continues. Maintenance 

dredging and dredge spoil disposal repeatedly impact bottom habitat in and around the 

channel. While the direct impacts of these activities are readily apparent, secondary 

impacts can also be significant. For example, altered circulation patterns, increased 

turbidity, and release of potentially toxic materials, can all be significant secondary 

impacts due to dredge and spoils operations. 

Shoreline modification due to increased urbanization typically involves disruption of 

the shallow and intertidal habitats, including areas covered by submerged vegetation. 

There is also typically a loss of such intertidal habitats as marshes and mangroves 

associated· with shoreline modification. Increased shoreline erosion can be one 

significant secondary impact due to shoreline modification. 

The physical and biological impacts of dredging, spoil disposal, and shoreline 

modification have been the subject of earlier studies in Tampa Bay. Goodwin (1984) 

conducted an in-depth investigation of the impacts of dredge and fill operations on 

tidal flow, circulation, and flushing in Tampa Bay. He estimated that the surface area 

of Tampa Bay has been reduced by 3.6% due to dredge and fill activities. These 

losses were due to causeway construction, residential and commercial development, 

and port development. In addition to the direct loss of habitat, impacts caused by 

physical alterations to Tampa Bay include a decreased tidal prism and increased 

volume and depth in Hillsborough Bay, large changes in net circulation in both 

Hillsborough Bay and Old Tampa Bay, and increased landward and seaward exchange 

caused by tidal flushing. As pointed out by Lewis and Estevez (1988), changes in 

circulation and flushing can have severe impacts, especially in areas such as 

Hillsborough Bay where discharges of municipal and domestic wastes are 

concentrated. 

1 
Lewis (1977) examined the effects of dredging in Tampa Bay during the period of 

1876 through 1976. He estimated that 44% of the marsh and mangrove habitat have 

been lost due to filling and excavation. He also hypothesized that much of the loss 

of sea grasses in Tampa Bay has resulted from direct excavation, burial, and decreased 

water clarity caused by physical alterations of Tampa Bay. 

Fehring (1985) reported on the history of port development in Tampa Bay. He 

followed the changes due to dredging and spoil disposal since 1879 and provides a 

map showing the areas dredged or filled for port development over the past 100 

years. Tiffany and Wilkinson (1989) also reported port development in Tampa Bay. 

They also discussed the potential environmental problems associated with port 

development and operation. 

1.2 OBJECTIVES 

The Tampa Bay National Estuary Program (TBNEP) will be developing a 

Comprehensive Conservation and Management Plan (CCMP) in which plans for the 

restoration, protection, and enhancement of critical living resources will be 

recommended. The Living Resources Subcommittee of the TBNEP Technical Advisory 

Committee held two workshops in the Fall of 1992 to identify a list of living resources 

to be targeted by this effort. In October of 1992, the TBNEP Management Committee 

agreed upon the following targeted living resources: 

• Seagrass (bay) and submerged aquatic vegetation (tributaries); 

• Salt marshes; 

• Mangroves; 

• Non-seagrass subtidal and intertidal benthic habitats; 

• Pelagic. 

Living resource restoration and protection targets will be established using data on the 

current and historical distributions of these resources, as well as the extent of 

permanently altered areas within Tampa Bay. 

The objective of this project was to develop a GIS data base on these physically 

altered areas. Mapping the extent of physical impacts in the Bay will provide a key 

input to the development of living resource targets in a subsequent TBNEP project. 

These impacts will be related to the current and historical resource distributions using 

geographic information system (GIS) analyses. From these analyses, areas which are 

deemed nonrestorable or potentially restorable will be identified. 

2 
2. METHODS 

The general approach to this project was to delineate the specific targeted living 

resources of Tampa Bay related to benthic habitats, and to compute baseline 

estimates of the anthropogenic physical impacts which have occurred within these 

areas. The specific data needs of the Tampa Bay National Estuary Program {TBNEP) 

guided the methods to be used for this study. In particular, this project provided GIS 

data layers of benthic characteristics, bathymetry, seagrass distribution, and 

physically altered habitats. The following text describes the methods used to classify 

these habitat characteristics and delineate the physical impacts to the bay. 

2.1 STUDY AREA 

The area of interest for this project is presented in Figure 1 . For scientific and 

management purposes, Tampa Bay can be divided into seven geographic segments 

(Figure 2). These segments are based on those developed by Lewis and Whitman 

(1985), and vary in terms of surface water hydrology, salinity regime, habitat 

distribution, living resources, and patterns of anthropogenic impacts. 

2.2 HABITAT 

A classification scheme was developed to classify benthic habitats into several groups 

based on mapped characteristics of Tampa Bay. Since fine grain (muddy) sediments 

may be associated with accumulation of contaminants and are particularly susceptible 

to resuspension, sediment grain size was added to the classification scheme. Each 

individual habitat characteristic was mapped at a segment-wide scale using the same 

map projection, distance units, and horizontal datum. Classification was based on 

depth (deep vs. shallow), sediment texture (fine vs. coarse), and the presence or 

absence of seagrass. Bottom salinity regimes were observed to follow the seven bay 

segment delineations shown in Figure 2. Therefore, bay segment was included as a 

component of the benthic habitat classification scheme. The habitat classification 

layers were then combined using GIS techniques. 

3 
28 

27°45' 

STUDY AREA LOCATION 

Tampa Bay National Estuary Program, Physical Impacts Study 

82°45' 82°30' 

GULF OF 

MEXICO 

8r45' 82°30' 

Inset Scale 1:800,000 

Projection UTM 

Datum NAD 27 

FLORIDA 

28 

27°45' 

Map Prepared by Coastal Environmental, Inc. 

Figure 1 . Map of study area location. 

4 
Scale 1:350,000 

Projection UfM 

Datum NAD 27 0 

TAMPA BAY SEGMENTS 

Based on Lewis and Whitman, 1985 

miles Manatee River 

5 

Map Prepared by Coastal Environmental, Inc. 

Figure 2. Tampa Bay segments. 

5 
An ongoing project is being conducted by the TBNEP to identify and map the 

distribution of submerged aquatic vegetation (SAV) within the estuarine portions of 

the tributaries to Tampa Bay. Hence, the results of the SA V study were not included 

in this physical impacts report. Preliminary results of a literature and common 

knowledge survey conducted for the SAV study indicate that the distribution of SAV 

within Tampa Bay tributaries is very limited. 

Consideration was also given to inclusion of live bottom habitat within the benthic 

habitat classification scheme. These habitats support a diverse community of 

organisms such as sea fans, sea whips, hydroids, sponges, and corals, and they are 

usually associated with hard substrates. A general pattern of distribution of this 

habitat within the Bay is presented by Derrenbacker and Lewis (1982). Discussions 

with the TBNEP and its advisors in the Fall of 1991 resulted in the exclusion of this 

habitat from the present classification scheme. This was an attempt to avoid 

disclosure of more specific locations ofthis very sensitive habitat. The TBNEP, based 

on input from its Technical Advisory Committee in March of 1992 has since funded 

a separate task to map these areas under another project. The location of live bottom 

habitat will be included in the draft CCMP. 

The methods used to delineate each component of the habitat classification scheme 

are discussed in the following text. 

2.2.1 Salinity 

Bottom salinity was delineated as the first component of the habitat classification 

scheme. The Environmental Protection Commission of Hillsborough County and the 

Pinellas County Department of Environmental Management record monthly salinity 

data at a network of fixed stations within the bay and its watershed (EPCHC 1991, 

PCDEM 1991 ). Hillsborough County bottom salinity data from 55 bay stations (1986 

to 1990), and Pinellas County bottom salinity data from 11 bay stations ( 1990-1991) 

were used for this analysis. 

The distribution of bottom salinity was computed for each station. These data 

indicate that the 7 bay segments (Figure 2) provide a suitable framework for 

classifying salinity regimes for this analysis. An interpolated pattern for the fifth 

percentile, median, and ninety-fifth percentile of bottom salinity for the Bay is 

presented in Figures 3a, 3b, and 3c. Tide and wind actions cause Tampa Bay to be 

a well mixed estuary, and differences in salinity between surface and bottom waters 

is minimal in most areas (Goodwin, 1987). However, since this study examines 

primarily benthic habitat, bottom salinities were used exclusively. 

6 
Scale 1:350,000 

Projection Ul'M 

Datum NAD 1:1 

BOTTOM SALINITY 5th. PERCENTILE 

Baywide Distribution 

ST. PmRSBURG 

Salinity 5th. Pctl. (ppt): 

0 <= 22 

ill <= 24 

8 <- 26 

1m <- 28 

• <= 30 

II > 30 

• EPC of HC Station 

"' PC DEM Station 

M&p Prepared by Coastal Enviroomental, Inc. 

Figure 3a. Interpolated distribution of the 5th percentile of bottom salinity. 

7 
Scale 1:350,000 

Projection U1M 

Datum NAD 27 0 

MEDIAN BOTTOM SALINITY 

Baywide Distribution 

ST. PETERSBURG 

miles 

5 

Median Salinity (ppt): 

D <= 26 

0 <= 28 

D <= 30 

D <= 32 

~ <= 34 

Ill <= 36 

• EPC of HC Station 

"' PC DEM Station 

Map Prepared by Coastal Environmental, Inc. 

Figure 3b. Interpolated distribution of median bottom salinity. 

8 
Scale 1:350,000 

Projection UIM 

Datum NAD 27 

BOTTOM SALINITY 95th. PERCENTILE 

Baywide Distribution 

ST. PmRSBURG 

Salinity 95th Pctl. (ppt): 

0 <= 28 

0J <= 30 

El <- 32 

m <- 34 

• <= 36 

II > 36 

• EPC of HC Station 

• PC DEM Station 

Map Prepared by Coastal Envirorunental, Inc. 

Figure 3c. Interpolated distribution of the ninety-fifth percentile of bottom salinity. 

9 
2.2.2 Bathymetry 

A bathymetric model was developed as the next component of the habitat 

classification scheme. Mean lower low water depth was interpolated from point 

soundings and an existing shoreline data set of the Bay. 

A data set of digital hydrographic soundings was obtained from the National 

Oceanographic and Atmospheric Administration for 357,130 points within the Tampa 

Bay vicinity (NOAA, 1993). These mean low water data were recorded in a 

comprehensive survey during 1947 to 1958, and were corrected for tide or water 

level, vessel draft, and sound velocity. A subset of these data are represented as 

soundings and bathymetry contours on the current NOAA navigational charts (NOAA 

1991 ). The vertical datum for these data was the Gulf Coast low water datum, and 

the horizontal datum was the NAD 1927 datum. 

The digital shoreline GIS data for the bay was obtained from the 1990 seagrass 

survey conducted by the Southwest Florida Water Management District (SWFWMD, 

1990). This shoreline is the official shoreline for the TBNEP. These data were photointerpreted from 1 :24,000 scale color photographs made in December of 1990. 

,Using Triangular Irregular Network (TIN) interpolation software (Arc Info, 1993), the 

point soundings and the shoreline delineation were used to interpolate a bathymetric 

model of the Bay at a horizontal resolution of 25 meters and a vertical resolution of 

0.5 meters. This model was carefully visually compared to the bathymetric contours 

presented on the 1991 navigational charts (NOAA 1991). An area east of and 

adjacent to Cat's Point in Boca Ciega Bay was updated with the 1991 information. 

A summary of the completed bathymetric model is presented in Figure 4. 

Two depth classes were selected from the bathymetric model. These classes were 

shallow areas less than or equal to 2 meters, and deep areas greater than 2 meters. 

This depth break point was chosen because seagrasses typically occur at depths less 

than 2 meters in Tampa Bay (Lewis et al., 1985). 

2.2.3 Sediment Texture 

Bottom sediment texture classes were delineated as the next component of the 

habitat classification scheme. Bay bottom sediment texture data were digitized from 

values reported in a literature review conducted by Doyle and others 

10 
Scale 1:350,000 

Projection U1M 

Datum NAD 27 

TAMPA BAY BATHYMETRY 

Data Source: NOAA, Digital Hydrographic Data 

ST. PETERSBURG 

miles 

0 5 

Depth (meters mlw): 

0 <= lm 

0 <=2m 

lilll <=3m 

m <= 4m 

Fill <= 5m 

1111 <= 10m 

• >10m 

• Nav Channel 

Map Prepared by Coastal Environmental, Inc. 

Map Not Intended for Navigational Use 

Figure 4. Tampa Bay bathymetry. Data Sources: NOAA Soundings, SWFWMD 

1990 Shoreline. 

1 1 
(Doyle et al., 1989). These data included relatively recent observations, and 

observations from an extensive survey conducted in the 1960's (Taylor et al., 1969). 

The station locations for these data are presented in Figure 5. A GIS data layer was 

developed by interpolating these data and by considering local depth conditions. 

Bottom texture data mapped by a recent survey conducted by the City of Tampa 

{Johansson and Squires, 1989) were used as the data source for Hillsborough Bay 

because of its greater spatial resolution and overall level of precision. 

Two sediment texture classes were selected from the interpolated data. These 

classes were coarse grained areas with less than 50 percent of sediment smaller than 

63pm grain size, and fine grained areas with more than 50 percent of sediment 

smaller than 63pm grain size. The grain size break was selected in order to classify 

fine grain {muddy) sediments in a manner consistent with the methods of the 

Johansson and Squires {1989) data set. Such fine grain sediments may be associated 

with accumulation of contaminants and are particularly susceptible to resuspension. 

2.2.4 Seagrass 

Existing seagrass meadow distribution data were compiled as the final component of 

the habitat classification scheme. The data were obtained in a GIS format from the 

1990 Seagrass Survey conducted by the Southwest Florida Water Management 

District {SWFWMD, 1990). These data were photo-interpreted from 1:24,000 scale 

color photographs made in December 1990. Two categories of seagrass coverage 

{continuous and patchy) were combined into a single seagrass presence coverage. 

2.3 PHYSICAL IMPACTS 

Physical impact data sets for channels, spoil and borrow areas, filled areas, modified 

shorelines, and sea grass bed prop scar intensity were developed for this project. Each 

physical impact type was compiled into a GIS data set in order to quantify the extent 

of impacted habitat and to provide data sets of physically altered habitat for the future 

setting of living resource protection and restoration goals. 

12 
Sediment Grain Size Data Sources 

Tampa Bay National Estuary Program, Physical Impacts Study 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 0 

miles 

5 

Figure 5. Distribution of sediment sampling sites. 

13 

Map Prepared by Coastal Environmental, Inc. 
Existing navigational channels, designated dredge spoil areas, and borrow areas were 

delineated from 1991 NOAA 1:40,000 scale navigational charts. A set of historical 

maps including USGS 1:24,000 quadrangles (1950 and present) and NOAA 

navigational charts were obtained from the National Archives in Washington, D.C. and 

examined. The navigational charts covered the following years and scales: 

• 1877 

• 1926 

• 1928 

• 1930 

• 1950 

• 1951 

• 1961 

• 1970 

1:40,000 scale {southern Tampa Bay only); 

1:40,000 scale (southern Tampa Bay only); 

1 :40,000 scale; 

1 :80,000 scale; 

1 :40,000 scale; 

1:80,000 scale; 

1 :80,000 scale; 

1:80,000 scale . 

Information from these sources was used to interpret and delineate areas of Tampa 

Bay which have been filled and shorelines which have been modified. The historical 

materials were arranged in chronological order, and the patterns of development and 

physical impacts to bay habitat classes through the decades were examined. The 

impacted areas were then delineated on the shoreline from the SFWFMD 1 990 

seagrass survey. This shoreline, as stated previously, is the official shoreline specified 

for use on all TBNEP projects. 

The physical impacts GIS data layers were overlaid on the benthic habitat 

classification scheme. The results of this procedure were mapped and tabulated on 

a baywide and bay segment basis. The impacts due to the construction of major 

shipping channels were developed using the methods described above. The more 

local impacts of seawalls, smaller channels, and boat basins were assessed by 

examining the relationship between percentage of seagrass coverage and distance 

from modified and unmodified shorelines. To accomplish this analysis, the mapped 

benthic data was used to compute percentages of seagrass coverage for areas 

between 0 to 100, 100 to 200, 200 to 300, and 400 to 500 meters of modified and 

unmodified shorelines. 

2.4 SEAGRASS BED PROP SCAR INTENSITY 

At the time of initiation of this study, data concerning the intensity of prop scar 

damage to seagrass beds in Tampa Bay were primarily anecdotal and limited in their 

geographic extent. To fill this data gap, aerial surveys were conducted by the TBNEP 

to provide estimates of the relative degree of prop scar damage in areas throughout 

14 
the bay. A synoptic survey was conducted on March 6, 1992 from a fixed wing 

aircraft flying at a height of 500 feet over water and 1000 feet over land. These low 

altitudes and relatively clear water conditions on this day enabled ari accurate 

qualitative assessment of the intensity of seagrass prop scars. 

The areas with different amounts of prop scar damage were digitized and overlaid on 

the SWFWMD 1990 seagrass coverage. Values of prop scar intensity were then 

assigned to each seagrass area delineated by SWFWMD, and the extent of scar 

damage was quantified. 

A lack of boat traffic data was a second data gap. Two aerial surveys were 

conducted by the TBNEP to estimate the relative intensity of boat traffic in different 

portions of the bay. The two surveys were conducted on Saturday, May 9 and 

Sunday, May 10 of 1992 from a fixed wing aircraft flying at an altitude of 500 feet 

over water and 1000 feet over land. The surveys were conducted between 1100 and 

1300 hours at slack before ebb tide. These times were expected to have high levels 

of recreational boating activity in seagrass bed areas. During each flight around the 

periphery of the bay, two observers counted recreational boats in the seagrass bed 

areas, and a single observer counted recreational boats in the mid bay area. Boat 

positions were recorded to within approximately 0.25 miles of true position. Boats 

at port in marinas and boat basins were not counted. 

The boat traffic data were digitized and overlaid with the prop scar intensity data to 

examine the relationship of relative boating intensity to scar intensity. The results of 

these analyses are summarized in this report. 

15 
3.0 RESULTS 

3.1 BENTHIC HABITAT CLASSIFICATION 

A scheme was developed to classify and delineate selected benthic habitats of Tampa 

Bay. Classification was based on depth (deep vs. shallow), sediment texture (fine vs. 

coarse), the presence or absence of seagrass, and salinity regime (seven bay 

segments). Maps and tabulated results are presented for each habitat class. 

Approximately 240,000 acres of benthic habitats are distributed within Tampa Bay, 

and Figure 6 presents the results of the classification of this habitat. Table 1 presents 

a tabulation of the areal extent of each habitat class. 

The general pattern of distribution of habitat classes is comprised of a relatively deep, 

high energy, central basin of coarse grained sediments with localized areas of fine 

grained sediments adjacent to the freshwater inputs of the Hillsborough Bay 

(Johansson and Squires, 1989) and Old Tampa Bay drainage basins. Several large 

areas of fine grain sediments in the deeper portions of Middle Tampa Bay are 

presented in Figure 6. These areas resulted from the interpolation of several groups 

of fine grained samples (Figure 5) reported by Doyle and colleagues (Doyle et al, 

1989). It is likely that the actual extent of fine grain sediments within these areas is 

far less, and according to Brooks and Doyle (1991) may exist in localized bathymetric 

depressions. Figure 5 indicates that the sampling transect for which these fine 

grained samples were observed may have coincided with the East to West orientation 

of the deep areas containing the Cut G and Gadsden Point Cut channels (Figure 4). 

The general pattern of distribution of benthic habitat classes for the shallow periphery 

of the Bay is comprised of a shelf of varying width surrounding the deeper basin. 

Sea grasses once covered most of this shelf. Table 1 indicates that approximately 400 

acres of seagrass were located in areas classified as deeper than 2 meters. This 

estimate represents the sum of many smaller areas in the lower portion of Tampa and 

Boca Ciega Bays where sea grasses exist in the vicinity of the 2 meter depth contour. 

Given the resolution of these data and the shifting nature of the sediments in this 

area, the precision of the estimates in these extreme areas is likely to be relatively 

low. 

The distribution of seagrasses has declined throughout the bay. Figures 7 and 8 

present the change in seagrass coverage from the 1950's to present, and they were 

prepared as part of an ongoing TBNEP project to set goals for the restoration and 

protection of seagrass meadows in Tampa Bay. The overall decline in seagrass 

coverage is particularly evident in the northern areas of the bay (e.g. Old Tampa and 

Hillsborough bays). Recent reviews of the seagrass loss trend are presented in Lewis 

et al (1991) and Haddad (1989). 

16 
Figures 9 through 14 present more detailed views of the benthic habitat classes for 

each bay segment, and corresponding tabulated results are presented by acres and 

percent coverage in Tables 2 through 15. The least detailed of these data are the 

sediment data in areas other than Hillsborough Bay. Some of the mapped areas of 

fine sediments were the result of a relatively small number of fine grained point 

samples which influenced the interpolation of data in the adjacent areas. The depth 

data are relatively more detailed, but localized inaccuracies may result due to the 

shifting nature of the sediments and recent anthropogenic activities. The most 

detailed and most recent of the habitat class data are the seagrass data from the 

SWFWMD 1990 photo-interpretation. 

A bay-wide qualitative survey of the benthic macroinvertebrates occurring in Tampa 

Bay was conducted in the 1960's, and the results of this survey were compiled by 

Hall and Saloman (1975). The collection methods for this survey included two 

qualitative sampling devices (1 meter dredge and shovels) which were used in 

conjunction with a 0. 701 mm mesh sieve to collect and separate the organisms from 

the sediment. Several of the more predominant species encountered during this effort 

are presented in Figures 15 through 30. The presence or absence of each species is 

labeled for the location of each sample. 

Many surveys of benthos have been conducted in various locations throughout Tampa 

Bay, and some such as Taylor (1971) were synoptic in nature. The Hall and Saloman 

survey, however, represents a single source, intensive sampling effort, conducted on 

a baywide scale. The sampling effort of this survey was focused primarily on soft 

bottom habitats, and hence, organisms associated with oyster bars, mangroves, and 

live bottom areas are not emphasized. The geographic presence or absence of species 

presented by these results indicates the broad scale distribution of organisms which 

existed following the occurrence of major physical impacts to the bay in the years 

prior to the 1960's. An ongoing synoptic survey will be completed by the TBNEP in 

1994, and the results will provide more current bay-wide benthic information. 

The typical patterns of estuarine macroinvertebrate distribution can be seen in these 

plots. The distributions range from that of the relatively persistent polychaete worm 

Paraprionospio pinnata which occurs in most of the habitats of the bay (Figure 22) to 

those of the opportunists such as the polychaete worms Streblospio benedicti and 

Capitella capitata (Leverone et al., 1991) which occur primarily in disturbed areas such 

as Boca Ciega and Hillsborough bays. 

Other taxonomic groups, such as Ophiophragmus echinoderm species, and the 

cephalochordate Branchiostoma caribaeum appear to be distributed along gradients 

of environmental conditions such as salinity, depth, and water quality (Figures 29 and 

30). In addition to being indicators of habitat conditions, many of these organisms 

can create localized benthic habitats such as the bar-forming oyster Crassostrea 

virginica or the tube-constructing worm Diopatrea cuprea (Killam et al, 1992) (see 

Figures 15 and 24). 

17 
Table 1. Number of acres within each habitat class in Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine Coarse Fine Coarse 

Shallow 116 24,295 1,079 56,431 

Deep 17 394 14,848 142,519 

18 
0 

GULF OF 

MEXICO 

miles 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

5 

TAMPA BAY BENTHIC HABITAT 

ST. PETERSBURG 

Habitat Classes: 

- Coarse Grained 

Fine Grained 

• Seagrass Meadow 

Map Prepared by Coastal Environmental, Inc. 

Figure 6. Tampa Bay benthic habitat classification. Data sources: NOAA; 

SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

19 
Scale 1:350,000 

Projection U1M 

Datum NAD 27 

1950 SEAGRASS DISTRIBUTION 

ST. PETERSBURG 

Study Boundary: ---

• Seagrass Present 

lilll Seagrass Absent. Deep 

D Seagrass Absent. Shallow 

miles 

~= 

0 2 

Map Prepared by Coastll Environmental, Inc. 

Figure 7. Tampa Bay ca 1950 seagrass distribution. Data source: FDNR/USFWS. 

20 
Scale 1:350,000 

Projection UTM 

Datum NAD 27 

1990 SEAGRASS DISTRIBUTION 

ST. PETERSBURG 

Study Boundary: ---

• Seagrass Present 

!ill Seagrass Absent. Deep 

0 Seagrass Absent. Shallow 

miles 

-= 

0 2 

Map Prepared by Coastal Environmental, Inc. 

Figure 8. Tampa Bay 1990 sea grass distribution. Data sources: SWFWMD, NOAA. 

21 
Table 2. Number of acres within each habitat class in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

36 

I 

5A69 

I 

32 

I 

15,585 

I Deep 0 51 1,258 29,903 

Table 3. Percentage of acres within each habitat class in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0.1 

I 

10.5 

I 

0.1 

I 

29.8 

I Deep 0 0.1 2.4 57.1 

22 
BENTHIC HABITAT CLASSIFICATION 

Old Tampa Bay 

Habitat Classes: 

0 Shallow, Coarse Grained 

0 Shallow, Fine Grained 

Q Deep, Coarse Grained 

1!1 Deep, Fine Grained 

• Seagrass Meadow 

miles - Scale 1:150,000 

Projection UTM 

Datum NAD 27 

0 2 

Figure 9. 

Map Prepared by Coastll Environmentll, Inc. 

Old Tampa Bay benthic habitat classification. Data sources: NOAA; 

SWFWMD; Doyle et al, 1989. 

23 
Table 4. Number of acres within each habitat class in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

47 

I 

49 

I 

9,392 

I Deep 0 0 4,988 10,304 

Table 5. Percentage of acres within each habitat class in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

0.2 

I 

0.2 

I 

37.9 

I Deep 0 0 20.1 41.6 

24 
BENTHIC HABITAT CLASSIFICATION 

Hillsborough . Bay 

0 

Habitat Classes: 

miles 

Scale 1:110,000 

Projection UfM 

Datuni NAD 27 

0 Shallow, Coarse Grained 

lilll Shallow, Fine Grained 

[] Deep, Coarse Grained 

Ill Deep, Fine Grained 

• Seagrass Meadow 

2 

Map Prepared by Coastal Environmental, Inc. 

Figure 10. Hillsborough Bay benthic habitat classification. Data sources: NOAA; 

SWFWMD; Johansson and Squires, 1989. Note, Johansson and Squires 

assumed sediments in channels were fine grained and did not survey. 

Channels and spoil areas for 1990 presented in Figures 38 through 44. 

25 
Table 6. Number of acres within each habitat class in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

5,013 

I 

0 

I 

10,840 

I Deep 0 24 8,012 46,768 

Table 7. Percentage of acres within each habitat class in Middle Tampa Bay. 

Sea grass Present Seagrass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

7.1 

I 

0 

I 

15.3 

I Deep 0 <0.1 11.3 66.2 

26 
BENTHIC HABITAT CLASSIFICATION 

Middle Tampa Bay 

miles 

0 2 

Scale 1:155,000 

Projection UfM 

Datum NAD 27 

Habitat Classes: 

CJ Shallow, Coarse Grained 

[] Shallow, Fine Grained 

0 Deep, Coarse Grained 

llllll Deep, Fine Grained 

• Seagrass Meadow 

Map Prepared by Coastal Environmental, Inc. 

Figure 11. Middle Tampa Bay benthic habitat classification. Data sources: NOAA; 

SWFWMD; Doyle et al, 1989. Channels and spoil areas for 1990 

presented in Figures 38 through 44. 

27 
Table 8. Number of acres within each habitat class in Lower Tampa Bay. 

Sea grass Present Seagrass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

6,165 

I 

0 

I 

5,900 

I Deep 0 188 0 47,798 

Table 9. Percentage of acres within each habitat class in Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

10.3 

I 

0 

I 

9.8 

I Deep 0 0.3 0 79.6 

28 
Scale 1:145,000 

Projection UTM 

Datum NAD 27 

BENTHIC HABITAT CLASSIFICATION 

Lower Tampa Bay 

miles 

0 2 

Habitat Classes: 

0 Shallow, Coarse Grained 

lilll Shallow, Fine Grained 

00 Deep, Coarse Grained 

II Deep, Fine Grained 

• Seagrass Meadow 

Map Prepared by Coastal Environmental, Inc. 

Figure 12. Lower Tampa Bay benthic habitat classification. Data sources: NOAA; 

SWFWMD; Doyle et al, 1989. Channels and spoil areas for 1990 

presented in Figures 38 through 44. 

29 
Table 10. Number of acres within each habitat class in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

75 

I 

6,337 

I 

987 

I 

9,003 

I Deep 17 129 590 4,141 

Table 11. Percentage of acres within each habitat class in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0.4 

I 

29.8 

I 

4.6 

I 

42.3 

I Deep 0.1 0.6 2.8 19.5 

30 
Scale 1:165,000 

Projection UTM 

Datum NAD 27 

BENTHIC HABITAT CLASSIFICATION 

Boca Ciega Bay 

Habitat ClasseS: 

0 Shallow, Coarse Grained 

Q Shallow, Fine Grained 

[] Deep, Coarse Grained 

1111 Deep, Fine Grained 

• Seagrass Meadow 

miles 

0 2 

) 

Map Prepared by Coastal Environmental, Inc. 

Figure 13. Boca Ciega Bay benthic habitat classification. Data sources: NOAA; 

SWFWMD; Doyle et al, 1989. Channels and spoil areas for 1990 

presented in Figures 38 through 44. 

31 
Table 12. Number of acres within each habitat class in Terra Ceia Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

998 

I 

0 

I 

1,633 

I Deep 0 0 0 1,259 

Table 13. Percentage of acres within each habitat class in Terra Ceia Bay. 

Seagrass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

25.6 

I 

0 

I 

42.0 

I Deep 0 0 0 32.4 -· 

32 
Table 14. Number of acres within each habitat class in Manatee River. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

6 

I 

266 

I 

11 

I 

4,079 

I Deep 0 1 0 2,346 

Table 15. Percentage of acres within each habitat class in Manatee River. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine T Coarse 

Shallow 

I 

0.1 

I 

4 

I 

0.2 

I 

60.8 

Deep <0.1 0 I 0 35.0 

33 
Scale 1:135,000 

Projection UTM 

Datum NAD 27 

BENTHIC HABITAT CLASSIFICATION 

0 

Terra Ceia Bay/Manatee River 

miles 

2 

Habitat Classes: 

0 Shallow, Coarse Grained 

Q Shallow, Fine Grained 

m Deep, Coarse Grained 

!llll Deep, Fine Grained 

• Seagrass Meadow 

Map Prepared by Coastal Environmental, Inc. 

Figure 14. Terra Ceia Bay and Manatee River benthic habitat classification. Data 

sources: NOAA; SWFWMD; Doyle et al, 1989. Channels and spoil areas 

for 1990 presented in Figures 38 through 44. 

34 
3.2 PHYSICAL IMPACTS 

Physical impact data sets were developed for this project for channels, spoil and 

borrow areas, filled areas, modified shorelines, and seagrass bed prop scar intensity. 

Each physical impact was compiled into a GIS data set following the methods outlined 

earlier. The physical impacts GIS data layers were then overlaid on the benthic habitat 

classification scheme. The results of this procedure are mapped and tabulated on a 

baywide and bay segment basis. 

3.2.1 Filled Areas 

Much of the original mangrove shorelines and shallow seagrass beds of Tampa Bay 

have been filled for the development of residential communities, roadways, ports, and 

other commercial facilities. Figure 31 presents the existing distribution of these filled 

areas. An estimated total of 13,161 acres has been filled since the early 1900's 

(Table 16). An estimated 91% of this fill activity has occurred in the shallow shelf 

portions of the Bay, and an estimated 9% of the fill activity has occurred in the deeper 

areas of the Bay. 

Except for communities such as Palmetto and Tampa, the bay shoreline remained 

relatively undisturbed as late as the 1870's. In the 1930's, the period of majorfilling 

had begun. At this time the Gandy Bridge causeways, Port Tampa and St. Petersburg 

waterfront areas had been developed.and the major port facilities of Hillsborough Bay 

were begun with filling of the Davis Islands. In the 1950's major circulation patterns 

of Boca Ciega Bay and Old Tampa Bay had been altered (Goodwin, 1987 and 1989) 

by the construction of causeways, the most notable of these being the Courtney 

Cambell and Gandy Bridge causeways of Old Tampa Bay. By the early 1960's, the 

period of major residential development had begun with the filling of much of Boca 

Ciega Bay, the eastern shoreline of St. Petersburg, and Anna Maria Island. 

Transportation development had proceeded with the construction of the Pinellas 

Bayway, Skyway, and Howard Frankland causeways, and most of the major port 

facilities in Old Tampa Bay and Hillsborough Bay had been completed. Development 

in recent decades has resulted in the addition of major filled areas such those at 

Hooker's Point, Apollo Beach, Hillsborough Bay spoil islands 2D and 3D, Big Bend, and 

the Pinellas Bayway. 

With the exception of the causeways and several fill islands, the majority of these 

filled areas (approximately 12,000 acres) have occurred on shallow bay bottom which 

formerly supported seagrass beds. An estimate of approximately half of these filled 

areas exist adjacent to areas which continue to support sea grass today. The filled 

areas and the existing groups of habitats adjacent to the filled areas is presented on 

a bay segment basis in Figures 32 through 37 and Tables 17 through 30. 

35 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Crassostrea virginica 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

[ill Seagrass Meadow 

2m Depth Contour 

Species Present 

Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Figure 15. Distribution of the oyster, Crassostrea virginica. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

36 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UfM 

Datum NAD 27 

Mercenaria campechiensis 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

[:] Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 16. Distribution of the hard shelled clam, Mercenaria campechiensis. Base 

map data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and 

Squires, 1989. 

37 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Tagelus spp. 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

q-Coarse Grained 

L~ Fine Grained 

ffil Seagrass Meadow 

2m Depth Contour 

Species Present 

Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Figure 17. Distribution of the bivalves, Tagelus spp. Base map data sources: NOAA; 

SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

38 
GULF OF 

MEXICO 

Scale l :350,000 

Projection UTM 

Datum NAD 27 

Figure 18. 

Nassarius spp. 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

0l Seagrass Meadow 

2m Depth Contour 

Species Present 

Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Distribution of the gastropods, Nassarius spp. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

39 
GULF OF 

MEXICO 

Scale 1 :350,000 

Projection UTM 

Datum NAD 27 

Amygdalum papyria 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

Coarse Grained 

Fine Grained 

!il Seagrass Meadow 

2m Depth Contour 

• Species Present 

6 Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Figure 19. Distribution of the bivalve Amygdalum papyria. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

40 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Mulinia lateralis 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

!;:;l-Coarse Grained 

L::::J Fine Grained 

GJ Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 20. Distribution of the bivalve Mulina latera/is. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

41 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Mysella spp. 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

c-Fine Grained 

8 Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Jnc. 

Figure 21. Distribution of the bivalves, Mysella spp. Base map data sources: NOAA; 

SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

42 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Paraprionspio pinnata 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

I o I ~~~~=ed til Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 22. Distribution of polychaete Paraprionospio pinnata. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 

1989. 

43 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Streblospio benedicti 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

[J Seagrass Meadow 

2m Depth Contour 

4 Species Present 6 Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Figure 23. Distribution of the polychaete Streblospio benedicti. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 

1989. 

44 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Diopatra cuprea 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

r;::;l- Coarse Grained 

~Fine Grained 

[iJ Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 24. Distribution of the polychaete Diopatra cuprea. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

45 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Nereis spp. 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

r;=;l- Coarse Grained 

~Fine Grained 

B Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 25. Distribution of the polychaetes Nereis spp. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

46 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UI'M 

Datum NAD 27 

Capitella capitata 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

ill! Seagrass Meadow 

2m Depth Contour 

Species Present 

Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Figure 26. Distribution of the polychaete Capitella capitata. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

47 
GULF OF 

MEXICO 

Scale 1 :350,000 

Projection UTM 

Datum NAD 27 

Heteromastus filiformis 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~ 

~-C. ?arse ~rained Fme Grained 

El Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 27. Distribution of the polychaete Heteromastus filiformis. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 

1989. 

48 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Glottidia pyramidata 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

0 Seagrass Meadow 

2m Depth Contour 

Species Present 

Species Absent 

Map Prepared by Coastal Environmental, Inc. 

Figure 28. Distribution of Glotidia pyramidata. Base map data sources: NOAA; 

SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

49 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Figure 29. 

Ophiophragmus spp. 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

!nl-

~ 

C~arse ~rained 

Frne Gramed 

[:] Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Distribution of the echinoderms Ophiophragmus spp. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 

1989. 

50 
GULF OF 

MEXiCO 

Scale l :350,000 

Projection UTM 

Datum NAD 27 

Branchiostoma caribaeum 

Source: Hall and Saloman, 1975 

ST. PETERSBURG 

Map Legend: 

r-;:::;l- Coarse Grained 

~Fine Grained 

(ill Seagrass Meadow 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 30. Distribution of the cephalochordate Branchiostoma caribaeum. Base map 

data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and 

Squires, 1989. 

51 
Table 16. Number of acres of filled areas within the proximity of each habitat class 

in Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

1,055 

I 

4,749 

I 

0 

I 

6,190 

I Deep 0 0 0 1,167 

52 
FILLED AREAS 

Tampa Bay National Estuary Program, Physical Impacts Study 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

Map Prepared by Coastal Environmental, Inc. 

Figure 31. Distribution of filled areas in Tampa Bay. Base map data sources: NOAA; 

SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

53 
Table 17. Number of acres of filled areas within proximity to each habitat class in 

Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

141 

I 

1,309 

I 

0 

I 

600 

Deep 0 0 0 139 I 

Table 18. Percentage of acres of filled areas within proximity to each habitat class 

in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

6.4 

I 

59.8 

I 

0 

I 

27.4 

I Deep 0 0 0 6.4 

54 
! 

J 

- Scale 1:350,000 

Projection UfM 

Datum NAD 27 

Map Legend: 

I o I ;::~ed 

FILLED AREAS 

Old Tampa Bay 

00 Seagrass Meadow 

• Filled Areas 

2m Depth Contour 

Scale 1:150,000 

miles 

0 2 ~· 

Map Prepared by Coastal Environmental, Inc. 

Figure 32. Distribution of filled areas in Old Tampa Bay. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989. 

55 
Table 19. Number of acres of filled areas within proximity to each habitat class in 

Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

15 

I 

0 

I 

2,546 

Deep 0 0 0 992 I 

Table 20. Percentage of acres of filled areas within proximity to each habitat class 

in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

0.4 

I 

0 

I 

71.7 

I Deep 0 0 0 27.9 

56 
•. 

FILLED AREAS 

Hillsborough Bay 

Map Legend: 

I o I ~~:~~r:ed 8 Seagrass Meadow 

• Filled Areas 

2m Depth Contour 

miles 

0 2 

Map Prepared by Coastal Environmental, Inc. 

Figure 33. Distribution of filled areas in Hillsborough Bay. Base map data sources: 

NOAA; SWFWMD; Johansson and Squires, 1989. 

57 
Table 21. Number of acres of filled areas within proximity to each habitat class in 

Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

772 

I 

0 

I 

2,246 

Deep 0 0 0 9 I 

Table 22. Percentage of acres of filled areas within proximity to each habitat class 

in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

-- Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

25.5 

I 

0 

I 

74.2 

I Deep 0 0 0 0.3 

58 
miles 

0 2 

Scale 1:155,000 

Projection UTM 

Datum NAD 27 

FILLED AREAS 

Middle Tampa Bay 

Map Legend: 

I D I ~:s~ed 

ill Seagrass Meadow 

• Filled Areas 

2m Depth Contour 

l

o·_:;:,:,.,,,:,.;.,:,,;-i:' ·=·· 

J 

1·:-:-·-·.·.·.·. 

Map Prepared by Coastal Environmental, Inc. 

Figure 34. Distribution of filled areas in Middle Tampa Bay. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989. 

59 
Table 23. Number of acres of filled areas within proximity to each habitat class in 

Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

51 

I 

0 

I 

92 

Deep 0 0 0 27 I 

Table 24. Percentage of acres of filled areas within proximity to each habitat class 

in Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

81.4 

I 

0 

I 

14.3 

I Deep 0 0 0 4.2 

60 
0 

Scale 1:145,000 

miles 

Projection UIM 

Datum NAD 27 

2 

F1LLED AREAS 

Lower Tampa Bay 

I.J 

Map Legend: 

r;;;l- C~arse ~rained 

u-FmeGrained 

[:] Seagrass Meadow 

• Filled Areas 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 35. Distribution of filled areas in Lower Tampa Bay. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989. 

61 
Table 25. Number of acres of filled areas within proximity to each habitat class in 

Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

914 

I 

1,946 

I 

0 

I 

507 

Deep 0 0 0 0 I 

Table 26. Percentage of acres of filled areas within proximity to each habitat class 

in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

27.1 

I 

57.8 

I 

0 

I 

15.1 

I Deep 0 0 0 0 

62 
Scale 1:165,000 

FILLED AREAS 

Boca Ciega Bay 

Map Legend: 

I o I ~~~o:ed El Seagrass Meadow 

• Filled Areas 

2m Depth Contour 

) 

t 

( 

miles J/ 

0 2 

Projection UIM 

Datum NAD 27 

Map Prepared by Coastal Environmental, Inc. 

Figure 36. Distribution of filled areas in Boca Ciega Bay. Base map data sources: 

NOAA; SWFWMD; Doyle et al, 1989. 

63 
Table 27. Number of acres of filled areas within proximity to each habitat class in 

Terra Ceia Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

159 

I 

0 

I 

0 

Deep 0 0 0 0 I 

Table 28. Percentage of acres of filled areas within proximity to each habitat class 

in Terra Ceia Bay. 

Seagrass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

100 

I 

0 

I 

0 

Deep 0 0 0 0 

Table 29. Number of acres of filled areas within proximity to each habitat class in 

Manatee River. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

26 

I 

0 

I 

200 

Deep 0 0 0 0 

I 

I 

Table 30. Percentage of acres of filled areas within proximity to each habitat class 

in Manatee River. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

88.4 

I 

0 

I 

11.6 

Deep 0 I 0 0 0 

64 
FILLED AREAS 

Terra Ceia Bay/Manatee River 

Map Legend: 

I D I ~~~~=ed Ill Seagrass Meadow 

• Filled Areas 

2m Depth Contour 

Scale 1:135,000 

miles 

0 2 

Projection UTM 

Datum NAD 27 

Map Prepared by Coastal Environmental, Inc. 

Figure 37. Distribution of filled areas in Terra Ceia Bay and Manatee River. Base 

map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

65 
Several areas on these maps for which modified shorelines are readily apparent were 

not identified as filled areas, and this is due to our visual interpretation of the historic 

charts of these areas as cuts into the existing shoreline rather than filled shoreline. 

Estimates of the total extent of filled areas within mangrove forests developed in this 

study are likely to be underestimated due to a lack of distinguishing features visible 

in the historical materials. A more precise estimate of the lost mangrove and 

saltmarsh habitat is being developed for an ongoing TBNEP project to set living 

resource targets for Tampa Bay. The draft results of this study indicate that an 

estimated 9, 705 acres (43 %) of the 22,516 acres of mangrove and salt marsh habitat 

which existed in the 1950's have been lost. 

3.2.2 Channels and Dredge Spoil Areas 

The major navigational channels and designated dredge spoil areas which exist in 

Tampa Bay are presented in Figure 38 and the extent of these features within the 

proximity of each habitat class is tabulated in Tables 31 and 32. The designated 

dredge spoil areas include submerged spoils only, and emergent portions of spoil 

islands were operationally defined as filled areas for this report. 

The development of navigational channels in Tampa Bay has proceeded in a pattern 

similar to that of the filled areas. With the exception of Boca Ciega Bay, most of the 

navigational features were developed within deep, coarse grained areas lacking in 

sea grass (approximately 11 ,000 acres). Out of an estimated 14,381 acres of channel 

and spoil areas, an estimated 87% (12,455 acres) has occurred in the deep portions 

of the study area, and an estimated 13% (1 ,926 acres) has occurred in the shallow 

portions of the study area. The principle navigational routes extend along a naturally 

occurring deep channel extending from the bay mouth, splitting south of the inter-bay 

peninsula, and continuing into Old Tampa and Hillsborough Bays. Submerged dredge 

spoil areas are included in this analysis, and emergent dredge spoil islands such as the 

two large islands in Hillsborough Bay (20 and 30) were classified and discussed in the 

previous section as filled areas. 

The channels and spoil areas and adjacent benthic habitat classes are presented on 

a bay segment basis in Figures 39 through 44 and the areal coverages are tabulated 

in Tables 33 through 56. Clearly, there are many smaller channels, boat basins, and 

finger canals which have been dredged in the Bay and are too small to appear on the 

1 :40,000 scale navigational charts. The physical impacts of these smaller channels 

are included in a discussion of modified shoreline impacts in the next section. In 

addition, a mapping of impacts including these smaller features is being completed for 

an ongoing TBNEP project to estimate the loss of sea grass beds within the bay. 

Preliminary results from this work in progress indicate that an estimated total of 

12,756 acres of physical impacts have occurred within the shallow areas of Tampa 

Bay. 

66 
The most extensive development of navigational features in shallow habitat classes 

has occurred within Boca Ciega Bay (Figure 43). Approximately 60% of the channels 

in Boca Ciega Bay were estimated to have been developed adjacent to, or in, shallow 

areas. However, a series of relatively naturally occurring channels have been cut 

through the barrier islands to Boca Ciega Bay by hurricanes and the effects of tidal 

actions. Navigational channels have often been located within these natural features. 

The most notable of these features occur at John's Pass and Bunce's Pass. 

Sediment resuspension represents another form of potential physical impact related 

to channels and dredge spoil areas. Increased turbidity at specific times and locations 

within the bay is likely related to vessel traffic and maintenance dredging activities. 

Schoellhamer ( 1991) reported that both storm water runoff and resuspension of 

bottom sediments by large vessel traffic contributed significantly to increased turbidity 

at specific locations and times within the bay. For example, the turbidity plumes 

observed during major channel excavation activities in 1977 and 1978 were reviewed 

by Goodwin and Michaelis ( 1984). The Environmental Protection Commission of 

Hillsborough County has reported a generally increasing trend for turbidity from 1989 

through the 1991 period of this study (EPCHC, 1991 ). The EPCHC also indicates that 

no specific reason for the apparent trend was identified, and that possibilities included 

vessel traffic, maintenance dredging, algal blooms, suspended solids in runoff, and 

wind driven resuspension from shallow areas of the bay. 

67 
Table 31. Number of acres of channel areas within the proximity of each habitat 

class in Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

38 

I 

540 

I 

31 

I 

751 

Deep 0 36 312 3,412 

Table 32. Number of acres of spoil/borrow areas within the proximity of each 

habitat class in Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

6 

I 

260 

I 

0 

I 

300 

Deep 0 25 1,129 7,541 

68 

I 

I 
DISTRIBUTION OF CHANNELS AND SPOIL AREAS 

IN TAMPA BAY, 1990 

Map Prepared by Coastal Environmental, Inc. 

Not Intended for Navigational Use 

Figure 38. Distribution of channels and designated spoil areas in Tampa Bay. Base 

map data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and 

Squires, 1989. 

69 
Table 33. Number of acres of channel areas within proximity to each habitat class 

in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

38 

I 

204 

I 

5 

I 

194 

I Deep 0 0 0 84 

Table 34. Percentage of acres of channel areas within proximity to each habitat 

class in Old Tampa Bay. 

Seagrass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

7.2 

I 

38.8 

I 

0 

I 

37.0 

Deep 0 0 16.0 0.9 

Table 35. Number of acres of spoil/borrow areas within proximity to each habitat 

class in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

17 

I 

0 

I 

46 

Deep 0 0 0 15 

Table 36. Percentage of acres of spoil/borrow areas within proximity to each 

habitat class in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

21.9 

I 

0 

I 

59.1 

Deep 0 0 0 18.9 

70 

I 

I 

I 
l 

0 

Scale 1:150,000 

miles 

Projection UI'M 

Datum NAD 27 

CHANNELS AND SPOIL AREAS 

Old Tampa Bay 

Map Legend: 

I o I ~:~~ed 

2 

El Seagrass Meadow 

• Channels and Spoil Areas 

2m Depth Contour 

Map Not Intended For Navigational Purposes. 

Figure 39. Distribution of channels and designated spoil areas in Old Tampa Bay. 

Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

71 
Table 37. N-umber of acres of channel areas within proximity to each habitat class 

in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

5 

I 

53 

I 

319 

Deep 0 0 1,165 26 

Table 38. Percentage of acres of channel.areas within proximity to each habitat 

class in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

0.3 

I 

1. 7 

I 

20.4 

Deep 0 0 3.4 74.3 

Table 39. Number of acres of spoil/borrow areas within proximity to each habitat 

class in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

0 

I 

0 

I 

128 

Deep 0 0 528 996 

Table 40. Percentage of acres of spoil/borrow areas within proximity to each 

habitat class in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

0 

I 

0 

I 

7.8 

Deep 0 0 32.0 60.3 

72 

I 

I 

I 

I 
CHANNELS AND SPOIL AREAS 

Hillsborough Bay 

Map Legend: 

I CJ I ;:~~!X:ed 

IIl Seagrass Meadow 

• Channels and Spoil Areas 

2m Depth Contour 

Map Not Intended For Navigational Purposes. 

Figure 40. Distribution of channels and designated spoil areas in Hillsborough Bay. 

Base map data sources: NOAA; SWFWMD; Johansson and Squires, 

1989. 

73 
Table 41. Number of acres of channel areas within proximity to each habitat class 

in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

55 

I 

0 

I 

69 

Deep 0 1 219 1,249 

Table 42. Percentage of acres of channel areas within proximity to each habitat 

class in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

3.4 

I 

0 

I 

4.3 

Deep 0 <0.1 13.7 78.5 

Table 43. Number of acres of spoil/borrow areas within proximity to each habitat 

class in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

38 

I 

0 

I 

3 

Deep 0 0 587 3,997 

Table 44. Percentage of acres of spoil/borrow areas within proximity to each 

habitat class in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

0.8 

I 

0 

I 

0.1 

Deep 0 0 12.7 86.4 

74 

I 

I 

I 

I 
Projection UTM 

Datum NAD 27 

CHANNELS AND SPOIL AREAS 

Middle Tampa Bay 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

1illl Seagrass Meadow 

• Channels and Spoil Areas 

2m Depth Contour 

miles 

0 2 

Map Not Intended For Navigational Purposes. 

Figure 41. Distribution of channels and designated spoil areas in Middle Tampa Bay. 

Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

75 
Table 45. Number of acres of channel areas within proximity to each habitat class 

in Lower Tampa Bay. 

Sea grass Present Seagrass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

194 

I 

0 

I 

9 

Deep 0 32 0 752 

Table 46. Percentage of acres of channel areas within proximity to each habitat 

class in Lower Tampa Bay. 

- Seagrass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

19.6 

I 

0 

I 

0.9 

Deep 0 3.3 0 76.2 

Table 47. Number of acres of spoil/borrow areas within proximity to each habitat 

class in Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

59 

I 

0 

I 

17 

Deep 0 5 0 2,442 

Table 48. Percentage of acres of spoil/borrow areas within proximity to each 

habitat class in Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

2.3 

I 

0 

I 

0.7 

Deep 0 0.2 0 96.8 

76 

I 

I 

I 

I 
CHANNELS AND SPOIL AREAS 

Lower Tampa Bay 

• 

---

Map Legend: 

Scale 1:145,000 

miles 

0 

Projection UTM 

Datum NAD 27 

2 

I D I ;~~~~r:ed 

rnl Seagrass Meadow, 

• Channels and Spoil Areas 

2m Depth Contour 

Map Not Intended For Navigational Purposes. 

Figure 42. Distribution of channels and designated spoil areas in Lower Tampa Bay. 

Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

77 
Table 49. Number of acres of channel areas within proximity to each habitat class 

in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine 1 Coarse 

Shallow 

I 

0 

I 

78 

I 

0 

I 

161 

Deep 0 3 40 127 

Table 50. Percentage of acres of channel within proximity to each habitat class in 

Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

19.1 

I 

0 

I 

39.4 

Deep 0 0.7 9.8 31.0 

Table 51. Number of acres of spoil/borrow areas within proximity to each habitat 

class in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

6 

I 

146 

I 

0 

I 

104 

Deep 0 20 14 92 

Table 52. Percentage of acres of spoil/borrow areas within proximity to each 

habitat class in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

1.5 

I 

38.2 

I 

0 

I 

27.4 

Deep 0 5.3 3.5 24.1 

78 

I 

I 

I 

I 
Scale 1:165,000 

miles 

0 2 

Projection UIM 

Datum NAD 27 

CHANNELS AND SPOIL AREAS 

Boca Ciega Bay 

Map Legend: 

Q-Coarse Grained 

~Fine Grained 

rnl Seagrass Meadow 

• Channels and Spoil Areas 

2m Depth Contour 

) 

i 

( 

~ 

Map Not Intended Foe Navigational Purposes. 

Figure 43. Distribution of channels and designated spoil areas in Boca Ciega Bay. 

Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

79 
Table 53. Number of acres of channel areas within proximity to each habitat class 

in Terra Ceia Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

4 

I 

0 

I 

0 

Deep 0 0 0 0 

Table 54. Percentage of acres of channel areas within proximity to each habitat 

class in Terra Ceia Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

100 

I 

0 

I 

0 

Deep 0 0 0 0 

I 

I 

Table 55. Number of acres of channel areas within proximity to each habitat class 

in Manatee River. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

1 

I 

0 

I 

0 

Deep 0 0 0 35 

Table 56. Percentage of acres of channel areas within proximity to each habitat 

class in Manatee River. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

3.3 

I 

0 

I 

0 

Deep 0 0 0 96.7 

80 

I 

I 
0 

Scale 1:135,000 

miles 

Projection UTM 

Datum NAD 27 

2 

CHANNELS AND SPOIL AREAS 

Terra Ceia Bay/Manatee River 

Map Legend: 

I D I ~~~~~=ed til Seagrass Meadow 

• Channels and Spoil Areas 

2m Depth Contour 

Map Not Intended For Navigational Purposes. 

Figure 44. Distribution of channels and designated spoil in Terra Ceia Bay and 

Manatee River. Base map data sources: NOAA; SWFWMD; Doyle et al, 

1989. 

81 
3.2.3 Modified Shoreline 

Much of the original mangrove and salt marsh shoreline of Tampa Bay has been 

hardened by the construction of seawalls, piers, and jetties, and by the backfilling of 

saltwater wetlands. These modified shorelines include both what has been delineated 

as original shorelines and new shorelines created by the construction of filled areas. 

The National Estuarine Inventory conducted by NOAA (Orlando et al, 1988) estimated 

that approximately one third of the shoreline in Tampa Bay is of the modified type. 

However, based on the results of this TBNEP study, approximately 50% of the 

shoreline in Tampa Bay is estimated to be of the modified type. The major areas of 

modified shoreline which exist in Tampa Bay are presented in Figure 45 and are 

tabulated in Table 57. 

The modified shorelines and adjacent habitats are presented on a bay segment basis 

in Figures 46 through 51 and are tabulated in Tables 58 through 69. The least 

percentage of modified shoreline exists in the southern portions of Tampa Bay, and 

the highest percentage of modified shoreline (73%) exists in Boca Ciega Bay. 

As noted previously, there are many smaller channels, boat basins, and high energy 

shoreline areas associated with hardened shorelines that are too small to appear on 

the 1 :40,000 scale navigational charts. A tabulation of these areas is included in the 

results of the modified shoreline impacts analyses in this section. The areas of the 

various benthic habitat classes within 0 to 100, 100 to 200, 200 to 300, 300 to 400, 

and 400 to 500 meters of both modified and unmodified shorelines (Figures 52 

through 56) were calculated. The benthic habitats adjacent to shorelines was 

summarized by relating the percent coverage of seagrass in shallow areas to the 

distance from modified and unmodified shorelines. The causeways in Old Tampa Bay 

(Figure 46) are approximately 100 to 200 meters wide, and they provide a convenient 

reference point for interpreting these analyses. 

In Old Tampa Bay slightly lower values of percent coverage of seagrasses were 

observed in areas adjacent to modified shorelines. However, approximately one 

quarter of the area within 1 00 meters of modified shoreline is covered by sea grass in 

Old Tampa Bay. These seagrass areas include the areas adjacent to the north and 

south sides of the causeways. Part of the shallow habitats adjacent to the causeways 

was created in formerly deep waters, and these shallow areas now support seagrass 

meadows. The results for Hillsborough Bay were difficult to interpret due to the fact 

that they were based on an extremely limited area of existing seagrass near Big Bend. 

The Results for Middle and Lower Tampa Bay, Boca Ciega Bay and Terra Ceia Bay 

demonstrate a striking pattern of reduced seagrass coverage adjacent to modified 

shoreline. These results are likely due to direct physical impacts such as channels, 

and marinas that have been dredged adjacent to modified shorelines, and also to 

82 
Table 57. Estimated number of miles and percentage of total miles composed of 

modified shorelines in each bay segment. 

SEGMENT Modified Total Modified 

Shoreline Length Shoreline Length Shoreline 

(miles) (miles) (%) 

Old Tampa 128 290 44 

Bay 

Hillsborough 74 128 58 

Bay 

Middle Tampa 170 329 52 

Bay 

Lower Tampa 40. 118 34 

Bay 

Boca Ciega 172 237 73 

Bay 

Terra Ceia 15 47 32 

Bay 

Manatee 31 91 35 

River 

83 
MODIFIED SHORELINE 

Tampa Bay National Estuary Program, Physical Impacts Study 

Scale 1:350,000 

Projection UfM 

Datum NAD 27 

Map Prepared by Coastal Environmental, Inc. 

Figure 45. Distribution of modified shorelines in Tampa Bay. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 

1989. 

84 
Table 58. Estimated area (acres) of various habitat classes within 100 m of 

unmodified shoreline in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0.1 

I 

551 

I 

1 1 

I 

2,103 

Deep 0 0.5 0.3 9 

Table 59. Estimated area (acres) of various habitat classes within 100 m of 

modified shoreline in Old Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

1 

I 

567 

I 

8 

I 

1,788 

Deep 0 34 19 405 

85 

I 

I 
- Scale 1:350,000 

Projection UTM 

Datum NAD 27 

MODIFIED SHORELINE 

Old Tampa Bay 

Map Legend: 

I o I ~~:~:ed 00 Seagrass Meadow 

Modified Shoreline __ __,.,-~ 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 46. Distribution of modified shorelines in Old Tampa Bay. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989. 

86 
Table 60. Estimated area (acres) of various habitat classes within 100 m of 

unmodified shoreline in Hillsborough Bay. 

Seagrass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

14 

I 

0.4 

I 

1,082 

Deep 0 0 5 73 

Table 61. Estimated area (acres) of various habitat classes within 100 m of 

modified shoreline in Hillsborough Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

3 

I 

8 

I 

1, 715 

Deep 0 0 26 485 

87 

I 

I 
·· $Ci;lei :350,000 

}>roj~on UTM: · Daium NAD 21 

.. 

MODIFIED SHORELINE 

Hillsborough Bay 

Map Legend: 

I o I ~~~!~ed 

O

O.,o.o:o:.:o:o<.>>·: . 

. 

. 

d 

0 

Iii Seagrass Meadow 

Modified Shoreline 

2m Depth Contour 

Map Prepared by Coastal Environmental. Inc. 

Figure 4 7. Distribution of modified shorelines in Hillsborough Bay. Base map data 

sources: NOAA; SWFWMD; Johansson and Squires, 1989. 

88 
Table 62. Estimated area (acres) of various habitat classes within 100 m of 

unmodified shoreline in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

766 

I 

0 

I 

2,240 

Deep 0 1 0 101 

Table 63. Estimated area (acres) of various habitat classes within 100 m of 

modified shoreline in Middle Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

175 

I 

370 

I 

1,779 

Deep 0 1 1 0 0 

89 

I 

I 
Scale 1:155,000 

miles 

0 

Projection UTM 

Datum NAD 27 

2 

MODIFIED SHORELINE 

Middle Tampa Bay 

Map Legend: 

~-Coarse Grained 

~Fine Grained 

filll Seagrass Meadow 

Modified Shoreline 

2m Depth Contour 

lJ;ti 

I··.·.·.·.· ... 

Map Prepared by Coastal Environmental, Inc. 

Figure 48. Distribution of modified shorelines in Middle Tampa Bay. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989. 

90 
Table 64. Estimated area (acres) of various habitat classes within 100 m of 

unmodified shoreline in Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

1,532 

I 

0 

I 

561 

Deep 0 3 0 49 

Table 65. Estimated area (acres) of various habitat classes within 100 m of 

modified shoreline in Lower Tampa Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

229 

I 

0 

I 

536 

Deep 0 3 0 39 

91 

I 

I 
Scale 1:145,000 

miles 

0 2 

Projection UfM 

Datum NAD 27 

MODIFIED SHORELINE 

Lower Tampa Bay 

v 

Map Legend: 

~-C~arse ~rained 

u-FmeGramed 

0 Seagrass Meadow 

Modified Shoreline 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 49. Distribution of modified shorelines in Lower Tampa Bay. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989. 

92 
Table 66. Estimated area (acres) of various habitat classes within 100 m of 

unmodified shoreline in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

25 

I 

967 

I 

35 

I 

676 

Deep 0.6 4 6 47 

Table 67. Estimated area (acres) of various habitat classes within 100 m of 

modified shoreline in Boca Ciega Bay. 

Sea grass Present Sea grass Absent 

Fine Coarse Fine Coarse 

Shallow 25 392 668 2,829 

Deep 2 23 90 469 

93 

I 
Scale 1:165,000 

MODIFIED SHORELINE 

Boca Ciega Bay 

Map Legend: 

I o I ;~~~~ed D Seagrass Meadow 

Modified Shoreline 

2m Depth Contour 

) 

r 

( 

miles J/ 

0 2 

Projection liTM 

Datum NAD 27 

Map Prepared by Coastal Environmental, Inc. 

Figure 50. Distribution of modified shorelines in Boca Ciega Bay. Base map data 

sources: NOAA; SWFWMD; Doyle et al, 1989. 

94 
Table 68. Estimated area (acres) of various habitat classes within 100 m of 

unmodified shoreline in Terra Ceia Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

518 

I 

0 

I 

242 

Deep 0 0.03 0 2 

Table 69. Estimated area (acres) of various habitat classes within 100 m of 

modified shoreline in Terra Ceia Bay. 

Sea grass Present Sea grass Absent 

Fine I Coarse Fine I Coarse 

Shallow 

I 

0 

I 

103 

I 

0 

I 

191 

Deep 0 0.06 0 3 

95 

I 

I 
0 

·.' 

Scale 1:135,000 

miles 

Projection UfM 

Datum NAD 27 

2 

MODIFIED SHORELINE 

Terra Ceia Bay/Manatee River 

Map Legend: 

I o I ~~~~~:ed 1m Seagrass Meadow 

Modified Shoreline 

2m Depth Contour 

Map Prepared by Coastal Environmental, Inc. 

Figure 51. Distribution of modified shorelines in Terra Ceia Bay and Manatee River. 

Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

96 
(I) 

ro 

Q) 

.... 

<( 

~ 0 

ro 

..c 

en 

c 

Q) 

0) 

ro 

.... 

Q) 

> 0 

(.) 

(I) 

(I) 

ro 

.... 

40 

30 

20 

g> 10 

Q) 

en 

?ft. 

0 

Old Tampa Bay 

100 200 300 400 500 

Distance from Shoreline (m) 

• Modified Shoreline 0 Unmodified Shoreline 

Figure 52. Percentage of seagrass coverage adjacent to modified and unmodified 

shorelines as a function of distance from the shoreline in Old Tampa Bay. 

97 
Middle Tampa Bay 

80 .-------------------------------------------------------------~ 

(I) 

ro 

Q) 

.... 

<( 

~ 60 

ro 

.c 

en 

c 

Q) 

~ 40 .... 

Q) 

> 0 

(.) 

(I) 

(I) 

~ 20 

0) 

ro 

Q) 

en 

"#. 

0 

0- 100 100-200 200-300 300-400 400-500 

Distance from Shoreline (m) 

• Modified Shoreline D Unmodified Shoreline 

Figure 53. Percentage of seagrass coverage adjacent to modified and unmodified 

shorelines as a function of distance from the shoreline in Middle Tampa 

Bay. 

98 
Lower Tampa Bay 

80 

Cl) 

co 

Q.) 

'-

<( 

!;: 

0 60 

co 

.c 

Ul 

c:: 

Q.) 

0) 40 co 

'-Q.) 

> 0 

(.) 

Cl) 

Cl) 

co 20 '-

0) 

co 

Q.) 

Ul 

~ 

0 

0- 100 100-200 200-300 300-400 400-500 

Distance from Shoreline (m) 

• Modified Shoreline 0 Unmodified Shoreline 

Figure 54. Percentage of seagrass coverage adjacent to modified and unmodified 

shorelines as a function of distance from the shoreline in Lower Tampa 

Bay. 

99 
Boca Ciega Bay 

80 

Cl) 

ro 

Q) 

...... 

<{ 

~ 0 60 

ro 

.c 

CJ) 

c 

Q) 

Ol 40 ro 

..... 

Q) 

> 0 

() 

Cl) 

Cl) 

ro 

..... 20 

Ol 

ro 

Q) 

CJ) 

rfi 

0 

0- 100 100-200 200-300 300-400 400-500 

Distance from Shoreline (m) 

• Modified Shoreline 0 Unmodified Shoreline 

Figure 55. Percentage of seagrass coverage adjacent to modified and unmodified 

shorelines as a function of distance from the shoreline in Boca Ciega Bay. 

100 
Terra Ceia Bay 

80 .-------------------------------------------------------------~ 

Cl) 

ro 

Q) 

..... 

<( 

~ 60 

Ci5 

..c 

en 

c: 

Q) 

g> 40 ..... 

Q) 

> 0 

() 

Cl) 

Cl) 

~ 20 

Ol 

ro 

Q) 

en 

eft. 

0 

0- 100 100- 200 200-300 

0 

300-400 

Distance from Shoreline (m) 

• Modified Shoreline l:J Unmodified Shoreline 

0 

400-500 

Figure 56. Percentage of seagrass coverage adjacent to modified and unmodified 

shorelines as a function of distance from the shoreline in Terra Ceia Bay. 

101 
indirect impacts related to the disturbance of bottom sediments, alterations of flow 

and wave energy patterns, existence of nearby stormwater or wastewater outfalls, 

and increased local boat traffic. The results for Terra Ceia Bay indicate that seagrass 

coverage declines with distance from unmodified shorelines, and this is due primarily 

to the relatively narrow shallow shelf located around the periphery of Terra Ceia Bay. 

3.2.4 Prop Scar and Boat Traffic Surveys 

As described above, an aerial survey was conducted to estimate the levels of prop 

scar damage in various areas of the bay. This survey was based on the judgement 

of the observers, and provides a qualitative description of the occurrence of prop 

. scarring in the bay. The results from this survey, conducted in early March 1992, are 

shown in Figure 57. Those areas which reflected the greatest degree of prop scar 

damage included Mullet Key and the Fort DeSoto Park area, Bishop Harbor, Weedon 

Island, and the northeastern portion of Old Tampa Bay near Double Branch and Rocky 

creeks. No estimate of the prop scar damage within the narrow channels of 

Cockroach Bay was made during this broad scale survey. This area is widely known 

to be severely impacted by prop scars in localized areas, and portions of Cockroach 

Bay have been closed to motor boats until 1995 (TBRPC, 1993). By overlaying the 

prop scar damage map on the map showing the current extent of seagrasses in the 

bay, an estimate of the proportion of the seagrass meadows in each of the prop scar 

damage categories can be obtained. Figure 58 shows that approximately 35% of the 

total seagrass area in Tampa Bay was classified as being in the heavy damage and 

moderately heavy damage categories. More than 40% of the seagrass areas was 

classified as having sparse or no scar damage. 

The data obtained from the boat traffic surveys conducted in early May are shown in 

Figures 59 and 60. Figure 59 shows that, on the first day, the majority of the boat 

traffic was found in the following areas: Bunce's Pass, Egmont Key, Mullet Key, Anna 

Maria Island and Manatee River mouth, Weedon Island, and near the Courtney 

Campbell Causeway. On the second day, a similar pattern was observed with perhaps 

greater intensity of traffic in lower Boca Ciega Bay. Figure 61 shows the proportion 

of the total number of boats found in each bay segment. By overlaying the boat 

traffic map on the map showing the degree of prop scar damage, an estimate of the 

number of boats found in the various areas of prop scar damage was calculated. 

Figure 62 shows that most of the boats observed were found in the areas 

characterized as having either heavy or sparse prop scar damage (264 boats out of 

a total of 431 boats on day 2). 

102 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UIM 

Datum NAD 27 

1992 SEAGRASS PROP SCAR SURVEY 

Tampa Bay National Estuary Program 

ST. PETERSBURG 

Seagrass Bed Scar Level: 

Q None/Sparse 

lilll Sparse/Moderate 

1!1 Moderate 

Ill Moderate/Heavy 

• Heavy 

Map Prepared by Coastal Environmental, Inc. 

Figure 57. Relative scale of prop scar damage to sea grass in Tampa Bay. 

103 
No Scars 

Sparse 

Sparse-Moderate 

Moderate 

Moderate-Heavy 

Heavy 

5 15 25 35 

% of Seagrass Area 

Figure 58. Percentage of sea grass area within each prop scar damage category. 

104 
GULF OF 

MEXICO 

Scale I :350,000 

Projection UTM 

Datum NAD 27 

1992 TBNEP Boat Traffic Census 

Saturday, May 9 - Slack Before Ebb 

ST. PETERSBURG 

Seagrass Bed Scar Level: 

0 None - Sparse 

1]:] Sparse/Mod. - Moderate 

1!1 Mod./Heavy - Heavy 

1 Boat 

Map Prepared by Coastal Environmental, Inc. 

Figure 59. Midday distribution of Boats in Tampa Bay, May 9, 1992. 

105 
GULF OF 

MEXICO 

Scale 1:350,000 

Projection UTM 

Datum NAD 27 

1992 TBNEP Boat Traffic Census 

Sunday, May 10 - Slack Before Ebb 

ST. PETERSBURG 

Seagrass Bed Scar Level: 

0 None - Sparse 

BJ Sparse/Mod. - Moderate 

!l! Mod./Heavy - Heavy 

1 Boat 30 Boats 

• 

Map Prepared by Coastal Environmental, Inc. 

Figure 60. Midday distribution of Boats in Tampa Bay, May 10, 1992. 

106 
Old Tampa Bay 

Hillsborough Bay 

Middle Tampa Bay 

Lower Tampa Bay 

Boca Ciega Bay 

Terra Ceia Bay 

Manatee River 

0 10 

%of Boats 

Figure 61. Percentage of boats in each bay segment. 

107 

20 30 
No Scars 

Sparse 

Sparse-Moderate 

Moderate 

Moderate-Heavy 

Heavy 

0 50 100 150 

Number of Boats 

Figure 62. Number of boats found in each prop scar damage category. 

108 
No Scars 

Sparse 

Sparse-Moderate 

Moderate 

Moderate-Heavy 

Heavy 

0 2 4 6 8 

# Boats/1 00 ha 

Figure 63. · Number of boats per 100 ha in each prop scar damage category. 

109 
Since the surface area of those areas with various degrees of prop scar damage is not 

constant, the estimate ofthe number of boats in each damage category was weighted 

by the surface area of that category (Figure 63). This analysis shows that the boat 

traffic intensity was greatest in those areas characterized as having no scar damage. 

Examination of the nautical charts for Tampa Bay shows that these areas of high boat 

traffic intensity and little or no prop scar damage have well-marked channels, such as 

in upper Old Tampa Bay. Other areas, such as near the mouth of Bishop Harbor, 

which show much greater damage with lower boat traffic intensity, have channels 

which are apparently less well-marked. As discussed in the following text, it also 

possible that high levels of boating activity have occurred at sites such as Bishop 

Harbor and were not observed during this initial survey. 

These results were intended to provide a first glimpse into the nature of a particularly 

large data gap for Tampa Bay. It should be noted here that these results, especially 

those related to boat traffic data, are exploratory in nature. There are a variety of 

factors which affect boat traffic intensity. Boat traffic can vary significantly due to 

factors such as season, day of the week, time of day, tides, and weather. Other 

factors such as depth and the presence of seagrass also influence the distribution of 

boat traffic associated with recreational fishing in seagrass meadows. Still other 

factors, such as locations of boat ramps and marinas affect the distribution of all 

recreational boat traffic. 

3.2.5 Commercial Fisheries 

Tampa Bay has historically been, and continues to be an active commercial fishing 

center. Fish and shellfish harvested from the bay and the surrounding waters of the 

Gulf of Mexico are commonly sold (i.e., landed) in the Tampa Bay region. Lombardo 

and Lewis (1985) reviewed the Tampa Bay historical landings data, and reported that 

landings of fish commonly caught in the bay totalled 11 million pounds in 1963. 

Recent commercial fishing activities in Tampa Bay were reviewed by Haddad ( 1989), 

and he estimated that fisheries landings for Tampa Bay in 1986 were 35 million 

pounds with a dockside value of over 24 million dollars. Commercial use codes are 

recorded at the time of registering a commercial vessel in the State of Florida. 

Although, a particular vessel may be used to fish for multiple types of fishing activities 

at various times throughout a year, these data provide useful information on the 

current status of the commercial fishing fleet registered in the immediate Tampa Bay 

region. The current vessel registration data indicate that the majority of vessels 

(1 ,620) in the vicinity of Tampa Bay have a recorded commercial use code for finfish 

harvesting, 11 vessels are currently registered as live bait harvesters, and 89 vessels 

are currently registered as blue crab harvesters (Norris, 1994). 

110 
Finfish species commonly harvested in the Tampa Bay region include mullet, 

menhaden, sheepshead, and spotted seatrout (Haddad, 1989). It is likely that a 

portion of the seagrass meadow prop scar damage observed during the survey 

conducted for this project can be attributed to these commercial fishing activities. 

Many of the fishing vessels used in the fishery typically have propellers which are 

recessed into the vessel hull and do not contact the bottom. However, current data 

do not allow conclusions to be made regarding the proportion of prop scars caused 

by unprotected propellers, nets, and other gear which comes into contact with the 

bottom used by commercial v.s. recreational vessels. In recent times, regulations 

have been enacted to restrict the use of certain gears in certain areas of the bay. 

According to the Florida Department of Environmental Protection, these restrictions 

include the prohibition of fishing nets (other than hand cast nets, landing nets, and 

small bait nets) from areas including the Manatee River, Terra Ceia Bay and tributaries, 

bayous and inlets in Manatee County, all tributaries and inlets between Rock Creek 

and Double Branch Creek, E.G. Simmons Park. The regulations also prohibit mullet 

fishing in areas including Riviera Bay, Bayou Grande, Papy's Bayou, Placido Bayou, 

Snell Island Harbor, and Coffee Pot Bayou. 

Food shrimping activities occur within Tampa Bay South of the Gandy Bridge typically 

in deep waters in the Spring. The Florida Department of Environmental Protection has 

issued approximately 25 to 28 permits to conduct food shrimping activities in this 

area (Ohop, 1994). These permits are not transferable from the current permit holder 

to any other, and will be phased out through attrition upon the cessation of food 

shrimping activities by the current holders. Food shrimping activities in Tampa Bay 

may contribute to physical impacts of the bay by direct disturbance of bottom habitats 

and resuspension of sediments. As discussed in the channels and dredge spoil areas 

portion of this report, Schoellhamer ( 1991) reported that res us pension of bottom 

sediments by large vessel traffic contributed significantly to increased turbidity at 

specific locations and times within the bay. The Environmental Protection 

Commission of Hillsborough County has reported a generally increasing trend for 

turbidity from 1989 through the 1991 period of this study (EPCHC, 1991 ). The 

EPCHC also indicates that no specific reason for the apparent trend was identified, 

and that possibilities included vessel traffic, maintenance dredging, algal blooms, 

suspended solids in runoff, and wind driven resuspension from shallow areas of the 

bay. The relative contribution of commercial fishing activities to the overall turbidity 

of the bay remains equivocal. 

The shellfish species most commonly harvested in the Tampa Bay region is the bait 

shrimp (Haddad, 1989). Following World War II, an increase in sport fishing and 

tourism was followed by the development of the bait shrimp fishery in the Lower 

Tampa and Boca Ciega Bays (Joyce and Eldred, 1966; Hartley, 1993). The bait 

shrimp fishing fleet grew to greater than 55 vessels in the early 1980s, and has 

subsequently declined to a current 1992 to 1993 level of 10 to 11 vessels (Hartley, 

1993; Norris, 1994). Bait shrimp harvesting activities occur primarily within the 

111 
shallow sea grass meadows in the middle and lower portions of the bay. Small nets 

equipped with roller bars are used in these areas to minimize damage to the seagrass 

meadows. Areas where bait shrimp activities primarily occur include the seagrass 

meadows of lower Boca Ciega Bay (except where restricted inside Mullet Key), and 

the sea grass meadows adjacent to Anna Maria Island, Pinellas Point, Terra Ceia Bay, 

Bishop Harbor, and Weedon Island (Hartley, 1993). 

Several studies have been conducted to assess the impacts of shrimp trawling in 

Florida (CSA, 1992a; CSA, 1992b, Meyer et al., 1991; Coleman et al., 1992). Two 

of these studies (CSA, 1992a, Meyer et al. 1991) examined the specific physical 

impacts of bait shrimp trawls on Thalassia meadows. The studies were conducted 

by examining the physical condition of the seagrass plants before and after being 

subjected to repeated trawling by standard bait shrimp roller trawls. Results were 

equivocal for both studies. Meyer and others (1991) reported that no statistically 

significant change in mean shoot density, number of blades per shoot, longest blade, 

total blade length, or below ground biomass were observed for experimentally trawled 

seagrass beds in Lower Tampa Bay. CSA (1992a) reported a temporary (approx. 140 

minutes) increase in local turbidity following trawling in Pine Island Sound, and no 

significant decrease in shoot density, leaf blade length, leaf blade area, or number of 

blades per shoot. Neither of these two studies reported the statistical power of the 

test used to assess significant impacts. The power of the test quantifies the 

magnitude of change in seagrass meadows which could have been caused by the 

trawling treatments but not detected by the experiment due to the natural variability 

in characteristics such as blade length from seagrass plant to seagrass plant. 

However, no physical impacts to seagrass meadows from the experimental trawling 

were readily apparent from the reported results of either study (Meyer et al., 1991; 

CSA, 1992a). 

Hard clam and oyster fisheries are very limited in Tampa Bay due to closures of 

shellfish beds in areas where bacterial contamination have been associated with urban 

development (Hesselman and Seagle, 1991 ). Major shellfish harvesting areas within 

Tampa Bay are used primarily by recreational clam harvesters, and these areas are 

lower Tampa Bay between Bishop Harbor and Perico Bayou, Boca Ciega Bay clam 

areas adjacent to Mullet and Cabbage Keys, Cockroach Bay (oyster beds and offshore 

clam beds), and Passage Key clam areas between Egmont Key and Perico Island 

(Seagle, 1992). There are currently no active shellfish leases in Tampa Bay (Seagle, 

1992). 

112 
Water Quality and Sediment Quality Impacts 

In addition to the physical impacts discussed above, there are other impacts to the 

bottom habitats in Tampa Bay which are related to water and sediment quality. Two 

studies recently published by Long et al. (1991) and Brooks and Doyle (1991) 

examined the distribution of metal and organics contamination of Tampa Bay 

sediments. The former study concluded that Tampa Bay sediments had considerably 

higher concentrations of such contaminants as mirex, dieldrin, chlordane, DDT, PCB's, 

silver (Ag), Copper (Cu), and Lead (Pb) than have been observed in other Gulf Coast 

sites in Florida. High concentrations of Cadmium (Cd) and Zinc (Zn) were also found 

in Tampa Bay. Figures 64 through 67 present the contaminant concentration and 

distribution data presented by Long et al. (1991 ). Brooks and Doyle also found metals 

concentrations that exceeded those expected in relatively uncontaminated sediments. 

Figures 68 through 73 present the sites in Tampa Bay with possible anthropogenic 

inputs of Cd, Chromium (Cr), Cu, Pb, Nickel (Ni), and Zn, respectively. Both of these 

studies point to Hillsborough Bay, and in some cases, Middle Tampa Bay, as having 

sediments that are relatively the most contaminated, with little contamination found 

in Lower Tampa Bay. 

The Environmental Protection Commission of Hillsborough County has conducted 

extensive water quality monitoring in Tampa Bay since the mid-1970's, and the 

Pinellas County Department of Environmental Management has reported surface water 

quality monitoring data for 1990 and 1991 (PCDEM, 1992). Included in these data 

are measurements at fixed stations of bottom dissolved oxygen (DO) concentrations 

on a monthly basis. Figure 74 presents a summary of the recent (1986-1991) bottom 

DO data for these fixed stations, expressed as the percentage of months sampled for 

which bottom DO was less that 5 mg/L. Although statistically unbiased estimates of 

bottom DO should not be extrapolated for areas adjacent to a set of fixed stations, 

a useful general pattern is presented in this figure. This summary indicates that the 

areas with greater propensity for low DO include the deeper portions of lower 

Hillsborough Bay, the northern navigational channels, and several localized areas in 

upper Tampa Bay. The low levels of dissolved oxygen and toxic contamination of 

sediments have created conditions which may be unsuitable for supporting a healthy 

and diverse assemblage of benthic organisms. The spatial extent of low dissolved 

oxygen levels in Tampa Bay is likely to be underestimated by these data due to the 

daily occurrence of depressed oxygen levels when plant respiration rates exceed 

photosynthesis rates. This is particularly true of the shallow areas of the bay. 

113 
rn

Ag 

1 

clw 

Cr 

[J] 

Figure 64. Mean Ag, Cd, Cr, and Cu concentrations (ppm dw) in the surficial 

sediments from Tampa Bay, 1984-1988. From Long et al. (1991). 

114 
Zn 

[!] 

Figure 65. Mean Hg, Pb, and Zn concentrations (ppm dw) and percent fines in the 

surficial sediments from Tampa Bay, 1984-1988. From Long et al. 

(1991 ). 

115 
Chlordane • 

[!] • ""' 

tDDT 

[] 

Figure 66. Mean concentrations (ppm dw) of chlordane, dieldrin, tOOT, and mirex 

in the surficial sediments from Tampa Bay, 1984-1988. From Long et 

al. (1991 ). 

116 
A 

[!] 

Figure 67. Mean concentrations (ppm dw) of tPCB in the surficial sediments from 

Tampa Bay, 1984-1988. From Long et al. ( 1991). 

117 
/@ 

q 

Figure 68. Stations with possible anthropogenic inputs of Cd as determined by 

metal to aluminum ratios. From Brooks and Doyle (1992). 

118 
!iJ 

~t 

Figure 69. Stations with possible anthropogenic inputs of Cr as determined by metal 

to aluminum ratios. From Brooks and Doyle (1992). 

119 
Figure 70. Stations with possible anthropogenic inputs of Cu as determined by 

metal to aluminum ratios. From Brooks and Doyle (1992). 

120 
f 

Figure 71. Stations with possible anthropogenic inputs of Pb as determined by 

metal to aluminum ratios. From Brooks and Doyle ( 1992). 

121 
!& 

~ 

J-3.0 

, 

45.0~- P·i 

.;s.o 

Figure 72. Stations with possible anthropogenic inputs of Ni as determined by metal 

to aluminum ratios. From Brooks and Doyle (1992). 

122 
1M 

It 

_:28.8 

Figure 73. Stations with possible anthropogenic inputs of Zn as determined by 

metal to aluminum ratios. From Brooks and Doyle ( 1992). 

123 
GULF OF 

MEXICO 

Scale l :350,000 

Projection tiTM 

Datum NAD 27 

BOTIOM DISSOLVED OXYGEN 

EPC of Hillsborough County, 1986-1990 

ST. PETERSBURG 

Map Prepared by Coastal Fnvironmental, Inc. 

Figure 74. Bottom dissolved oxygen data measured by the EPC of Hillsborough 

County from 1986 to 1990. 

124 
3.3 DATA GAPS 

This project also entailed identifying, and where possible, filling data gaps in the 

available data concerning potential physical impacts in Tampa Bay. One of the major 

data gaps encountered by this project involved the live bottom habitats in Tampa Bay. 

As discussed above, mapping of these particular habitats will be completed in another 

project funded by TBNEP. 

Two other major data gaps were also identified. These included information on the 

geographic extent and degree of prop scar damage to seagrasses and spatial and 

temporal variation in recreational boat traffic in Tampa Bay. Over the last several 

years, a great deal of concern has been voiced over the damage to seagrass beds 

caused by scarring by boat props. Areas where the damage was particularly severe, 

such as Cockroach Bay and Weedon Island, are widely recognized. However, a 

uniform assessment and mapping of prop scar damage at a bay-wide scale had not 

been conducted. The Florida Department of Natural Resources (FDNR) Marine 

Research Institute has conducted some assessment and mapping of prop scar damage 

in Tampa Bay and is currently conducting detailed bay-wide assessments. The initial 

results are being revised, and the results are expected to be released in May of 1994 

(personal communication, Frank Sargent, FDEP). Pinellas County is also currently 

conducting prop scar damage studies in the Mullet Key area. However, none of these 

data sources had been available during the completion of the work for this project. 

Therefore, as described above, a bay-wide survey of prop scar damage in Tampa Bay 

was conducted to fill the data gap that existed at the time. It may be fruitful to repeat 

this simple bay-wide survey as a means of monitoring future changes in prop scar 

damage in the bay. However, the methods outlined in the Tampa Bay Monitoring Plan 

(Squires et al., 1994) for sea grass monitoring can be modified to provide data that 

would support a more statistically robust assessment of temporal trends in prop scar 

damage. 

The boat traffic data gap was particularly evident. Over twenty agencies and local 

groups were contacted for information on boat traffic in Tampa Bay. Little if any 

information was available from these sources and many of those contacted expressed 

that such data would be of great interest and utility. Therefore, it was decided to 

attempt to obtain at least some information on boat traffic intensity in Tampa Bay, 

and the survey was conducted as described above. Clearly, there are important 

sources of variability that could not be fully incorporated in the survey conducted in 

May 1992. Such sources include time of day, day of week, month or season, tidal 

state, and weather conditions. If future surveys are attempted, then those surveys 

should include estimates that reflect the influence of those sources of variation. 

Therefore, the sampling effort should be stratified to ensure that estimates are 

obtained under a wide range of conditions. For example, sampling should be 

conducted on both weekends and weekdays, in several months or seasons, and under 

several tidal states. 

125 
4. DISCUSSION 

The transformation of Tampa Bay from an undeveloped estuary to a major urban 

center has impacted the benthic habitats which it encompasses. The transformation 

has occurred rapidly and on an immense scale. The Tampa Bay Regional Planning 

Council reports that the bay area population has grown nearly 24 percent since 1970, 

and that it is the nation's third fastest growing urban area (TBRPC, 1993). The 

citizens of the bay area rely on the economic benefits of the Bay, build their homes 

on its shores, make their living on its waters, and have an active interest in the health 

of its living resources. The 1992 State of Tampa Bay Report (TBRPC, 1993) 

summarizes many of the activities which the community is currently undertaking to 

protect the resources of the Bay. This physical impacts study report provides a 

baywide accounting of the magnitude of the development of the Bay to date. By 

examining the results and using the GIS data sets in further analyses, the Tampa Bay 

National Estuary Program, in cooperation with the citizens of the bay area, will be able 

to establish goals for the protection, restoration, and enhancement of the valuable 

living resources of the Bay. 

The original shoreline of Tampa Bay consisted primarily of mangrove forests and salt 

marshes growing around a periphery of broad seagrass meadows. These structurally 

diverse habitats support a large number of benthic organisms and other associated 

fauna (eg., snook, red drum), reduce nonpoint source sediment loading, and stabilize 

shorelines. The life histories of species utilizing these areas were summarized for the 

TBNEP by Killam and colleagues (Killam et al., 1992). 

Much of the existing shoreline has been hardened by the construction of seawalls, 

jetties, piers, and backfilled land areas. These modified shorelines include both the 

original shoreline that was modified and the new shorelines created during the 

construction of filled areas. The results of the modified shoreline analysis indicate 

that modifications to shorelines have directly and indirectly impacted adjacent benthic 

habitats. Approximately half of the shoreline existing in Tampa Bay is estimated to 

be of the modified type. In some areas, such as Boca Ciega Bay, as much as 73 

percent of the shoreline is of the modified type. Much of the original benefits of the 

non-hardened shoreline such as shoreline stabilization, reduction of suspended solids 

loads, and diverse estuarine habitats have been lost. The TBNEP is currently working 

on plans for protecting remaining areas of the original shoreline. 

In addition to direct impacts to the living resources of the bay, the filled areas in 

Tampa Bay have caused changes to circulation patterns and have decreased the total 

volume of the bay. Goodwin ( 1987) has modeled the physical effects on the tidal 

circulation within the Tampa Bay caused by the filling of a substantial portion of the 

126 
bay. Goodwin's results indicate that the physical changes have caused a reduction 

in the quantity of water that enters and leaves the bay on each tidal cycle. This 

volume of tidal flow has been reduced by an estimated 4 percent between 1880 and 

1972 and by 1 percent between 1972 and 1985. Goodwin's results indicate that the 

tidal prism for Hillsborough Bay has been reduced by an estimated 8 percent between 

1880 and 1972 and by 7 percent between 1972 and 1985. With the exception of 

Hillsborough Bay, Goodwin indicates that in most of the areas of Tampa Bay flushing 

by tidal action exceeds flushing by surface water stream flow inputs, and that 

physical alterations to the bay have resulted in conditions where the bay can now 

more rapidly exchange water with the Gulf of Mexico. Goodwin concludes that these 

physical changes may have caused an increase in salinity in some areas of the bay. 

In some areas, the seagrass meadows of Tampa Bay have experienced heavy levels 

of scarring. These scars are likely to have been caused by a combination of 

recreational and commercial activities. Also, a large part of the original shallow 

seagrass meadows have been buried during the construction of filled areas for 

transportation networks, commercial facilities, residential areas, and dredge disposal 

sites. An estimated total of 13,161 acres have been filled since the early 1900's. 

With the exception of the principal causeways, the majority of these areas 

(approximately 12,000) acres have been filled in shallow waters which formerly 

supported seagrass. It is encouraging to note that many of the areas adjacent to 

these filled areas continue to support sea grass today. Pinellas County and 

Hillsborough County have recently enacted regulations to protect severely scarred 

seagrass meadows (TBRPC, 1993), and the TBNEP is currently coordinating a baywide 

effort to establish further protection and restoration goals. 

The major navigational features which have been developed in Tampa Bay are 

channels and spoil disposal areas. These navigational features have provided the 

economic basis for much of the development the bay area has experienced. There 

have been two principle types of dredging activities within Tampa Bay. The first type 

is the dredge and spoil disposal activities associated with the construction of major 

shipping channels and the development of port facilities. Most of this activity has 

been associated with the navigational features developed within deep, coarse grained 

areas lacking in seagrass (approximately 11,000 acres). The second principle type of 

navigational feature development which has occurred within the bay has been the 

construction of small boat channels, marinas, and finger canals associated with 

residential development and recreational boating facilities. The most extensive 

development of these channels and spoil areas in shallow habitats has occurred within 

Boca Ciega Bay. 

As discussed in the introduction, the objective for this project was to develop a GIS 

data base on permanently altered areas (i.e., physical impacts) of the targeted benthic 

living resources in Tampa Bay. Mapping the extent of physical impacts in the Bay 

provides a key input to the process of developing living resource restoration and 

127 
protection targets. The next step of the restoration and protection target setting 

process will be to relate the current and historical resource distributions of the 

targeted habitats using a geographic information system (GIS). The non-restorable 

areas identified by this project will then be overlaid with these distributions and areas 

which previously supported a living resource, no longer support a living resource, and 

have not been permanently altered by the physical impacts delineated by this project 

will be are deemed potentially restorable. This report provides an accounting of the 

magnitude of non-restorable areas on a bay-wide basis. This accounting will provide 

a management perspective which incorporates the magnitude of the restoration 

targets in relation to the extent of living resources which have been lost to 

development and its related physical impacts. 

The final phase of the TBNEP program will include the generation and assessment of 

specific management options for the restoration, protection, and enhancement of 

targeted living resources. The management options may include endorsement of 

specific regulations such as the limiting of motorized vessel use in areas prone to prop 

scarring, or the protection of remaining sea grass meadows from channelization. The 

management options may include physical restoration efforts such as the softening 

of hardened shorelines, the protection of naturally colonizing emergent wetlands, or 

the posting of boater warning signs in particularly sensitive shallow habitats. The 

management options may also include education initiatives to inform the public about 

the potential physical impacts of their actions in the bay. Ultimately, The TBNEP and 

cooperating agencies will present these options as prioritized and cost evaluated 

management recommendations within a Comprehensive Conservation and 

Management Plan for Tampa Bay. 

128 
5. LITERATURE CITED 

Brooks, G.R. and L.J. Doyle. 1991. Distribution of sediments and sedimentary 

contaminants in Tampa Bay. In S.F. Treat and P.A. Clark, eds. Proceedings of the 

Tampa Bay Scientific Information Symposium, February, 1991. Tampa, Florida. pp. 

399-414. 

Coleman, F.C., C. Koenig, and W.F. Herrnkind. 1992. Survey of Florida inshore 

shrimp trawling by-catch and preliminary tests of by-catch reduction devices. Annual 

Report. Department of Biological Sciences, Florida State University. Tallahassee, 

Florida. 

Continental Shelf Associates (CSA). 1992a. Roller frame trawl bait shrimp fishery 

impacts on by-catch, seagrass meadows, and habitat quality in Pine Island Sound, 

Florida. Prepared for Florida Department of Environmental Protection, Marine 

Research Institute. St. Petersburg, Florida 

Continental Shelf Associates (CSA). 1992b. Commercial food shrimp fishery impacts 

on by-catch in the lower St. Johns River, Florida. Prepared for Florida Department of 

Environmental Protection, Marine Research Institute. St. Petersburg, Florida 

Doyle, L.J., G.R. Brooks, K.A. Fanning, E.S. Van Vleet, R.H. Byrne, and N.J. Blake. 

1989. A Characterization of Tampa Bay Sediments. The Center for Near Shore Marine 

Science of the University of South Florida, St. Petersburg, Florida. 101 pp. 

Derrenbacker, J.A., Jr. and R.R. Lewis, Ill. 1985. Live bottom communities of 

Tampa Bay. In S.F. Treat, J.L. Simon, R.R. Lewis Ill, and R.L. Whitman, Jr., eds. 

Proceedings of the Tampa Bay Scientific Information Symposium, May, 1982. 

Tampa, Florida. pp. 385-392. 

Environmental Protection Commission of Hillsborough County (EPCHC). 1991. R. 

Boler, ed. Surface Water Quality, Hillsborough County, Florida. EPCHC Tampa, 

Florida. 

129 
Fehring, W.K. 1985. History and development of the port of Tampa. l.o. S.F. Treat, 

J.L. Simon, R.R. Lewis Ill, and R.L. Whitman, Jr., eds. Proceedings of the Tampa Bay 

Scientific Information Symposium, May, 1982. Tampa, Florida. pp. 512-524. 

Goodwin, C.R. 1984. Changes in tidal flow, circulation, and flushing caused by 

dredge and fill in Tampa Bay, Florida. U.S. Geol. Surv. Open File Rep. 84-447. U.S. 

Geological Survey, Alexandria, Virginia. 

Goodwin, C.R. 1987. Tidal-flow, circulation, and flushing changes caused by dredge 

and fill in Tampa Bay, Florida. U.S. Geol. Surv. Water Supply Paper 2282. U.S. 

Geological Survey, Alexandria, Virginia. 

Goodwin, C.R. 1989. Circulation of Tampa and Sarasota Bays. ln. E.D. Estevez, ed. 

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pp. 49-64. 

Goodwin, C.R. and D.M. Michaelis. 1984. Appearance and water quality of turbidity 

plumes produced by dredging in Tampa Bay, Florida. U.S. Geological Survey Water 

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Haddad, K. 1989. Habitat trends and fisheries in Tampa and Sarasota Bays. ln. E. D. 

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Washington, D.C. pp. 113-128. 

Hall, J.R. and C. H. Saloman. 1975. Distribution and abundance of macroinvertebrate 

species of six phyla in Tampa Bay, Florida, 1963-64 and 1969. National Marine 

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Hartley, K. 1993. Personal Communication. Tampa Bay National Estuary Committee, 

Citizens Advisory Committee Member. 

Hesselman, D. and J. Seagle. Draft 1991. Comprehensive Shellfish Harvesting Area 

Survey, Lower Tampa Bay, Manatee County, Florida. Florida Department of Natural 

Resources, Shellfish Environmental Assessment Section. Tallahassee, Florida. 

130 
Johansson, J.O.R. and A. Squires. 1989. Surface sediments and their relationship 

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Program. St. Petersburg, Florida. 

Leverone, J.R., J.K. Culter, J.S. Sprinkel, M.R. Milligan, and S. Mahadevan. 1991. 

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132 
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pp. 171-185. 

133 
6. DATA SOURCES FOR GIS COVERAGES 

134 
Habitat and Background Elements 

Data Layer: Bathymetry 

Source: National Ocean Service (Formerly Coast and Geodetic Survey) 

National Oceanographic and Atmospheric Administration 

{Soundings) 

Southwest Florida .Water Management District 

1990 Seagrass Survey 

(Shoreline) 

Data Type: Digital Hydrographic Soundings (mean low water) 

Period: 

Reduction/ 

Corrected for tide or water level, vessel draft, and sound velocity. 

Vertical datum - Gulf Coast tow water datum 

Digitized by NOS from original survey plots 

357,130 soundings from Tampa Bay vicinity, 1947-1958 

1991 Shoreline 

Refinement: Corrected portion of 1957 data for horizontal error. 

Computed bathymetry from point data and shoreline. 

Data Layer: Seagrass Meadows 

Source: Southwest Florida Water Management District 

1990 Seagrass Survey 

Data Type: Seagrass Bed Polygons 

Photo-interpreted from 1:24,000 Scale, Natural Color Photographs 

Period: Photographs made December, 1990 

Reduction/ 

Refinement: None 
Data Layer: Tampa Bay Digital Shoreline 

Source: Southwest Florida Water Management District 

1990 Seagrass Survey Data 

Data Type: Land Mass Polygons 

Photo-interpreted from 1 :24,000 scale, natural color photography 

Period: Photographs made December, 1990 

Reduction/ 

Refinement: G.I.S. Operation to classify survey polygons as land or water 

Data Layer: Historic shorelines 

Source: 

(Used to deduce impacted areas) 

National Ocean Service (formerly U.S. Coast and Geodetic Survey) 

National Oceanographic and Atmospheric Administration 

Navigational Surveys 

Data Type:· Navigational Charts and Topography Survey Sheets 

Various Scales 

Period: 1:80,000 Scale charts for Tampa Bay, 1900 to 1961 

-1 :40,000 Scale charts for Tampa Bay, 1926 

1:40,000 Scale charts for Southern Tampa Bay, 1885 to 1881 

Reduction/ 

Refinement: None 

Data Layer: ca 1950 Land Cover Data 

{Used to Generate G.I.S. quality check of impact identifications) 

Source: Florida Department of Natural Resources 

and U.S. Fish and Wildlife Service Cooperative Study 

Data Type: Land use/land cover polygons 

Photo-interpreted from 1 :24,000 scale photographs 

Period: ca 1950 
Reduction/ 

Refinement: G.I.S. operation to converted from raster to vector data 

Data Layer: Mangroves 

Source: Southwest Florida Water Management District 

1990 Land Use Data 

Data Type: Mangrove forest polygons 

Period: 

Photo-interpreted from 1 :24,000 sc·ale and 1 :40,000 scale, color, 

infrared photos 

Photographs made December, 1990 

Reduction/ 

Refinement: None 

Data Layer: Salt Marshes 

Source: Southwest Florida Water Management District 

1990 Land Use Data 

Data Type: Salt marsh polygons 

Period: 

Photo-interpreted from 1:24,000 scale and 1:40,000 scale, color, 

infrared photos 

Photographs made December, 1990 

Reduction/ 

Refinement: None 

Data Layer: Sediment Texture 

Tampa Bay, except for Hillsborough Bay 

Source: Doyle et al, 1989, literature compilation of sediment studies 

Data Type: Percent sediment < 63 fJm grain size 

Period: 1961-1965 extensive survey, Taylor et al, 1969 
1971-1989 compilation of surveys 

Reduction/ 

Refinement: Digitized point data 

Computed response surface from point data 

Data Layer: Sediment Texture 

Hillsborough Bay 

Source: Johansson and Squires, 1989 

Remote sensing survey of sediments 

Data Type: Percent sediment < 63 flffi grain size 

Period: 

Reduction/ 

1986 synoptic survey of Hillsborough Bay 

and ground truthing samples 

Refinement: £?igitized 1:40,000 scale survey drawing 

Data Layer: Bottom Salinity and Bottom Dissolved Oxygen 

Source: Environmental Protection Commission of Hillsborough County 

Water quality monitoring data 

Pinellas County 

Department of Environmental Management 

Water quality monitoring data 

Florida Department of Natural Resources 

Marine Fisheries Independent Monitoring Program 

Water quality monitoring data 

Data Type: Salinity and Dissolve Oxygen grab samples 

Period: EPC of Hillsborough Co., 55 stations, from 1986 to 1990 

Pinellas Co. OEM, 11 stations, from 1990 to 1991 

FDNR MARFIM, samples from non-fixed stations, from 1990 to 1991 
Reduction/ 

Refinement: Computed cumulative frequency distributions by geographic point 

Computed response surfaces from point data 

Data Layer: Benthic Organisms 

Source: Hall and Saloman, 1975 

Benthic Survey 

Data Type: Presence or absence of 20 key taxa 

Period: 350 stations sampled collectively between 1963, 1964 and 1969 

Reduction/ 

Refinement: Taxonomic data/counts, None 

Station locations digitized from reported charts 

Data Layer: Tidal Flats 

Source: Southwest Florida Water Management District 

1990 Seagrass Survey 

Data Type: Tidal flat polygons 

Photo-interpreted from 1:24,000 scale, true color photography 

Period: Photographs made December, 1990 

Reduction/ 

Refinement: None 
Physical Impacts 

Data Layer: Dredged Areas, Borrow Areas, Dredge Spoil Areas, 

Channels, Channel Markers 

Source: National Ocean Service (formerly U.S. Coast and Geodetic Survey) 

National Oceanographic and Atmospheric Admin_istration 

Navigational Surveys 

Data Type: Feature polygons and points 

Period: 1:40,000 Scale charts for Tampa Bay, 1991 

Reduction/ 

· Refinement: Digitized from 1:40,000 scale charts 

Data Layer: Filled Areas 

-

Source: National Ocean Service (formerly U.S. Coast and Geodetic Survey) 

National Oceanographic and Atmospheric Administration 

Navigational Surveys 

Data Type: Navigational Charts 

Period: 1:40,000 Scale charts for Tampa Bay, 1991 

Reduction/ 

Refinement: Filled areas deduced by comparison of modern and historical charts 

Identified impacted habitat digitized 
Data Layer: Modified Shorelines 

Source: National Ocean Service (formerly U.S. Coast and Geodetic Survey) 

National Oceanographic and Atmospheric Adminis.tration 

Navigational Surveys 

U.S. Geological Survey 

1 :24,000 Scale topographic maps 

Data Type: Linear identification of modified shoreline 

Period: 

Reduction/ 

1:40,000 Scale charts for Tampa Bay, 1991 

Current topographic maps 

Refinement: Modified shorelines deduced by comparison of modern and historical 

charts and by seawall construction readily apparent on maps and charts. 

Identified impacted habitat digitized 

Data Layer: Seagrass Prop Scars 

Source: Tampa Bay National Estuary Program 

1992 Prop Scar Survey 

Southwest Florida Water Management District 

1990 Seagrass Survey 

Data Type: Prop scar level classification of seagrass meadow polygons 

Survey from fixed wing aircraft 

soo· ft. flight elevation over water I 1000 ft. over land 

Period: Synoptic survey, March 6, 1992 

Reduction/ 

Refinement: Scar levels used to classify existing SWFWMD seagrass polygons 
Data Layer: Recreational Boating Intensity 

Source: Tampa Bay National Estuary Program 

1992 Boat Traffic Survey 

Dat.a Type: Boat counts and positions recorded to within approximately 0.25 miles 

of true position 

Survey from fixed wing aircraft 

500 ft. flight elevation over water, 1000 ft. over land 

Period: Two replicated instantaneous (2 hour) counts, May 11 and 12, 1992 of 

bay perimeter (seagrass meadows) 

Two single counts, May 11 and 12, 1992 of bay mouth and bay center 

Reduction/ 

Refinement: Count data recorded on 1 :40,000 scale NOAA charts 

Data digitized as point data