# I**Estuar~**

# Program Tampa Bay National Estuary Program Technical Publication#03-93



# PHYSICAL IMPACTS TO HABITATS IN TAMPA BAY

FINAL REPORT

MAY 199492-444-03 

### PHYSICAL IMPACTS 

## TO HABITATS IN TAMPA BAY

Prepared for: Tampa Bay National Estuary Program 111 7th Avenue 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 RecycledPaper 

### #03-93TABLE 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 SedimentTexture

..............................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

.............................823.2.4 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

iiACKNOWLEDGMENTS
This report was authored by David Wade and Anthony Janicki of Coastal Environmental, Inc. The authors gratefully acknowledge all ofthose whose assistance contributed to the completion ofthis project. Technical review and recommendation were provided by the members ofthe Tampa Bay National Estuary Program (TBNEP) staff and the members ofthe Living Resources Subcommittee ofthe TBNEP Technical Advisory Committee, in particular, Roger Johansson (City ofTampa), 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 bythe following agencies and staff: Tom Ries, Leah Polomchak, Lela Clark, and Steve Dicks ofthe Southwest Florida Water Management District; Ken Haddad, Gail MacAuly, Frank Sargent ofthe Florida Department of Natural Resources; Ron Schmied, Rosalie Shaffer, John Witzig, and Lt. Lee Cohen ofthe National Oceanographic and Atmospheric Administration; Ken Hartley ofthe TBNEP Citizens Advisory Committee; and James Cassedy ofthe National Archives. This is Technical Publication 

### # 03-93 ofthe Tampa Bay National Estuary Program.

iiiEXECUTIVE 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 whichwere 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 12,000 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.

iv1. 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 varietyofhabitats in estuarineecosystems such as Tampa Bay. Land use alterations, discharge of domestic and industrial wastes, and agricultural runoff are some ofthe activities that have received a great deal ofattention 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 channelsand, insomecasesthe needfor newchannels, also continues. Maintenance dredgingand dredgespoildisposal repeatedlyimpactbottom habitatinandaroundthe channel. Whilethe direct impacts ofthese 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 shallowand intertidal habitats, includingareas covered bysubmergedvegetation. 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 beenthe subjectofearlierstudies in Tampa Bay. Goodwin (1984) conducted an in-depth investigation ofthe impacts of dredge and fill operations on tidalflow, circulation, and flushing inTampa Bay. He estimated thatthesurfacearea of Tampa Bay has been reduced by 3.6% due to dredge and fill activities. These losses were dueto 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 Bayand Old Tampa Bay, and increased landward and seawardexchange 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.

1Lewis (1977) examined the effects of dredging in Tampa Bay during the period of 1876through 1976. He estimatedthat44% ofthe marsh and mangrovehabitathave been lost due to filling and excavation. He also hypothesized that much of the loss ofseagrasses in Tampa Bay has resultedfromdirectexcavation,burial, anddecreased water clarity caused by physical alterations ofTampa 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 ResourcesSubcommitteeoftheTBNEPTechnicalAdvisory Committee heldtwo workshops in the Fall of 1992to identifya listofliving resources to betargeted bythis effort. In Octoberof 1992,theTBNEP ManagementCommittee 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 protectiontargetswill be established usingdataonthe 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 subsequentTBNEP project. These impactswill be related tothe currentand historical resourcedistributions using geographicinformationsystem (GIS) analyses. Fromthese analyses, areaswhichare deemed nonrestorable or potentially restorable will be identified. 

### 22. 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 ofthe Tampa Bay National Estuary Program {TBNEP) guided the methodsto be used for this study. In particular,this project provided GIS data layers of benthic characteristics, bathymetry, seagrass distribution, and physicallyaltered habitats. Thefollowingtextdescribesthe 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 schemewasdevelopedtoclassifybenthichabitats intoseveral groups based on mapped characteristics ofTampa Bay. Since fine grain (muddy) sediments maybe associatedwith accumulationofcontaminantsand are particularlysusceptible to resuspension, sediment grain size was added to the classification scheme. Each individual habitatcharacteristicwas mapped at asegment-widescale usingthe 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 ofseagrass. Bottom salinity regimes were observedto followthe 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.



### 328

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. 

### 4Scale 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. 5An ongoing project is being conducted by the TBNEP to identify and map the distribution of submerged aquatic vegetation (SAV) within the estuarine portions of thetributariesto Tampa Bay. Hence,the results ofthe SAV study were not included in this physical impacts report. Preliminary results of a literature and common knowledge survey conducted forthe SAVstudy indicatethat 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 Derrenbackerand Lewis (1982). Discussions with the TBNEP and its advisors in the Fall of 1991 resulted in the exclusion ofthis habitat from the present classification scheme. This was an attempt to avoid disclosureof morespecific locationsofthisverysensitive habitat. TheTBNEP, based on input from its Technical Advisory Committee in March of 1992 has since funded aseparatetaskto mapthese areas underanotherproject. The locationoflive bottom habitat will be included in the draft CCMP. The methods used to delineate each component ofthe 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 Countybottomsalinitydatafrom 55 baystations (1986 to 1990), and Pinellas County bottomsalinitydatafrom 11 baystations (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.



### 6Scale 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. 

### 7Scale 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 ofHC Station "' PC DEM Station

Map Prepared by Coastal Environmental, Inc.
Figure 3b. Interpolated distribution of median bottom salinity. 

### 8Scale 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. 

### 92.2.2 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 ofthe Bay. A data set of digital hydrographic soundings was obtained from the National Oceanographicand AtmosphericAdministrationfor357,130 pointswithintheTampa 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 soundingsand bathymetrycontoursonthe current NOAA navigationalcharts (NOAA 1991). The vertical datum forthese data was the Gulf Coast lowwater 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 bythe Southwest Florida Water Management District (SWFWMD, 1990). This shoreline is the official shorelinefortheTBNEP. These datawere 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 carefullyvisually compared tothe bathymetriccontours 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 greaterthan 2 meters. This depth break pointwas chosen because seagrassestypicallyoccuratdepths 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 sedimenttexture data were digitizedfrom values reported in a literature review conducted by Doyle and others

10Scale 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 observationsfrom an extensivesurveyconducted in the 1960's (Tayloret al., 1969). The station locations forthese data are presented in Figure 5. A GIS data layerwas 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 lessthan 50 percentofsedimentsmallerthan 

### 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 orderto classify fine grain {muddy) sediments in a manner consistent with the methods of the Johanssonand Squires {1989) dataset. Suchfine grainsediments may be associated with accumulation of contaminants and are particularlysusceptible to resuspension.
2.2.4 Seagrass Existing seagrass meadowdistribution data were compiled as the final componentof 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 borrowareas, filled areas, modified shorelines, andseagrass bed propscarintensityweredevelopedforthis project. Each physical impacttype was compiled into a GIS data set in orderto quantifythe extent ofimpacted habitatandto providedatasetsofphysicallyaltered habitatforthefuture 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 navigationalchannels, designated dredgespoil areas, and borrowareaswere 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 navigationalchartswereobtainedfromthe NationalArchives inWashington, 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 ofTampa Bay which have been filled and shorelines which have been modified. The historical materials were arranged in chronologicalorder, and the patterns ofdevelopmentand physical impacts to bay habitat classes through the decades were examined. The impacted areas were then delineated on the shoreline from the SFWFMD 1990 seagrasssurvey. This shoreline,as stated previously, istheofficialshorelinespecified for use on all TBNEP projects. The physical impacts GIS data layers were overlaid on the benthic habitat classification scheme. The results ofthis 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, 100to 200, 200 to 300, and 400to 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 damageto seagrass beds in Tampa Bay were primarily anecdotal and limited in their geographicextent. To fill this data gap, aerial surveys were conducted bytheTBNEP to provide estimates ofthe relative degree of prop scar damage in areas throughout 14the bay. A synoptic survey was conducted on March 6, 1992 from a fixed wing aircraftflying at a heightof500feet overwaterand 1000feet over land. These low altitudes and relatively clear water conditions on this day enabled ari accurate qualitative assessment ofthe intensity of seagrass prop scars. The areas with differentamounts of propscardamagewere 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 bythe TBNEP to estimate the relative intensity of boattraffic 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 overwaterand 1000feet overland. Thesurveyswereconducted between 1100and 1300 hours at slack before ebbtide. These times were expected to have high levels of recreational boating activity in seagrass bed areas. During each flight around the periphery ofthe 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 boattraffic data were digitized and overlaid with the prop scar intensitydata to examinethe relationship of relative boating intensityto scar intensity. The results of these analyses are summarized in this report.

153.0 RESULTS
3.1 BENTHIC HABITAT CLASSIFICATION A schemewasdevelopedtoclassifyand delineateselected benthic habitats ofTampa Bay. Classification was based on depth (deepvs. shallow), sedimenttexture (finevs. 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 presentsthe results oftheclassification ofthis habitat. Table 1 presents a tabulation ofthe areal extent of each habitat class. The general patternofdistributionofhabitatclasses is comprised ofa relativelydeep, 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 likelythatthe actual extent offine grain sediments withinthese areas is far less, and accordingto Brooks and Doyle (1991) mayexistin localized bathymetric depressions. Figure 5 indicates that the sampling transect for which these fine grainedsamples wereobserved may havecoincided withthe EasttoWestorientation ofthe deep areas containing the Cut G and Gadsden Point Cut channels (Figure 4). The general pattern ofdistributionofbenthic habitatclasses forthe shallowperiphery of the Bay is comprised of a shelf of varying width surrounding the deeper basin. Seagrassesoncecovered mostofthisshelf. Table 1 indicatesthatapproximately400 acres of seagrass were located in areas classified as deeper than 2 meters. This estimate representsthesumof manysmallerareas inthe lowerportion ofTampaand Boca Ciega Bays where seagrasses exist in thevicinityofthe 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 presentthe change in seagrass coveragefromthe 1950'sto 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 particularlyevident in the northern areas ofthe bay (e.g. Old Tampa and Hillsborough bays). Recent reviews oftheseagrass loss trend are presented in Lewis et al (1991) and Haddad (1989).



### 16Figures 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 ofthe 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 a0.701 mm mesh sieve to collectand separate theorganismsfrom thesediment. Severalofthe more predominantspeciesencounteredduringthiseffort are presented in Figures 15through 30. The presence or absence ofeach species is labeled for the location of each sample. Manysurveysofbenthoshave beenconducted invarious locationsthroughoutTampa Bay, and some such as Taylor (1971) were synoptic in nature. The Hall and Saloman survey, however, represents asinglesource, intensivesamplingeffort, 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 bottomareasare notemphasized.The geographic presenceorabsenceofspecies presented bythese results indicates the broad scale distribution of organisms which existed following the occurrence of major physical impacts to the bay in the years priorto the 1960's. An ongoing synoptic survey will be completed bythe TBNEP in 1994, and the results will provide more current bay-wide benthic information. Thetypical patterns ofestuarine macroinvertebrate distribution can be seen in these plots. The distributions range fromthat ofthe relatively persistent polychaete worm Paraprionospiopinnatawhich occurs in mostofthe habitats ofthe bay (Figure 22)to those of the opportunists such as the polychaete worms Streblospio benedictiand Capitellacapitata(Leveroneetal., 1991)whichoccurprimarilyindisturbedareassuch 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 ofenvironmentalconditionssuchas salinity, depth,and waterquality (Figures 29and 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).

17Table 1. Number of acres within each habitat class in Tampa Bay. Seagrass Present Seagrass Absent Fine Coarse Fine Coarse Shallow 116 24,295 1,079 56,431

Deep 17 394 14,848 142,519

180 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. 19Scale 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 1950seagrass distribution. Data source: FDNR/USFWS. 

### 20Scale 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 1990seagrassdistribution. Datasources: SWFWMD, NOAA.
21Table 2. Number of acres within each habitat class in Old Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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.



### 23Table 4. Number of acres within each habitat class in Hillsborough Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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;Johanssonand Squires, 1989. Note,Johanssonand Squires assumed sediments in channels were fine grained and did not survey. Channels and spoil areas for 1990 presented in Figures 38 through 44. 

### 25Table 6. Number of acres within each habitat class in Middle Tampa Bay. Seagrass Present Seagrass 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. Seagrass 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. MiddleTampa Bay benthic habitat classification. Data sources: NOAA; SWFWMD; Doyle et al, 1989. Channels and spoil areas for 1990 presented in Figures 38 through 44. 

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



### 28Scale 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. 

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

30Scale 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. 31Table 12. Number of acres within each habitat class in Terra Ceia Bay. Seagrass Present Seagrass 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 Seagrass 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

-·

32Table 14. Number of acres within each habitat class in Manatee River. Seagrass Present Seagrass 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. Seagrass Present Seagrass Absent Fine 

# I Coarse Fine 

# T Coarse Shallow 

# I 0.1 

# I 4 

# I 0.2 

# I 60.8 

# I

Deep <0.1 

### 0 0 35.0

33Scale 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 

## mDeep, 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 spoilareas for 1990 presented in Figures 38 through 44. 

### 343.2 PHYSICAL IMPACTS Physical impact data sets were developed for this project for channels, spoil and borrowareas, filled areas, modified shorelines, and seagrass bed prop scar intensity. Each physical impactwas compiled intoa GIS datasetfollowingthe methodsoutlined earlier. The physical impactsGIS data layerswerethen overlaidonthe benthichabitat classification scheme. The results ofthis 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 ofTampa Bay have beenfilled forthedevelopmentofresidentialcommunities, roadways, ports, and othercommercial facilities. Figure 31 presentsthe existing distribution ofthesefilled areas. An estimated total of 13,161 acres has been filled since the early 1900's (Table 16). An estimated 91% ofthis fill activity has occurred in the shallow shelf portionsofthe Bay, and an estimated 9% ofthefill activity has occurred in thedeeper areas ofthe 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. Atthistimethe Gandy Bridgecauseways, PortTampa and St. Petersburg waterfrontareas had been developed.andthe major portfacilities of Hillsborough Bay were begun with filling ofthe 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'sPoint,Apollo Beach, Hillsborough Bayspoil islands2D 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 12,000acres) haveoccurredon shallowbaybottomwhich formerly supported seagrass beds. An estimate of approximately half ofthese filled areas exist adjacent to areas which continue to support seagrass today. The filled areas and the existing groups of habitats adjacentto the filled areas is presented on a bay segment basis in Figures 32 through 37 and Tables 17 through 30.

35GULF 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. Distributionofthe oyster, Crassostrea virginica. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

### 36GULF 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 mapdata sources: NOAA; SWFWMD; Doyle etal, 1989;Johansson and Squires, 1989. 

### 37GULF 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. Distributionofthebivalves, Tagelusspp. Base mapdatasources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989.


### 38GULF 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.



### 39GULF OF MEXICO

Scale 1:350,000 Projection UTM Datum NAD 27 

## Amygdalumpapyria 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 ofthe bivalve Amygdalumpapyria. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989.


### 40GULF 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::::JFine 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.

41GULF 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. Distributionofthe bivalves, Mysellaspp. Base mapdatasources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989.


### 42GULF OF MEXICO

Scale 1:350,000 Projection UTM Datum NAD 27 

## Paraprionspio pinnata Source: Hall and Saloman, 1975

ST. PETERSBURG

Map Legend: 

# Io 

# 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. 

### 43GULF 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. 

### 44GULF 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 ofthe polychaete Diopatra cuprea. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

### 45GULF 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. 

### 46GULF 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. Distributionofthe polychaete 

### Capitella capitata. Base mapdata sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

### 47GULF OF MEXICO

Scale 1:350,000 Projection UTM Datum NAD 27 

## Heteromastusfiliformis 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. 

### 48GULF OF MEXICO

Scale 1:350,000 Projection UTM Datum NAD 27 

## Glottidiapyramidata 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. 49GULF 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. 

### 50GULF 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. Distributionofthecephalochordate Branchiostoma caribaeum. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

### 51Table 16. Number of acres of filled areas within the proximity of each habitat class in Tampa Bay. Seagrass Present Seagrass 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 offilled areas inTampa Bay. Base mapdatasources: NOAA; SWFWMD; Doyle et al, 1989; Johansson and Squires, 1989. 

### 53Table 17. Number of acres of filled areas within proximity to each habitat class in Old Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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: 

# Io 

# 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. 

### 55Table 19. Number of acres of filled areas within proximity to each habitat class in Hillsborough Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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: 

## Io 

## 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. 

### 57Table 21. Number of acres of filled areas within proximity to each habitat class in Middle Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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



### 58miles 0 2

Scale 1:155,000 Projection UTM Datum NAD 27 

## FILLED AREAS Middle Tampa Bay

Map Legend: 

# ID 

# I**~:s~ed**

ill Seagrass Meadow 

# • Filled Areas 2m Depth Contour 

# l o·_:;:,:,.,,,:,.;.,:,,;-i:'
·=·· J 1·:-:-·-·.·.·.·.

Map Prepared by Coastal Environmental, Inc. Figure 34. Distributionoffilled areas in MiddleTampa Bay. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 59Table 23. Number of acres of filled areas within proximity to each habitat class in Lower Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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



### 600Scale 1:145,000 miles Projection UIM Datum NAD 272 

## 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 offilled areas in LowerTampa Bay. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

### 61Table 25. Number of acres of filled areas within proximity to each habitat class in Boca Ciega Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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

62Scale 1:165,000 

## FILLED AREAS Boca Ciega Bay

Map Legend: 

# Io 

# 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. 

### 63Table 27. Number of acres of filled areas within proximity to each habitat class in Terra Ceia Bay. Seagrass Present Seagrass 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 Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass Absent Fine 

# I Coarse Fine 

# I Coarse Shallow 

# I 0 

# I 88.4 

# I 0 

# I 11.6 

# I

Deep 0 0 0 0


### 64

## FILLED 

## AREAS Terra Ceia Bay/Manatee River

Map Legend: 

## ID 

## 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. 

### 65Several areas onthese maps forwhich modified shorelines are readily apparentwere not identified as filled areas, and this is dueto ourvisual interpretation ofthe historic charts of these areas as cuts into the existing shoreline rather than filled shoreline. Estimates ofthe total extentoffilled areas within mangroveforests developed in this study are likelyto 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%) ofthe 22,516acresofmangroveand 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 similartothat ofthe filled areas. With the exception of Boca Ciega Bay, most ofthe navigational features were developed within deep, coarse grained areas lacking in seagrass (approximately 11 ,000acres). Outofan estimated 14,381 acresofchannel and spoil areas, an estimated 87% (12,455 acres) has occurred in the deep portions ofthe study area, and an estimated 13% (1 ,926 acres) has occurred in the shallow portions ofthe study area. The principle navigational routes extend along a naturally occurringdeepchannel extendingfromthe bay mouth, splitting south ofthe inter-bay peninsula, and continuing into Old Tampa and Hillsborough Bays. Submerged dredge spoil areas are included inthis analysis, and emergentdredgespoil islandssuchasthe two large islands in Hillsborough Bay (20and 30) were classified and discussed inthe 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 onthe 1:40,000 scale navigational charts. The physical impacts ofthese smaller channels are included in a discussion of modified shoreline impacts in the next section. In addition, a mappingofimpacts includingthesesmallerfeatures is beingcompletedfor an ongoing TBNEP project to estimate the loss of seagrass 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. 66The most extensive development of navigational features in shallow habitat classes has occurredwithin Boca Ciega Bay (Figure43). Approximately 60% ofthe channels in Boca Ciega Baywere estimated to have been developed adjacentto, 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 oftidal actions. Navigationalchannels haveoften been located withinthese naturalfeatures. The most notable ofthese features occur at John's Pass and Bunce's Pass. Sediment resuspension represents another form of potential physical impact related to channelsand dredgespoil areas. Increasedturbidityatspecifictimes 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 bottomsedimentsbylargevesseltrafficcontributedsignificantlyto increasedturbidity at specific locations and times within the bay. For example, the turbidity plumes observedduringmajorchannelexcavationactivities in 1977and 1978were reviewed by Goodwin and Michaelis (1984). The Environmental Protection Commission of HillsboroughCountyhas reported agenerallyincreasingtrendforturbidityfrom 1989 throughthe 1991 periodofthisstudy (EPCHC, 1991). The EPCHC also indicatesthat nospecific reasonfortheapparenttrendwas identified,and that possibilities included vessel traffic, maintenance dredging, algal blooms, suspended solids in runoff, and wind driven resuspension from shallow areas ofthe bay.



### 67Table 31. Number of acres of channel areas within the proximity of each habitat class in Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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 ofchannels and designated spoil areas in Tampa Bay. Base map data sources: NOAA; SWFWMD; Doyleetal, 1989;Johanssonand Squires, 1989. 

### 69Table 33. Number of acres of channel areas within proximity to each habitat class in Old Tampa Bay. Seagrass Present Seagrass 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 Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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

0Scale 1:150,000 miles
Projection UI'M Datum NAD 27 

## CHANNELS AND SPOIL AREAS Old Tampa Bay

Map Legend: 

# Io 

# 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. 

### 71Table 37. N-umber of acres of channel areas within proximity to each habitat class in Hillsborough Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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: 

## ICJ 

## I

# ;:~~!X:ed

IIl Seagrass Meadow
• Channels and Spoil Areas 2m Depth Contour

Map Not Intended For Navigational Purposes. Figure 40. Distribution ofchannels and designated spoil areas in Hillsborough Bay. Base map data sources: NOAA; SWFWMD; Johansson and Squires, 

### 1989. 

### 73Table 41. Number of acres of channel areas within proximity to each habitat class in Middle Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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

IProjection 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. Distributionofchannelsand designatedspoilareas in MiddleTampa Bay. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 75Table 45. Number of acres of channel areas within proximity to each habitat class in Lower Tampa Bay. Seagrass 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 Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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 0Projection UTM

Datum NAD 27 2 

# ID 

# I**;~~~~r:ed** rnl Seagrass Meadow,
• Channels and Spoil Areas 2m Depth Contour

Map Not Intended For Navigational Purposes. Figure 42. Distributionofchannelsand designatedspoil areas in LowerTampa Bay. Base map data sources: NOAA; SWFWMD; Doyle et al, 1989. 

### 77Table 49. Number of acres of channel areas within proximity to each habitat class in Boca Ciega Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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

IScale 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. 79Table 53. Number of acres of channel areas within proximity to each habitat class in Terra Ceia Bay. Seagrass Present Seagrass 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.Seagrass Present Seagrass 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. Seagrass Present Seagrass 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.Seagrass Present Seagrass 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

I0 Scale 1:135,000 miles Projection UTM Datum NAD 27 2 

## CHANNELS AND SPOIL AREAS Terra Ceia Bay/Manatee River

Map Legend: 

# ID 

# 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 etal, 

### 1989. 813.2.3 Modified Shoreline Much of the original mangrove and salt marsh shoreline of Tampa Bay has been hardened bythe construction ofseawalls, piers, and jetties, and bythe backfilling of saltwaterwetlands. These modifiedshorelines includebothwhathas been delineated as original shorelines and new shorelines created bythe construction offilled areas. The National Estuarine Inventoryconducted byNOAA (Orlandoetal, 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 ofthe 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 baysegment 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 ofTampa 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 navigationalcharts. A tabulation ofthese areas is included inthe results ofthe modified shoreline impacts analyses in this section. The areas ofthe various benthichabitatclasses within0 to 100, 100to 200, 200to 300, 300to400, 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 distancefrom modified and unmodified shorelines. Thecauseways in Old Tampa Bay (Figure 46) are approximately 100to 200 meterswide,andthey provideaconvenient 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 quarterofthe area within 100 meters of modified shoreline is covered byseagrass in Old Tampa Bay. These seagrass areas include the areas adjacent to the north and southsides ofthecauseways. Partoftheshallowhabitatsadjacenttothecauseways was created in formerly deep waters, and these shallowareas nowsupportseagrass meadows. The results for Hillsborough Bay were difficultto interpretduetothe fact thattheywere based on an extremely limited area ofexisting 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 adjacentto modified shorelines, and also to

82Table 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. 

### 84Table 58. Estimated area (acres) of various habitat classes within 100 m of unmodified shoreline in Old Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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: 

# Io 

# 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. 

### 86Table 60. Estimated area (acres) of various habitat classes within 100 m of unmodified shoreline in Hillsborough Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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: 

# Io 

# 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. 88Table 62. Estimated area (acres) of various habitat classes within 100 m of unmodified shoreline in Middle Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass 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

IScale 1:155,000 miles 0 Projection UTM Datum NAD 272 

## 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 MiddleTampa Bay. Base mapdata sources: NOAA; SWFWMD; Doyle et al, 1989. 90Table 64. Estimated area (acres) of various habitat classes within 100 m of unmodified shoreline in Lower Tampa Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass Absent Fine 

# I Coarse Fine 

# I Coarse Shallow 

# I 0 

# I 229 

# I 0 

# I 536

Deep 0 3 0 39



### 91 

# I



# IScale 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. 

### 92Table 66. Estimated area (acres) of various habitat classes within 100 m of unmodified shoreline in Boca Ciega Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass Absent Fine Coarse Fine Coarse Shallow 25 392 668 2,829

Deep 2 23 90 469

93 

# IScale 1:165,000 

## MODIFIED SHORELINE Boca Ciega Bay

Map Legend: 

# Io 

# 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. 94Table 68. Estimated area (acres) of various habitat classes within 100 m of unmodified shoreline in Terra Ceia Bay. Seagrass Present Seagrass 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. Seagrass Present Seagrass Absent Fine 

# I Coarse Fine 

# I Coarse Shallow 

# I 0 

# I 103 

# I 0 

# I 191

Deep 0 0.06 0 3

95 

# I



# I0 ·.'

Scale 1:135,000 miles Projection UfM Datum NAD 27 2 

## MODIFIED SHORELINE Terra Ceia Bay/Manatee River

Map Legend: 

# Io 

# 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 shorelinesas afunction ofdistancefromtheshoreline in OldTampa Bay. 97MiddleTampa 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 afunction of distance from the shoreline in MiddleTampa Bay. 

### 98LowerTampa Bay 80 Cl) co Q.) '- <( !;: 60 0 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 LowerTampa Bay. 

### 99Boca Ciega Bay 80 Cl) ro Q)
...... <{**~** 60 0 

### 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 afunctionofdistancefromthe shoreline in Boca Ciega Bay. 100Terra 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 afunction ofdistancefromthe shoreline in Terra Ceia Bay. 101indirect 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 boattraffic. The results forTerra Ceia Bay indicatethatseagrass coverage declineswith distancefrom unmodifiedshorelines, and this is due primarily tothe relatively narrowshallowshelf located aroundthe peripheryofTerra 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 inthe bay. The results fromthis 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 portionofOld Tampa Bay near Double Branch and Rocky creeks. No estimate of the prop scar damage within the narrow channels of Cockroach Bay was made duringthis 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 ofthe proportionofthe seagrass meadows in each ofthe prop scar damage categories can be obtained. Figure 58 showsthatapproximately35% ofthe 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 fromthe boattraffic surveys conducted in early Mayare shown in Figures 59 and 60. Figure 59 shows that, on the first day, the majority ofthe boat traffic wasfound in thefollowing areas: Bunce's Pass, Egmont Key, Mullet Key, Anna Maria Island and Manatee River mouth, Weedon Island, and near the Courtney CampbellCauseway. Onthesecondday,asimilarpatternwasobservedwith perhaps greater intensity oftraffic 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 ofthe 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 of431 boats on day 2).

102GULF 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 seagrass in Tampa Bay. 103

## No Scars Sparse Sparse-Moderate Moderate Moderate-Heavy Heavy 

## 5 

# 15 25 35 

## %ofSeagrassArea

Figure 58. Percentage of seagrass area within each prop scar damage category. 104GULF 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. 105GULF 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

## OldTampaBay HillsboroughBay MiddleTampaBay

LowerTampaBay
BocaCiegaBay
TerraCeiaBay
ManateeRiver 0 

## 10 %ofBoats

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 NumberofBoats

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/100ha

Figure 63. · Number of boats per 100 ha in each prop scar damage category. 109Sincethesurfaceareaofthose areaswithvariousdegreesofpropscardamage is not constant,theestimateofthe numberofboats ineach damagecategorywasweighted bythe surface area ofthat category (Figure 63). This analysis shows that the boat traffic intensitywas greatest in those areas characterized as having no scar damage. Examinationofthe nauticalchartsforTampa Bay showsthattheseareas ofhigh boat traffic intensityand littleor no prop scardamage havewell-marked channels,suchas 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 intendedto provideafirst glimpse intothe natureofa 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 boattraffic intensity. Boat traffic can vary significantly dueto factors such as season, day of the week, time of day, tides, and weather. Other factors such as depth and the presence ofseagrass also influencethe 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 boattraffic.
3.2.5 Commercial Fisheries Tampa Bay has historically been, and continues to be an active commercial fishing center. Fish and shellfish harvested fromthe bay and the surroundingwaters ofthe Gulfof Mexico are commonlysold (i.e., landed) inthe Tampa Bay region. Lombardo and Lewis (1985) reviewed theTampa Bay historical landings data, and reported that landings of fish commonly caught in the bay totalled 11 million pounds in 1963. Recent commercialfishing activities in Tampa Bay were reviewed byHaddad (1989), and he estimated that fisheries landings for Tampa Bay in 1986 were 35 million pounds with a docksidevalue 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 particularvessel maybe usedtofish for multipletypesoffishing activities at various times throughout a year, these data provide useful information on the current status ofthe commercialfishing fleet registered in the immediateTampa Bay region. The current vessel registration data indicate that the majority of vessels (1 ,620) inthevicinity ofTampa Bay havea recorded commercial use code forfinfish harvesting, 11 vessels are currently registered as live bait harvesters, and 89 vessels are currently registered as blue crab harvesters (Norris, 1994).

110Finfish 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 baitnets)fromareas includingthe Manatee River,TerraCeia Bayandtributaries, 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 shrimpingactivitiesoccurwithinTampa Bay South ofthe Gandy Bridgetypically indeepwaters inthe Spring. The Florida DepartmentofEnvironmental Protection has issued approximately 25 to 28 permits to conduct food shrimping activities in this area (Ohop, 1994). These permits are nottransferablefromthe current permitholder to any other, and will be phased out through attrition upon the cessation of food shrimping activities bythe current holders. Food shrimping activities in Tampa Bay maycontributeto physicalimpactsofthebaybydirectdisturbanceofbottomhabitats and resuspension ofsediments. As discussed in the channels and dredgespoil areas portion of this report, Schoellhamer (1991) reported that resuspension 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 ofthe bay. The relative contribution ofcommercial fishing activities to the overallturbidity 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 1992to 1993 level of 10to 11 vessels (Hartley, 1993; Norris, 1994). Bait shrimp harvesting activities occur primarily within the 111

### shallow seagrass meadows in the middle and lower portions ofthe bay. Small nets equipped with roller bars are used inthese areasto minimize damagetothe 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 seagrass meadows adjacentto 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 etal., 1991; Coleman etal., 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 significantchange in mean shootdensity, numberofblades per shoot, longestblade, total blade length,orbelowground biomasswereobservedforexperimentallytrawled seagrass beds in LowerTampa Bay. CSA (1992a) reported atemporary (approx. 140 minutes) increase in local turbidity following trawling in Pine Island Sound, and no significantdecrease in shootdensity, leaf blade length, leaf blade area, or numberof blades per shoot. Neither ofthese two studies reported the statistical power ofthe 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 trawlingtreatments but notdetected bythe experimentdueto the naturalvariability 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 areaswherebacterialcontamination have been associatedwith urban development (Hesselman and Seagle, 1991). Majorshellfish 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 adjacentto Mulletand Cabbage Keys, Cockroach Bay (oysterbedsand 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).

112Water 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. TheformerstudyconcludedthatTampa Baysediments had considerably higherconcentrationsofsuchcontaminantsas mirex,dieldrin,chlordane, DDT,PCB's, silver (Ag), Copper (Cu), and Lead (Pb) than have been observed in other GulfCoast sites in Florida. Highconcentrations of Cadmium (Cd) and Zinc (Zn) were also found in Tampa Bay. Figures 64 through 67 present the contaminant concentration and distributiondata presented byLong etal. (1991). Brooksand Doylealsofound metals concentrationsthatexceededthoseexpected inrelativelyuncontaminatedsediments. Figures 68 through 73 present the sites in Tampa Bay with possible anthropogenic inputs ofCd, Chromium (Cr), Cu, Pb, Nickel (Ni), and Zn, respectively. Both ofthese studies pointto Hillsborough Bay, and in some cases, Middle Tampa Bay, as having sedimentsthat are relatively the mostcontaminated, 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 PinellasCountyDepartmentofEnvironmentalManagementhas reportedsurfacewater quality monitoring data for 1990 and 1991 (PCDEM, 1992). Included in these data are measurements atfixed stations of bottom dissolved oxygen (DO) concentrations ona monthly basis. Figure 74presentsasummaryofthe recent (1986-1991) bottom DO dataforthesefixed stations, expressed as the percentage ofmonths sampled for which bottom DO was lessthat 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 havecreated conditions which maybe 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).
114Zn 

# [!]

Figure 65. Mean Hg, Pb, and Zn concentrations (ppm dw) and percentfines in the surficial sediments from Tampa Bay, 1984-1988. From Long et al. (1991).
115Chlordane • 

# [!] • ""'

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). 116A 

# [!]

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 possibleanthropogenicinputsofCras determined bymetal to aluminum ratios. From Brooks and Doyle (1992). 119Figure 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 possibleanthropogenicinputs ofNi 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). 123GULF 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 1990.1243.3 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 ofthe major data gapsencountered bythis project involvedthe livebottom habitats inTampa Bay. Asdiscussed above, mappingofthese particularhabitatswill be completed inanother 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 byscarring by boat props. Areas wherethe 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 hasconductedsomeassessmentand mappingofpropscardamage inTampa Bayand is currentlyconducting detailed bay-wide assessments. The initial results are being revised, and the results are expected to be released in Mayof 1994 (personal communication, Frank Sargent, FDEP). Pinellas County is also currently conducting propscardamagestudies inthe MulletKey area. However, noneofthese data sources had been available during the completion of the work for this project. Therefore, as described above, a bay-widesurveyofpropscardamage inTampa Bay was conducted tofill thedata gapthatexisted atthetime. Itmaybe fruitful to repeat this simple bay-wide survey as a means of monitoring future changes in prop scar damage inthe bay. However,the methodsoutlined in theTampa Bay Monitoring Plan (Squires et al., 1994) for seagrass monitoring can be modified to provide data that would support a morestatistically robustassessment oftemporal 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 informationwasavailablefromthesesourcesand manyofthosecontacted 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 ofvariability 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. Iffuture 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 conductedon bothweekendsand weekdays, inseveral monthsorseasons, and under several tidal states. 1254. DISCUSSION
The transformation of Tampa Bay from an undeveloped estuary to a major urban center has impacted the benthic habitats which itencompasses. Thetransformation has occurred rapidly and on an immense scale. The Tampa Bay Regional Planning Council reportsthatthe bayarea population has grownnearly24percentsince 1970, and that it is the nation's third fastest growing urban area (TBRPC, 1993). The citizens ofthe bay area rely on the economic benefits of the Bay, build their homes on its shores, maketheir livingon itswaters, and havean active interest inthe health of its living resources. The 1992 State of Tampa Bay Report (TBRPC, 1993) summarizes many ofthe 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 examiningthe results and usingthe GIS data sets in further analyses,theTampa Bay National Estuary Program, in cooperationwiththecitizens ofthe bayarea, will be able to establish goals for the protection, restoration, and enhancement of the valuable living resources of the Bay. The original shoreline ofTampa Bay consisted primarilyof mangroveforests and salt marshes growing around a peripheryof broad seagrass meadows. These structurally diverse habitats support a large number of benthic organisms and other associated fauna (eg., snook, red drum), reduce nonpointsourcesediment loading, and stabilize shorelines. The life histories ofspecies utilizing these areas were summarized forthe 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 modificationstoshorelines havedirectlyand indirectlyimpacted adjacentbenthic 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 ofthe shoreline is ofthe modified type. Much ofthe original benefits ofthe non-hardenedshoreline suchas shorelinestabilization, reduction ofsuspended solids loads, and diverseestuarine habitats have been lost. TheTBNEP is currentlyworking on plans for protecting remaining areas ofthe original shoreline. In addition to direct impacts to the living resources of the bay, the filled areas in Tampa Bay havecaused changestocirculation patterns and havedecreased thetotal volume of the bay. Goodwin (1987) has modeled the physical effects on the tidal circulation within the Tampa Bay caused bythe filling of a substantial portion ofthe 126bay. 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 oftidal flow has been reduced by an estimated 4 percent between 1880and 1972and by 1 percent between 1972and 1985. Goodwin's results indicatethatthe tidal prismfor Hillsborough Bay has been reduced byan estimated 8 percent between 1880 and 1972 and by 7 percent between 1972 and 1985. With the exception of Hillsborough Bay, Goodwin indicatesthat in most ofthe areas ofTampa 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 rapidlyexchangewaterwiththe Gulfof Mexico. Goodwinconcludesthatthese physical changes may have caused an increase in salinity in some areas of the bay. In some areas, the seagrass meadows ofTampa 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 dredgedisposal 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 seagrass today. Pinellas County and Hillsborough County have recently enacted regulations to protect severely scarred seagrass meadows(TBRPC, 1993),andtheTBNEP is currentlycoordinatingabaywide 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 ofthe development the bay area has experienced. There have beentwo principletypes ofdredging activities withinTampa Bay. Thefirsttype 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 withthe navigationalfeatures developed withindeep, coarse grained areas lacking in seagrass (approximately 11,000acres). Thesecond principletypeof 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 developmentofthesechannelsand spoilareas inshallowhabitats hasoccurredwithin Boca Ciega Bay. As discussed inthe introduction, the objective forthis project was to develop a GIS data base onpermanentlyaltered areas (i.e., physical impacts)ofthetargeted 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 127protection 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 bythis projectwillthen be overlaid withthese distributions and areas which previouslysupported a living resource, no longersupporta living resource, and have not been permanentlyaltered bythe physical impacts delineated bythis project will be are deemed potentially restorable. This report provides an accounting ofthe 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 ofthe TBNEP program will includethe 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 suchasthe limiting ofmotorizedvessel use in areas proneto prop scarring, orthe protection of remaining seagrass meadowsfrom 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 managementoptions mayalso includeeducation initiativesto informthe publicabout the potential physical impacts oftheir actions inthe bay. Ultimately, TheTBNEP and cooperating agencies will present these options as prioritized and cost evaluated management recommendations within a Comprehensive Conservation and Management Plan for Tampa Bay.

1285. 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 ofthe 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 shrimptrawling by-catchand preliminarytests ofby-catch reductiondevices. 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
ContinentalShelfAssociates (CSA). 1992b. Commercialfoodshrimpfisheryimpacts on by-catch in the lowerSt. 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 CharacterizationofTampa Bay Sediments. TheCenterfor NearShoreMarine Science ofthe 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.

129Fehring, W.K. 1985. Historyand developmentofthe portofTampa. 

### l.o. S.F. Treat, J.L. Simon, R.R. Lewis Ill, and R.L. Whitman, Jr.,eds. ProceedingsoftheTampa 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 changescaused bydredge 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 ofTampa and Sarasota Bays. 

### ln. E.D. Estevez, ed. Tampa and Sarasota Bays: Issues, Resources, Status, and Management. NOAA Estuary-of-the-MonthSeminarSeries No. 11. U.S. Dept. Commerc.Washington, D.C. pp. 49-64. Goodwin, C.R. and D.M. Michaelis. 1984. Appearanceand waterqualityofturbidity plumes produced by dredging in Tampa Bay, Florida. U.S. Geological SurveyWater Supply Paper 2192. U.S. Geological Survey, Alexandria, Virginia. Haddad, K. 1989. Habitattrends and fisheries in Tampa and Sarasota Bays. 

### ln. E.D. Estevez, ed. Tampaand Sarasota Bays: Issues, Resources, Status, and Management. NOAA Estuary-of-the-Month Seminar Series No. 11. U.S. Dept. Commerc. Washington, D.C. pp. 113-128. Hall,J.R. and C.H. Saloman. 1975. Distributionand abundanceofmacroinvertebrate species of six phyla in Tampa Bay, Florida, 1963-64 and 1969. National Marine Fisheries, Panama City, Florida. Data Report 100. Hartley, K. 1993. PersonalCommunication. Tampa Bay National EstuaryCommittee, Citizens Advisory Committee Member. Hesselman, D. and J. Seagle. Draft 1991. Comprehensive Shellfish HarvestingArea Survey, LowerTampa 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 to water quality in Hillsborough Bay, a highly impacted subdivision of Tampa Bay, Florida. 

## 1n E.D. Estevez, ed. Tampa and Sarasota Bays: Issues, Resources, Status, and Management. NOAA Estuary-of-the-Month Seminar Series No. 11. U.S. Dept. Commerc. Washington, D.C. pp. 129-143. Joyce, E.A. and B. Eldred. 1966. The Florida Shrimping Industry. Educational Series No. 15. Florida DepartmentofEnvironmental Protection,Marine Research Laboratory, St. Petersburg Florida (Formerly Florida Board of Conservation Marine Laboratory}. Killam, K.A., R.J. Hochberg, and E.C. Rzemien. 1992. Synthesis of basic life histories of Tampa Bay species. Prepared for the Tampa Bay National Estuary Program. St. Petersburg, Florida. Leverone, J.R., J.K. Culter, J.S. Sprinkel, M.R. Milligan, and S. Mahadevan. 1991. EvaluationofLong-termStudiesofthe BenthicCommunityintheVicinityofBig Bend, Tampa Bay. 

## 1n S.F. Treat and P.A. Clark, eds. Proceedings of the Tampa Bay Scientific Information Symposium, February, 1991. Tampa, Florida. pp. 399-414. Lewis, R.R.,III 1977. Impacts ofdredging intheTampa Bay estuary, 1876-1976. 

## 1n E.L. Pruitt, ed. Proceedingsofthe SecondAnnual Conferenceofthe Coastal Societytime-stressed environments: assessments and future actions. Coastal Society, Arlington, Virginia. pp. 31-55. Lewis, R.R.,III and E.D. Estevez. 1988. The ecology of Tampa Bay, Florida: an estuarine profile. U.S. Fish WildI. 

### Serv. Bioi. Rep. 85(7.18}. Lewis, R.R.,III and Robert L. Whitman,Jr. 1985. A newgeographicdescriptionofthe boundaries and subdivisions ofTampa Bay. 

## 1n 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. 10-18. Lewis, R.R.,III, M.J. Durako, and R.C. Phillips. 1985. Seagrass meadows ofTampa Bay- a review. 

## 1n 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. 210-246. 131Lewis, R.R., Ill, K.D. Haddad, and J.O.R. Johansson. 1991. Recent areal expansion of seagrass meadows in Tampa Bay, Florida: real bay improvement or droughtinduced? 

### lo. S.F. Treat and P.A. Clark, eds. Proceedings ofthe Tampa Bay Scientific Information Symposium, February, 1991. Tampa, Florida. pp. 189-192. Lombardo, R., and R.R. Lewis Ill. 1985. A review of commercial fisheries data: Tampa Bay Florida. 

### lo. 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. 614-634. Long, E.R., D. MacDonald, and C. Cairncross. 1991. Status and trends intoxicants and the potential fortheir biological effects in Tampa Bay, Florida. NOAATechnical Memorandum NOS OMA 58. NOAA- National Ocean Service, Rockville, Maryland. Meyer, D.L., M.S. Fonseca, P.L Murphey, M.W. LaCroix, P.E. Whitfield, D.R. Colby, and Gordon W. Thayer. 1991. Impactof baitshrimptrawling on seagrass beds and fish by-catchinTampaBay, Florida. PreparedforFlorida DepartmentofEnvironmental Protection, Marine Research Institute. St. Petersburg, Florida. Norris, M.B. 1994. Personal Communication and Vessel Registration Data. Florida Department of Environmental Protection, Fisheries Statistics. Ohop, J. 1994. Personal Communication. Florida Department of Environmental Protection, Fisheries Statistics. Orlando, S.P., F. Shirzad,J.M. Schuerholz, D.P. Mathieux, and S.S. Strassner. 1988. National Estuarine Inventory: ShorelineModification, DredgedChannels,and Dredged Material DisposalAreas inthe Nation's Estuaries. National Oceanic and Atmospheric Administration, U.S. Department of Commerce. Rockville, Maryland. Pinellas CountyDepartmentofEnvironmental Management (PCDEM). 1992. Ambient surface water monitoring report, data year October, 1990 - December, 1991. PC DEM, Pinellas County, Florida. 194 pp. Schoellhamer, D.H. 1991. Tributary storm runoff and vessel-generated sediment resuspension atthe PortofSt. Petersburg, Florida. 

### lo. S.F. Treatand P.A. Clark, eds. 132

### Proceedings of the Tampa Bay Scientific Information Symposium, February, 1991. Tampa, Florida. pp. 429-438. Seagle,J. 1992. PersonalCommunication. Florida DepartmentofNatural Resources, Shellfish Environmental Assessment Section. Tallahassee, Florida Tampa Bay Regional Planning Council (TBRPC). 1993. State ofTampa Bay, 1991- 1992. TBRPC, St. Petersburg Florida. Taylor,J.L. 1971. PolychaetousannelidsandthebenthicenvironmentinTampa Bay, Florida. Ph.D. Dissertation. Published by University of Florida. Gainesville, Florida. Taylor, J.L. and C.H. Saloman. 1969. Sediments, Oceanographic Observation, and Floristic Data from Tampa Bay, Florida and Adjacent Waters. University of South Florida, St. Petersburg, Florida. Tiffany,W.J. and D.E.Wilkinson. 1989. Portsand portimpacts.lnE.D. Estevez, ed. Tampa and Sarasota Bays: Issues, Resources, Status, and Management. NOAA Estuary-of-the-MonthSeminarSeries No. 11. U.S. Dept. Commerc.Washington, D.C. pp. 171-185.

1336. DATA SOURCES FOR GIS COVERAGES

134Habitat 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 1990Seagrass 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: NoneData 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, 1900to 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 1950Reduction/ 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, 19691971-1989 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 

## < 63flffi 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 1986to 1990 Pinellas Co. OEM, 11 stations, from 1990to 1991 FDNR MARFIM, samples from non-fixed stations, from 1990to 1991Reduction/ 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, 1964and 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: NonePhysical 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 digitizedData 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 chartsand byseawall construction readilyapparenton 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 polygonsData 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, 1992of 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