Feeding Ecology of Green Sea Turtles (Chelonia Mydas) at South Padre Island, Texas Was Characterized from April 1991 - March 1993

FEEDING ECOLOGY OF SUBADULT GREEN SEA TURTLES IN SOUTH TEXAS WATERS

A Thesis by MICHAEL SCOTT COYNE

Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

May 1994

Major Subject: Wildlife and Fisheries Sciences

Table of Contents FEEDING ECOLOGY OF SUBADULT GREEN SEA TURTLES IN SOUTH TEXAS WATERS

A Thesis by MICHAEL SCOTT COYNE

Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

Approved as to style and content by:

______André M. Landry, Jr. Robert B. Ditton (Co-Chair of Committee) (Co-Chair of Committee)

______David W. Owens Robert Brown (Member) (Head of Department)

May 1994

Major Subject: Wildlife and Fisheries Sciences

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ABSTRACT

Feeding ecology of subadult green sea turtles in South Texas waters. (May 1994) Michael Scott Coyne, B.S., University of Florida Co-Chairs of Advisory Committee: Dr. André M. Landry, Jr. Dr. Robert B. Ditton

Feeding ecology of green sea turtles (Chelonia mydas) at South Padre Island, Texas was characterized from April 1991 - March 1993. Ninety turtle captures in entanglement and cast-nets were comprised of 24 individuals from jetty habitat at Brazos Santiago Pass and 27 others over grassbed habitat of South Bay/Mexiquita Flats. Size range of captured turtles [22.2 - 81.5 cm straight carapace length (SCL)] indicated that green sea turtles use the two sites as developmental habitats. Size of turtles differed significantly between sites (jetty: 22.2 - 47.9 cm, mean - 31.3 cm SCL; grassbeds: 29.6 - 81.5 cm, mean - 44.6 cm SCL). Comparison of food items flushed from green turtle stomachs with available forage material suggested significant feeding selectivity. Turtles from jetty environs fed strictly on algae, showing a preference for Ulva fasciata, Rhodymenia pseudopalmata, Family Ceramiaceae, Bryocladia sp., and Hypnea musciformis. Grassbed turtles fed primarily on seagrasses and exhibited a preference for the least abundant taxon, Halodule wrightii. The von Bertalanffy -0.0768t growth interval equation was Lt = 113.84(1 - 0.960e ). Age at maturity estimates ranged from 18 to 26 years. Highest growth rate was observed in spring and summer (0.62 and 0.64 cm/month, respectively) and lowest in winter (0.14 cm/month). Activity patterns varied seasonally, with increased movement during months when mean water temperature exceeded 25 C. Strong site fidelity also was observed during warmer months.

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ACKNOWLEDGMENTS

There are many to whom I am indebted for their assistance, advice, and moral support in the completion of my thesis. Lack of space and a poor memory makes it impossible to name everyone. However, I offer my sincerest gratitude to all who have made this effort possible. To the members of my committee, Dr. André M. Landry, Jr., Dr. Robert B. Ditton, and Dr. David W. Owens, I owe many thanks. Their patience and wisdom proved invaluable. Special thanks goes to Dr. André M. Landry, Jr., my principal advisor. His own drive made it possible for me to accomplish my goals and pushed me to always improve myself. My gratitude extends to the many agencies whose cooperation made it possible to complete this research. These include the National Marine Fisheries Service, U.S. Army Corps of Engineers, Texas A&M University Sea Grant Program, and U.S. Fish and Wildlife Service. Special mention goes to University of Texas’ Pan American Laboratory for allowing us free run of their facility. Extraordinary praise go to the turtle crew. The many brave souls that risked sharks, stingrays, and mind-numbing grass sorting in collecting and processing data: David Costa, Kelly Craig, Brett Williams, Russel O’brien, Karen St. John, Vicky Poole, Leonard Kenyon, Stacie Arms, Travis Hanna, Sarah Werner, John Christensen, Randy Clark, all of the MARB 485 students, and others who lent assistance. I would like to acknowledge the Biology department in College Station and the Marine Biology department in Galveston for providing Teaching Assistantships and other sources of funding enabling the completion of this degree. Finally, I would like to recognize friends and family who said the right things at the right times, and who enabled me to enjoy every aspect of the experience: Dr. George W. and Laura J. Coyne, Christean Coyne, Matthew Polly, Nancy Mettee, Hava Berman, Denise Brown, Lynette Goodman, the Ultimate players that have touched my life, and all the graduate students with whom I’ve worked.

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TABLE OF CONTENTS

Page

ABSTRACT ...... iii ACKNOWLEDGMENTS ...... iv TABLE OF CONTENTS...... v LIST OF TABLES ...... vii LIST OF FIGURES ...... ix LIST OF APPENDIX TABLES ...... xi INTRODUCTION ...... 1 STUDY AREA ...... 5 METHODS ...... 9 TURTLE CAPTURE AND RELATED ACTIVITIES ...... 9 Turtle Capture ...... 9 Visual Observations ...... 9 Tagging Activities ...... 10 Stomach Sample Analysis ...... 10 HABITAT CHARACTERIZATION ...... 10 Hydrological Monitoring ...... 11 SCUBA Surveys ...... 11 GROWTH MODELING ...... 12 RESULTS ...... 13 SEA TURTLE CAPTURE AND RELATED ACTIVITIES...... 13 Sea Turtle Sightings ...... 19 STOMACH EVACUATION ...... 23 HABITAT CHARACTERIZATION ...... 24 Hydrological Monitoring ...... 24 Jetty Characterization ...... 26 Grassbed Characterization ...... 29 HABITAT UTILIZATION...... 35 Recaptures ...... 35 Tracking ...... 35 GROWTH...... 36

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Page

DISCUSSION...... 43 POPULATION DYNAMICS ...... 43 BEHAVIOR ...... 46 FEEDING ECOLOGY ...... 47 SUMMARY ...... 50 LITERATURE CITED ...... 51 APPENDICES ...... 55 VITA ...... 76

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LIST OF TABLES

Table Page

1 Sea turtle capture effort in the South Padre Island study area during April 1991 - March 1993...... 13

2 Number of green sea turtles taken by capture method in the South Padre Island study area during April 1991 - March 1993...... 14

3 Percent biomass and frequency of occurrence of identifiable phyla found in stomach contents of green sea turtles ( n = 76 ) captured in the South Padre Island study area during April 1991 - March 1993...... 25

4 Dominant (≥ 5% of total identifiable biomass) food items found in stomach contents of green sea turtles ( n = 76 ) captured in the South Padre Island study area during April 1991 - March 1993 ...... 25

5 Dominant (≥ 5% of total identifiable biomass) food items in green sea turtles captured from Brazos Santiago Pass and South Bay/Mexiquita Flats sites during April 1991 - March 1993 ...... 26

6 Seasonal occurrence of dominant (≥ 5% of total identifiable biomass) food items in green sea turtles captured from Brazos Santiago Pass and South Bay/Mexiquita Flats sites during April 1991 - March 1993 ...... 27

7 Average monthly air and water temperature and salinity in the South Padre Island study area during April 1991 - March 1993. Detailed monthly hydrological data are presented in Appendix Table 3...... 28

8 Epiphytic and encrusting taxa found at Brazos Santiago Pass habitat characterization stations during summer 1991 and 1992 ...... 30

9 Date, location, and straight carapace length (SCL) of repeated green sea turtle captures from Brazos Santiago Pass during April 1991 - March 1993. See Appendix Table 1 for a complete description of each capture...... 37

10 Date, location, and straight carapace length (SCL) of repeated green sea turtle captures from South Bay/Mexiquita Flats during April 1991 - March 1993. See Appendix Table 1 for a complete description of each capture ...... 38

11 ID number, capture and release date, straight carapace length (SCL), and date of last contact of green sea turtles tracked at Brazos Santiago Pass by National Marine Fisheries Service personnel during 1992 ...... 39

12 Average annual growth rate between each capture of 10-cm size classes (N = sample size) for green sea turtles from the South Padre Island study area...... 40

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Table Page

13 Average annual growth rate across seasons ( N = sample size ) for green sea turtles in the South Padre Island study area...... 40

14 Estimated values for the parameters a, k, and b from non-linear regression of von Bertalanffy growth interval equations for green turtles...... 41

15 Estimated values of asymptotic length (a), intrinsic growth rate (k), and age at sexual maturity from non-linear regression of the von Bertalanffy growth interval equation for green turtles at various locations...... 45

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LIST OF FIGURES

Figure Page

1 Number of stranded green sea turtles within NMFS statistical zones 1 through 21 during April 1980 - May 1991. Data provided by NMFS Sea Turtle Stranding and Salvage Network...... 4

2 Sea turtle capture and habitat characterization study area...... 6

3 Brazos Santiago Pass sampling zones A - Z...... 7

4 South Bay and Mexiquita Flats sampling stations ...... 8

5 Location and number of green sea turtles taken at Brazos Santiago Pass during April 1991 - March 1993 ...... 15

6 Location and number of green sea turtles taken at South Bay/Mexiquita Flats sampling stations ...... 16

7 Length frequency at first capture of green sea turtles from Brazos Santiago Pass and South Bay/Mexiquita Flats during April 1991 - March 1993 ...... 17

8 Number of green sea turtle captures and stationary netting hours at South Bay/Mexiquita Flats during each month...... 18

9 Number of green sea turtle captures and days of effort at South Bay/Mexiquita Flats during each hour...... 18

10 Number of sea turtle sightings per hour of observation effort at Brazos Santiago Pass during April 1992 - March 1993. Total number of monthly sightings is shown on top of histogram bars ...... 19

11 Average number of sea turtle sightings per hour of observation effort at Brazos Santiago Pass jetty-zone observation posts (A - Z) during April 1992 - March 1993 ...... 20

12 Average number of sea turtle sightings per observation hour at Brazos Santiago Pass from April 1992 - March 1993 (8 = 0800 - 0900 hrs, 9 = 0900 - 1000 hrs, etc...) ...... 21

13 Number of sea turtle sightings at increasing distances from Brazos Santiago Pass jetties during April 1992 - March 1993 ...... 22

14 Number of individual sea turtles sighted per month at Brazos Santiago Pass during April 1992 - March 1993...... 23

15 Average monthly air and surface water temperature (C) and salinity (ppt) in the South Padre Island study area from April 1991 - March 1993...... 29

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Figure Page

16 Percent composition of sea grasses, epiphytic algae, and bryozoans at habitat characterization stations in South Bay and Mexiquita Flats...... 32

17 Percent composition of dominant (≥ 5%) seagrass and algae taxa at Mexiquita Flats station 15 during April 1992 - February 1993 ...... 33

18 Percent composition of dominant (≥ 5%) seagrass and algae taxa at South Bay station 21 during August 1991 - March 1993 (* June 1992 samples were taken from an adjacent grassbed separated from station 21 by a narrow channel)...... 34

19 Percent composition of dominant (≥ 5%) seagrass and algae taxa at South Bay station 28 during September 1991 - March 1993 ...... 34

20 Predicted growth curve for green sea turtles from the South Padre Island study area during April 1991 - March 1993. Dotted lines indicate size classes for which no data were available...... 42

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LIST OF APPENDIX TABLES

Table Page

1 Capture statistics for green sea turtles from the South Padre Island study area during April 1991 - March 1993 ...... 56

2 Stomach contents from green sea turtles captured in the South Padre Island study area during April 1991 - March 1993...... 58

3 Hydrological data from the South Padre Island study area during April 1991 - March 1993 ...... 65

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INTRODUCTION

All sea turtles in U.S. waters are listed as either endangered or threatened (Public Law 93-205), and as such, are covered under the Endangered Species Act of 1973 which provides for their conservation, protection, and propagation. Congress amended the Endangered Species Act in 1988 (Public Law 100-478) to authorize an independent review of scientific information on sea turtles by the National Academy of Sciences (NAS) in order to establish a sound technical basis for protecting these species (Magnuson et al., 1990). The subsequent review reported that human activities, including commercial fisheries, dredging, boat collisions, oil platform removal, and discard of plastics and debris, are major causes of sea turtle mortality. The committee’s recommendations to optimize research on these stocks included identifying and charac- terizing the status, size, age structure, distribution, and concentration, of the green sea turtle (Chelonia mydas). The green turtle is the only herbivorous sea turtle, and, as such, its feeding habits have been the subject of much research. Descriptive information on feeding habits has been collected from the Bahamas (Bjorndal, 1980), U.S. Virgin Islands (Ogden et al., 1983; Williams, 1988), Nicaragua (Mortimer, 1981), and Mosquito Lagoon, Florida (Mendonca, 1983). A review of the literature (Bjorndal, 1985) sug- gests that green turtles feed on either sea grasses or algae, possibly as a result of their hindgut fermentation. Because the complex carbohydrates found in sea grasses and algae are different, a different microflora may be required to digest each efficiently. Cellulose, the major structural carbohydrate in sea grasses, is present in only small amounts in algae (Percival, 1964), most of which contain complex structural carbohydrates such as glucan, mannan, xylan, agar, carrageenan, alginic acid, and uronic acid (Chapman and Chapman, 1973). However, it has been suggested that gut microflora may change over time allowing for long term adjustment to both grass and algae diets (Bjorndal, 1980). The green turtle forages primarily on sea grasses in most of its’ range (Hirth, 1971), with algae making up the bulk of the diet where seagrasses are lacking, e.g., off the coast of Brazil, Tahiti, and Hawaii (Balazs, 1979a, b), Galapagos Islands (Pritchard, 1971), and South African coast (Hughes, 1974). In addition, some locales support green turtle colonies that feed mainly on sea grasses within a few kilometers of others

______This thesis follows style and format of the journal Copeia 2

that forage primarily on algae. Such conditions exist along the west coast of Honduras (Carr, 1952), Gulf of California (Felger and Moser, 1973), Fiji (Hirth, 1971), Gulf of Aden (Hirth et al., 1973), and Torres Strait of Australia (Garnett and Murray, 1981). Green turtles feed predominantly on three seagrass species: Thalassia testudinum, Syringodium filiforme, and Halodule wrightii. Syringodium was found to be twice as abundant as Halodule from green turtles studied at Mosquito Lagoon, Florida (Mendonca, 1983). Thalassia was the primary dietary component for green turtles in Bahamian waters (Bjorndal, 1980, 1985) and in the U.S. Virgin Islands (Ogden et al., 1983; Williams, 1988). Green turtles also forage on green, brown, and red algae. Ferreira (1968) found red algae dominated the diet of Brazilian green turtles. Only red and green algae were found in stomachs of 26 green turtles from Torres Strait, Australia (Garnett and Murray, 1981). Green turtles in Tokelau, south central Pacific, fed largely on green algae, with some brown algae (Balazs, 1983). Two species of green and red algae were major dietary components of green turtles near islands of the Hawaiian Archipelago. Three green, one red and one brown alga comprised the bulk of green turtles’ diet in the northwestern islands of the same archipelago (Balazs, 1980). Brown algae has only been reported as a major dietary component in green turtles from the Ogasawara Islands, Japan (Kurata et al., 1978). It is uncertain what roles feeding selectivity and relative abundance of different forage species play in determining green turtle diet. Ferreira (1968) attributed the high incidence of red algae in green turtle stomachs solely to greater abundance of red algae in Brazilian feeding areas. Conversely, Balazs (1980) presented evidence that both factors influence feeding habits of Hawaiian green turtles. Neck (1978) described historical occurrence of green turtles in Texas waters during the late 1800’s in a review of the journals of geologist Robert Penrose. These journal entries indicated that green turtles may have nested in abundance on beaches adjacent to the Rio Grande during 1889. Doughty’s (1984) review of data from turtle canneries at Indianola, Fulton, Corpus Christi, and Point (Port) Isabel presents strong evidence that green turtles were abundant in inshore Texas waters during the 1800’s. Landings estimates for Texas indicate that the fishery peaked in 1890 when 265,000 kg of turtle (approximately 2,159 turtles) were processed. Thereafter, a steady decline in turtle landings resulted in all canneries closing or moving to Mexico by 1897. The last year for which data were available indicated 680 kg (approximately 6 turtles) were

Table of Contents 3 landed in 1927. Rabalais and Rabalais (1980) reported 10 green turtles stranded along the Texas coast from 1976 to 1979, five of which were juveniles heavily fouled with oil from the August 1979 Ixtoc I well blowout. More recently, Shaver (1990a) reported the capture of one green turtle in the Laguna Madre near Mansfield Pass and 40 captures of 25 turtles at the Mansfield Pass jetties during June 1989 - May 1990. Addi- tionally, Shaver (1990b) reported 45 green turtles cold stunned in the Laguna Madre during February 1989. Information concerning feeding behavior is restricted to gut contents of a few stranded animals (Stanley, unpublished). The limited data available on green turtles in Texas waters, especially those from near shore, mandate research on this species’ natural history to improve development of management decisions (i.e. regulation of commercial fisheries, dredging, oil platform removal, and habitat protection). Recent sightings near jetties and in bays along the lower Texas coast (Williams and Manzella, 1990) indicate that green turtles are moderately abundant in South Texas waters. In addition, data collected by the National Marine Fisheries Service’s (NMFS) Sea Turtle Stranding and Salvage Net- work (Fig. 1) indicate the lower Laguna Madre is second only to the Florida Keys in green turtle strandings. These data confirm that South Texas waters are ideal for the study of green sea turtles. This study was conducted to generate information on feeding ecology of green sea turtles from South Texas waters in order to: 1) identify food items consumed and feeding preferences; 2) delimit foraging areas; 3) assess seasonal variations in diet and possible causes for this variation; and 4) compare and contrast size composition and growth of turtles captured in different foraging areas.

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Number of stranded turtles 0 10 - 25 50 - 99 1 - 9 26 - 49 100 +

MS AL TX LA 12 7 19 10 9 11 8 13 6 18 17 16 15 14 FL 20 5 21 4 Gulf of Mexico 3

2 1

Figure 1. Number of stranded green sea turtles within NMFS statistical zones 1 through 21 during April 1980 - May 1991. Data provided by NMFS Sea Turtle Stranding and Salvage Network.

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STUDY AREA

The study was conducted in inshore waters adjacent to South Padre Island, Texas from April 1991 through March 1993 (Fig. 2). Specifically, jetty habitat at Brazos Santiago Pass (BSP) and grassbed habitats in South Bay and Mexiquita Flats were sampled. Brazos Santiago Pass is a narrow (92-m wide) channel between the south end of South Padre Island and the north end of Brazos Island with a maximum depth of 11.6 m. Two 1.5-km long granite mound structures known as the North and South Jetties border north and south sides of BSP at its entrance into the Gulf of Mexico. Shallow, relatively flat coves (Dolphin and Barracuda Coves along the north and south sides, respectively) with a hard sand bottom and average depth of 2.1 m are located inside the west end of each jetty. The Gulf side of each jetty exhibits a gentle-sloping, barren, hard-sand-bottom beach out to a maximum depth of 5.5 m. The BSP area was divided into 40 100-m long zones to identify sampling locations (Fig. 3). South Bay and Mexiquita Flats consisted of grassbed and channel habitats along the easternmost reaches of the Brownsville Ship Channel (BSC) between Chan- nel Markers 28 and 16 (Fig. 4). Grassbed habitats in South Bay and Mexiquita Flats were less than 1.5-m deep and consisted of a silt and hard sand substrate. The BSC was 2.25-km long, 61.0-m wide with an average maximum depth of 11.0 m and was bordered on the south and north by seagrass habitats of South Bay and Mexiquita Flats, respectively. BSC channel substrate consisted of mud with varying proportions of sand, clay, and silt extending to grassbed habitat at a depth of 1.8 m. This area contained six sampling stations.

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Galveston LA Bay N TEXAS

Matagorda Bay

Corpus Christi GULF Bay OF MEXICO

Padre Island

Port Brazos Isabel Santiago Mexiquita Pass Flats Brazos Island Brownsville Ship Channel Lower Laguna Madre South Bay

MEXICO

Figure 2. Sea turtle capture and habitat characterization study area.

Table of Contents 7 N Jetty South North Jetty A M B N Gulf of Mexico C O D P E Q F R G S Brazos Island H T I J U K L V W X South Padre Island Cove Y Barracuda Brazos Santiago Pass Z Dolphin Cove Jetty Characterization Stations Figure 3. Brazos Santiago Pass sampling zones A - Z.

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South Padre Island Brazos Santiago Pass 31 Brownsville Ship Channel

Long Island Mexiquita 16 Flats 29 22 Brazos 15 Island 28 Gulf of Mexico

South Bay 30

Sampling Station # Channel Marker

Figure 4. South Bay and Mexiquita Flats sampling stations.

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METHODS

TURTLE CAPTURE AND RELATED ACTIVITIES

Turtle Capture: Turtle capture was accomplished with 91.4-m long entanglement nets of different depth and mesh size specifications deployed in two configurations. These nets were 3.7- or 7.4-m deep with 12.7-cm bar mesh of #9 twisted nylon or 4.9-m deep with 25.4-cm bar mesh of #9 twisted nylon. Jetty, grassbed and channel habitats of BSP and South Bay/Mexiquita Flats (SB/MF) were sampled during the day with one to four stationary entanglement nets set adjacent to one another for 8 to 12 hours. In addition, a more active capture method of encircling turtles with entanglement nets was deployed at jetty habitats when turtles displayed certain behavioral traits. These traits included: 1) exhibiting a predictable pattern of surfacing and sounding; and 2) surfacing occurs no more than 10 m from and along a limited length of jetty. Encirclement sets were deployed from a boat with the net secured to the jetty creating a “semi-circle” around a turtle’s expected surfacing spot . Standard bait cast nets (2-m diameter) were utilized to capture turtles in areas unfavorable for stationary or encirclement netting. Ability to capture turtles with cast nets was dependent on a turtle’s behavior and proximity to the jetty. Cast nets were utilized only when turtles exhibited frequent and extended surface intervals within 5 m of the jetty proper. Any day in which multiple attempts were made to capture sea turtles using a cast-net was considered to be a cast-netting day. Visual Observations: Observations were initially conducted throughout the BSP study area in April 1992 to identify sea turtle occurrence and potential capture sites. These observations continued at random through June 1992. Thereafter, a systematic observation protocol was deployed at all North and South Jetty zones to generate data on number of sightings and individual turtles seen per hour of observation as well as to characterize spatial distribution of turtles in relation to jetty and channel habitats. Vi- sual sightings were conducted along the North and South Jetties to locate turtles, aid in their capture and define the habitats they frequented. Jetties were divided into 38 100- m lengths and each tip for a total of 40 sampling zones at BSP (Fig. 3). Observations were made by 2-5 individuals each surveying a randomly chosen jetty zone for one hour at random times of day from July 1992 through March 1993. Species, date, time, location, and any observed behaviors were recorded each time a turtle was sighted.

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Tagging Activities: Immediately following capture, all turtles were transported to the University of Texas’ Pan American Coastal Studies Laboratory on South Padre Island where they were held in a 3.0-m diameter fiberglass holding tank for 24 to 72 hours before being tagged and released. All turtles were measured to the nearest 0.1 cm, photographed and tagged at the lab. Straight line carapace length and width were measured with a forester’s caliper. Over-the-curve carapace length and width were measured with a soft measuring tape. Turtles were tagged with an inconel flipper tag, provided by NMFS, on the trailing edge of each fore flipper and released at the same location as captured. Tagging data were submitted to NMFS (Miami) on two data forms entitled “NMFS/SEFC Marine Turtle Tagging Data (Rehabilitated, Netted or other Release)” and “NMFS/SEFC Marine Turtle Tagged/Recapture Data”. Turtles meeting certain size and weight criteria were provided to NMFS (Galveston) and Texas A&M University (TAMU) personnel for attachment of sonic and radio transmitters and subsequent tracking. Stomach Sample Analysis: A stomach evacuation technique developed by Balazs (1980) was used to flush the foregut of each turtle captured to obtain material for food habit analysis. In short, sea water was flushed into the foregut through a plastic tube introduced into the esophagus. Food material was backwashed out through the mouth and collected in a plastic tub. All food material obtained was preserved in 10% formalin, labeled and held for laboratory analysis. Each sample was sorted in the laboratory and observed under a compound microscope to identify vegetation and animal matter to the lowest possible taxon. Resulting data were used to analyze frequency of occurrence of food items. A one-way analysis of variance (ANOVA) was used to determine seasonal variability.

HABITAT CHARACTERIZATION

Turtles captured during netting activities across the study area, meeting size and weight criteria, were released in the same area in which they were captured, and were tracked by the aforementioned personnel. Tracking data were used to pinpoint habitats occupied by turtles. These habitats were then characterized by on-site efforts which consisted of: 1) hydrological monitoring; and 2) SCUBA surveys. A description of these characterization techniques follows.

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Hydrological Monitoring: Surface and bottom measurements (depth permitting) were taken whenever a netting site was occupied to characterize hydrological conditions. Temperature, salinity, and conductivity were measured (to the nearest 0.01-C, -ppt, and - mΩ/s, respectively) with a Beckman Instrument Company SCT meter; visibility was measured to the nearest 0.1 m with a Secchi disk; and tidal flow was estimated by field personnel. SCUBA Surveys: Turtle capture locations and telemetric tracking by NMFS and TAMU personnel resulted in a total of six sampling stations. Two stations were in South Bay, one at the mouth of South Bay, and three in Mexiquita Flats (Fig. 4). Each station was characterized initially by a SCUBA survey to describe habitat and potential food sources available to sea turtles. This survey consisted of several tasks: 1) subsurface visual observations; 2) quantitative transects; and 3) sample quadrates (flora and fauna). Subsurface visual observations were conducted by two to four SCUBA divers to describe the habitat (i.e. channel, grassbed, barren-bottom) and assess prevailing water conditions (i.e. visibility, current). This assessment dictated which characterization task(s) could be conducted and the number of samples taken for each task. Quantitative transects were deployed to characterize available forage species. Three 25-m transect lines laid parallel to one another approximately 20-m apart were visually surveyed by two SCUBA divers swimming down either side of the line. Each diver recorded all organisms and habitat characteristics along a 1-m corridor. Quadrates were utilized to characterize prey availability, vegetative cover and sediment texture. After swimming transects were completed, 0.25-m2 quadrates were placed randomly within each site and contents recorded and collected. Algae and sea grasses within the 0.25-m2 quadrate were cut 2.54 cm above the sediment, bagged, labeled and frozen or preserved in 10% formalin and returned to the laboratory for analysis. Six quadrates were deployed at each SB/MF station every two months to determine seasonal variation. Each vegetation sample was rinsed with sea water and separated to the lowest possible taxon. Separated taxa were placed in paper bags, labeled and stapled shut. Each paper bag was dried in an oven for approximately 40 hr at 82 C. After drying, each bag and its contents were weighed and the mass of an empty, stapled bag subtracted. The resulting weight was used as dry mass for each species. Percent biomass was determined by dividing the dry mass of each species in a quadrate by the dry mass of all taxa in the quadrate. An ANOVA of the dry mass of dominant species (≥ 5% biomass) at

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stations 15, 21 and 28, was used to determine whether changes observed within quadrates were due to seasonal variation. Vegetation also was collected at BSP jetty stations to develop a species list. Nine of 40 zones at the BSP jetties (Fig. 3) were designated as characterization stations. Five stations were sampled during summer 1991 and 1992 (P outside, P inside, A outside, E, and W). The other four stations (K, G-H, A-B inside, and Y) were sampled only during summer 1992.

GROWTH MODELING

Preliminary attempts to develop a growth curve for green turtles from the study area follow methodology of Frazer and Ehrhart (1985). Straight line carapace measurements at capture and recapture and time intervals between capture and recapture were fit to the von Bertalanffy growth interval equation with JMP v. 2 non-linear least squares regression procedure (SAS Institute Inc., 1989). The general von Bertalanffy equation used was:

L = a(1 - be-kt), (1)

where L is carapace length, a is asymptotic length, b is a parameter related to length at hatching, e is the base of the natural logarithm, k is the intrinsic growth rate, and t is age in years. The von Bertalanffy growth interval equation (Fabens, 1965) for recapture data was:

-kd Lr = a - (a - Lc)e , (2)

where Lr is carapace length at recapture, Lc is length at first capture, and d is time in years between capture and recapture. Once an estimate was available for a, equation 1 was rearranged to calculate a value for b if the size of the organism at birth (L0) was known (Fabens, 1965). At hatching (t = 0), equation 1 simplifies to:

L0 = a(1 - b). (3)

Rearranging equation 3 yielded:

b = 1 - L0/a. (4)

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RESULTS

SEA TURTLE CAPTURE AND RELATED ACTIVITIES

Capture activities consisted of 1,649 hours of stationary entanglement netting effort at 7 locations, 45 encirclement-net attempts, and 7 days of cast-netting effort (Table 1). All stationary netting effort during 1991 at BSP took place in zones W and K, in Dolphin and Barracuda Coves, respectively. Most capture efforts at BSP during 1992 and 1993 were deliberate attempts to catch observed turtles through encirclement or cast-netting. Entanglement netting efforts at SB/MF were divided between stations 15 (743 hours), 28 (74 hours), and 29 (74 hours), with an additional 5 hours of effort in South Bay proper. Encirclement netting was first attempted at BSP in July 1991 and became the standard sampling technique for that site. Four encirclement attempts at SB/MF during 1993 were concerted efforts to capture turtles previously equipped with radio and sonic telemetric gear. The cumulative netting effort yielded 90 green sea turtle captures, 48 from BSP and 42 from SB/MF (Table 2 and Appendix Table 1). Thirty-nine recaptures involved 15 individuals and produced a 43.3% recapture rate. Thirty-six individuals were captured once, four twice, five on three occasions, two on four occasions, three on five occasions, and one individual was captured eight times.

Table 1. Sea turtle capture effort in the South Padre Island study area during April 1991 - March 1993. Brazos Santiago Pass South Bay/Mexiquita Flats 1991 1992 1993 1991 1992 1993

Stationary Netting (hours) 454 14 2 360 605 214 Encirclement Netting (attempts) 7 31 3 004 Cast-Netting (days) 0 7 0 000

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Table 2. Number of green sea turtles taken by capture method in the South Padre Island study area during April 1991 - March 1993.

Brazos Santiago Pass South Bay/Mexiquita Flats 1991 1992 1993 1991 1992 1993

Stationary Netting 3 5 1 12 22 4 Encirclement Netting 1 26 4 0 0 3 Cast-Netting 0 5 0 0 0 0 Incidental 2 1 0 0 1 0

Over 83% of all turtle captures (40) at BSP occurred along the South Jetty (Fig. 5). Of these, 31 captures were made along a 500-m length of jetty between zones G and L. This area was characterized by submerged granite blocks on a silt bottom extending to the channel from zones G to K changing to small boulders on a sand/silt bottom out to the channel toward the cove. One capture was made between zones A and B (channel side) consisting of submerged granite blocks dropping quickly into the channel, and eight captures were along the outermost 200 m (Gulf side) made up of submerged and partially submerged granite blocks on a sand bottom extending along the beachfront. Captures along the North Jetty were limited to seven green turtles taken from the channel side - four at zone P (3 captures were of one turtle) and three along a 200 m span between zones R through T. Gulf and channel sides of the North Jetty exhibited physical attributes similar to those along corresponding sides of the South Jetty. Incidental captures included one green turtle foul-hooked by a fisherman, another found entrapped between granite blocks near the end of North Jetty, and two hand captured while feeding on algae along the jetty. Mexiquita Flats stations 15 and 29 along the BSC and opposite the mouth of South Bay yielded 37 turtle captures from grassbed locales (Fig. 6). Two captures were made on the opposite side of the Brownsville Ship Channel (BSC) at station 28 while one turtle was caught in a bay shrimpers trawl in the BSC between channel markers 16 and 22. Two additional turtles were taken in encirclement nets in the northwest corner of Mexiquita Flats (station 31).

Table of Contents 15 Jetty N South North Jetty A 4 M 1 4 B N Gulf of Mexico C O D P 4 E Q F R G 1 S 11 Brazos Island 3 H 1 T 1 I 1 J U 2 K 1 6 L V 5 11 W X South Padre Island Cove Y Barracuda Brazos Santiago Pass Z Capture Location and Number Taken Dolphin Cove # Figure 5. Location and number of green sea turtles taken at Brazos Santiago Pass during April 1991 - March 1993.

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Long 2 31 Island CM 16 l e Mexiquita Flats n n a h 16 C 29 p i h CM 22 Brazos S Island 1 21 e 15 l 2 l 28 i v s n w o r B 21

# Sampling Station

North # Capture Location South Bay

Figure 6. Location and number of green sea turtles taken at South Bay/Mexiquita Flats sampling stations.

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Straight carapace length at initial capture for green sea turtles taken at BSP ranged from 22.2 to 47.9 cm and averaged 31.3 cm with a S.D. of 5.25. Turtles captured at SB/MF ranged from 29.6 to 81.5 cm and averaged 44.6 cm with a S.D. of 11.58. A pooled t-test of these data indicate a statistical difference ( t = -5.159 ) in the SCL of turtles captured from the two sites (Fig. 7). Monthly stationary netting efforts at SB/MF ranged from 34 hours during April to 236 hours during October (Fig. 8). Days of effort made in stationary netting at SB/ MF during each daytime hour ranged from 17 at 0700 hrs, peaked at 124 between 1100 and 1500 hrs, down to 8 at 1900 hrs (Fig. 9). Over half of all turtle captures (48) occurred between 0900 and 1300 hrs. Number of captures was closely related to effort except for low captures rates between 1000 and 1100 hrs, from 1300 to 1700 hrs, and no captures between 1800 and 1900 hrs.

16 14 Brazos Santiago Pass

12 South Bay/Mexiquita 10 Flats 8 6 4 Number of Individuals 2 0 80.0 + 20.0 -29.9 30.0 -39.9 40.0 -49.9 50.0 -59.9 60.0 -69.9 70.0 -79.9 Straight Carapace Length (cm)

Figure 7. Length frequency at first capture of green sea turtles from Brazos Santiago Pass and South Bay/Mexiquita Flats during April 1991 - March 1993.

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8 250

Captures 200 6 Hours

150 Hours 4

Captures 100

2 50

0 0 J FMAM J J A S OND Month

Figure 8. Number of green sea turtle captures and stationary netting hours at South Bay/Mexiquita Flats during each month.

Captures Days

8 125

100 6

75 Days 4

Captures 50

2 25

0 0 7 8 9 10111213141516171819 Time of Day

Figure 9. Number of green sea turtle captures and days of effort at South Bay/ Mexiquita Flats during each hour.

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Sea Turtle Sightings: Observations at BSP during April 1992 - March 1993 resulted in 448 hours of effort producing 447 sea turtle sightings. Green sea turtles constituted nearly all of these sightings. Monthly number of sightings ranged from 9 in December to 85 in August (Fig. 10). The rate at which turtles were sighted varied from less than 1.0 sighting/observation-hour during the cooler months of April - May and November - March to ≥ 2 sightings/observation-hour in June and August (Fig. 10). Frequency of turtle sightings and overall sighting rates were highest near South Jetty environs during April 1992 - March 1993 (Fig. 11). Overall, highest sea turtle sightings/observation-hour statistics were reported from the easternmost section of South Jetty, specifically zones A - D. Rates exceeding 5.0 sightings/observation- hour characterized gulf waters adjacent to zone A while rates at the jetty tip, along the inside of zones A, B, and D, and outside zones C and B ranged from 1.2 to 3.2 sightings/observation-hour.

2.5 85 83 78 2

1.5 47 38 1 21 Sightings/Hour 15 20 9 26 0.5 15 10

0 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR Month

Figure 10. Number of sea turtle sightings per hour of observation effort at Brazos Santiago Pass during April 1992 - March 1993. Total number of monthly sightings is shown on top of histogram bars.

Table of Contents 20 Jetty N South North Jetty A M B N Gulf of Mexico C O D P E Q F R G S Brazos Island H T I J U K L V W X South Padre Island Cove Y Barracuda Brazos Santiago Pass Z 5.0 0.9 ≥ ≤ 2.0-2.9 3.0-4.9 1.0-1.9 Dolphin Cove # of Sightings/Hour Figure 11. Average number of sea turtle sightings per hour observation effort at Brazos Santiago Pass jetty-zone observation posts (A - Z) during April 1992 March 1993.

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Another area yielding a considerable number of sightings was the westernmost end of South Jetty, where zones H to L exhibited 1.3 to 2.3 sightings/observation-hour. Turtle sightings along the North Jetty were patchy at best, with observation rates over 1.0 sighting/observation-hour only along zone U, inside zones S and P, and outside zones O and R. An analysis of observation rates in relation to time of day indicated a high of 1.8 sightings/observation-hour occurred between 1800 and 1900 hrs (Fig. 12). Obser- vation rates started with a low of 0.3 sightings/observation-hour at 0800 hrs and increased to 1.4 at 1000 hrs. Activity peaked again at 1300 and 1600 hrs with rates > 1.3 sightings/observation-hour.

1.5

1 Sightings/Hour 0.5

0 8 9 10 11 12 13 14 15 16 17 18 Time of Day

Figure 12. Average number of sea turtle sightings per observation hour at Brazos Santiago Pass from April 1992 - March 1993. (8 = 0800 - 0900 hrs, 9 = 0900 - 1000 hrs, etc...... )

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A distributional analysis of sightings in relation to distance from the jetties provided a well defined pattern of sea turtle affinity for jetty habitats (Fig. 13). Four- hundred-thirty sightings could be assigned to distance-from-jetty zones including 0 - 5, 5 - 15, 16 - 30 and > 30 m. Sightings reported to cross into more than one distance- from jetty zone or in which the observer was unable to judge distance from jetty were excluded. Over 61% of all turtle sightings occurred within 5 m of jetty habitat. The frequency of sightings beyond 5 m declined to approximately 30% for distances out to 15 m, and was less than 10% for all greater distances. A total of 170 turtles was individually recognized among the 447 sightings made during April 1992 - March 1993 (some individually recognized turtles were the same turtles observed from month to month or at different zones during one month). Area sea turtle abundance, as estimated from these sightings, varied with season (Fig. 14). Monthly abundance estimates during cooler periods of April - May and November - March were ≤ 15 turtles while those for summer - early fall ranged from 17 to 26 turtles. Peak abundance was recorded in June, with 26 individual turtles recognized.

300

250

200

150

100

Number of Turtle Sightings 50

0 0-5 6-15 16-30 >30 Distance from Jetty (m)

Figure 13. Number of sea turtle sightings at increasing distances from Brazos Santiago Pass jetties during April 1992 - March 1993.

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10 Number of Turtles

0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Month

Figure 14. Number of individual sea turtles sighted per month at Brazos Santiago Pass during April 1992 - March 1993.

STOMACH EVACUATION

Seventy-six stomach evacuation samples were analyzed from 47 green turtles captured in the study area (Appendix Table 2). All stomach samples were small due to inherent limitations of the evacuation protocol and procedures taken to reduce stress on turtles. Consequently, the total mass of individual samples ranged from 0.01 to 1.55 g and averaged 0.13 g. Although 42 of 76 samples each contributed less than 0.1 g of material and a majority of food items (68.19% by mass) were unidentifiable because of their advanced state of digestion, remnants from a vast array of these food items could be distinguished in green turtle stomachs. These food items belonged to 24 taxonomic groups comprising seven different divisions/phyla and various debris (plastic, metal, etc.).

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The most commonly encountered food group in green turtle stomachs was the red algae Division Rhodophycophyta (Table 3 and Appendix Table 2). These red algae exhibited the greatest species diversity (ten taxa) and frequency of occurrence (67.53%) recorded among food items and collectively comprised 54.63% of the identifiable biomass in stomach samples. Highest frequency of occurrence among identifiable food items (Table 4) was reported for the seagrass Halodule wrightii (31.58%) and the red alga Bryocladia sp. (28.95%). Food items that made up the greatest proportion of the total biomass included miscellaneous (not identifiable at least to family) red algae (20.13%) and Halodule wrightii (15.97%). There were notable differences between the stomach contents of green sea turtles captured from BSP and SB/MF sites (Table 5). Dominant food items in BSP turtles consisted of four red algae and one green alga. Miscellaneous red algae made up the bulk of dry biomass (20.87%) and occurred in 30 (75.00%) samples. Other dominant taxa included Hypnea musciformis (16.60% in 8 samples), Bryocladia sp. (11.88% in 22 samples), family Ceramiaceae (9.04% in 17 samples), Rodymenia pseudopalmata (8.67% in 4 samples), and Ulva fasciata (8.19% in 21 samples). Domi- nant food items in SB/MF turtles consisted of two sea grasses and miscellaneous red algae. Halodule wrightii made up the greatest proportion (35.20%) of biomass and occurred in 20 (55.56%) samples. Other dominant taxa included miscellaneous sea grasses (22.84% in 6 samples), miscellaneous red algae (18.40% in 11 samples), and Syringodium filiforme (11.85% in 11 samples). An ANOVA indicated no statistically significant variation in food items across seasons (Table 6) from turtles at BSP (F = 1.28, p = 0.3166) and slight variation in turtles at SB/MF (F = 3.42, p = 0.0526). Halodule wrightii and miscellaneous grasses were the dominant species during each season sea turtles were taken at SB/MF. Turtles at BSP selected miscellaneous red algae, Hypnea musciformis, or Bryocladia sp..

HABITAT CHARACTERIZATION

Hydrological Monitoring: The study period was characterized by homogenous average monthly surface and bottom (when available) water temperatures and salinities (Table 7). Surface water temperature during April 1991 - March 1993 ranged from 13.65 C on 12 January 1993 to 32.17 C on 5 July 1991. Highest average monthly water temperature (Figure 15) occurred during September of both 1991 and 1992 (29.1 and 28.7 C,

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Table 3. Percent biomass and frequency of occurrence of identifiable phyla found in stomach contents of green sea turtles (n = 76) captured in the South Padre Island study area during April 1991 - March 1993.

Percent Frequency of Percent Food Items Biomass Occurrence Frequency

Anthophyta 34.19 47 61.84 Chlorophycophyta 5.11 24 31.58 Phaeophycophyta 1.60 7 9.21 Rhodophycophyta 54.63 52 68.42 All other items (9) 4.47

Table 4. Dominant (≥ 5% of total identifiable biomass) food items found in stomach contents of green sea turtles (n = 76) captured in the South Padre Island study area during April 1991 - March 1993.

Percent Frequency of Percent Food Items Biomass Occurrence Frequency

Anthophyta Syringodium filiforme 7.35 17 22.37 Halodule wrightii 15.97 24 31.58 Miscellaneous grass 9.90 14 18.42 Rhodophycophyta Hypnea musciformis 9.90 8 10.53 Rhodymenia pseudopalmata 5.11 4 5.26 Family Ceramiaceae 5.43 19 25.00 Bryocladia sp. 6.71 22 28.95 Miscellaneous red algae 20.13 41 53.95 All other taxa (23) 19.49

respectively). Lowest average monthly water temperature (15.66 C) occurred during January 1993. Surface salinity ranged from 25.28 ppt on 11 June 1992 to 40.00 ppt on 21 November 1991 (Appendix Table 3). Highest average monthly salinities occurred during July 1991 (36.00 ppt) and November 1992 (38.33 ppt). Lowest average monthly salinity occurred during May 1991 and April 1992 (29.56 and 29.58 ppt, respectively).

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Table 5. Dominant (≥ 5% of total identifiable biomass) food items in green sea turtles captured from Brazos Santiago Pass and South Bay/Mexiquita Flats sites during April 1991 - March 1993.

Percent Frequency of Percent Food Items Biomass Occurrence Frequency

Brazos Santiago Pass n = 40

Chlorophycophyta Ulva fasciata 8.19 21 52.50 Rhodophycophyta Hypnea musciformis 16.69 8 20.00 Rhodymenia pseudopalmata 8.67 4 10.00 Family Ceramiaceae 9.04 17 42.50 Bryocladia sp. 11.88 22 55.00 Misc. Red Algae 20.87 30 75.00 All other taxa (22) 24.66

South Bay/Mexiquita Flats n = 36

Anthophyta Syringodium filiforme 11.85 11 30.56 Halodule wrightii 35.20 20 55.56 Misc. grass 22.84 6 16.67 Misc. red algae 18.40 11 30.56 All other taxa (14) 11.71

Average monthly air temperature ranged from 16.67 C in December 1992 to 31.00 C in September 1992. Jetty Characterization: Jetty habitat at Brazos Santiago Pass consisted of three distinct biological zones. The first zone, extending 2 m out from the jetties to a depth of 1 m, was characterized by lush algae growth covering large granite boulders of uniform size. Underlying this nearsurface zone was a second stratum extending 10 m from the jetty to a depth of 3 m. This second biological zone contained various-sized boulders exhibiting only scattered algae growth. An exception to this pattern existed from zones W to Z along the North Jetty where the intermediate zone consisted only of a flat sandy bottom extending to the channel proper. The final zone encompassed deeper waters

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Table 6. Seasonal occurrence of dominant (≥ 5% of total identifiable biomass) food items in green sea turtles captured from Brazos Santiago Pass and South Bay/ Mexiquita Flats sites during April 1991 - March 1993.

Food Items Percent Biomass

Winter Spring Summer Fall

Brazos Santiago Pass n = 6 7 16 11

Ulva fasciata 14 4 13 9 Soliera tenera 04 116 Hypnea musciformis 18 32 0 0 Family Ceramiaceae 4 4 23 11 Bryocladia sp. 14 12 5 16 miscellaneous red algae 18 16 43 13

South Bay/Mexiquita Flats n = 8 9 4 15

Syringodium filiforme 14 8 0 12 Halodule wrightii 8467365 miscellaneous grass 48 0 2 3 miscellaneous red algae 18 25 0 17

beyond 10 m of the jetties where primary habitat was either: 1) small boulders typically devoid of algae or 2) a barren, silty-mud bottom. Transects completed at jetty stations yielded 34 species of algae belonging to three divisions (Table 8), Chlorophycophyta (6 species), Phaeophycophyta (7 species), and Rhodophycophyta (21 species). Species exhibiting the greatest frequency of occurrence (≥ 5 stations) were Ulva fasciata, Ceramium byssoideum, Padina vickersiae, Bryocladia cuspidata, Bryocladia thyrsigera, Sargassum fluitans, Soliera tenera, Rhodymenia pseudopalmata, and Spyridia aculeata. Layering of algae species was fairly uniform at all zones, with green alga in the intertidal zone and brown and red algae interspersed below that to a depth of up to 1 m. Of special note was the presence of large stands of the benthically attached Sargassum filipendula along the South Jetty in zones K and L and the North Jetty from zones S to V. No seasonal data are available for algae growth at the jetties, but there was an apparent increase in the width of the green algae layer during winter. An enlarged intertidal zone due to increased wave action may account for the increase in these hardier species.

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Table 7. Average monthly air and water temperature and salinity in the South Padre Island study area during April 1991 - March 1993. Detailed monthly hydrological data are presented in Appendix Table 3.

Month Air Temp (C) Water Temp (C) Salinity (ppt) surface bottom surface bottom

Apr-91 23.97 22.00 n/a 31.00 n/a May-91 26.74 26.22 n/a 29.56 n/a Jun-91 28.69 26.74 28.40 35.43 34.96 Jul-91 27.74 27.19 27.55 36.01 35.12 Aug-91 28.18 28.47 28.14 35.64 35.59 Sep-91 28.43 29.12 n/a 35.32 n/a Oct-91 26.68 26.81 n/a 33.69 n/a Nov-91 20.91 20.67 n/a 34.60 n/a Dec-91 26.39 26.45 27.84 35.05 35.35

Apr-92 25.83 23.81 23.64 29.58 29.59 May-92 26.93 24.66 24.63 33.61 33.30 Jun-92 30.50 27.58 27.27 31.62 31.89 Jul-92 30.65 26.58 26.43 32.92 33.10 Aug-92 30.08 27.76 27.86 33.43 33.00 Sep-92 31.00 28.68 28.57 33.06 32.99 Oct-92 26.94 25.94 25.79 36.13 35.86 Nov-92 23.28 22.60 22.43 38.33 38.29 Dec-92 16.67 17.37 17.06 34.41 34.46 Jan-93 17.63 15.66 15.63 32.46 32.62 Feb-93 19.24 18.13 17.94 32.28 31.74 Mar-93 20.89 19.30 19.23 32.20 32.13

n/a - not available

Other common epiphytes included sponges of the Class Demospongeae which occurred at 3 of 9 characterization stations (Table 8). The gorgonian Leptogorgia virgulata and two bryozoan species were common in the second and third biological zones at several stations. Small gastropods, copepods, and the crab Acanthonyx petiverii often were found amongst algae mats in the first biological zone. Xanthid crabs were observed at two jetty zones. Epiphytic diversity, ranging from 11 to 15 taxa, was fairly uniform across all stations with the exception of those at zones A outside and E during 1991 (3 and 6 species, respectively) and P outside during 1992 (6 species).

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10 Oct-91 Oct-92 Jun-91 Jun-92 Apr-91 Dec-91 Apr-92 Dec-92 Feb-93 Aug-91 Aug-92 Month

Air Temp (°C) Water Temp (°C) Salinity (ppt)

Figure 15. Average monthly air and surface water temperature (C), and salinity (ppt) in the South Padre Island study area from April 1991 - March 1993.

Grassbed Characterization: Analysis of vegetation collected from SB/MF characterization stations identified four species of marine plants, 12 species of marine algae, the bryozoan Bugula neritina, and miscellaneous other epiphytic organisms. The most abundant species was manatee grass (Syringodium filiforme) which accounted for 47.32% of the dry mass across all grassbed stations and seasons. Other dominant taxa (≥ 5% dry mass) included turtle grass (Thalassia testudinum - 15.74%), shoal grass (Halodule wrightii - 5.26%), and the red algae Corallina cubensis (11.92%) and Soliera tenera (5.95%). All other species exhibited less than one percent by dry mass except for the red algae Laurencia poitei (4.09%), Gracillaria foliifera (2.23%), Digenia simplex (1.39%), and Hypnea musciformis (1.23%).

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Table 8. Epiphytic and encrusting taxa found at Brazos Santiago Pass habitat characterization stations during summer 1991 and 1992.

Year 1991 1992 Zone Ao E Pi Po Y AB Ao E G-H K Pi Po W Y N Division Chlorophycophyta Ulothrix flacca X1 Ulvella lens XX 2 Codium fragile X1 Ulva fasciata XXX XXXX XXX10 Cladophora deliculata XXXX4 Ectocarpus siliculosus X1 Division Phaeophycophyta Dictyota ciliolata XXX3 Dictyota dichotoma XX2 Padina vickersiae XX X XX X X X 8 Myriotrichia subcorymbosa X1 Sargassum filipendula XX X XX 5 Sargassum fluitans XX X X X X 6 Sargassum natans XX 2 Division Rhodophycophyta Gelidium crinale X1 Pterocladia bartlettii X1 Pterocladia capillacea XXX X 4 Corallina cubensis XX 2 Corallina subulata XX X 3 Soliera tenera XX X X X XX 7 Hypnea musciformis XX 2 Gracilaria debilis X1 Gracilaria foliifera XX X X4 Rhodymenia pseudopalmata X XX XXX X X 8 Rosenvingea intricata X1 Lomentaria baileyana XX X 3 Ceramium byssoideum XXX XXXX XX X10 Centrocerus clavulatum XXX3 Spyridia aculeata XX XX X XX7 Polysiphonia boldii X1 Polysiphonia echinata XX X X 4 Bryocladia cuspidata XXXX X5 Bryocladia thyrsigera XX X XX X 6 Chondria littoralis XXX3 Laurencia poitei X1

Class Demospongiae X X X 3 Leptogorgia virgulata XX 2 Class Gastropoda X X X X X X 6 Class Copepoda X X 2 Acanthonyx petiverii XX X3 Family Xanthidae X X 2 Phyla Bryozoa X X X 3 Class Gymnolaemata X X X 3 Class Stelleroidea X X 2 Number of species in zone 3 6 16 10 12 12 12 13 15 12 11 6 11 10 i - inside jetty (channel) o - outside jetty (Gulf)

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Mexiquita Flats stations 15, 29, and 31 supported the most uniform distribution of forage species (Fig. 16). Thalassia testudinum and Syringodium filiforme were dominant species at stations 15 (30.76 and 35.65%, respectively) and 31 (35.82 and 30.35%, respectively), while Halodule wrightii and S. filiforme were most abundant at station 29 (35.06 and 29.86%, respectively). Other dominant taxa at station 15 included the red alga Corallina cubensis and the seagrass H. wrightii. Station 29 also exhibited abundant Halophila engelmanii and T. testudinum, while station 31 supported only one other dominant taxon, the bryozoan Bugula neritina. South Bay stations 21 and 28 were the most homogenous in terms of aquatic vegetation, while station 30 exhibited the greatest overall heterogeneity (Fig. 16). Syringodium filiforme was clearly the most abundant taxon at stations 21 and 28 (78.54 and 79.07%, respectively). Other dominant species reported were Soliera tenera at station 28 and Halodule wrightii at both stations. Corallina cubensis (32.62%) was the most abundant species at station 30, which consisted of a hard mud bottom with interspersed bundles of algae approximately 0.5 m deep. Other dominant taxa included the red algae S. tenera, Laurencia poitei, Gracilaria foliifera, Digenia simplex, and the seagrass Thalassia testudinum. An ANOVA of grassbed composition at station 15 indicated that seasonal variation was significant in all dominant species except Halodule wrightii (F = 1.46, p = 0.2229). Thalassia testudinum and Syringodium filiforme exhibited similar abun- dances during April - October 1992 (Fig. 17). This was followed by a decline in T. testudinum in December 1992 and S. filiforme in February 1993. This period exhibited a corresponding increase in the red alga Corallina cubensis which was the most abundant species in January and February 1993 (74.08 and 69.29%, respectively). An ANOVA of dominant vegetation taxa at station 21 indicated that seasonal variations in Halodule wrightii (F = 5.24, p = 0.0023), Syringodium filiforme (F = 15.6, p = 0.0000), and Hypnea musciformis (F = 13.3, p = 0.0000) were statistically significant. Syringodium (range: 42.88 - 98.59%) was most abundant all months except June 1992 when H. wrightii (75.65%) dominated (Fig. 18). Station 21 was bisected by a narrow channel approximately 4 m wide and less than 2 m deep, which may explain this June 1992 variation. Samples were taken from the south side of the channel during June 1992 and from the north side all other months. There was an increase in the red alga H. musciformis (24.61%), although S. filiforme remained the most abundant species during winter.

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South Padre Island Brazos Santiago Pass 31

Long Island Mexiquita Flats 29

15 28 Gulf of Mexico

Bugula neritina Corallina cubensis Digenia simplex Gracilaria South foliifera Bay Halophila engelmannii 30 Halodule wrightii Laurencia poitei Syringodium filiforme Soliera tenera Thalassia testudinum Miscellaneous Sampling Station # Other

Figure 16. Percent composition of sea grasses, epiphytic algae, and bryozoans at habitat characterization stations in South Bay and Mexiquita Flats.

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60 Halodule wrightii

Thalassia testudinum

40 Syringodium filiforme Corallina cubensis

Percent Composition 20 Soliera tenera

0 Apr-92 Jul-92 Nov-92 Feb-93 Month

Figure 17. Percent composition of dominant (≥ 5%) seagrass and algae taxa at Mexiquita Flats station 15 during April 1992 - February 1993.

Of dominant vegetation taxa at station 28, significant seasonal variation was observed only in Syringodium filiforme (F = 5.23, p = 0.0003) and Hypnea musciformis (F = 2.69, p = 0.0209). Syringodium, ranging from 41.93 to 95.29%, was the dominant taxon during all sampling months excluding one (Fig. 19). During January 1993, the red alga H. musciformis (40.58%) and the seagrass Halodule wrightii (40.02%) were most abundant.

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100

60 Halodule wrightii Thalassia testudinum 40 Syringodium filiforme Percent Composition 20

0 Aug-91 Dec-91 May-92 Oct-92 Mar-93 Month Figure 18. Percent composition of dominant (≥ 5%) seagrass and algae taxa at South Bay station 21 during August 1991 - March 1993. (* June 1992 samples were taken from an adjacent grassbed separated from station 21 by a narrow channel) 100

60 Halodule wrightii

Syringodium filiforme 40 Corallina cubensis Percent Composition 20

0 Sep-91 Jan-92 Jun-92 Oct-92 Mar-93 Month Figure 19. Percent composition of dominant (≥ 5%) seagrass and algae taxa at South Bay station 28 during September 1991 - March 1993.

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HABITAT UTILIZATION

Recaptures: All turtles taken at BSP were recaptured within 400 m of their original capture location with two exceptions (Table 9). The first (92-6-1) was a 32.1-cm SCL green turtle originally captured between zones K and L, recaptured there three more times, and once between zones A and B outside the North Jetty. Another green (93-1- 2), originally captured at BSP on 14 January 1993, was recaptured at the Port Mansfield jetties (approximately 40 km north) on 16 September 1993 (Donna Shaver, pers. comm.). Turtles captured at SB/MF stations were recaptured along a 500-m length of the Brownsville Ship Channel at either station 15 or 29 (Table 10). Tracking: Thirteen radio- and sonic-tagged green sea turtles were tracked by NMFS to identify habitat utilization in the South Padre study area during 1991 and 1992. Ten turtles were captured at BSP (1 in 1991, 9 in 1992) while the other three were captured from SB/MF during 1991. The first green turtle tracked was a 34.2-cm SCL individual netted at BSP zone S (channel side) on 15 July 1991. After release, this turtle continued to utilize jetty environs at BSP [See Landry et al. (1992) for areal extent of movement] and was frequently observed between 5 to 10 m off the Gulf side of the North Jetty (Zone P) by TAMU personnel through October 1991. The next three turtles used in NMFS’ tracking program were captured at Mexiquita Flats Station 15 (Fig. 4). A 53.6-cm SCL green (92-2-3) captured on 26 July 1991 remained in the BSC (between channel markers 16 and 22), adjacent grassbeds of Mexiquita Flats and entrance to South Bay. Similar habitat utilization was exhibited by a 49.9-cm SCL green captured on 1 August 1991. This turtle restricted its movements to grassbed habitats bordering the BSC along Mexiquita Flats and northeastern shore of Brazos Island. The last turtle tracked was a 54.1-cm SCL green taken on 1 August 1991. This individual exhibited the most wide-spread movement among tagged turtles by utilizing grassbed and channel habitats within the BSP and SB/MF. It also moved into the lower Laguna Madre ranging approximately 3 km north of the study area, utilizing the Intracoastal Waterway immediately north of the causeway and flats to the west. The remaining nine turtles tracked were captured at BSP during 1992 (Table 11) (Landry et al., 1993). Core areas, defined as a span of jetty in which a turtle spent more than 50% of its time, were all less than 200 m in length. Overall movement of individual turtles ranged from 366 - 1235 m along the jetties. Periods of highest

Table of Contents 36 activity occurred mostly during dusk and dawn. Resting behavior was observed at night and sometimes during afternoon when little areal movement was noted. Most individuals displayed more restricted movement at night.

GROWTH

Analysis of growth was based only on recaptures that occurred at least two weeks from the previous capture. Thirty-three recaptures of 15 turtles were used in this analysis, 20 from Brazos Santiago Pass and 13 from South Bay/Mexiquita Flats. Additionally, only SCLs were used in growth analysis because reliable curved length measurements were made difficult by attached radio transmitters and weight data were unreliable. Size of green turtles at first capture ranged from 22.2 to 58.8-cm SCL. Time intervals between captures ranged from 14 to 390 days (mean = 95 days). The greatest time interval from first to last capture for an individual turtle was 1.52 yrs. Overall mean growth rate, measured from first to last capture of each turtle, was 5.26 cm/yr, with a range of 0.54 to 12.88 cm/yr. Measurements between each capture exhibited an annual growth rate of 5.41 cm/yr, with a range of 0.54 to 19.04 cm/yr. A pooled t-test indicated no significant difference between growth rates of turtles captured at BSP and SB/MF (mean = 5.58 and 5.15 cm/yr, respectively, t = -0.296, d.f. = 31). An ANOVA indicated no significant difference in growth rates among 10-cm size classes (F = 1.68, d.f. = 4,28) (Table 12). Highest growth rates were observed in the 20 - 30 and 50 - 60 cm size classes (7.18 and 8.82 cm/yr, respectively), with all other size classes between 4.04 and 4.51 cm/yr. An analysis of seasonal growth rate variation

Table of Contents 37

Table 9. Date, location, and straight carapace length (SCL) of repeated green sea turtle captures from Brazos Santiago Pass during April 1991 - March 1993. See Appendix Table 1 for a complete description of each capture.

Turtle ID# Date SCL Zone 92-1-3 4/24/92 27.3 L 5/16/92 27.7 L 7/27/92 29.1 H 7/29/92 n/a L 8/25/92 29.8 L 9/3/92 n/a K-L 10/9/92 30.5 K 11/10/92 30.7 L 92-1-4 4/24/92 22.2 L 4/27/92 22.3 L 5/11/92 22.8 L 92-2-1 5/11/92 28.2 L 6/9/92 28.4 G-H 7/29/92 29.3 I-J 8/25/92 29.7 L 92-3-4 4/12/91 36.6 K 5/16/91 37.5 K 6/9/92 44.2 G-H 7/30/92 44.7 J 10/16/92 45.2 G 92-4-1 7/28/92 47.9 I-J 10/9/92 49.1 I 10/15/92 n/a K-L 92-4-2 7/30/92 30.1 Pi 9/3/92 31.1 Pi 11/16/92 n/a Pi 92-6-1 9/3/92 32.1 K-L 10/16/92 32.5 K 11/10/92 32.6 L 2/12/93 32.8 A-Bo 3/1/93 32.9 K-L i - inside jetty (channel) o - outside jetty (Gulf) n/a - not available

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Table 10. Date, location, and straight carapace length (SCL) of repeated green sea turtle captures from South Bay/Mexiquita Flats during April 1991 - March 1993. See Appendix Table 1 for a complete description of each capture.

Turtle ID# Date SCL Station 92-1-1 10/22/91 48.2 15 10/24/91 n/a 15 4/23/92 48.4 15 5/12/92 48.7 15 12/11/92 52.8 29 92-1-2 11/21/91 45.3 15 4/23/92 46.0 15 92-2-2 5/14/92 42.2 15 10/14/92 46.7 29 12/10/92 47.3 29 12/11/9247.3 29 92-2-3 7/26/91 53.6 15 5/14/92 56.3 15 92-3-1 6/8/92 50.5 15 7/24/92 52.9 15 11/13/92 54.7 29 92-3-2 10/22/91 58.8 15 6/8/92 61.1 15 2/17/93 64.2 29 92-8-1 11/13/92 36.6 29 3/6/93 36.8 31 92-9-4 12/10/92 36.4 29 2/16/93 36.5 29 n/a - not available

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Table 11. ID number, capture and release date, straight carapace length (SCL), and date of last contact of green sea turtles tracked at Brazos Santiago Pass by National Marine Fisheries Service personnel during 1992.

ID# Capture Date Release Date Straight Length Last Contact (cm)

92-4-1 28-Jul-92 31-Jul-92 47.9 26-Sep-92 92-3-4 30-Jul-92 1-Aug-92 44.7 25-Sep-92 92-4-2 30-Jul-92 1-Aug-92 30.1 26-Sep-92 92-1-3 29-Jul-92 1-Aug-92 29.1 15-Oct-92 92-1-2 29-Jul-92 1-Aug-92 29.2 26-Sep-92 92-4-3 31-Jul-92 2-Aug-92 31.5 26-Sep-92 92-5-1 4-Aug-92 6-Aug-92 33.3 26-Sep-92 92-5-3 8-Aug-92 9-Aug-92 31.5 26-Sep-92 92-5-4 8-Aug-92 10-Aug-92 33.0 23-Aug-92

Table of Contents 40 was made using capture intervals of three months or less. Growth rates were lowest in winter (0.14 cm/month) and highest in spring and summer (> 0.6 cm/month); however an ANOVA indicated that differences were insignificant for all seasons (F = 1.85, d.f. = 3,19) (Table 13). Estimates of a (asymptotic length) and k (intrinsic rate of growth) from the non- linear regressions on the von Bertalanffy growth interval equation (Equation 2) were calculated (Table 14) for intervals between each capture (equation 5) and first to last capture intervals (equation 6).

Table 12. Average annual growth rate between each capture of 10-cm size classes (N = sample size) for green sea turtles from the South Padre Island study area.

Size Class X S.D. N (cm) (cm/yr) (cm/yr)

20 - 30 7.18 3.15 7 30 - 40 4.04 3.67 11 40 - 50 4.51 3.10 9 50 - 60 8.82 6.98 4 60 - 70 4.05 0.57 2 Overall 5.41 4.02 33

Table 13. Average annual growth rate across seasons ( N = sample size ) for green sea turtles in the South Padre Island study area.

Season X S.D. N (cm/month) (cm/month)

Winter 0.14 0.15 3 Spring 0.62 0.34 5 Summer 0.64 0.46 7 Fall 0.41 0.26 8 Overall 0.45 0.34

Table of Contents 41

Table 14. Estimated values for the parameters a, k, and b from non-linear regression of von Bertalanffy growth interval equations for green turtles.

d.f. a k b

Equation 5 31 113.84 0.0768 0.960 Standard Error 40.96 0.0478

Equation 6 13 134.91 0.0554 0.967 Standard Error 75.88 0.0480

An estimate of size at hatching (L0) for green turtles was needed to find b (length at t = 0 function) with equation 4. Because the nesting beach(es) of these turtles is not known an L0 of 5.27 cm was estimated as found in 54 green turtle hatchlings from St. Croix in 1984 (Frazer and Ladner, 1986). Using values of a =

113.84 and 134.91 and L0 = 5.27 in equation 4 resulted in b = 0.960 and 0.967, respectively (Table 14). Incorporating values for a, b, and k into equation 1 provided the complete von Bertalanffy growth equation (Fig. 20) for intervals between each capture (Equation 5) and first and last capture intervals for each turtle (Equation 6):

-0.0768t Lt = 113.84(1 - 0.960e ) (5) and -0.0554t Lt = 134.91(1 - 0.967e ). (6)

Smallest residual mean square error can be used as a criterion for the best model (Schoener and Schoener, 1978). Non-linear regressions yielded a residual mean square error of 0.878 for equation 5 and 1.265 for equation 6, indicating that equation 5 represented the better growth interval equation.

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120

100

Straight Carapace Length (cm) 20 L(t) = 113.84(1 - 0.960exp(-0.0768t)) 0 0 20406080 Age (yrs)

Figure 20. Predicted growth curve for green sea turtles from the South Padre Island study area during April 1991 - March 1993. Dotted lines indicate size classes for which no data were available.

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DISCUSSION

POPULATION DYNAMICS

Turtle capture operations conducted at Brazos Santiago Pass and in portions of the lower Laguna Madre from April 1991 through March 1993 indicate that green sea turtles are moderately abundant in the area. A total of 90 live turtles was captured, with animals taken at both jetty (24 individuals) and grassbed habitats (27 individuals). However, these catch totals may underestimate green turtle abundance in the area as evidenced by 45 green turtles reported cold stunned in the Laguna Madre over an 8-day period during February 1989 (Shaver, 1990b). Green turtle captures from other inshore habitats have indicated similar abundance and size structure. Shaver (1990a) reported 40 captures of 25 individuals (27.8- 57.8 cm SCL) at Mansfield Pass, Texas during June 1989 - May 1990. Mendonca and Ehrhart (1982) reported tagging 94 individuals in Mosquito Lagoon, Florida during July 1976 - March 1979, including 82 green turtles taken during cold-stunning episodes (29.5 - 75.4 cm SCL, overall). Data collected from a protected bay in the southern Bahamas, where 149 captures of 122 green turtles (28.3 - 75.5 cm SCL) were made from 1979 - 85, may give some indication as to the abundance potential for these populations. In addition, carrying capacity of turtle grass for the green turtle was calculated to be 138 adults per hectare (Bjorndal, 1977). Mexiquita Flats alone, encompassing an area of approximately 250 hectares, could support many more turtles than are currently found. These studies indicate this species has made only a minor comeback in south Texas waters since the complete collapse of the green turtle fishery during the 1890’s (Doughty, 1984). Little is known of the green turtle’s habits between the time it leaves the nesting beach as a hatchling and appears (20+ cm SCL) in near shore benthic feeding grounds. Green turtles captured in the study area included juveniles through subadults typically ranging from 20 to 60 cm SCL (38.9 cm average). This preponderance of younger cohorts implies that green sea turtles use BSP and SB/MF sites as “developmental” habitats to provide shelter and vegetative food source needed during early life history. Mendonca and Ehrhart (1982) suggest a similar pattern of green turtles remaining in Mosquito Lagoon until they approach maturity, possibly leaving only during cold- stunning events.

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Green turtles captured across the study area appeared to segregate themselves by size and habitat. Turtles captured at BSP were never recaptured in SB/MF, and vice versa. Additionally, 20 to 40 cm SCL turtles were common to the jetty while those larger than 30 cm SCL were netted most frequently among grassbed environs. The significance of this segregation is unclear. Jetty habitat may initially attract smaller individuals that utilize the protection provided by the many submerged boulders and granite blocks, as evidenced by their close association with the jetty and presence of urchin spine wounds about the head and neck. Developing individuals may then seek new forage grounds when the quantity or quality of algae no longer sustains sufficient growth. Abundant forage material available in grassbeds of SB/MF may attract older individuals who become less dependent on protection provided by the jetties as they grow larger. The only evidence supporting movement of green turtles from BSP into SB/MF comes from tracking data obtained by NMFS personnel. One green (33.3-cm SCL) captured at BSP was tagged and released on 6 August 1992. By 18 August 1992, the turtle had moved into South Bay and remained there for the final 37 days of the tracking study. All other green turtles tracked by NMFS and TAMU personnel remained within the habitat in which captured, except those SB/MF turtles that passed through BSP to move offshore. Development of management and conservation plans for endangered sea turtles depends on knowledge of species growth rate. Demographic models, which can aid management decisions, are especially sensitive to fluctuations in mean age at sexual maturity (Lewontin, 1965; Gadgil and Bossert, 1970). Use of the von Bertalanffy growth equation yields similar age at maturity estimates (Table 15) to those reported in other studies. Age at maturity estimates for green turtles range between 5.5 years in Mauritania (Le Toquin et al., 1980) and 59.4 years in the Hawaiian Archipelago (Balazs, 1982). Several assumptions must be made in estimating age at maturity for South Padre green sea turtles. First, natal beach origin is not known, and estimates of size at hatching must be taken from other locations. However, this should have no appreciable effect on the model as mean size of green hatchlings worldwide presently ranges between 4.6 - 5.4 cm (Hirth, 1980). Applying this range to estimates of b (equation 4) results in approximately the same value. Second, size at first maturity must be estimated. Investigators using size of smallest nesting female (Caldwell, 1962; Mendonca, 1981)

Table of Contents 45

Table 15. Estimated values of asymptotic length (a), intrinsic growth rate (k), and age at sexual maturity from non-linear regression of the von Bertalanffy growth interval equation for green turtles at various locations.

Location Growth a k Age at maturity Reference Intervals (yrs) Florida 1 1 108.9 0.0887 18 - 27 Frazer and Ehrhart, 1985 U.S. Virgin Islands* 8 121.64 0.075 27 - 33 Frazer and Ladner, 1986 Texas 3 3 113.84 0.0768 18 - 26 Current study

* based on cured carapace length measurements

may have underestimated mean size at sexual maturity for a population since Carr and Goodman (1970) provide evidence that a female’s growth slows greatly after her first nesting season. Consequently, size of smallest nesting female was used as a lower estimate while average size of all nesting adults yielded an upper estimate as suggested by Frazer and Ladner (1986). Again, since the natal beach is unknown the identity of the adult population must be assumed. Size data are not available for the closest green turtle rookery at Rancho Nuevo, Mexico. Therefore, data from 24 green turtles nesting at Merrit Island, Florida from 1974 to 1978 were used to obtain a lower and upper limit of 88.0 and 99.0 cm SCL, respectively (Frazer and Ehrhart, 1985). Incorporating these values into the von Bertalanffy model (Equation 5) yields an estimated age at maturity between 18 and 26 years for South Padre Island green turtles. There was no significant change in growth rate with increasing 10-cm size classes as shown by an ANOVA (F = 1.68, p = 0.1824). Other researchers have reported decreasing growth rate with increasing body size; this may be due to an inability to ingest sufficient food material to maintain growth rates and increased energy de- mands for reproduction and migration at larger sizes (Mendonca, 1981; Frazer and Ehrhart, 1985; Frazer and Ladner, 1986; Bjorndal and Bolten, 1988). The lack of a similar inference in this study may result from small sample size of the larger size classes. Although not significant (F = 1.85, p = 0.1717), there was an observable change in seasonal growth rates. Turtles recaptured during winter months exhibited the lowest

Table of Contents 46 average growth rates (0.14 cm/month) and those captured during spring and summer months the greatest (0.62 and 0.64 cm/month, respectively). This is to be expected as water temperatures drop during fall and winter months bringing a corresponding decrease in available forage material (Dawes and Lawrence, 1980) and sea turtle metabolism.

BEHAVIOR

Sighting data on green sea turtles at BSP indicate increased activity during warmer summer and fall and a decrease in cooler winter and spring months. Months of increased activity (June to October) typically coincided with mean water temperatures over 25 C while decreased activity was observed during months exhibiting lower temperatures ( November to May). Winter tracking tends to support this observation as turtles apparently left the area or remained relatively inactive, possibly burying in the mud bottom, during extremely cold weather (Stacie Arms, TAMU, pers. comm.). Turtles were captured in water temperatures ranging from 16 C during January 1993 to 30 C during September 1992. The low end of this range is near temperatures at which Felger et al. (1976) found green turtles dormant and embedded in the mud in the Gulf of California. Daily movement patterns were similar for turtles captured at both BSP and SB/ MF sites. Sighting data at BSP and time of capture data at SB/MF both indicate greater movement during early morning and early and late afternoon. Ogden et al. (1983) found similar patterns in green turtles at St. Croix that fed approximately 9 hrs per day in two bouts, one in the morning and one in the afternoon. Increased capture rates during early morning and late afternoon in SB/MF turtles may indicate individuals leaving and returning to night resting areas. This is substantiated by observed behavior of two green turtles at BSP during August 1992. The ID number of these individuals was marked on their carapace with marine epoxy paint and was identifiable for one week. Each turtle was consistently observed at the same approximate location in Barracuda Cove during early morning and late afternoon, ranging away from the area during the day. These observations indicate that green turtles may utilize the extensive stands of Sargassum filipendula for cover while resting in Barracuda Cove. Poor water clarity made it difficult to draw conclusions about foraging behavior in grassbeds. No green turtles were observed feeding and few sightings were made of

Table of Contents 47 turtles over grassbed habitat. NMFS tracking data of two green turtles from SB/MF during 1991 indicate forage behavior generally was restricted to movement along either side of the BSC (Landry et al., 1992). Additionally, resting behavior was apparent at night, with movements restricted to an area less than 100 m in diameter (Sharon Manzella, NMFS-Galveston, pers. comm.). An ongoing study of green turtles at SB/ MF also is reporting relatively restricted night resting areas on Mexiquita Flats and in South Bay (Stacie Arms, TAMU, pers. comm.). Daylight hours were characterized by expanded movement patterns with a return to resting areas in late afternoon. Extensive observations at jetty environs indicated green sea turtles exhibited a well-defined pattern of proximity to this habitat. Turtles remained close to the jetty at the surface, with most (61%) sightings occurring within 5 m of the jetty structure (Fig. 13). External wounds around the head and neck resulting from contact with sea urchins attached to granite boulders lend additional evidence of turtles’ close association with the jetty for feeding or refuge purposes. Tracking data indicated that the extent of most linear movement along the jetty was less than 200 m. Capture/recapture location data also suggest strong site fidelity with recaptures of all but one individual within 450 m of its original capture location. Average distance of recaptures from original capture location for seven turtles ranged from 0 to 275 m. One turtle (92-1-3) was captured eight times during April - November 1992 because of its loyalty to Barracuda Cove at BSP.

FEEDING ECOLOGY

Ferreira (1968) found that Brazilian green sea turtles fed on forage species of greatest abundance. However, Balazs (1980) suggested that Hawaiian green turtles are selective in their food choice. Turtles caught over a Necker Island, Hawaii feeding area with dense stands of Caulerpa sp., Sargassum sp., Laurencia sp., Turbinaria sp. and Asparagopsis sp., had only Caulerpa in their stomachs. Food items in stomach samples from turtles captured at BSP coincided somewhat with the most abundant algae found at the jetties (Ulva fasciata, Rhodymenia pseudopalmata, Family Ceramiaceae, and Bryocladia sp.), but there was evidence of some selectivity. Species common to the jetties but only occurring in a few turtles included Padina vickersiae, Sargassum filipendula, Sargassum fluitans, and Spyridia aculeata. Most notable was the absence of S. filipendula from stomach evacuation samples despite its vast presence

Table of Contents 48 along the inside of the jetties, particularly in Barracuda Cove. Conversely, Hypnea musciformis was a dominant item in stomach samples but occurred at only two sampling zones. There was also some apparent feeding selectivity exhibited by green sea turtles captured at SB/MF. The least abundant seagrass species, Halodule wrightii, was the dominant food item in stomach samples (55% occurrence), while the dominant forage species (Syringodium filiforme ) occurred in only 30% of stomach samples. The relatively high incidence of red algae in stomach samples is most likely incidental due to the many species found to grow epiphytically on and amongst seagrass blades. Seasonal changes in stomach contents compared with available forage species was another good indicator of feeding selectivity. Seasonal change in algae taxa at BSP was not measured. There was some seasonal variation in food items taken, although not statistically significant (Table 9). Most notable was the dominance of Hypnea musciformis in stomach samples during winter and spring and its complete absence during summer and fall. Overall, no individual taxon was dominant across all seasons. Analysis of seasonal variation in seagrasses and algae at SB/MF stations 15, 21, and 28 indicates a small decrease in seagrass biomass and an increase in some algae taxa during winter and early spring (Figs. 18, 19, and 20). Variations observed within sampling stations each month were probably a result of sampling method as water depths across SB/MF were never sufficiently different so as to impact vegetation composition. Cooler water temperatures during winter can cause declines in leaf growth rates and protein and soluble carbohydrate levels in seagrasses (Tomasko and Dawes, 1990). This provides further evidence for SB/MF green turtles’ preference for Halodule wrightii, the least abundant seagrass. Halodule wrightii was found in turtle stomachs with the greatest frequency (73% of the samples) during summer when seagrass biomass was greatest. Green turtles continue to consume H. wrightii (Table 9) as seagrass biomass decreases during winter, but are probably forced to supplement their diet with other seagrasses and algae. Continued study of green sea turtles in the South Padre Island area is critical to determining factors influencing segregation between jetty and grassbed habitats. Can these green turtles be considered one temporally divided population or are they two spatially discrete populations? If size is the influencing factor, then it is simply a matter of time before each turtle moves from jetty to grassbed environs. However,

Table of Contents 49 strong dietary or habitat preferences may render two spatially discrete populations, rarely mixing on feeding grounds. Recapture of BSP turtles in SB/MF as they grow larger would support temporal separation. Additional telemetric tracking may help to answer this question, further defining the extent of green turtle movement and foraging patterns. It also may determine when and why they leave the area. Growth rate estimates also could be improved through long-term study. Larger sample sizes, longer capture/recapture intervals, and additional data on smaller and larger cohorts are critical to improving growth estimates. Since food type has been found to affect growth rates in captive sea turtles, this may also provide further insights into differences between turtles from BSP and SB/MF environs and relative quality of algae versus seagrass diets (Stickney et al., 1973; Wood and Wood, 1977). Finally, identification of the natal beach(es) and better estimates of mean size at first maturity would provide more accurate predictions of age at maturity. Improved demographic models would then allow managers and conservationists to better evaluate the relative importance of each life history stage.

Table of Contents 50

SUMMARY

1. A moderate abundance of green sea turtles exists in the South Padre Island area, but remains well below theoretical carrying capacity and historically reported biomass.

2. Two possibly distinct groups of green turtles utilize jetty and grassbed environs as developmental habitats.

3. Smaller cohorts (< 40 cm SCL) typically utilize the jetties at Brazos Santiago Pass for protection and forage on available algae species. Turtles’ close association with the jetty was well defined.

4. Larger cohorts (> 30 cm SCL) were found over grassbeds of South Bay/ Mexiquita Flats feeding primarily on seagrasses.

5. Preliminary von Bertalanffy growth estimates were similar to those reported for other green turtle populations. Length at time t (age in years) was calculated to be: -0.0768t Lt = 113.84(1 - 0.960e )

6. Age at maturation of local green turtles was estimated between 18 and 26 years.

7. Some seasonal change in growth rate was observed, with a low of 0.14 cm/month in winter and a high of 0.64 cm/month in summer.

8. Seasonal variation in activity patterns was closely linked to water temperature, with an increase in activity at higher temperatures.

9. Telemetric tracking and capture/recapture location data suggest strong site fidelity.

10. Green turtles at Brazos Santiago Pass were found to feed selectively on some, but not all, of the more abundant algae species.

11. Green turtles from South Bay/Mexiquita Flats exhibited a preference for the least abundant seagrass, Halodule wrightii.

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Neck, R. W. 1978. Occurrence of marine turtles in the lower Rio Grande of South Texas (Reptilia, Testudines). Journal of Herpetology 12:422-427. Ogden, J. C., L. Robinson, K. Whitlock, H. Daganhardt and R. Cebula. 1983. Diel foraging patterns in juvenile green turtles (Chelonia mydas L.) in St. Croix United States Virgin Islands. Journal of Experimental Marine Biology and Ecology 66:199-205. Percival, E. 1964. Algal polysaccharides and their biological relationships, p. 18-35. In: Proceedings of the international seaweed symposium, vol. 4. D. de Virville and J. Feldmann (eds.). Pergamon Press, London. Pritchard, P. C. H. 1971. Galapagos sea turtles-preliminary findings. Journal of Herpetology 5:1-2.

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Rabalais, S. C., and N. N. Rabalais. 1980. The occurrence of sea turtles on the South Texas Coast. Contributions in Marine Science 23:123-129. SAS Institute Inc. 1989. JMP user’s guide: version 2 of JMP. SAS Institute Inc., Cary, North Carolina. Schoener, T. W., and A. Schoener. 1978. Estimating and interpreting body-size growth in some Anolis lizards. Copeia 1978:390-405. Shaver, D. J. 1990a. Sea turtles in South Texas inshore waters. A report to U. S. Fish and Wildlife Service, interagency agreement 14-16-0002-89-919, 57 pp. Shaver, D. J. 1990b. Hypothermic stunning of sea turtles in Texas. Marine Turtle Newsletter 48:25-27. Stickney, R. D., D. B. White and D. Perlmutter. 1973. Growth of green and loggerhead sea turtles in Georgia on natural and artificial diets. Bulletin of the Geor- gia Academy of Science 31:37-44. Tomasko, D. A., and C. J. Dawes. 1990. Influences of season and water depth on the clonal biology of the seagrass Thalassia testudinum. Marine Biology 105:345- 351. Williams, J. A., and S. A. Manzella. 1990. Sea turtle sighting signs on the Texas Gulf Coast, p. 277-280. In: Proceedings of the Tenth Annual Workshop on Sea Turtle Biology and Conservation. T.H. Richardson, J.J. Richardson, and M. Donnelly (eds.). NOAA Technical Memorandum NMFS-SEFC-278. Williams, S. L. 1988. Thalassia testudinum productivity and grazing by green turtles in a highly disturbed seagrass bed. Marine Biology 98:447-455. Wood, J. R., and F. E. Wood. 1977. Quantitative requirements of the hatchling green sea turtle for lysine, tryptophan and methionine. Journal of Nutrition 107:171- 175.

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APPENDICES

Table of Contents 56

Appendix Table 1. Capture statistics for green sea turtles from the South Padre Island study area during April 1991 - March 1993.

Capture Net Size Weight Flipper Tracking Turtle # Date Time Station Site Method (m) SCL SCW CCL CCW (kg) Tag # Tag 92-3-4 4/12/91 1712 K BSP p 3.66 36.6 29.6 38.5 36.0 n/a QQC701/702 None 5/16/91 0803 K BSP p 3.66 39.4 32.5 42.6 37.2 n/a QQC703/704 None 92-3-4 5/16/91 1201 K BSP r p 3.66 37.5 29.8 39.8 36.5 n/a QQC701/702 None 7/15/91 0815 Si BSP a 4.88 34.2 29.0 36.5 33.5 n/a QQC707/NNZ612 RS 92-2-3 7/26/91 1210 15 MF p 3.66 53.6 42.0 56.0 49.0 n/a QQC708/709 RS 8/1/91 0958 15 MF p 4.88 54.1 42.1 57.0 49.4 n/a QQC711/NNZ753 RS 8/1/91 1225 15 MF p 4.88 49.9 39.1 53.4 44.9 n/a QQC710/NNZ611 RS 9/12/91 1750 28 SB p 4.88 40.3 32.0 42.3 36.5 n/a QQC712/713 None 92-3-2 10/22/91 1015 15 MF p 4.88 58.8 46.7 60.8 52.2 n/a QQC714/715 None 10/22/91 1137 15 MF p 4.88 46.7 37.9 48.3 43.4 n/a QQC716/717 None 92-1-1 10/22/91 1150 15 MF p 4.88 48.2 36.8 50.6 41.2 n/a QQC718/719 None 10/23/91 1143 28 SB p 4.88 40.2 31.4 41.6 36.1 n/a QQC720/721 None 92-1-1 10/24/91 n/a 15 MF r p n/a n/a n/a n/a n/a n/a QQC718/719 None 11/18/91 1345 Pi BSP h n/a 26.0 n/a n/a n/a n/a QQC722/723 None 11/21/91 0940 15 MF p 4.88 58.9 46.5 63.8 54.9 n/a QQC724/725 None 92-1-2 11/21/91 1214 15 MF p 4.88 45.3 35.6 48.1 40.4 n/a QQC726/727 None 11/21/91 1227 15 MF p 4.88 51.5 42.6 55.1 48.9 n/a QQC728/729 None 11/22/91 1720 n/a BSP f n/a 28.6 23.1 30.7 27.9 n/a QQC730/731 None 92-1-1 4/23/92 0744 15 MF r p 4.88 48.4 37.7 50.9 42.7 13.90 QQC718/719/732 None 92-1-2 4/23/92 0939 15 MF r p 4.88 46.0 35.7 47.8 41.0 10.80 QQC726/727/733 None 92-1-3 4/24/92 1033 L BSP a 3.66 27.3 21.0 28.9 24.0 2.10 QQC734/735 None 92-1-4 4/24/92 1114 L BSP a 3.66 22.2 18.6 23.5 21.0 0.85 QQC736/737 None 92-1-5 4/24/92 1610 L BSP a 3.66 25.7 20.8 26.4 24.2 1.55 QQC738/739 None 92-1-4 4/27/92 0941 L BSP r a 3.66 22.3 18.2 24.0 21.0 0.80 QQC736/737 None 92-1-4 5/11/92 1338 L BSP r a 3.66 22.8 18.2 23.9 21.4 0.80 QQC736/737 None 92-2-1 5/11/92 1405 L BSP a 3.66 28.2 22.6 29.8 24.5 2.15 QQC740/741 None 92-1-1 5/12/92 1748 15 MF r p 4.88 48.7 37.8 51.4 43.3 14.90 QQC718/719/732 None 92-2-2 5/14/92 1300 15 MF p 4.88 42.2 34.2 44.6 38.6 9.20 QQC742/743 None 92-2-3 5/14/92 1630 15 MF r p 4.88 56.3 44.4 60.4 50.5 17+ QQC709/744 None 92-1-3 5/16/92 1103 L BSP r a 3.66 27.7 21.4 29.2 24.5 2.25 QQC734/735 None 92-3-1 6/8/92 0829 15 MF p 4.88 50.5 40.8 55.0 47.9 17+ QQC745/746 None 92-3-2 6/8/92 1212 15 MF r p 4.88 61.1 47.9 64.4 55.5 17+ QQC714/715/747 None 92-3-3 6/8/92 1759 15 MF p 4.88 81.5 62.6 86.5 75.5 17+ QQC748/749 None 92-3-4 6/9/92 1004 G-H BSP r a 3.66 44.2 35.2 46.5 40.6 11.20 QQC750/751 None 92-2-1 6/9/92 1015 G-H BSP r a 3.66 28.4 21.8 30.0 25.0 2.25 QQC740/741 None 92-3-5 6/9/92 1033 G-H BSP a 3.66 33.4 27.5 34.6 31.1 3.80 QQC752/753 None 92-3-6 6/12/92 0845 R-S BSP c n/a 32.3 27.4 34.5 32.6 4.25 QQC754/755 None 92-3-1 7/24/92 1046 15 MF r p 3.66 52.9 41.7 55.0 49.2 20.00 QQC745/746 None 92-1-3 7/27/92 1429 H BSP r a 7.32 29.1 22.6 31.0 25.5 2.65 QQC734/735 None

n/a - not available Capture Station: i - inside jetty; o - gulfside of jetties; capital letters denote jetty zone in which turtle was taken Capture Site: BSP - Brazos Santiago Pass; BSC - Brownsville Ship Channel; MF - Mexiquita Flats; SB - South Bay Tracking Tag: R - radio; S - sonic; T - trailing time/depth recorder Notes: a - active encirclement captured; c - cast net captured; f - foul hooked; h - hand captured; p - passive entanglement net captured; r - recapture; t - caught in bay shrimpers trawl

Table of Contents 57

Appendix Table 1. Continued.

Capture Net Size Weight Flipper Tracking Turtle # Date Time Station Site Method (m) SCL SCW CCL CCW (kg) Tag # Tag 92-4-1 7/28/92 1837 I-J BSP a 4.88 47.9 39.4 51.5 45.2 14.80 QQC765 RST 92-1-3 7/29/92 1557 K BSP r a n/a n/a n/a n/a n/a n/a QQC734/735 RS 92-2-1 7/29/92 1800 I-J BSP r a 3.66 29.3 22.7 30.8 25.5 2.55 QQC740/741 RS 92-4-2 7/30/92 1125 Pi BSP c n/a 30.1 24.3 31.6 27.6 3.15 QQC766 RS 92-3-4 7/30/92 1430 J BSP r a 7.32 44.7 47.6 35.8 43.0 11.50 QQC750/751 RST 92-4-3 7/31/92 1042 A-Bi BSP c n/a 31.5 24.9 33.2 29.5 3.55 QQC767 RS 92-5-1 8/4/92 1243 Ti BSP c n/a 33.3 26.7 35.2 29.8 3.95 QQC768 RS 92-5-2 8/8/92 0925 Ao BSP p 7.32 26.6 22.0 28.3 23.9 2.00 QQC769 S 92-5-3 8/8/92 1002 Ao BSP p 7.32 31.5 26.0 32.4 29.8 3.40 QQC770 RS 92-5-4 8/9/92 1244 Ao BSP p 7.32 33.0 25.4 35.3 n/a 4.15 NNZ641 RS 92-2-1 8/25/92 0944 L BSP r a 7.32 29.7 n/a 23.1 n/a 2.60 QQC740/741 RS 92-1-3 8/25/92 0945 L BSP r a 7.32 29.8 31.9 22.8 26.7 2.88 QQC734/735 RS 92-4-2 9/3/92 1212 Pi BSP r c n/a 31.1 32.4 24.9 28.0 3.48 QQC766/771 S 92-6-1 9/3/92 1529 K-L BSP a 7.32 32.1 25.8 33.4 28.3 3.45 QQC772/773 None 92-1-3 9/3/92 1602 K-L BSP r a 7.32 n/a n/a n/a n/a n/a QQC734/735 RS 92-6-2 9/5/92 0931 n/a BSC t 4.88 30.0 24.5 31.1 27.6 2.68 QQC774/775 None 92-6-3 9/5/92 1453 15 MF p 4.88 55.7 43.2 58.5 49.9 22.50 QQC776/777 None 92-6-4 9/5/92 1933 15 MF p 4.88 46.3 37.8 47.3 43.5 12.30 QQC778/779 None 92-4-1 10/9/92 1034 I BSP r a 7.32 49.1 39.8 52.2 45.5 15.60 QQC765/BBD501 None 92-1-3 10/9/92 1450 K BSP r a 7.32 30.5 23.6 n/a n/a 3.45 QQC734/735 None 92-2-2 10/14/92 0909 29 MF r p 4.88 46.7 38.1 49.0 43.0 13.20 QQC742/743 RS 92-7-1 10/14/92 1300 29 MF p 4.88 29.6 24.8 30.9 27.2 2.80 QQC782/783 None 92-4-1 10/15/92 1215 K-L BSP r a n/a n/a n/a n/a n/a n/a QQC765/BBD501 None 92-3-4 10/16/92 1112 G BSP r a 7.32 45.2 36.5 48.1 43.8 11.90 QQC750/751 None 92-6-1 10/16/92 1150 K BSP r a 7.32 32.5 26.2 34.1 29.5 4.05 QQC772/773 None 92-1-3 11/10/92 1518 L BSP r a 7.32 30.7 23.6 33.2 27.0 3.25 QQC734/735 None 92-6-1 11/10/92 1527 L BSP r a 7.32 32.6 26.0 34.4 30.0 4.10 QQC772/773 None 92-3-1 11/13/92 0852 29 MF r p 4.88 54.7 43.2 57.4 50.4 22.00 QQC746/784BBD502 RS 92-8-1 11/13/92 1102 29 MF p 4.88 36.6 30.1 38.3 33.9 5.85 QQC785/786 RS 92-8-3 11/14/92 1709 29 MF p 3.66 34.0 28.4 35.2 30.9 4.50 QQC789/790 None 92-4-2 11/16/92 0922 Pi BSP r h n/a 32.6 26.2 34.1 29.7 3.95 QQC766/771 None 92-9-1 12/7/92 1406 A-Bo BSP p 7.32 30.9 25.5 32.5 28.6 3.28 QQC791/792 None 92-9-2 12/7/92 1426 A-Bo BSP p 7.32 33.2 27.2 35.5 30.3 4.05 QQC793/794 None 92-9-3 12/10/92 0756 29 MF p 4.88 31.8 26.3 33.3 28.9 3.16 QQC795/796 None 92-9-4 12/10/92 0852 29 MF p 4.88 36.4 31.2 38.4 35.0 5.50 QQC797/798 RS 92-2-2 12/10/92 0907 29 MF r p 4.88 47.3 39.0 49.7 43.2 13.65 QQC742/743 RS 92-1-1 12/11/92 1107 29 MF r p 4.88 52.8 41.5 56.2 46.7 19.00 QQC718/719 RS 92-2-2 12/11/92 1118 29 MF r p 4.88 n/a n/a n/a n/a n/a QQC742/743 RS 92-9-5 12/11/92 1220 29 MF p 4.88 43.5 36.8 46.0 40.5 9.70 QQC799/800 None 93-1-1 1/12/93 1255 K-L BSP a 3.66 32.6 26.8 34.4 30.4 3.95 QQZ801/802 None 93-1-2 1/14/93 1110 Ao BSP p 7.32 25.1 21.3 26.1 23.5 1.60 QQZ803/804 None 93-2-1 2/11/93 0846 31 MF a 3.66 34.6 28.9 36.2 32.9 4.80 QQZ 826/827 None 93-2-2 2/12/93 1309 A-Bo BSP a 7.32 30.3 24.5 31.3 27.0 2.80 QQZ 828/829 None 92-6-1 2/12/93 1236 A-Bo BSP r a 7.32 32.8 26.9 34.1 30.1 3.95 QQC 772/773 None 92-9-4 2/16/93 0659 31 MF r a 3.66 36.5 31.4 39.0 35.4 5.80 QQC 797/798 RS 92-3-2 2/17/93 0932 29 MF r p 4.88 64.2 51.2 68.1 58.5 35.00 QQC714/715/747QQZ830 None 92-6-1 3/1/93 1107 K-L BSP r a 7.32 32.9 26.8 34.6 29.7 3.66 QQC772/773 None 92-8-1 3/6/93 1443 31 MF r a 3.66 36.8 30.4 39.2 34.2 6.30 QQC785/786 RS 93-3-1 3/7/93 1215 29 MF p 4.88 35.8 29.5 37.7 33.0 5.35 QQZ805/806 None 93-3-2 3/8/93 1324 29 MF p 3.66 35.9 29.3 37.5 32.9 5.10 QQZ807/808 None 93-3-3 3/8/93 1333 29 MF p 3.66 32.4 27.5 33.7 30.3 3.70 QQZ809/810 None

Table of Contents 58

Appendix Table 2. Stomach contents from green sea turtles captured in the South Padre Island study area during April 1991 - March 1993.

Date: 10/22/91 10/22/91 10/22/91 10/23/91 10/24/91 11/18/91 11/21/91 11/21/91 11/21/91 4/23/92 4/23/92

Turtle ID: 92-1-1 #10 #11 #12 92-1-1 #14 #15 92-1-2 #17 92-1-1 92-1-2 Anthophyta Thalassia testudinum Syringodium filiforme 0.01 Halodule wrightii 0.05 0.02 0.04 tr 0.02 tr 0.02 0.06 0.06 tr Miscellaneous 0.01 Chlorophycophyta Ulva fasciata Chaetomorpha linum Miscellaneous Phaeophycophyta Dictyota dichotoma Padina vickersiae Sargassum fluitans Miscellaneous Rhodophycophyta F. Gelidiaceae Corallina sp. Soliera tenera 0.01 Hypnea musciformis Rhodymenia pseudopalmata Lomentaria baileyana F. Ceramiaceae Polysiphonia echinata Bryocladia sp. Laurencia poitei tr Miscellaneous tr 0.02 tr 0.05 Egg case tr C. Gastropoda C. Bivalvia C. Cirripedia O. Decapoda O. Isopoda Bryozoa Plastic tr Metal 0.02 Miscellaneous 0.11 0.06 0.09 0.08 0.05 0.02 0.04 0.06 0.07 0.03 0.05 Total mass (g) of sample 0.16 0.08 0.13 0.10 0.07 0.02 0.05 0.08 0.19 0.10 0.07 tr - sample < 0.01g but > 0

Table of Contents 59

Appendix Table 2. Continued.

Date: 4/24/92 4/24/92 4/27/92 5/11/92 5/11/92 5/12/92 5/14/92 5/14/92 5/16/92 6/8/92 6/8/92

Turtle ID: 92-1-3 92-1-5 92-1-4 92-1-4 92-2-1 92-1-1 92-2-2 92-2-3 92-1-3 92-3-1 92-3-2 Anthophyta Thalassia testudinum Syringodium filiforme tr Halodule wrightii 0.07 tr 0.01 Miscellaneous tr tr tr tr Chlorophycophyta Ulva fasciata Chaetomorpha linum Miscellaneous Phaeophycophyta Dictyota dichotoma Padina vickersiae tr Sargassum fluitans Miscellaneous Rhodophycophyta F. Gelidiaceae tr 0.03 0.02 0.01 Corallina sp. Soliera tenera 0.02 0.01 0.01 Hypnea musciformis tr 0.01 0.02 Rhodymenia pseudopalmata Lomentaria baileyana F. Ceramiaceae tr tr 0.01 Polysiphonia echinata tr Bryocladia sp. 0.01 0.02 0.02 0.01 Laurencia poitei Miscellaneous 0.03 0.01 tr 0.01 tr tr Egg case C. Gastropoda C. Bivalvia C. Cirripedia O. Decapoda 0.01 0.02 O. Isopoda Bryozoa tr Plastic tr Metal Miscellaneous 0.06 0.07 0.01 0.08 0.07 0.04 0.07 0.07 0.07 0.10 0.07 Total mass (g) of sample 0.11 0.10 0.01 0.14 0.13 0.11 0.09 0.07 0.13 0.11 0.07 tr - sample < 0.01g but > 0

Table of Contents 60

Appendix Table 2. Continued.

Date: 6/8/92 6/9/92 6/9/92 6/9/92 6/12/92 7/24/92 7/27/92 7/28/92 7/29/92 7/30/92 7/30/92

Turtle ID: 92-3-3 92-2-1 92-3-4 92-3-5 92-3-6 92-3-1 92-1-3 92-4-1 92-2-1 92-3-4 92-4-2 Anthophyta Thalassia testudinum Syringodium filiforme Halodule wrightii 0.01 0.01 Miscellaneous tr Chlorophycophyta Ulva fasciata tr tr 0.03 tr tr tr tr Chaetomorpha linum Miscellaneous 0.01 Phaeophycophyta Dictyota dichotoma tr Padina vickersiae Sargassum fluitans tr Miscellaneous Rhodophycophyta F. Gelidiaceae 0.01 Corallina sp. Soliera tenera Hypnea musciformis Rhodymenia pseudopalmata Lomentaria baileyana F. Ceramiaceae 0.03 0.01 tr tr Polysiphonia echinata Bryocladia sp. tr tr tr tr tr tr 0.01 Laurencia poitei Miscellaneous 0.01 tr tr 0.03 0.01 tr 0.01 tr 0.01 Egg case C. Gastropoda C. Bivalvia tr tr C. Cirripedia O. Decapoda tr O. Isopoda tr Bryozoa Plastic 0.01 Metal Miscellaneous 0.08 0.04 0.04 0.05 0.04 0.04 0.02 0.03 0.05 0.03 0.01 Total mass (g) of sample 0.10 0.08 0.05 0.09 0.07 0.05 0.03 0.03 0.06 0.03 0.04 tr - sample < 0.01g but > 0

Table of Contents 61

Appendix Table 2. Continued.

Date: 7/31/92 8/4/92 8/8/92 8/8/92 8/9/92 8/25/92 8/25/92 9/3/92 9/3/92 9/5/92 9/5/92

Turtle ID: 92-4-3 92-5-1 92-5-2 92-5-4 92-5-4 92-1-3 92-2-1 92-4-2 92-6-1 92-6-2 92-6-3 Anthophyta Thalassia testudinum Syringodium filiforme tr tr Halodule wrightii tr 0.02 0.04 Miscellaneous tr tr Chlorophycophyta Ulva fasciata tr tr 0.01 tr 0.01 Chaetomorpha linum Miscellaneous tr Phaeophycophyta Dictyota dichotoma Padina vickersiae Sargassum fluitans Miscellaneous Rhodophycophyta F. Gelidiaceae Corallina sp. tr Soliera tenera tr tr Hypnea musciformis Rhodymenia pseudopalmata Lomentaria baileyana F. Ceramiaceae 0.04 tr tr Polysiphonia echinata tr tr tr 0.01 Bryocladia sp. tr tr 0.01 Laurencia poitei Miscellaneous 0.03 0.01 0.01 0.01 tr tr 0.02 0.01 0.02 0.01 Egg case tr tr tr C. Gastropoda C. Bivalvia 0.01 C. Cirripedia tr O. Decapoda O. Isopoda Bryozoa Plastic tr 0.01 tr Metal Miscellaneous tr 0.05 0.04 0.02 0.04 0.02 0.05 0.04 0.06 0.09 0.02 Total mass (g) of sample 0.07 0.06 0.05 0.04 0.05 0.02 0.08 0.06 0.10 0.12 0.06 tr - sample < 0.01g but > 0

Table of Contents 62

Appendix Table 2. Continued.

Date: 9/5/92 10/9/92 10/9/92 10/14/92 10/14/92 10/16/92 10/16/92 11/10/92 11/10/92 11/13/92 11/13/92

Turtle ID: 92-6-4 92-1-3 92-4-1 92-2-2 92-7-1 92-3-4 92-6-1 92-1-3 92-6-1 92-3-1 92-8-1 Anthophyta Thalassia testudinum tr Syringodium filiforme 0.04 0.01 0.01 0.02 Halodule wrightii tr 0.02 tr Miscellaneous tr tr tr Chlorophycophyta Ulva fasciata tr 0.02 tr Chaetomorpha linum Miscellaneous Phaeophycophyta Dictyota dichotoma Padina vickersiae Sargassum fluitans Miscellaneous tr 0.02 Rhodophycophyta F. Gelidiaceae Corallina sp. Soliera tenera 0.03 0.02 tr 0.01 Hypnea musciformis Rhodymenia pseudopalmata tr tr 0.05 Lomentaria baileyana F. Ceramiaceae tr 0.02 tr Polysiphonia echinata Bryocladia sp. tr 0.02 tr tr Laurencia poitei Miscellaneous 0.01 Egg case tr C. Gastropoda C. Bivalvia C. Cirripedia O. Decapoda O. Isopoda Bryozoa Plastic Metal Miscellaneous 0.07 0.04 0.09 0.05 0.06 0.07 0.03 0.06 0.01 0.05 Total mass (g) of sample 0.11 0.04 0.10 0.05 0.03 0.10 0.20 0.07 0.07 0.01 0.05 tr - sample < 0.01g but > 0

Table of Contents 63

Appendix Table 2. Continued.

Date: 11/14/92 11/16/92 12/7/92 12/7/92 12/10/92 12/10/92 12/10/92 12/11/92 12/11/92 1/12/93 1/14/93

Turtle ID: 92-8-3 92-4-2 92-9-1 92-9-2 92-2-2 92-9-3 92-9-4 92-1-1 92-9-5 93-1-1 93-1-2 Anthophyta Thalassia testudinum Syringodium filiforme tr 0.02 0.02 0.01 0.04 Halodule wrightii 0.01 0.02 Miscellaneous tr Chlorophycophyta Ulva fasciata tr tr 0.01 tr Chaetomorpha linum tr Miscellaneous Phaeophycophyta Dictyota dichotoma Padina vickersiae Sargassum fluitans Miscellaneous Rhodophycophyta F. Gelidiaceae Corallina sp. Soliera tenera Hypnea musciformis tr 0.03 0.01 Rhodymenia pseudopalmata Lomentaria baileyana F. Ceramiaceae tr 0.02 tr Polysiphonia echinata tr Bryocladia sp. 0.03 tr 0.04 Laurencia poitei Miscellaneous tr 0.02 0.02 0.02 0.07 Egg case C. Gastropoda tr C. Bivalvia C. Cirripedia O. Decapoda O. Isopoda Bryozoa Plastic Metal Miscellaneous 0.04 0.11 0.04 0.07 0.11 0.05 0.05 0.20 0.04 0.08 1.00 Total mass (g) of sample 0.04 0.16 0.06 0.13 0.13 0.09 0.07 0.26 0.11 0.08 1.05 tr - sample < 0.01g but > 0

Table of Contents 64

Appendix Table 2. Continued.

Date: 2/11/93 2/12/93 2/12/93 2/16/93 2/17/93 3/1/93 3/6/93 3/7/93 3/8/93 3/8/93 N

Turtle ID: 93-2-1 92-6-1 93-2-2 92-9-4 92-3-2 92-6-1 92-8-1 93-3-1 92-3-2 93-3-3 76 Anthophyta Thalassia testudinum 0.02 0.01 3 Syringodium filiforme 0.02 0.02 tr 0.01 17 Halodule wrightii 0.02 24 Miscellaneous 0.30 tr 14 Chlorophycophyta Ulva fasciata 0.02 0.01 0.03 tr 23 Chaetomorpha linum 1 Miscellaneous 0.01 3 Phaeophycophyta Dictyota dichotoma 1 Padina vickersiae 0.01 2 Sargassum fluitans 1 Miscellaneous 0.02 3 Rhodophycophyta F. Gelidiaceae 0.01 0.01 7 Corallina sp. 1 Soliera tenera tr 11 Hypnea musciformis 0.01 0.23 8 Rhodymenia pseudopalmata 0.11 4 Lomentaria baileyana tr 1 F. Ceramiaceae 0.01 0.02 0.01 19 Polysiphonia echinata 0.01 7 Bryocladia sp. 0.04 22 Laurencia poitei 0.01 2 Miscellaneous 0.03 0.08 0.04 tr 0.02 0.01 41 Egg case 0.01 6 C. Gastropoda 1 C. Bivalvia 0.01 4 C. Cirripedia 0.02 2 O. Decapoda 3 O. Isopoda 1 Bryozoa 0.02 2 Plastic 6 Metal 1 Miscellaneous 0.09 0.13 0.17 0.28 0.13 1.00 0.06 0.08 0.13 0.09 75 Total mass (g) of sample 0.39 0.25 0.20 0.35 0.17 1.55 0.11 0.09 0.16 0.10 tr - sample < 0.01g but > 0

Table of Contents 65 0.7 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 27.00 29.00 0.5 26.5128.00 34.71 35.00 53.78 0.7 0.3 28.0026.5427.00 37.00 35.10 38.50 54.65 0.7 0.1 0.1 27.41 27.3628.44 35.10 28.56 34.96 35.00 55.06 35.00 54.88 56.00 56.00 0.2 0.3 Surface 20.526.7 22.0029.4 21.5022.8 23.00 20.50 30.00 29.00 34.00 1.0 0.3 0.3 1.0 26.118.3 23.00 22.0023.929.4 26.0027.2 27.00 27.00 30.00 32.00 28.00 29.00 27.00 0.3 0.3 0.5 0.5 0.5 27.223.9 25.5031.1 25.0023.3 26.5027.8 26.00 26.00 30.00 32.00 29.00 32.00 30.00 0.5 0.1 0.1 0.8 0.8 28.029.0 26.05 26.6528.3 27.00 34.80 34.60 34.00 53.60 53.82 1.0 1.0 0.1 29.4 27.00 36.50 2.0 28.0 28.00 28.00 38.00 36.00 2.0 Temperature ( Depth Air Zone W Zone W Zone W Walt's Bar 2.0 Walt's BarWalt's Bar 1.5 1.5 Walt's Bar 1.0 Time Location (m) Date 7/1/917/1/91 14127/2/917/2/91 0945 Site 1 South Cove South Cove 27.00 38.00 0.3 4/12/914/12/914/14/914/14/91 1730 South Cove South Cove South Cove South Cove 3.0 3.0 3.0 3.0 4/15/914/15/915/13/915/13/915/15/91 South Cove South Cove South Cove 3.0 South Cove 3.0 South Cove 3.0 3.0 3.0 5/16/915/16/91 12015/17/915/17/915/18/91 South Cove 5/18/91 South Cove South Cove South Cove South Cove 2.5 South Cove 2.5 2.5 2.5 2.5 6/24/916/24/91 6/25/91 6/25/916/25/916/26/916/26/91 1258 South Cove Mouth to South Bay South Cove 1.0 South Cove 26.15 28.48 25.95 34.82 28.25 34.70 34.84 53.63 55.82 34.93 53.84 0.7 56.15 0.7 6/26/91 6/27/916/27/91 6/28/916/28/91 6/28/91 South Cove South Cove North Jetty 2.5 26.01 28.47 35.24 35.24 54.01 56.16 0.7 Appendix Table 3. Hydrological data from the South Padre Island study area during April 1991 - March 1993.

Table of Contents 66 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 28.0029.8629.78 29.7929.00 29.86 34.82 34.66 37.00 34.86 34.66 57.05 57.13 57.25 35.00 57.06 1.5 2.0 0.3 1.5 32.1726.82 32.01 26.8026.62 35.2529.50 34.80 26.60 35.21 29.50 34.55 35.05 59.96 34.70 59.87 54.10 34.86 53.80 35.00 54.15 54.20 57.06 57.12 0.1 1.0 28.4226.00 28.2826.00 25.7827.26 35.39 35.58 27.17 35.34 35.35 35.42 56.31 56.28 54.23 38.00 35.52 53.87 55.44 55.41 25.0525.92 24.96 25.85 35.50 35.60 32.35 35.43 53.85 49.30 54.43 54.44 0.5 25.2025.24 25.2625.20 25.1026.70 35.50 25.50 35.48 26.50 35.44 35.44 35.56 35.50 53.63 35.48 53.61 53.76 35.62 58.76 53.86 53.86 55.31 1.5 55.14 1.5 1.5 28.16 28.02 35.60 35.64 56.90 56.81 1.0 Surface 32.2 31.2226.0 29.79 27.00 35.67 34.46 58.86 57.30 37.00 0.2 30.0 28.0028.027.0 26.00 36.00 26.00 37.00 38.00 1.0 27.026.0 26.5028.0 27.0026.0 30.00 27.2026.0 38.00 24.00 38.00 35.00 35.16 39.00 55.17 1.5 0.3 1.5 4.0 26.028.0 25.00 28.00 39.00 37.00 0.3 0.3 26.028.0 25.00 28.0027.029.0 25.00 29.00 39.00 37.00 38.00 34.00 0.3 0.3 0.3 0.3 Temperature ( Depth Air Zone W ICWW 141 ICWW 141 5.0 ICWW 113 4.0 Port Isabel channel 1.5 Port Isabel channel Port Isabel channel 1.5 ICWW cm 131-133 ICWW cm 125-127 5.0 Time Location (m) Date 7/3/91 7/4/917/4/91 07277/5/91 1030 1125 ICWW cm 131 South Cove 6.0 3.0 7/5/917/5/91 13007/8/91 18007/8/91 0820 ICWW cm 1217/9/91 ICWW cm 1417/9/91 0845 1545 ICWW & PI channel 4.0 600m E of ICWW 135 4.0 1.5 1.5 South Cove 2 to 4 7/9/91 South Cove 7/11/917/12/91 08457/13/91 07457/13/91 0838 North side Jetty 7/14/91 15357/15/91 0800 Jetty Port Islabel cm 2 North Jetty North Jetty North Jetty 7/16/917/17/917/17/91 7/18/917/22/91 07407/22/91 0815 7/22/91 1310 South Cove North Jetty Jetty ICWW c.m. 141 7/22/917/23/91 7/24/917/24/91 0700 7/24/91 11307/24/91 PI channel c.m. 2 14357/24/91 Port Isabel cm 5 2.0 2.0 ICWW c.m. 141 ICWW c.m. 141 3.5 3.5 1.5 38.00 0.3 7/24/917/24/917/25/917/25/91 0815 7/25/91 PI channel c.m. 2 PI channel c.m. 3 3.5 Mexiquita Flats 3.5 Mexiquita Flats 2.0 2.0 Table 3. Continued.

Table of Contents 67 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 25.5428.95 25.35 28.9228.84 35.66 35.67 28.68 35.54 35.67 35.10 54.15 53.83 57.72 35.22 57.72 56.87 56.88 0.6 0.6 28.06 35.51 56.62 0.5 30.2328.41 27.96 35.67 35.79 35.83 57.08 58.90 56.92 0.3 27.7029.76 29.7429.00 35.90 35.80 28.76 35.92 35.10 58.76 35.18 58.62 56.36 56.94 56.82 1.3 0.5 29.0030.5029.0029.0029.0029.00 36.00 35.00 37.00 35.50 36.00 36.00 2.0 1.5 1.5 0.8 30.00 35.00 Surface 29.0 26.00 26.00 27.030.0 25.00 28.0028.028.0 24.00 26.00 37.00 34.00 37.00 36.00 1.0 1.0 0.3 0.3 27.627.6 28.00 29.4229.5 29.62 35.53 35.56 36.18 56.44 58.00 59.12 0.3 0.3 1.0 28.0 26.89 35.66 56.12 28.127.5 28.0027.0 28.0028.0 29.00 35.00 37.00 35.00 35.00 1.5 1.0 1.5 Temperature ( Depth Air Zone G Walts Bar 1.5 Walt's Bar 1.0 Walt's Bar 1.5 ICWW 141 2.0 ICWW 141 ICWW 125-127 lower Laguna Madre 1.0 South Padre Causeway 3.0 Time Location (m) Date 8/1/91 1012 Mexiquita Flats 2.0 8/1/918/1/91 12258/1/918/1/91 Mexiquita Flats8/2/918/3/91 1500 1015 2.0 Mexiquita Flats Mexiquita Flats South Jetty 1 3.0 27.40 27.40 35.10 35.00 55.10 54.90 8/4/918/4/91 08018/5/918/6/91 Mexiquita Flats 8/6/91 15358/7/91 South Jetty South Jetty South Jetty North Jetty 27.20 26.80 28.40 35.74 28.17 35.90 35.73 55.80 35.70 55.70 57.10 56.88 0.3 0.3 9/4/919/5/919/5/91 09179/6/91 1428 9/7/919/8/91 1345 South Jetty9/8/91 0930 South Jetty Mouth of South Bay 1030 1.0 6.0 3.0 30.00 33.00 2.0 7/26/917/26/91 0800 7/26/91 1010 7/26/91 1210 1550 Mexiquita Flats Mexiquita Flats 2.0 2.0 7/26/917/26/917/27/917/29/917/29/91 Mexiquita Flats Mexiquita Flats 2.0 Zone C inside 2.0 BSP Zone C inside 5.0 5.0 28.00 37.00 0.5 9/10/919/11/919/12/919/12/919/13/91 1750 1230 Mouth of South Bay Mexiquita Flats Mouth of South Bay Mexiquita Flats 2.0 Table 3. Continued.

Table of Contents 68 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 27.1226.96 33.90 34.40 53.25 53.88 26.76 32.6420.00 51.20 34.00 0.6 24.72 21.52 29.22 30.70 44.35 43.68 Surface 30.030.0 29.00 29.0027.0 26.60 34.00 35.00 34.00 1.5 1.5 26.926.9 26.62 27.1426.0 26.5026.5 26.80 34.00 33.66 34.33 32.60 52.77 52.97 53.33 1.0 1.0 1.0 0.8 28.024.0 22.0016.0 23.0015.6 20.00 20.00 32.00 32.00 40.00 1.5 0.6 21.0 19.0020.022.0 20.6422.0 21.0022.0 20.63 20.0022.0 20.40 21.00 29.54 35.00 21.00 32.40 29.78 32.48 41.80 41.94 45.52 26.00 45.68 35.00 35.00 1.0 1.0 0.6 1.0 1.5 1.0 25.025.0 23.6627.0 24.1933.5 23.66 24.70 24.34 23.33 29.66 24.63 30.20 29.66 29.54 30.12 44.16 27.54 44.18 45.14 45.16 45.10 28.96 41.90 0.5 43.67 0.6 23.521.0 24.05 22.00 25.0 24.0627.5 24.65 29.9227.0 24.00 24.62 29.92 24.62 23.78 32.54 24.53 44.92 32.72 44.90 32.44 31.60 32.85 48.93 31.65 48.93 48.60 48.44 47.50 47.70 0.5 1.0 Temperature ( Depth Air Time Location (m) Date 9/13/919/14/91 1130 Brazos Santiago Pass North Jetty 12/9/91 Mexiquita Flats 1.5 4/23/924/23/92 08304/24/92 18004/24/92 0830 Mexiquita Flats4/25/92 1610 0000 South Cove(L) 1.8 South Cove 2.5 1.8 2.5 4/26/924/27/92 0900 09205/11/92 South Cove(L)5/11/92 0737 South Cove(L)5/12/92 1300 0814 2.5 South Cove 2.5 Mexiquita Flats 4.0 2.0 3.0 10/22/91 Mexiquita Flats 1.5 10/22/91 101510/22/91 113710/22/91 115010/23/91 Mexiquita Flats 10/23/91 Mexiquita Flats 112310/24/91 Mexiquita Flats Mouth of South Bay 2.0 2.0 Mexiquita Flats Mexiquita Flats 1.5 10/24/91 094511/18/91 114411/19/91 Mexiquita Flats11/21/9111/21/91 0940 South Cove 11/21/91 1.5 1214 Mouth of South Bay Mexiquita Flats 2.0 Mexiquita Flats Mexiquita Flats 1.5 1.7 11/22/9112/10/91 083012/11/9112/12/91 Mexiquita Flats12/13/91 Mexiquita Flats 1.5 Brazos Santiago Pass 1.5 South Cove South Cove Table 3. Continued.

Table of Contents 69 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 26.14 25.83 33.28 33.56 51.24 51.44 27.5026.70 26.75 26.61 32.69 33.63 26.30 33.73 51.87 43.10 52.10 52.12 0.5 0.7 Surface 29.028.5 25.1424.0 25.6431.0 25.13 22.90 25.92 24.33 31.66 22.75 31.78 23.52 31.66 34.02 31.84 34.27 48.10 34.22 48.18 48.66 34.30 48.70 49.29 49.20 50.90 1.0 50.56 1.0 0.3 0.7 26.028.0 25.1927.5 26.1024.5 23.97 26.9026.0 26.00 22.84 33.2827.0 26.73 23.00 32.98 22.80 34.32 23.50 33.46 33.18 35.53 50.31 32.66 50.68 50.74 36.96 50.73 51.96 50.96 51.21 35.00 1.0 51.51 38.00 2.0 0.7 0.5 0.5 2.0 26.0 25.0028.531.0 27.50 28.44 27.52 34.00 28.47 31.20 31.76 31.86 31.78 49.70 50.40 51.48 51.42 1.2 0.7 0.7 29.027.5 30.0031.0 25.7233.0 31.20 25.3532.0 25.60 25.77 31.0028.0 24.62 27.64 34.2032.0 25.60 28.00 28.00 34.34 27.56 34.20 29.56 34.37 26.70 51.53 34.86 33.24 28.05 47.53 52.23 33.24 25.90 50.68 52.40 33.50 25.28 52.34 52.90 33.05 1.0 50.66 53.00 30.60 0.3 53.00 42.40 0.5 51.00 42.32 0.5 48.42 0.8 1.0 1.0 32.028.0 30.1634.0 26.29 29.60 27.46 25.97 26.20 27.46 34.49 26.22 34.36 34.86 44.38 34.24 45.54 53.30 53.62 54.07 54.06 0.7 1.8 31.0 29.4634.0 29.30 25.44 33.14 24.98 33.42 32.43 54.24 33.03 54.20 48.66 50.23 0.5 0.5 Temperature ( Depth Air 2.1-2.42.1-2.4 28.51.2-1.5 32.0 24.80 29.5 29.10 24.50 30.00 29.22 33.20 30.28 32.93 33.10 33.22 32.92 49.42 35.16 49.50 53.80 53.80 55.15 55.06 1.0 0.9 0.6 1.5-1.81.5-2.1 28.5 32.0 25.001.5-2.1 28.24 25.0 25.20 28.23 24.66 32.95 33.24 24.70 32.40 33.12 32.98 50.13 49.32 53.10 32.79 53.04 50.10 1.5 50.02 1.0 0.5 Time Location (m) Date 6/7/926/7/92 09176/8/92 14466/8/92 0829 1212 South Cove Mexiquita Flats 2.5 2.5 2.5 2.5 6/8/926/9/92 17596/9/92 07526/9/92 10046/9/92 1300 South Cove(K) 1800 2.0 1.8 1.8 4.0 2.0 5/12/925/12/92 12285/13/92 17005/13/92 0738 1222 South Cove 2.0 2.0 2.0 2.0 5/13/925/14/92 18005/14/92 08485/14/92 13095/15/92 1630 Mexiquita Flats5/16/92 11445/16/92 0000 1103 2.0 South Cove South Cove 3.0 2.0 2.5 1.5 1.5 2.5 5/16/92 1835 2.5 6/11/926/11/92 0815 1315 Mexiquita Flats 2.5 2.1 6/11/926/12/92 18006/12/92 0735 14207/29/927/29/92 0804 South Cove7/29/92 1328 1844 Mexiquita Flats Mexiquita Flats 2.1 Mexiquita Flats 2.1 2.5 7/25/927/25/92 08207/25/92 13007/27/92 1800 Mexiquita Flats 7/27/92 0721 Mexiquita Flats Mexiquita Flats South Jetty (K) 1.5 South Jetty (K) 2.0 Table 3. Continued.

Table of Contents 70 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) Surface 31.028.0 26.9633.5 24.36 26.87 25.02 24.09 32.80 24.40 32.86 32.74 32.54 32.96 52.17 32.94 51.66 49.73 49.58 50.38 49.83 0.5 0.8 2.0 32.5 24.7928.032.0 23.95 24.0031.5 26.00 32.7527.0 26.0030.0 32.69 24.30 25.05 23.67 50.03 25.03 49.34 35.00 33.00 35.00 32.93 37.00 32.72 1.2 32.88 49.50 49.00 50.33 50.27 1.4 0.6 1.2 1.2 1.0 33.027.5 27.3131.5 24.0232.0 37.11 26.4126.0 23.58 27.65 33.3832.0 26.20 24.82 32.5432.5 27.60 33.30 25.80 33.06 24.15 32.27 27.83 33.10 25.88 52.61 33.12 33.12 27.82 52.22 49.15 33.18 32.73 48.80 51.26 33.00 33.20 51.20 52.70 33.00 1.0 52.60 49.63 33.05 1.8 49.24 50.23 0.9 50.39 52.90 0.9 52.82 1.1 1.0 0.8 27.031.5 25.5332.0 26.3226.5 25.30 29.0334.0 25.83 24.67 32.7932.5 28.90 26.26 33.40 24.57 33.21 27.34 33.92 23.57 33.28 34.55 26.75 50.24 33.60 34.00 50.42 51.24 34.47 33.68 51.03 53.93 53.93 51.42 29.69 1.1 51.11 1.1 53.88 0.8 45.85 0.9 1.3 1.1 27.030.0 25.2729.0 25.9229.5 24.75 25.9430.5 23.63 25.19 33.1928.0 24.94 28.00 33.2128.5 33.11 27.00 33.31 33.00 27.82 50.44 33.08 27.48 50.74 51.04 48.97 51.22 31.78 33.30 49.97 36.50 1.3 34.00 33.22 1.5 1.3 52.94 52.62 49.36 2.7 1.8 4.8 1.2 28.028.0 28.1828.0 27.5530.5 27.98 28.2028.0 27.42 28.56 33.40 28.12 28.53 33.04 28.34 32.42 33.44 28.59 33.05 33.38 53.42 33.32 33.43 51.98 52.47 33.28 52.49 53.52 33.50 53.26 53.70 2.4 53.44 53.93 1.0 53.92 1.0 1.0 1.5 Temperature ( 36.0 33.0 27.72 27.85 32.96 33.08 52.90 52.81 0.5 Depth Air Time Location (m) Date 8/3/928/3/92 08348/3/92 12448/4/92 1741 South Jetty (K)8/4/92 0814 South Jetty (K) 1250 South Jetty (5) 3.0 South Jetty (J) 1.8 North Jetty (T) 4.6 2.7 3.3 8/4/928/5/92 17458/5/92 08188/5/92 1313 South Jetty (D)8/6/92 1801 South Jetty (J)8/6/92 0731 South Jetty (H)8/6/92 1252 4.5 South Jetty (8) 1754 South Jetty (J) 3.0 4.5 South Jetty (8) South Jetty (8) 5.5 3.3 4.0 4.0 8/7/928/7/92 07288/7/92 12508/8/92 1835 South Jetty (J)8/8/92 0729 South Jetty (J)8/8/92 1300 South Jetty (J) 1802 South Jetty (J) 3.3 South Jetty (AI) 2.7 South Jetty (AO) 2.7 2.4 1.5 3.3 8/9/928/9/92 0728 1257 South Jetty (J) South Jetty (1I) 3.3 5.5 7/27/927/28/92 18077/30/92 18107/30/92 0807 South Jetty (K) 1700 South Jetty South Jetty (K) South Jetty (K) 2.4 2.4 2.4 7/31/92 1248 South Jetty (C) 3.3 8/11/928/12/92 09578/12/92 10008/12/92 1245 North Jetty (VI)8/13/92 1604 0940 South Jetty South Jetty 2.4 South Jetty (AO) South Jetty 3.0 3.3 7.9 1.2 8/14/928/17/92 09408/18/92 09318/18/92 0909 South Jetty (AO)8/19/92 1412 Mexiquita Flats 0815 South Jetty (K) 6.1 North Jetty (W) 1.0 Mexiquita Flats 3.3 1.2 2.1 Table 3. Continued.

Table of Contents 71 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 29.5130.12 29.4729.21 30.01 33.14 29.1729.03 33.33 33.1830.15 33.21 29.00 33.31 30.16 54.20 33.21 32.92 54.24 55.17 33.16 55.12 54.00 32.97 53.99 32.99 0.6 53.54 0.9 53.74 54.80 0.9 54.71 0.6 0.6 27.9129.92 27.9728.54 29.7229.02 33.06 28.3426.94 32.94 28.95 33.17 33.01 26.87 33.0530.11 33.08 52.95 32.74 33.72 30.18 52.88 54.48 32.97 54.40 52.98 32.72 32.75 52.92 53.64 0.6 53.58 51.40 32.76 0.8 51.41 0.6 54.38 0.8 54.40 0.9 26.9926.86 26.7330.45 26.8627.16 32.95 30.52 32.85 26.40 32.97 33.16 32.95 33.09 33.18 51.64 33.25 51.60 55.24 55.40 52.08 51.38 1.3 0.8 0.8 1.4 Surface 31.028.0 29.8730.0 28.0732.0 29.69 28.2827.0 28.02 29.30 33.23 28.29 28.30 33.29 29.18 33.21 33.13 28.10 33.15 33.22 54.76 33.14 33.31 54.90 53.36 33.20 53.30 53.50 30.44 53.50 54.36 0.6 54.32 53.50 1.4 48.93 0.8 0.5 1.3 31.530.0 30.5429.5 31.7133.5 29.32 28.5630.0 31.56 29.07 33.3228.0 28.45 29.90 33.40 29.08 33.20 28.36 32.99 29.97 33.44 32.96 28.39 55.24 32.99 32.94 54.28 56.98 32.87 32.92 56.98 53.30 32.85 53.32 53.50 33.22 0.8 53.48 54.14 0.6 54.09 53.15 0.4 53.60 0.8 0.5 0.5 31.530.5 29.4829.0 30.0835.0 28.78 29.0028.0 29.90 29.55 32.6434.5 28.88 29.20 33.8029.0 29.01 32.88 31.26 33.04 29.12 33.01 29.80 33.24 30.56 53.53 33.14 33.04 29.75 53.34 54.60 33.16 33.07 54.64 53.90 33.22 33.40 53.85 54.64 32.82 0.8 54.02 54.08 33.34 0.5 54.16 55.90 0.4 54.78 55.01 1.3 54.98 0.6 0.5 34.5 29.75 29.86 33.37 33.33 55.02 54.94 0.6 31.0 29.70 29.67 33.04 33.13 53.88 53.96 0.9 Temperature ( Depth Air North Jetty (W) 2.4 North Jetty (W) Mexiquita Flats 1.5 c800 W Time Location (m) c1300 Date 9/2/929/2/92 0813 1333 North Jetty (Z) 2.4 9/3/929/3/92 08169/4/92 1731 9/4/92 13479/5/92 1739 9/5/92 0826 South Jetty (I)9/5/92 1815 6.1 Mexiquita Flats BSP 1.5 3.0 2.4-3 9/6/92 9/7/929/7/92 08339/8/92 1820 1012 Mexiquita Flats N.S. Jetty (4) 2.4-3 8/19/928/21/92 12538/21/92 09308/21/92 1302 Mexiquita Flats8/22/92 1709 North Jetty (W) 0737 North Jetty (W) 1.8 North Jetty (W) 2.4 Mexiquita Flats 2.4 2.4 1.5 8/22/928/22/92 13158/24/92 18008/24/92 0819 Mexiquita Flats8/24/92 1337 Mexiquita Flats8/25/92 1832 South Jetty (10) 0933 3.0 South Jetty (K) 1.8 North Jetty (X) 4.0 South Jetty (K) 3.7 2.1 4.3 8/25/928/25/92 13208/26/92 18048/26/92 1008 South Jetty (12)8/28/92 1250 South Jetty (12)8/28/92 08118/28/92 1330 4.3 1848 4.0 Mexiquita Flats BSP Mexiquita Flats BSP Mexiquita Flats 3.0 3.0 3.0 5.0 8/29/928/30/92 13008/30/92 0931 8/31/92 1428 0939 South Cove 3.5 1.8 Table 3. Continued.

Table of Contents 72 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 24.16 24.10 37.50 37.67 55.51 55.68 0.8 26.49 26.36 35.66 35.66 55.36 55.27 1.0 26.6026.82 26.97 26.78 35.80 37.01 36.63 36.23 55.67 56.98 57.67 56.47 1.1 1.1 23.21 23.0423.90 38.2323.90 24.04 38.44 24.04 38.30 55.73 38.30 55.52 37.80 37.80 56.48 0.6 55.76 56.48 55.76 0.5 0.5 24.04 24.22 38.54 38.60 57.02 57.00 1.3 Surface 25.029.0 24.3531.0 25.46 24.02 26.02 24.28 37.01 26.00 35.68 37.84 35.81 31.68 55.27 35.79 55.92 54.40 47.90 54.84 55.98 1.0 1.0 1.5 25.026.0 25.3726.0 25.4125.5 25.29 26.3129.0 25.36 25.50 37.1327.0 26.07 26.87 37.2626.0 25.52 37.30 27.30 35.15 26.28 37.45 24.47 35.78 27.15 55.99 35.49 36.70 25.15 56.28 56.53 36.20 36.54 56.59 54.26 36.42 35.07 54.53 54.44 36.67 1.0 55.10 57.46 36.58 1.0 56.54 57.57 1.0 57.57 52.45 1.4 55.24 0.8 0.8 1.0 29.027.0 26.0424.5 26.7628.0 25.68 25.3427.0 25.68 26.11 36.0027.0 25.36 26.13 35.17 26.15 36.60 25.98 34.75 26.13 35.15 35.82 25.82 55.15 31.38 35.18 55.56 54.54 35.74 35.68 54.56 52.86 35.19 47.94 55.13 35.81 1.0 55.16 54.11 1.0 54.16 54.82 0.9 54.89 0.8 0.8 1.0 27.026.0 26.67 26.5822.7 26.78 26.40 22.14 36.72 37.34 22.11 34.24 37.10 38.30 57.30 53.37 57.50 38.33 57.24 54.78 1.0 54.41 0.9 0.4 29.4 22.8525.027.0 22.76 23.13 23.50 38.43 23.0526.0 23.38 38.41 38.38 23.96 38.22 55.41 38.18 24.02 55.29 38.12 55.54 38.60 55.53 56.11 0.6 55.90 38.70 0.4 56.91 0.5 56.87 0.5 27.026.0 24.54 24.4620.0 24.3919.5 24.40 22.35 38.42 22.05 38.58 20.32 38.25 21.65 38.48 57.15 56.97 57.34 57.39 0.6 0.5 58.35 57.37 60.24 60.24 0.5 0.5 Temperature ( Depth Air South Jety (J) 3.0 Time Location (m) c0800 Date 10/9/9210/9/92 092410/9/92 103410/9/92 1310 N. Jetty (12) 1450 South Cove (I) S. Jetty (I) 2 to 3 S. Cove (K) 2.5 6 to 10 3 to 4 11/9/92 0800 South Jetty (K) 1.8 11/9/9211/9/92 1338 1610 South Jetty (K) South Jetty (J) 2.4 3.4 10/10/92 084510/10/92 130010/10/92 180010/11/92 Mexiquita Flats 081510/11/92 Mexiquita Flats 130510/11/92 Mexiquita Flats 180010/12/92 2.0 Mexiquita Flats 0922 2.0 Mexiquita Flats 2.0 Mexiquita Flats 2.3 Mexiquita Flats 1.8 1.8 1.5 10/12/92 125510/12/92 175610/14/92 083210/14/92 Mexiquita Flats 130010/14/92 Mexiquita Flats 171510/15/92 Mexiquita Flats 085510/15/92 1.5 Mexiquita Flats 1305 1.9 Mexiquita Flats 1.5 South Jetty (K) South Cove (12) 1.0 2.0 3.0 2.5 10/15/92 171510/16/92 083010/16/92 111210/17/92 South Cove (12) North Jetty (PI) N. of S. Jetty 2.5 6.0 3.5 11/10/92 075311/10/92 141711/10/92 151811/10/92 South Jetty (K) 152711/11/92 South Jetty (K) 0749 South Jetty (L) 1.8 South Jetty (L) 2.1 South Jetty (K) 0.6 0.6 2.1 11/11/92 124511/11/92 172011/12/92 075611/13/92 South Jetty (K) 074511/13/92 South Jetty (K) 0852 Mex. Flats 2.1 Mex. Flats 2.1 Mex. Flats 1.2 0.9 1.8 Table 3. Continued.

Table of Contents 73 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) 22.1022.09 21.9020.84 21.91 20.80 0.6 0.6 0.5 21.0021.18 21.05 20.73 37.83 37.70 37.93 38.04 52.75 52.74 52.82 52.64 0.6 0.7 17.7618.13 17.7118.55 18.0217.98 34.07 18.4018.82 34.47 17.99 34.07 34.84 18.37 34.46 34.39 44.84 35.00 34.12 44.81 45.44 34.39 45.46 46.50 34.12 46.46 45.30 0.8 45.28 45.63 0.8 45.45 0.3 0.9 1.8 Surface 20.0 21.42 21.44 38.73 38.65 53.99 53.90 0.6 20.020.0 20.9320.0 20.93 20.88 20.88 38.39 38.3912.0 38.43 38.43 15.20 53.24 14.85 53.30 53.24 53.36 34.89 0.6 34.76 0.6 42.86 42.90 0.6 19.015.5 16.6519.0 14.6816.5 16.15 16.6516.0 14.67 16.71 34.3017.0 16.15 17.04 35.3117.0 16.72 34.67 18.89 34.30 16.92 35.42 18.16 34.35 17.56 43.84 34.67 34.12 17.78 43.75 43.45 34.12 34.21 43.35 43.84 34.13 34.25 43.75 44.13 33.94 1.3 44.06 43.96 34.25 1.3 44.04 45.89 1.3 44.64 45.28 1.3 44.94 0.8 0.8 1.4 18.0 18.01 17.54 34.13 34.38 44.97 44.84 0.8 11.0 13.9413.516.5 13.91 13.6519.0 13.93 32.4416.0 13.53 15.15 13.75 32.20 14.72 30.35 15.15 32.24 14.57 39.62 32.40 32.30 39.32 32.32 32.44 39.13 32.40 39.19 39.37 32.61 0.9 39.19 40.66 40.62 40.32 0.8 40.16 0.9 1.2 0.8 17.021.0 14.9316.0 15.4414.0 14.85 15.6318.0 15.55 14.82 32.26 15.63 15.26 32.70 14.93 32.23 33.04 15.18 32.60 32.22 40.25 33.04 32.84 40.18 40.93 32.36 40.92 41.81 33.04 41.87 40.30 0.8 40.43 41.34 1.4 41.35 1.1 0.6 0.8 Temperature ( Depth Air Time Location (m) Date 12/7/92 0907 K 2.0 12/7/9212/8/92 132012/8/92 092212/8/92 132012/9/92 170512/9/92 081012/9/92 1412 K 1604 K K J #12&K J 3.0 K 2.1 3.0 2.7 3.7 3-3.5 3.4 1/12/931/12/93 08091/12/931/13/93 17061/13/93 08051/13/93 1225 1431 K K #12 K #12 #12 2.4 2.7 2.4 4.9 2.3 4.0 11.5 13.69 13.66 31.94 32.13 39.00 39.22 0.8 1/14/931/14/93 08151/14/93 11301/16/93 17081/16/93 0821 1311 K MF-W. of 16 K MF-W. of 16 K 3.0 3.0 3.0 3.1 3.0 11/13/92 110211/13/92 140911/14/92 080011/14/92 1300 Mex. Flats Mex. Flats Mex. Flats Mex. Flats 2.1 2.1 1.5 21 - 24 1.8 11/14/92 163011/14/92 170911/16/92 091511/16/92 132711/16/92 Mex. Flats 1627 Mex. Flats South Jetty (L) Point Alligator Cove South Jetty (K) 1.2 1.2 2.1 1.8 12/10/92 133812/10/92 163512/11/92 0845 MF btwn 16&2212/11/92 0505 MF btwn 16&2212/12/92 1002 MF btwn 16&2212/12/92 1.5 1600 MF btwn 16&22 1.5 1.2 1.2 K #9&H 4.3 1.8 Table 3. Continued.

Table of Contents 74 /s Visibility Bottom (m) Ω Surface Conductivity m Bottom Surface Salinity (ppt) C) ° Bottom 15.58 15.65 33.08 32.96 41.57 41.44 1.0 Surface Water 19.021.5 15.7319.0 16.13 15.89 16.23 16.21 32.64 16.15 33.11 32.30 33.04 33.13 41.10 32.92 40.90 42.07 42.01 41.97 41.74 0.8 0.8 1.0 21.020.3 16.8021.0 17.5522.0 16.66 20.34 17.45 18.00 32.4719.5 20.30 32.48 17.94 32.62 19.06 32.40 32.63 32.76 19.17 42.20 32.04 42.03 42.96 33.85 32.87 42.63 44.94 44.72 43.62 29.58 0.5 45.00 0.5 39.72 0.5 40.17 0.6 1.0 21.019.0 18.3614.0 17.9118.0 17.52 18.7219.5 17.67 17.58 32.9719.5 17.02 18.32 31.9522.0 17.34 32.11 19.54 30.82 18.66 32.13 18.24 32.04 19.42 43.73 29.50 31.84 18.16 42.02 42.39 32.14 31.46 42.29 41.64 26.10 31.58 38.73 42.02 31.34 1.5 41.80 42.66 31.64 2.4 38.52 42.88 1.0 42.86 42.22 2.5 42.20 3.0 0.5 1.3 22.020.0 18.6422.0 18.3621.5 18.64 18.4421.0 17.94 18.12 31.8023.5 18.07 18.46 31.6219.5 18.09 31.92 18.43 32.23 18.40 32.14 18.68 32.62 18.47 42.82 32.28 32.35 18.77 42.80 42.44 32.64 33.49 42.38 43.03 32.14 33.59 42.86 43.24 33.70 1.2 43.36 43.19 33.52 1.3 43.22 44.85 1.6 44.95 45.00 1.4 44.95 1.0 0.4 0.6 18.020.0 18.4718.0 18.7814.0 18.04 17.6717.0 18.69 16.27 33.5015.0 17.76 16.59 32.28 16.17 33.69 16.12 31.64 16.59 32.36 33.25 16.14 44.49 31.61 32.11 44.67 43.43 32.13 31.97 43.41 41.77 32.05 41.76 42.15 31.92 0.8 40.93 41.27 0.6 41.20 40.57 0.9 40.55 0.5 0.6 1.0 17.024.0 18.5121.0 18.3819.0 18.55 18.9021.0 18.48 19.45 18.69 18.64 19.43 18.59 31.69 30.88 31.37 30.74 43.20 42.80 41.63 41.44 1.1 2.0 1.1 2.0 1.5 Temperature ( Depth Air MF-NW corner 1.0 MF-NW cornerMF-NW cornerMF-NW corner 0.7 1.0 1.0 Time Location (m) Date 3/1/933/1/93 07053/1/93 12323/2/93 18023/2/93 0726 1334 K J J K K 2.4 3.0 2.4 2.0 2.0 1/16/931/17/93 16581/17/93 08391/17/93 1227 MF-W. of 16 1634 MF-W. of 16 MF-W. of 16 MF-W. of 16 3.0 1.0 1.0 1.5 1/18/931/19/93 11081/19/93 08121/19/93 12182/11/93 MF-E of 22 0846 MF-E of 22 K 1.5 MF-E of 22 0.8 2.0 2/11/932/11/93 12052/12/93 18062/12/93 07312/12/93 12362/13/93 15402/13/93 0826 K 1259 J MF-btwn 16&22 K Ao MF-btwn 16&22 K 1.0 1.7 2.3 3.0 3.0 3.0 2.7 2/13/932/14/93 16452/14/93 08162/14/93 1324 MF-btwn 16&222/15/93 16092/15/93 0750 1.7 2/16/93 1215 0659 K K MF-btwn 16&22 N I J 1.0 J 3.0 3.8 3.0 3.0 3.3 2/17/932/17/93 07272/17/93 13022/19/93 1633 MF-btwn 16&222/19/93 0924 MF-btwn 16&222/19/93 1302 MF-btwn 16&22 1.0 1705 1.3 1.3 Table 3. Continued.

Table of Contents 75 /s Visibility Bottom (m) Ω Surface m Bottom Surface C) Conductivity ° Bottom Water Salinity (ppt) Surface 16.023.5 18.8925.0 19.6021.0 19.07 18.79 19.61 20.07 32.13 18.29 31.50 20.04 32.26 31.38 31.53 32.65 43.35 31.35 43.70 43.32 32.67 43.14 42.50 42.05 45.06 0.8 45.08 1.6 2.0 0.8 23.022.0 20.3019.0 19.4220.0 20.31 19.3814.0 19.05 20.33 32.1520.0 19.36 16.80 31.5920.0 20.90 32.20 19.41 33.42 16.66 31.60 18.60 31.95 18.82 44.70 32.36 31.69 18.60 44.68 43.10 31.58 31.88 42.91 44.10 31.89 31.74 44.07 44.37 31.86 1.5 44.21 41.17 31.85 2.0 41.16 43.39 0.6 43.04 42.56 0.9 42.59 0.1 0.7 0.8 17.024.0 18.8423.0 20.4524.0 18.81 19.5924.0 20.47 20.11 31.9722.0 19.53 19.60 31.71 20.22 32.07 20.52 32.01 19.13 31.65 31.44 20.46 43.18 32.10 32.91 43.17 44.10 31.50 37.17 44.07 43.91 32.81 44.00 43.72 37.06 0.9 43.71 44.96 0.8 44.70 51.17 0.6 51.16 0.5 1.4 0.9 Temperature ( Depth Air Time Location (m) Date 3/3/933/3/93 07503/3/93 13473/4/93 1714 0753 L J K K 3.0 1.7 2.5 2.5 3/4/933/4/93 13123/5/93 17003/6/93 08243/7/93 14453/7/93 0711 MF-btwn 16&223/7/93 1220 MF-btwn 16&22 K 1750 K 1.0 1.0 MF MF MF 3.0 3.0 1.5 1.5 1.5 3/8/933/8/93 07193/8/93 13043/9/93 1650 MF-btwn 16&223/9/93 1228 MF-btwn 16&22 1532 MF-btwn 16&22 1.2 MF-btwn 16&22 1.0 1.3 0.8 K 3.0 3/11/93 0840 MF-btwn 16&22 1.1 Table 3. Continued.

Table of Contents 76

VITA

Michael Scott Coyne was born on March 8th, 1967 in Lafayette, Indiana to Dr. George W. and Laura J. Coyne. His family entered the Peace Corps from 1971 - 76 serving in Cape Coast, Ghana. He moved to Winter Park, Florida in 1979 with his family, where he graduated from Winter Park High School in May, 1985. He entered Valencia Community College (Orlando, Florida) that fall, then graduated in May 1987 with an Associate of Arts degree. He transferred to Drexel University (Philadelphia, Pennsylvania) to pursue a Bachelor of Science degree, transferring again to the Univer- sity of Florida (Gainesville, Florida) in May 1989, graduating with a Bachelor of Science degree in Zoology during May 1990. While an undergraduate he gained laboratory experience working for the U.S. Department of Agriculture (Germantown, Pennsylvania), the Department of Bioscience and Biotechnology of Drexel University, and the Department of Gastroenterology at Shands Hospital, University of Florida. He entered graduate school in the Department of Wildlife and Fisheries Sciences at Texas A&M University in September 1990. As a graduate student he served as a teaching assistant in the freshman biology program in College Station and Galveston and in the marine biology program at Galveston. In addition, he participated in projects involving sea turtles as a research assistant at the Institute of Marine Life Sciences (Texas A&M University at Galveston), presenting the results at scientific meetings. His permanent address is 2130 Cady Way, Winter Park, Florida, 32792.

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