Objectives:

1. Quantify the sub-lethal effect of debris ingestion (nutrient dilution) on nutrient gain

2. Model sub-lethal effects of debris ingestion on nutrient intake and growth

3. Evaluation of stress from entanglement on the loggerhead sea turtle

4. Movement patterns and behavior of pelagic-stage loggerheads in the eastern Atlantic

5. Document the genetic relationships of pelagic-stage loggerheads in the eastern

Atlantic with rookeries in the southeast US  (Document has 14 pages; lists publications resulting from research

Bjorndal, Karen A.

Bolten, Alan B.

English

Aquatic Commons

BIOLOGY OF PELAGIC SEA TURTLES: 
EFFECTS OF MARINE DEBRIS 
F i a l  Report to 
Florida Cooperative Fish and Wildlife Research Unit 
University of Florida 
Research Work Order 118 
.- * 
December 1998 
Karen A. Bjorndal and Alan B. Bolten 
Archie Cam Center for Sea Turtle Research 
University of Florida 
Gainesville, Florida 32611 USA 
BIOLOGY OF PELAGIC SEA TURTLES: 
EFFECTS OF MARINE DEBRIS 
Objectives: 
1. Quantify the sub-lethal effect of debris ingestion (nutrient dilution) on nutrient gain 
2. Model sub-lethal effects of debris ingestion on nutrient intake and growth 
3. Evaluation of stress from entanglement on the loggerhead sea turtle 
4. Movement patterns and behavior of pelagic-stage loggerheads in the eastern Atlantic 
5. Document the genetic relationships of pelagic-stage loggerheads in the eastern 
Atlantic with rookeries in the southeast US 
Results: 
All of the project objectives were met. The results have been analyzed and presented in 
the publications and Masters These3 listed below. The results of this project have also 
been presented at many international meetings, some of which are indicated below as 
publications in proceedings from those meetings. The success of this project is evident 
in the quality of the publications and Masters Theses that are based on data collected 
during the completion of the objectives of this project. These manuscripts are either in 
press or have been published. Cover pages and abstracts of the Masters Theses and 
manuscripts that are still in press are enclosed. 
Publications Based on Results from RWO 118 
Bjorndal, K.A., A.B. Bolten, J. Gordon and J.A. Camifias. 1994. Caretta caretta 
(loggerhead) growth and pelagic movement. Herpetological Review 25:23-24. 
Bjorndal, K. A., A.B. Bolten and C. J. Lagueux. 1994. Ingestion of marine debris by 
juvenile sea turtles in coastal Florida habitats. Marine Pollution Bulletin 
28: 154-158. 
Bolten, A.B. and G.H. Balazs. 1995. Biology of the early pelagic stage--the "lost 
year. " Pages 575-58 1 in K.A. Bjorndal (ed.), Biology and conservation of sea 
turtles, revised edition. Smithsonian Institution Press, Washington, D.C. 
Bolten, A.B., K.A. Bjorndal and H.R. Martins. 1994. Life history model for the 
loggerhead sea turtle (Caretta caretta) population in the Atlantic: Potential 
impacts of a longline fishery. Pages 48-54 in G.H. Balazs and S.G. Pooley 
(eds.), Research Plan to Assess Marine Turtle Hooking Mortality: Results of an 
Expert Workshop Held in Honolulu, Hawaii, November 16-18, 19%. NOAA 
Technical Memorandum NMFS-S WFSC-201. 
Bolten, A.B., K.A. Bjorndal and H.R. Martins. 1994. Biology of pelagic-stage 
loggerheads in the Atlantic. Pages 19-20 in K.A. Bjorndal, A.B. Bolten, D.A. 
Johnson and P.J. Eliazar (compilers), Proceedings of the 14th Annual 
Symposium on Sea Turtle Biology and Conservation. NOAA Technical 
Memorandum NMFS-SEFSC-35 1. 
Bolten, A.B., K.A. Bjorndal and H.R. Martins. 1995. Life history of the loggerhead 
sea turtle, Caretta caretta (Reptilia: Cheloniidae), in the Atlantic. In A. 
Domingo Abreu and M. Biscoito (eds.), Proceedings of the First Symposium 
Fauna and Flora of Atlantic Islands. Boletim do Museu Municipal do Funchal, 
Madeira, Portugal, Sup. no. 4: 1 15- 122. 
Bolten, A.B., K.A. Bjorndal, H.R. Martins and G.H. Balazs. 1996. Satellite 
telemetry of pelagic-stage juvenile loggerheads in the eastern Atlantic. Pages 
39-41 in J.A. Keinath, D.E, Barnard, J. A. Musick and B. A. Bell (compilers), 
Proceedings of the ~ifteenth Annual Symposium on Sea Turtle Biology and 
Conservation. NOAA Technical Memorandum NMFS-SEFSC-387. 
Bolten, A.B., K.A. Bjorndal, H.R. Martins, T. Dellinger, M.J. Biscoito, S.E. 
Encalada and B.W. Bowen. 1998. Transatlantic developmental migrations of 
loggerhead sea turtles demonstrated by mtDNA sequence analysis. Ecological 
Applications 8: 1-7. 
Bolten, A.B., H.R. Martins, K.A. Bjorndal and J. Gordon. 1993. Size distribution of 
pelagic-stage loggerhead sea turtles (Caretta caretta) in the waters around the 
Azores and Madeira. Arquipklago 11A:49-54. 
Encalada, S.E., K.A. Bjorndal, A.B. Bolten, J.C. Zurita, B. Schroeder, E. Possardt, 
C.J. Sears and B.W. Bowen. 1998. Population structure of loggerhead turtle 
(Caretta caretta) nesting colonies in the Atlantic and Mediterranean as inferred 
from mitochondrial DNA control region sequences. Marine Biology 130567- 
575. 
Gregory, L.F. 1994. Capture stress in the loggerhead sea turtle (Caretta caretta). 
Masters Thesis, University of Florida, Gainesville, Florida. 59 pages. 
Gregory, L.F., T.S. Gross, A.B. Bolten, K.A. Bjorndal and L.J. Guillette, Jr. 1996. 
Plasma corticosterone concentrations associated with acute captivity stress in 
wild loggerhead sea turtles (Caretta caretta). General and Comparative 
Endocrinology 1043 12-320. 
Gregory, L.F. 1994. Acute captivity stress in the loggerhead sea turtle (Caretta 
caretta). Page 49 in K.A. Bjorndal, A.B. Bolten, D.A. Johnson, and P. J. 
Eliazar (compilers), Proceedings of the Fourteenth Annual Symposium on Sea 
Turtle Biology and Conservation. NOAA Technical Memorandum NMFS- 
SEFSC-35 1. 
McCauley, S.J. 1997. Effects of dietary dilution in chelonians: implications for their 
ecology and conservation. Masters Thesis, University of Florida, Gainesville, 
Florida. 75 pages. 
McCauley , S. J. and K.A. Bjorndal. In press. Conservation implications of dietary 
dilution from debris ingestion: sublethal effects in post-hatchling loggerhead sea 
turtles. Conservation Biology. 
McCauley, S.J. and K.A. Bjorndal. In press. Response to dietary dilution in an 
omnivorous freshwater turtle: implications for ontogenetic dietary shifts. 
Physiological and Biochemical Zoology 72(1). 
In Press, Conservation Biology 
Conservation Implications of Dietary Dilution from Debris Ingestion: 
Sublethal Effects in Post-hatchling Loggerhead Sea Turtles 
Shannon J. McCauley and Karen A. Bjorndal 
Archie Carr Center for Sea Turtle Research and Department of Zoology, 
University of Florida, PO Box 1 18525, Gainesville, FL 3261 1 U.S. A. 
Running Head: Effects of di&.ry dilution in loggerheads 
Word Count: 2493 
Address correspondence to: Karen A. Bjorndal 
Department of Zoology 
P.O. Box 118525 
University of Florida 
Gainesville, FL 3261 1 USA 
email: kab@zoo.ufl.edu 
Abstract: Ingestion of anthropogenic debris by marine species has been documented 
extensively; fewer studies have attempted to quantify the sublethal effects caused by 
debris ingestion. One potential sublethal effect is reduced nutrient gains from diets 
diluted by consumption of debris. Post-hatchling and juvenile loggerhead sea turtles 
(Caretta caretta) consume substantial quantities of debris. Effects of dietary dilution 
on voluntary intake were evaluated in post-hatchling loggerheads to assess their ability 
to compensate for the presence of inert diluents in their diet by increasing dry mass 
intakes to maintain nutrient gains. Mean daily intakes of dry mass did not increase 
significantly with dietary dilution. As a result, intakes of energy and nitrogen on a 
50% dilution diet were significantly lower than on a 10% dilution diet. Therefore, 
post-hatchling loggerheads have an extremely limited ability to compensate for dietary 
dilution and would experience sublethal effects from decreased energy and nitrogen 
gains on dilute diets. Decreased nutrient intakes have serious conservation implications 
because of decreased growth rates, longer developmental periods at sizes most 
vulnerable to predation, depleted energy reserves, reduced reproductive output, and 
decreased survivorship. 
In Press, Physiological and Biochemical Zoology 
Response to Dietary Dilution in an Omnivorous Freshwater Turtle: 
Implications for Ontogenetic Dietary Shifts 
Shannon J. McCauley 
Karen A. Bjorndal* 
Archie Carr Center for Sea Turtle Research and Department of Zoology, 
PO Box 118525, University of Florida, Gainesville, Florida 326 11 USA 
.& *. 
*To whom oar in t  requests should be addressed. 
Running head: Response to Dietary Dilution in an Omnivorous Turtle 
Corresponding author: 
Karen A. Bjorndal 
Dept. of Zoology, PO Box 1 18525, University of Florida, Gainesville, FL 3261 1 
Phone: (352) 392-5 194 
Fax: (352) 392-9166 
Email: kab@zoo.ufl. edu 
ABSTRACT 
Several species of freshwater turtles in the family Emydidae undergo an 
ontogenetic dietary shift; as juvenile turtles mature they change from a primarily 
carnivorous to a primarily herbivorous diet. It has been hypothesized that this shift 
results from an unfavorable ratio of gut capacity to metabolic rate that prevents 
small reptiles from processing adequate volumes of plant material to meet their 
energetic demands. Effects of dietary dilution on intake were evaluated in 2 size 
classes of red-eared sliders (Trachemys scripta elegans) to test whether small 
reptiles have a lower capacity to compensate for low-quality diets through 
increased intake than do larger conspecifics. Artificial diets with an inert diluent 
were offered to 2 size classes of turtles, and mass-specific intakes of dry matter, 
energy, and nitrogen were calcur'ated. Both small (28.7 f 4.9 g body mass, mean 
mass f SD) and large (1230 _+ 94 g body mass) turtles compensated for dietary 
dilution and maintained constant energy and nitrogen intakes on diets with lower 
energy content than common aquatic plants. Thus, body size did not affect the 
ability to respond to nutritional dilution, which suggests that processing limitations 
imposed by small body size do not constrain juveniles from adopting an 
herbivorous diet. 
CAPTURESTRESS - 
IN THE LOGGERHEAD SEA TURTLE 
(CARETTACARETTA) 
BY 
-?LISA FLORES GREGORY 
A THESIS PRESENTED TO THE GRADUATE SCHOOL 
OF THE UMIVERSlTY OF FLORIDA IN PARTIAL FULFILLMENT 
OF THE REQUZREMENTS FOR THE DEGREE OF 
MASTER OF SCIENCE 
UNIVERSITY OF FLORIDA 
1994 
Abstract of Thesis Presented to the Graduate School 
of the University of Florida in Partial Fuffillment of the 
Requirements for the Degree of Master of Science 
CAPTURE STRESS 
IN THE LOGGERHEAD SEA TURTLE 
( m A  CARETTA) 
BY 
Lisa Flores Gregory 
April, 1994 
Chairman: Dr. Louis J. Guillette Jr. 
Major Department: Zoology - , 
Glucocorticoids and other secretions from the hypothalamic-pituitary-adrenal 
system have been used extensively as indices of the presence of stress. Minimal published 
data exist on the stress response in marine turtles. Given their endangered status, it is of 
interest to examine the effects of stress on sea turtle physiology. This study provided 
baseline data on circulating concentrations of corticosterone, and determined the effects of 
acute captivity (capture, repeated bleeding, and restraint up to six hours) on plasma 
corticosterone concentrations in wild, free ranging Carem carem. The effects of capture 
method, season, size class, and sex were examined. 
Initial blood samples were taken from C. caretta captured in a trawl (Port Canaveral 
ship channel FL) or tangle net (east of Cedar Key, FL). Serial blood samples were taken 
from a l l  netcaught turtles, and from turtles trawlcaught in June-August (summer) and 
January-March (winter). Plasma corticosterone concentrations dramatically increased over 
time with highest concentrations generally occurring at three hours after capture. Initial 
corticosterone concentrations were significantly higher in trawlcaught than in net-caught 
turtles. One hour after capture, corticosterone concentrations were not significantly 
different between capture methods. Due to small sample size, effects of sex, season, or size 
class could not be assessed utilizing data from turtles captured in a tangle net 
No effect of sex on corticosterone concentrations was observed for turtles captured 
in a trawL Plasma corticosterone concentrations of small turtles were significantly higher in 
summer than in winter. No signiscant difference in corticosterone concentrations of large 
turtles was observed between seasons until one hour after capture. Analysis of the data 
indicated that the variability between seasons was associated with temperature. Mean 
corticosterone concentrations were significantly higher in small versus large turtles within 
each season It is suggested that the lower adrenocortical response of large turtles may be 
associated with reproductive condition 
EFFE€TS OF DIETARY DILUTION IN CHELONIANS: IMPLICATIONS FOR 
THEIR ECOLOGY AND CONSERVATION 
BY 
SHANNON J. McCAULEY 
A THESIS PRESENTED TO THE GUDUATE SCHOOL OF 
THE UNrVERSITY OF FLORIDA 
IN PARTlAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF 
MASTER OF SCIENCE 
UNIVERSITY OF FLORIDA 
Abstract of Thesis Presented to the Graduate School 
of the University of Florida in Partial Fulfillment of the RequLements 
for the Degree of Master of Science 
EFFECTS OF DIETARY DILUTION IN CHELONIANS: IMPLICATIONS FOR 
THEIR ECOLOGY AND CONSERVATION 
Shannon J. McCauley 
December 1997 
Chair: Karen Bjorndal 
Major Department: Zoology :t 
Effects of dietary dilution on voluntary intake were evaluated in two size classes of a 
freshwater turtle, the red-eared slider (Tmchmys m$ta ebgans), and in one size class of 
juvenile marine turtle, the loggerhead (Caretta canffa). Artificial diets with inert diluents were 
used, and mass-specific dry matter intakes, energy intakes, and nitrogen intakes were 
calculated. 
Slider turtles undergo an ontogenetic dietary and habitat shift; as juvenile turtles 
mature they move into deeper water and shift from a primarily carnivorous diet to one 
dominated by plant material. It has been hypothesized that this shift is the result of an 
unfavorable ratio of gut capacity to metabolic rate which prevents small reptiles from 
processing adequate volumes of plant material to meet their energetic demands on 
herbivorous diets. The ability of both small (28.74 + 4.89g body mass, mean mass + 
standard deviation) and large (1230.35 It: 93.968 body mass, mean mass + standard deviation) 
slider turtles in this study to compensate for dietary dilution and maintain constant energy 
and nitrogen intakes on diets less concentrated than common aquatic plants suggests that 
both size classes of slider turtle are capable of subsisting on an herbivorous diet 
Juvenile loggerheads had a limited ability to compensate for dietary dilution by 
increasing intake. Consequently, they experienced reduced energy and nitrogen gains on 
diets diluted below 11.5 kJ/g drp matter and 8.4% nitrogen. The limited ability of juvenile 
l o ~ r h e a d s  to compensate for dietary dilution suggests that they may be vulnerable to sub- 
lethal effects from anthropogenic debris ingestion. Substantial amounts of anthropogenic 
debris have been found in the digestive tracts of post-hatchling and juvenile loggerheads. 
The results of this study suggest that the consumption of debris may result in decreased 
nitrogen and energy intakes. Decrease$ nutrient intakes may result in decreased growth rates, 
- *. 
a longer developmental period at sizes most vulnerable to predation, depleted energy 
reserves, and decreased survivorship due to starvation. 


Biology of pelagic sea turtles: effects of marine debris

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