Response of sea turtles to changing ambient temperatures: implications for heat exchange, metabolic rate and diving behaviour
PhD Project
Sandra Hochscheid
Objectives
· How do sea turtles regulate heat exchange with the environment?
Do they possess vascular control mechanisms in their appendices?
· How does temperature effect the metabolic rate and the
buoyancy control during diving in sea turtles?
Summary
Blood flow patterns in the front flippers of sea turtles, Chelonia
mydas and Caretta caretta, were determined during a series of
heating and cooling experiments at the Aquarium of Naples, Stazione
Zoologica "Anton Dohrn", Italy, in November 1999.
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Aquarium of Naples, Stazione Zoologica "Anton Dohrn" Italy |
Blood flow was significantly faster when the turtles came in
contact with warmer water and almost came to a halt in colder
water. The results suggest that the cardiovascular system of the
front flippers play an important role in the heat exchange between
these animals and the environment (Hochscheid et al., submitted).
The metabolic rate of loggerhead turtles at seasonal variable
temperatures was determined via an open-flow respirometry system
between September 2000 and February 2001. The turtles were kept
individually in tanks supplied with natural sea water from the
Gulf of Naples. During the study period water temperature dropped
from 25°C to 15°C. Body temperatures, activity and food
intake was determined simultaneously to the metabolic rate measurements.
In an additional experiment small weights were attached to the
carapace to investigate the energetic costs involved in gaining
buoyancy control. By this procedure the dive depth, which was
restricted by the dimensions of the tank (80 cm), was artificially
increased to 6 m (Hochscheid et al., submitted).
Publications
Hochscheid S., B.J. Godley, A.C. Broderick, and R.P. Wilson. 1999.
Reptilian diving: highly variable dive patterns in the green turtle
Chelonia mydas. Mar. Ecol. Prog. Ser. 185:101-112.
Hochscheid S. and R.P. Wilson. 1999. A new method for the determination
of at-sea activity in sea turtles. Mar. Ecol. Prog. Ser. 185:293-296.
Hays G.C., S. Hochscheid, A.C. Broderick, B.J. Godley, and J.D. Metcalfe. 2000. Diving behaviour of green turtles: dive depth, dive duration and activity levels. Mar. Ecol. Prog. Ser. 208: 297-298.
Work in submission
Hochscheid S., F. Bentivegna, J.R. Speakman. Regional blood flow
in sea turtles: implications for heat exchange in an aquatic ectotherm.
Hochscheid S., D. Grémillet, S. Wanless, M.A. Du Plessis.
Black and white under the South African sun: Are juvenile cape
gannets heat stressed?
Hochscheid S., F. Bentivegna, G.C. Hays, J.R. Speakman. An
experimental investigation of buoyancy control and dive duration
in sea turtles.
Bentivegna F., S. Hochscheid, C. Minucci. Seasonal variability in voluntary dive duration of the Mediterranean loggerhead turtle, Caretta caretta.