Physiological and Genetic Responses to Environmental Stress
This chapter presents an overview of the relationship between sea turtles and some of the more important stressful aspects of their environment. Because stress is such a broad topic, many aspects of stress have been treated in previous chapters and elsewhere in this volume (see Lutcavage et al., 1997; George, 1997; Epperly, Chapter 13; and Herbst and Jacobson, Chapter 15, this volume). This chapter reviews a few environmental stressors of particular significance to sea turtles: temperature, chemical pollutants (organic and inorganic) and habitat degradation, and the sea turtle’s physiological and potential genetic responses are discussed. Distinct environmental stressors affect the terrestrial nest and hatchlings, and are discussed separately from the other (oceanic) life stages
Sea turtles naturally encounter a wide variety of stressors, both natural and anthropogenic, including environmental factors (salinity, pollution, temperature), physiological factors (hypoxia, acid-base imbalance, nutritional status), physical factors (trauma), and biological factors (toxic blooms, parasite burden, disease). Although they are physically robust and able to accommodate severe physical damage, sea turtles appear to be surprisingly susceptible to biological and chemical insults (Lutcavage and Lutz, 1997). For example, in the green sea turtle even a short exposure to crude oil shuts down the salt gland, produces dysplasia of the epidermal epithelium, and destroys the cellular organization of the skin layers, thus opening routes for infection (Lutcavage et al., 1995). The effects of many stressors, however, are likely to be less obvious, as in the (unknown) long-term effects of toxin exposure and bioaccumulation.