The green sea turtle (Chelonia mydas) is a species of large sea turtle of the family Cheloniidae.
Green sea turtle habitat
Like most sea turtles, green turtles are highly migratory and use a wide range of broadly separated localities and habitats during their lifetimes (for review see Hirth 1997). Upon leaving the nesting beach, it has been hypothesized that hatchlings begin an oceanic phase (Carr 1987), perhaps floating passively in major current systems (gyres) that serve as open-ocean developmental grounds (Carr and Meylan 1980, Witham 1991). After a number of years in the oceanic zone, these turtles recruit to neritic developmental areas rich in seagrass and/or marine algae where they forage and grow until maturity (Musick and Limpus 1997). Upon attaining sexual maturity green turtles commence breeding migrations between foraging grounds and nesting areas that are undertaken every few years (Hirth 1997). Migrations are carried out by both males and females and may traverse oceanic zones, often spanning thousands of kilometers (Carr 1986, Mortimer and Portier 1989). During non-breeding periods adults reside at coastal neritic feeding areas that sometimes coincide with juvenile developmental habitats (e.g., Limpus et al. 1994, Seminoff et al. 2003).
Green sea turtle threats
Green turtles, like other sea turtle species, are particularly susceptible to population declines because of their vulnerability to anthropogenic impacts during all life-stages: from eggs to adults. Perhaps the most detrimental human threats to green turtles are the intentional harvests of eggs and adults from nesting beaches and juveniles and adults from foraging grounds. Unfortunately, harvest remains legal in several countries despite substantial subpopulation declines (e.g., Humphrey and Salm 1996, Fleming 2001, Fretey 2001). In addition, a number of incidental threats impact green turtles around the world. These threats affect both terrestrial and marine environments, and include bycatch in marine fisheries, habitat degradation at nesting beaches and feeding areas, and disease. Mortality associated with entanglement in marine fisheries is the primary incidental threat; the responsible fishing techniques include drift netting, shrimp trawling, dynamite fishing, and long-lining. Degradation of both nesting beach habitat and marine habitats also play a role in the decline of many Green Turtle stocks. Nesting habitat degradation results from the construction of buildings, beach armoring and re-nourishment, and/or sand extraction (Lutcavage et al. 1997). These factors may directly, through loss of beach habitat, or indirectly, through changing thermal profiles and increasing erosion, serve to decrease the quantity and quality of nesting area available to females, and may evoke a change in the natural behaviors of adults and hatchlings (Ackerman 1997). The presence of lights on or adjacent to nesting beaches alters the behavior of nesting adults (Witherington 1992) and is often fatal to emerging hatchlings as they are attracted to light sources and drawn away from the water (Witherington and Bjorndal 1990). Habitat degradation in the marine environment results from increased effluent and contamination from coastal development, construction of marinas, increased boat traffic, and harvest of nearshore marine algae resources. Combined, these impacts diminish the health of coastal marine ecosystems and may, in turn, adversely affect green turtles. For example, degradation of marine habitats has been implicated in the increasing prevalence of the tumor-causing Fibropapilloma disease (George 1997).