152
The Biology of Sea Turtles, Vol. II
Some equatorial rookeries that support year-round nesting may receive females from
foraging areas in both hemispheres; thus, regionally different climatic or oceanographic patterns may underlie some of the variation in nesting seasonality.
There are little data to confirm that some males are breeding outside of peak
courtship times, and it would seem likely that peak nesting periods occur despite
year-round activity because it makes sense to have some degree of synchronization
and high density during courtship. However, in year-round nesting locations, if we
assume that some males breed asynchronously, are the females that are nesting out
of sync from the rest of the nesting cohort limiting their potential reproductive fitness
by having limited mate selection? Are males limiting their fitness through the need
for increased effort in searching for mates and limited mate choice?
5.6 REPRODUCTIVE CYCLES AND SEA TURTLE
CONSERVATION
An increasing awareness exists of the role of sea turtles in the environment (Bjorndal,
1982; 1985; Rogers, 1989; Bouchard and Bjorndal, 2000); marine ecosystem effects
resulting from ecological extinction (Jackson, 1997; Jackson et al., 2001); and
anthropogenic and climatic impacts on our beaches, coasts, and seas (Davenport,
1997; Jackson, 1997; Jackson et al., 2001). We as managers, scientists, or conservation enthusiasts need to ask questions from the perspective of quickly changing
ecosystems. What impact will alterations to the marine and coastal environments
have on sea turtle life history characteristics? How has an altered environment
affected sea turtle populations, and how will it do so in the future?
First, to reiterate points made by Owens (1980; 1997), we need to understand
more about reproductive cycles, physiological processes, and how turtles respond
to environmental cues. Second, we need to react to the challenges of Miller
(1997). We need to collect quantitative data on breeding rates and reproductive,
physiological, and environmental cycles to gain a more complete understanding
of how (or whether) alterations to the environment are likely to influence sea
turtle populations. At least two areas of probable concern are apparent for sea
turtle managers: global warming and rising sea levels, and increased contamination of our oceans and beaches.
Global climate change is thought to influence the marine environments through
increased temperatures and rising sea levels. Potential impacts include an increased
frequency of coral bleaching, alterations to sea grass habitats, and habitat loss (see
Hoegh-Guldberg, 1999; Short and Neckles, 1999; Daniels et al., 1993). The potential
influence of increased temperatures on life history attributes and conservation of sea
turtles is significant (see Mrosovsky et al., 1984; Davenport, 1989; 1997). In foraging
habitats, increased temperatures may impact food sources and nutritional pathways.
Decreased food abundance or quality could slow growth rates and affect breeding
rates in sea turtles, particularly in C. mydas because these effects are likely to be
greatest at lower trophic levels (Limpus and Nicholls, 1988; 2000; Limpus and
Chaloupka, 1997; Short and Neckles, 1999; Bjorndal et al., 2000; Chaloupka and
Limpus, 2001). As the rates of climatic change vary between tropical and temperate
1123 book.book Page 152 Thursday, November 14, 2002 11:50 AM
The Biology of Sea Turtles, Vol. II
Some equatorial rookeries that support year-round nesting may receive females from
foraging areas in both hemispheres; thus, regionally different climatic or oceanographic patterns may underlie some of the variation in nesting seasonality.
There are little data to confirm that some males are breeding outside of peak
courtship times, and it would seem likely that peak nesting periods occur despite
year-round activity because it makes sense to have some degree of synchronization
and high density during courtship. However, in year-round nesting locations, if we
assume that some males breed asynchronously, are the females that are nesting out
of sync from the rest of the nesting cohort limiting their potential reproductive fitness
by having limited mate selection? Are males limiting their fitness through the need
for increased effort in searching for mates and limited mate choice?
5.6 REPRODUCTIVE CYCLES AND SEA TURTLE
CONSERVATION
An increasing awareness exists of the role of sea turtles in the environment (Bjorndal,
1982; 1985; Rogers, 1989; Bouchard and Bjorndal, 2000); marine ecosystem effects
resulting from ecological extinction (Jackson, 1997; Jackson et al., 2001); and
anthropogenic and climatic impacts on our beaches, coasts, and seas (Davenport,
1997; Jackson, 1997; Jackson et al., 2001). We as managers, scientists, or conservation enthusiasts need to ask questions from the perspective of quickly changing
ecosystems. What impact will alterations to the marine and coastal environments
have on sea turtle life history characteristics? How has an altered environment
affected sea turtle populations, and how will it do so in the future?
First, to reiterate points made by Owens (1980; 1997), we need to understand
more about reproductive cycles, physiological processes, and how turtles respond
to environmental cues. Second, we need to react to the challenges of Miller
(1997). We need to collect quantitative data on breeding rates and reproductive,
physiological, and environmental cycles to gain a more complete understanding
of how (or whether) alterations to the environment are likely to influence sea
turtle populations. At least two areas of probable concern are apparent for sea
turtle managers: global warming and rising sea levels, and increased contamination of our oceans and beaches.
Global climate change is thought to influence the marine environments through
increased temperatures and rising sea levels. Potential impacts include an increased
frequency of coral bleaching, alterations to sea grass habitats, and habitat loss (see
Hoegh-Guldberg, 1999; Short and Neckles, 1999; Daniels et al., 1993). The potential
influence of increased temperatures on life history attributes and conservation of sea
turtles is significant (see Mrosovsky et al., 1984; Davenport, 1989; 1997). In foraging
habitats, increased temperatures may impact food sources and nutritional pathways.
Decreased food abundance or quality could slow growth rates and affect breeding
rates in sea turtles, particularly in C. mydas because these effects are likely to be
greatest at lower trophic levels (Limpus and Nicholls, 1988; 2000; Limpus and
Chaloupka, 1997; Short and Neckles, 1999; Bjorndal et al., 2000; Chaloupka and
Limpus, 2001). As the rates of climatic change vary between tropical and temperate
1123 book.book Page 152 Thursday, November 14, 2002 11:50 AM