Turtles
From coraldigest
Sea Turtles
General
Evolution
Distribution
Behavior and Ecology
Habitat
- Fairly shallow waters inside reefs, bays, and inlets
- Attracted to abundance of marine grass and algae
- Nesting requires open beaches with minimal disturbance
Life Cycle
- Nesting season varies, occurs nocturnally at 2,3,4 year intervals
- May lay as many as 9 clutches in a nesting season
- Clutches range from 75-200 eggs
- Incubation ranges from 45-75 days
- Temperature affects incubation range and sex of hatchlings
- Strong nesting fidelity – green sea turtles
Orientation
Diet
- Hatchlings eat a variety of plants and animals
- Adults feed almost exclusively on sea-grasses and marine algae
Relationships with Humans
- Hunting history
- Hawksbill – endangered
- Green – endangered in FL and Mexico, threatened everywhere else
Importance in Ecosystems
- Maintaining healthy seagrass beds and coral reefs
- Increase productivity and nutrient content of seagrass bladeswhen grazing
- Decreasing supply of nitrogen
- Hawksbills especially play a key role in managing the diversity of coral reefs by limiting the growth of sponges
- Balancing marine food webs
- Facilitating nutrient cycling
Threats
- Desired for flesh and shell
- Fishing methods
- Bycatch
- Long-lining
- Shrimp trawling
- Oil spills and marine debris
- Fibropapillomatosis – tumor causing disease that can inhibit the turtle’s ability to swim, eat, and potentially cause other dangerous health problems
- Linked to environmentally disturbed ocean habitats
- Heavy pollution and high human population density
- Fibropapillomatosis – tumor causing disease that can inhibit the turtle’s ability to swim, eat, and potentially cause other dangerous health problems
- Beach Development – decreases nesting beach availability
- Turtles are habitual when it comes to nesting so removing their nesting locations is detrimental to reproduction
- Lighting – discourages females from nesting on developed beaches
- Erosion and armoring – these have affected the available space for nesting
- Use of turtle nesting habitat for leisure – discourages females from using that area for a nest – beach driving, furniture on beaches
- Climate change
- Predators
- Nests – raccoons, ants, and crabs
- Hatchlings – birds, crabs
- Adults – occasional shark attacks
Conservation Efforts
- Hard to monitor the effectiveness of conservation efforts because only nests are being observed – no idea of whole population status due to wide range and limited ability to track populations aside from nesting
- US Endangered Species Act – prohibits hunting of sea turtles and reduces incidental losses from shrimp trawling and development
- Turtle Excluder Devices – a grid of bars with an opening at either end of the net, catches larger animals and ejects them through the opening while still catching the smaller animals ie: shrimp