Sea turtles are ancient mariners, having navigated the world’s oceans for over 100 million years. These reptiles are found in tropical and subtropical waters globally. They are integral to marine ecosystems, playing diverse roles that support the health and balance of various habitats.
Seagrass Ecosystem Engineers
Green sea turtles, named for the greenish hue of their fatty tissue, are primarily herbivores as adults, consuming large quantities of seagrass and algae. Their grazing behavior, similar to mowing a lawn, prevents seagrass beds from becoming overgrown, promoting new growth and maintaining their health and productivity. Healthy seagrass beds are complex habitats that serve as nurseries for numerous marine species, including fish, shellfish, and crustaceans. These extensive underwater ecosystems also function as significant carbon sinks, absorbing carbon dioxide from the ocean and atmosphere. The continuous grazing by green turtles helps to ensure the vitality of these habitats, supporting a wide array of marine life and contributing to global carbon cycling.
Coral Reef Guardians
Hawksbill sea turtles contribute to the health of coral reef ecosystems. These turtles possess a sharp, hawk-like beak adapted for feeding on sponges, which constitute a major part of their diet. Sponges and corals often compete for space and light on reefs; sponges can aggressively overgrow corals. By consuming sponges, hawksbill turtles help to control sponge populations, preventing them from outcompeting and suffocating corals, which allows corals to thrive, maintaining the structural integrity and biodiversity of coral reefs. The activity of hawksbills ensures that corals have the necessary space to grow, supporting the organisms that rely on these vibrant underwater structures.
Coastal Dune Fertilizers
Nesting sea turtles provide a link between marine and terrestrial environments by transferring nutrients from the ocean to coastal dunes. When female sea turtles lay their eggs on sandy beaches, unhatched eggs, eggshells, and deceased hatchlings decompose, enriching the nutrient-poor sandy soil with compounds like nitrogen and phosphorus. These marine-derived nutrients are assimilated by dune vegetation, such as sea oats. The enhanced vigor of dune plants helps to stabilize coastal dunes, preventing erosion and protecting shorelines from storms. This natural fertilization process supports beach ecosystems, which are also essential nesting habitats for the turtles themselves.
Marine Food Web Regulators
Sea turtles influence the marine food web through their feeding habits and their role as a food source for other species. Leatherback sea turtles, the largest of all sea turtles, primarily feed on jellyfish and other gelatinous prey. Their consumption of jellyfish helps to regulate these populations, which can otherwise proliferate and impact fish stocks by preying on fish larvae. Sea turtle eggs and hatchlings serve as a food source for a variety of predators in coastal and nearshore environments, including crabs, raccoons, and birds on nesting beaches, and fish and sharks once hatchlings reach the water. This transfer of energy from sea turtles to other animals contributes to the flow of energy within marine and coastal food webs.