Healthy oceans need sea turtles. Sea turtles are a “keystone species”, which means they are an important part of their environment and influence other species around them. If a keystone species is removed from a habitat, the natural order can be disrupted, which impacts other wildlife and fauna in different ways.
Why Sea Turtles are Important for a Healthy Ocean
Green Sea Turtles – Keeping Seagrass Beds Healthy
A Green Sea Turtle is one of a small number of large herbivores that eat seagrass and consistent grazing increases the nutrient content and productivity of seagrass blades helping to maintain healthy seagrass beds.
A reduction in the Green Sea Turtle population leads to the seagrass becoming overgrown, interfering with Ocean currents and obstructing light reaching the seabed.
This causes an increase in decomposition that leads to the growth of slime mold and the seabed becomes overpopulated with algae, fungi, microorganisms and invertebrates.
Green Sea Turtle Identification & Behavior
Green Sea Turtles like eating fresher seagrass, a few centimeters from the bottom of the blade. This keeps the seabed well-groomed with older upper parts of the seagrass blade floating away rather than accumulating at the bottom.
Scientists have found this decreases the supply of nitrogen to seagrass roots that has a positive impact on the nutrient cycle, plant species, density of marine life and predation that maintains a healthy ecosystem.
A decrease in the population of Green Sea Turtles reduces the productivity of the food web and by default the amount of food available for people.
Hawksbill Sea Turtle – maintaining the Foundation of Coral Reefs
Hawksbill Sea Turtles are omnivorous, which means they eat plants and other animals, however, their favorite food are sea sponges.
Sea sponges compete aggressively with reef building corals for space on the reef and a healthy population of Hawksbill Sea Turtles ensure the population of sea sponges remains under control.
However, if the population of Hawksbill Sea Turtles decreases, sea sponges can quickly spiral out of control and cause fundamental damage to the Coral Reef.
Hawksbill Sea Turtle Identification & Behavior
Sea sponges have chemical defences and can also change their physical properties, which deters fish and other marine animals from eating them.
However, when a Hawksbill Sea Turtle eats a marine sponge, other species will eat parts of the sponge they usually cannot get too.
If the Hawksbill Sea Turtle population declines, sea sponges begin to dominate the reef, which changes the very foundation of the Coral Reef and marine ecosystem as we know it.
Nesting Sea Turtles – Sand Dune Ecosystems
Nesting Sea Turtles provide a concentrated and much needed source of high-quality nutrients to sand dune ecosystems.
Sea Turtle eggs provide vital nutrients such as nitrogen, phosphorus and potassium that soak into the beach dune ecosystems.
If the eggs hatch, nutrients are left behind in the eggshell and embryonic fluid.
Nesting Sea Turtles Species Distribution
If the eggs do not hatch, even more nutrients will enter the food chain with plants absorbing some nutrients and others dispersed to small organisms that live in the sand.
This helps sustain the growth of various plants and vegetation, stabilizes the shoreline, including their nesting habitats and provides food for a variety of herbivores.
This also leads to nesting Sea Turtles influencing species distribution. Sea Turtles play an important part in maintaining the food web balance.
Leatherback Sea Turtle – Jellyfish Predator
The largest Sea Turtle is the Leatherback and they travel further than any of the other species of Sea Turtles, grow over 2 meters in length and can weigh up to 700kg.
Leatherback Sea Turtles, somewhat surprisingly eat Jellyfish and they consume large amounts daily to maintain a healthy diet.
A Leatherback Sea Turtle has been known to consume 200kg of Jellyfish a day and this huge appetite also plays an important role in balancing the ecosystem.
Leatherback Sea Turtles migrate across entire Oceans and as they consume significant amounts of Jellyfish, they play an important role as one of the top jellyfish predators.
Leatherback Sea Turtle Identification & Behavior
A declining Leatherback Sea Turtle population means an increase in the jellyfish population.
This is a serious concern and when combined with declining fish stocks caused by overfishing, has seen a proliferation of Jellyfish across the world.
Less fish means less competition for food and as Jellyfish pray on fish eggs and larvae, this also impedes recovery of fish stocks.
Unfortunately, a continuing decline in the population of Leatherback Sea Turtles has seen further shifts in species dominance from fish to jellyfish.
Other species of Sea Turtle also consume Jellyfish including Loggerhead Sea Turtle and Green Sea Turtles.
Sea Turtles provide Habitat and Food
Sea Turtles are almost an ecosystem in themselves and they provide habitat to a large and diverse range of marine animals and form symbiotic relationships with a multitude of different species.
More than 100 different species of epibionts have been identified on Loggerhead Sea Turtle shells.
The barnacles, algae and other epibionts that live on Sea Turtles then provide a food source for small fish and shrimp that live on the reef.
Sea Turtles & Epibionts
Cleaner Wrasse and shrimp establish cleaning stations that Sea Turtles visit, which benefits the cleaner fish and the Sea Turtle, who gets a skin and shell manicure that reduces drag as it swims around the Ocean.
There is even a species of Wrasse that only eat specific barnacles found on Green Sea Turtle shells.
You often see a Remora sucker fish accompanying Sea Turtles (especially larger ones) when they are swimming around.
Sea Turtles & Symbiotic Relationships
Remora fish eat parasites such as Copepods that attach themselves to the shell of Sea Turtles and eat skin that the Sea Turtle sheds, plus small scraps of food the Sea Turtle does not eat.
This relationship is mutually beneficial for the Sea Turtle and the Remora, as it uses its host for transport and protection from predators.
As the population of Sea Turtles continue to decline, certain species of fish and shrimp are being forced to develop new, less successful methods of survival.
Sea Turtles distribute Marine Diversity across the Worlds Oceans
During their lifetime, Sea Turtles migrate thousands of miles across the worlds Oceans and seas.
These long migrations are thought to play an important part in increasing the range and genetic diversity of different species of barnacle.
Sea Turtle Migrations
Species of barnacle that live on a host, such as a Loggerhead Sea Turtle are thought to play an important role in sustaining the diversity of Oceans.
Continuing declines in Sea Turtle populations reduces these important impacts.
Why are Sea Turtles an Endangered Species?
Worldwide numbers of Sea Turtles have decreased dramatically over the last 200 years and this decline in species population is increasing.
Six of the seven species of Sea Turtles are classified as threatened or endangered due to human actions.
Two of those species, the Green Sea Turtle and the Hawksbill Sea Turtle live in the warm, tropical sea around Koh Tao and the Hawksbill Sea Turtle is listed as critically endangered.
What Significant Threats are Sea Turtles facing?
The International Union for Conservation of Nature (IUCN) has identified the five most significant threats to the Sea Turtle’s existence.
1. Commercial Fishing and Bycatch
Sea Turtles are accidentally caught or entangled in commercial fishing nets, which is often fatal as Sea Turtles breathe air and need to surface at regular intervals. If they become entangled, they will often drown.
Longline fishing is prone to the incidental catching and killing of Sea Turtles.
Modern fishing practices can also damage Sea Turtle habitat and severely impact the food web.
2. Direct take or illegal Fishing
Sadly, across our planet Sea Turtles are still illegally poached.
This is despite trade of all 7 species of Sea Turtle being banned by CITES (Convention on International Trade in Endangered Species of Wild Fauna & Flora)
Sea Turtles are poached and traded for their eggs, meat, skin and their shells.
For centuries Hawksbill Sea Turtles have been hunted for their beautiful gold and brown shells, which are used to create jewellery and other luxury items and is the main reason this species is critically endangered.
3. Coastal Development
The huge increase in coastal development over the last 20-30 years has had a negative impact on Sea Turtle nesting habitats.
Increases in construction, tourism, boat traffic, dredging and other environmental impacts have all had a detrimental effect on the natural habitats Sea Turtles use for nesting.
Artificial light from coastal infrastructure such as hotels pose another threat to nesting turtles.
The lights can cause disorientation with young hatchlings not finding their way to the Ocean and discourage females from nesting at all.
Ocean trash is a huge problem now with the ICCUN estimating approximately 8 million tons of plastic enters our Oceans annually.
Plastics, petroleum by-products and discarded fishing equipment make up a large percentage of deadly marine debris that can hurt or kill Sea Turtles who ingest or become entangled.
Jellyfish and sea sponges form a major part of the diet of some species of Sea Turtles and sadly, Sea Turtles can mistake plastic for jellyfish and other general marine debris as a food source.
A 2015 worldwide study partly funded by CSIRO Ocean & Atmosphere, estimated 52% of Sea Turtles have ingested trash.
5. Climate Change
The temperature of a Sea Turtle egg during the incubation period can determine the sex of the Sea Turtles off-spring.
Warming air temperature means warmer water and sand temperature and this rising temperature results in fewer male hatchlings and disrupts efficient reproduction patterns.
Rising global temperatures have also seen an increase in storms that can destroy the reef that some Sea Turtles live on, or the beaches they nest at.
As the frequency of extreme weather events increase, critical Sea Turtle habitats and normal Oceanographic processes will be seriously disrupted or even destroyed.
What Can You Do to Save Sea Turtles?
- Become a conscious and responsible seafood consumer by asking where and how your seafood was caught. Choose seafood caught in ways that do not harm or kill turtles. Consult sustainable seafood information networks to learn about how and where your seafood is caught.
- Contact your local sea turtle stranding network if you see a sick or injured sea turtle.
- Support sea turtle conservation by getting involved. Support actions that help sea turtles.
What Can You Do to Protect Sea Turtle Habitat?
- Reduce marine debris that may entangle or be accidentally eaten by sea turtles.
- Participate in coastal clean-ups and reduce plastic use to keep our beaches and ocean clean. Trash in the ocean can harm sea turtles and other creatures that live there.
- Carry reusable water bottles and shopping bags. Refrain from releasing balloons, they’ll likely end up in the ocean where sea turtles can mistake them for prey and consume them.
- Keep nesting beaches dark and safe for sea turtles. Turn off, shield, or redirect lights visible from the beach. Lights disorient hatchling sea turtles and discourage nesting females from coming onto the beach to lay their eggs.
- Do not disturb nesting turtles, nests, or hatchlings. Attend organized sea turtle watches that know how to safely observe nesting sea turtles.
- Remove recreational beach equipment like chairs, umbrellas, boats at night so sea turtles are not turned away.
- Fill in holes and knock down sandcastles before you leave the beach. They can become obstacles for nesting turtles or emerging hatchlings.