Marine turtles are extraordinary. Why do I say that? Well for more than 100 million years they’ve covered vast distances across the world’s oceans, filling a vital role in the balance of marine habitats.
That’s why as we celebrate World Turtle Day, we need to remember the importance of continuing the conservation work being done to protect these incredible creatures so they can continue to swim our oceans for millennia to come.
WWF is one of the organisations working hard to ensure the future of marine turtles. One country leading the way is Kenya. Five of the world’s seven marine turtles are found in Kenya’s seas – the green, the hawksbill, the loggerhead, the leatherback, and the olive ridley. Of these, green, hawksbill and olive ridley turtles are known to nest in Kenya.
A female will lay as many as eight clutches of eggs each nesting season and in Lamu peak nesting season is March to August. The baby turtles hatch after about six to eight weeks, digging their way to the surface of the sand to find their way to sea, where they hopefully grow to adulthood and start the cycle over. But life as a turtle is tough and only about one in 1,000 successfully hatched babies makes it to adulthood.
One of the fascinating things about marine turtles is that at each point in their lives they have an impact on their ecosystem. This happens in many ways.
As eggs, they’re part of the sand dune ecosystem. The eggs that never hatch break down into the sand and provide nutrients for plant life. And by hatching and crawling to the surface of the sand, baby turtles move nutrients around, providing food for small organisms living near the surface. Females also coming up onto nesting beaches bring new nutrients from the sea.
Eggs and hatchlings are an important food source for a number of predators including porcupines, hyenas and crabs. They dig up marine turtle eggs as well as hunt hatchlings as they make their way to the sea. If the hatchlings make it to the sea, they’re still not safe as fish and other marine creatures also like to prey on baby turtles. Only as marine turtles grow do the numbers of potential predators decrease; though some sharks and killer whales do hunt them. And of course, sadly, the threat of poaching by humans remains.
Green turtles are one of the few large herbivores that eat sea grass. Their grazing of the sea grass helps maintain healthy seas much in the same way that grazing on land is important for grassland health. The green turtle eats the new shoots, at the bottom of the sea grass, clipping away the older bits. This has a huge impact on the nutrient cycling – in areas where turtles have declined, and sea grass isn’t being grazed effectively, the biodiversity and density of other plant and animal species has also declined, including fish that local people catch for their own food supply. Overgrown sea grass beds can also disrupt currents.
Hawksbill turtles prey on sponges, which impacts the overall biodiversity of coral reef communities. Sponges will aggressively compete for space with reef-building corals. Hawksbill turtles, with their namesake ‘bill-like’ mouths, can prise sponges apart, and help balance the competition for corals, allowing them to colonise and provide key habitat for a wider range of species than if sponges were to take over the same space.
WWF’s work in Lamu, in helping to increase numbers of marine turtles, is also having a wider impact in supporting healthy seas and marine biodiversity. With the support from players of People’s Postcode Lottery, WWF and its partners are able to manage and protect the beaches to give marine turtles the best start in life as they play their part in the wider ecosystem.
Do you agree turtles are extraordinary? Let us know!