Corals – The oases of the oceans are turning to sand
Article written by marine biologist, Henrique Bravo Gouveia. He is the co-founder of the conservation NGO, Lonely Creatures, which aims to raise awareness about endangered species across the globe. Here is an account taken from his expedition from Argentina to Alaska in the search of endangered species.
Reefs, the marine equivalent of tropical rainforests, are one of the most diverse ecosystems on the planet. They are true oases in the vastness of the oceans. Fish, but also nudibranchs, sharks, turtles, sponges, lobsters, algae, sea stars or anemones are some of the species seeking refuge in reefs. They are also one of the most threatened ecosystems. Putting it simply, with the disappearance of coral reefs about 25% of marine species we know could vanish alongside since they wouldn’t stand a chance of survival outside them.
Humans also stand to lose plenty with the loss of this incredible ecosystem. Over 450 million people live in the vicinity of coral reefs, with many depending directly on the services provided by corals for sustenance and even survival, be it through the fish they provide, the actual coral material that is used for a myriad of things, the tourism it attracts, but also the protection they provide to coastlines. Corals are a first defense against storms, tsunamis or hurricanes, so their disappearance could have catastrophic consequences, mainly in regions that depend a lot on them, such as tropical islands.
In the crystal blue waters of the Caribbean there are about 100 different species of corals and roughly 500-700 reef-associated fish species. The famous French naturalist Lamarck (1744-1829) was responsible for the identification of many of these corals, probably sitting in a comfortable chair in Paris whilst his disciples had the pleasure of seeing some of these during the 19th century, most likely for the first time. They collected everything they came across and took pieces of all kinds of corals to later have them examined by the master. Two of those species that Lamarck first described in 1816 are now at the risk of extinction, leaving only the pickled museum specimens as proof of their existence. These elkhorn and staghorn corals are intricate and complicated looking specimens of the Acropora family, resembling elk and stag horns as their names suggest. Over the last 40 years more than 80% of the populations of both species disappeared, awarding them the title of critically endangered. These were the two species I was on the lookout for in Panama.
Isla Escudo Veraguas is an island inhabited by 120 fishermen, and their families, and of slightly difficult access for most tourists passing through the country. It has however pristine reefs, or that’s what I was told. It takes 2 hours each way on a speedboat, making for a bumpy ride, but the destination is definitely worth it. Taken out of a postcard, the colours of the water and sand were a bliss. Palm trees and mangroves everywhere one looks, the only thing missing to complete the picture were the corals.
It took me a while to process what I was seeing once I dipped my face in the water. Everywhere I looked there were elkhorn corals, everywhere! They came in all sizes, from a few centimetres to a couple of metres from ‘root’ to the tip of the branches. With their dark yellow colour and their incredible shapes, it was hard to look away. They even made you forget you were underwater and that some breaths were necessary from time to time. It was indeed an oasis, with fish swimming in all directions forming a rainbow of colours in those busy coral highways.
Looking at that incredible abundance of corals, it was hard to imagine they were on the verge of extinction. In sessile species, there can be a high level of abundance in specific areas if the conditions are right and if the threats are little, which happened to be the case. This also means that the conservation of these species is slightly easier compared to highly mobile ones. Preserving the area where the species lives, and its surroundings, can be achieved by setting up marine protected areas and is one of the most successful actions towards the preservation of species. Corals, however, face some additional challenges that we might not be able to solve in time to save them. Rising sea temperatures and ocean acidification are seriously threatening their survival. This is not so much a problem for the corals themselves, but for their algae symbionts (zooxanthellae), which don’t particularly enjoy waters that are too warm. Zooxanthellae form a symbiosis with corals by providing them with up to 90% of the energy they require and are also the ones responsible for the many colours we see in corals. When a certain temperature is reached, which varies from species to species, they detach themselves from the coral, and the coral undergoes a dying process called bleaching, which is what is happening in corals all over the globe (the latest survey at the Great Barrier Reef revealed that over 90% of corals showed signs of bleaching). When they die, the corals start disintegrating, eventually turning to sand.
They are also threatened by human activities like intensive fishing, trawling or high levels of tourism. They are in dire straits, and according to experts, it is likely that corals will disappear altogether within the course of this century. 90% of corals are estimated to vanish by 2050, so now is a good time to go see them and show them to your children.
I also spotted some staghorn corals while in Panama, albeit with more difficulty and in numbers that did not come close to those of elkhorn. Hiding in crevasses of rocks, or at depths that required scuba diving, and with sizes never exceeding 20-30 centimetres, they weren’t as memorable as their relatives, but still beautiful nonetheless and with more apparent delicate structures. Sadly, the majority of the ones I saw were in the process of bleaching. I’m sure there must be some spots where staghorn corals are still thriving and look as impressive as elkhorn did for me off the coast of Escudo Veraguas, I just didn’t get to see them.
Lamarck was one of the founders of the theories of evolution. It’s sad to think that the species he described for Science could soon disappear and might not play a role in the evolution of other species in the future.
Like all species that are facing extinction, things can look bleak and depressing, but there are almost always researchers and conservationists working towards their preservation, and corals are no exception. I have no doubt that the incredible level of species diversity we have now will take a toll, but corals might have a fighting chance if scientists, governments, and the general public work together to minimise the effects of climate change and grant coral reefs the protection they deserve.