Oceanographer Enric Sala studies coral reefs. But he studies ones that are very different from ones you’ve seen before. Sala is interested in studying pristine reefs, ones that have never been fished, and argues that they are profoundly different from the ones we generally understand.
He offers this analogy – imagine you’re an alien from outer space. You come down to earth and encounter a rusted, broken-down car. The engine doesn’t work, but there’s a slight charge left in the battery, and the wipers work. You’d conclude that the purpose of a car was to allow you to comfortably observe the outdoors, even in the rain. If someone told you this vehicle could be driven thousands of kilometers, you’d be amazed.
This, Sala argues, is how we’ve been studying coral reefs. We began studying them long after they were degraded. 99.9% of all studies are of reefs that are recovering. But Sala has been focusing on studying remote, uninhabited, unfished coral reefs. He’s recently been studying the Line Islands, which include the Christmas Atoll, discovered by Captain Cook on Christmas day in 1777. Cook was generally a very reliable narrator, and he declared that the Atoll was “filthy with sharks”. That atoll, which now houses 5,000 people, now features no sharks at all – Sala didn’t find a single one in 250 hours of diving.
What he found instead were tiny fish, most smaller than the size of a pencil. Many of these fish are sold to the global tropical fish market. The coral in these reefs is all dead – it’s covered with bacteria and algae. Once the algae covers the coral, it stops growing and dies.
Moving to a smaller, less inhabited atoll – Tabuaeran – he saw the classic coral reef: lots of small and midsize fish, but dying coral. That’s likely because there are 2500 people living on the atoll and they fish and dive, affecting the reef. Moving to a much less inhabited reef, Palmyra atoll, which hosts 10 wildlife management professionals, but historically has been fished, he saw sea turtles, large sharks, but dying corals, with a few small corals growing back.
What was most amazing was when he dove at Kingman reef, a reef that has never been fished. He discovered five hundred year old corals. The sea floor was paved with giant clams which filter the water, creating the lowest concentration of bacteria and viruses ever recorded at a coral reef. And you find an amazing number of predators – 10 to 25 sharks per reef, and huge numbers of red snapper. “The entire food web is upside down,” he tells us. On land, we assume that there are large numbers of prey species to support predators – one pound of lion needs ten pounds of wildebeest, each of which need ten pounds of vegetation. But in these reefs, 85% of the biomass is top predators.
We have destroyed coral reefs, he reports, by removing everything big and reducing the biomass. We’ve replaced coral with algae, enhanced domination of microbes, and reduced the resilience of the reefs. These dying reefs are more diverse, but they’re much more fragile than the healthy, pristine reefs.
Sala’s plan going forward is to discover the unexplored places in the ocean and work to protect them. His strategy is to document them, and invite a very small number of tourists. The money from tourism will compensate countries like Kiribati so they don’t sell fishing rights to people to destroy these ecosystems.
One of the questions put to Sala concerns the inversion of the food pyramid – how can a pyramid where 85% of biomass is predator? He explains that you need to consider time as well – those top predators have very long lifespans, while prey spawn again and again. At any moment in a healthy ecosystem, the predators are a huge majority… but over a long period of time, there’s much more prey than predators.
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This is a major problem to us all. I own an aquarium like many other people and have probably not helped the worlds coral reefs. I try to do my bit by ensuring any fish I buy goes into a quaranteen tank, so that hopefully I need not buy more. Tropical Fish Buying Guide
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It is a sad thing to think about all of the damaged and dying coral reefs in the world caused by overfishing and destruction of the natural habitat and it would be wonderful if there was a way to use them as a resource and upkeep them as well. I hope that your research leads to such a solution. People still need to eat and make money and they always will.
That makes a lot of sense, and is very scary. It’s very difficult to study the environment when we affect it so greatly.