Ocean Ecosystem Services Can Increase — But Only if We Take Less

National Geographic Fellow Enric Sala comments on a new study, released today, which shows that 75 percent of the world’s coral reefs are threatened by human overpopulation. The proximity of the corals to human settlements means their fish populations are being depleted. The impact of humanity reduces the biodiversity of reef fishes, which in turn has a negative impact on the many services the reefs provide to humans.

By Enric Sala

Ocean life and all the services it provides are free. These services include biomass (which we eat as delicious seafood), more than half of the oxygen we breath (produced by tiny plankton), storm protection (by living structures such as mangroves, marshes and coral reefs), and enormous scientific and recreational opportunities.

These are all great services that help make our life on this planet enjoyable, and bring hundreds of billions of dollars to our economy. Ocean life is our own goose with the golden eggs. Know the story? Well, it seems that we don’t, because we’re killing the goose. That is, we are degrading ocean life (biodiversity) by taking too much out of the ocean (that delicious seafood) and throwing in what we don’t like (pollution).

“By degrading ocean biodiversity we are diminishing the ability of the ocean to provide those services that we love so dearly.”

By degrading ocean biodiversity we are diminishing the ability of the ocean to provide those services that we love so dearly. Is this a good idea? I think not.

First, let’s analyze why is ocean biodiversity important. I have been asked many a time: “Do we really need all those species in the ocean? Couldn’t we just get rid of some and make more room for the species we eat?” This instrumental and arrogant view of nature is based in phenomenal ignorance of the complex workings of nature. All the species in the ocean have a role in the ecosystem; we may not know what’s the role of every one of them, but they have one, and that role could be one of tremendous importance for, say, creating oxygen or giving us food.

Let me put it another way: would you board a plane knowing that 10 parts are missing — even though you didn’t know what the function of those parts are? I wouldn’t, just for precaution. We should follow that same precautionary approach for nature — including the ocean.

Second, what is a precautionary approach? It is as simple as preventing the extinction or collapse of ocean species, and as complicated as having decision makers follow scientific advice. We need to ensure that all species remain in the ocean at abundances that are large enough for them to fulfill their important roles.

A new scientific collaboration between scientists from 49 countries, covering almost 2,000 coral reefs worldwide, shows that, the more reef fish biodiversity, the more biomass they can create. So we cannot have too much of a good thing. We cannot create new species and introduce them to reefs, but we can prevent some of those species from going away.

Third, what are the trends and the solutions? On the one hand, trends aren’t looking good, because 75 percent of the coral reefs in the world are near human settlements and, as the above study shows, the more people, the less services reefs can provide. On the other hand, we know how to bring ocean biodiversity back: with good fisheries management and creating more no-take marine reserves.

Fish biomass increases an average of five times in these reserves relative to adjacent unprotected areas — and after a few years fish spill over and fishermen increase their catch around the reserves.

In the end, it’s not just about the fishes, it’s about us enjoying all those wonderful services that we need so desperately — and the dollars they bring to our economy. If we want to be able to eat more fish, and to make more money out of the ocean, let’s keep more fish in it. Let’s be selfish for once.

Dr. Enric Sala was one of the scientists from 49 nations who collaborated in an analysis published today in the journal Plos Biology. The study documented that the capability of reef fish systems to deliver goods and services is being hampered by mounting pressures from growing human populations. The team also showed that the extent of such distress is widespread and likely to worsen as some 75 percent of the world’s coral reefs are near human settlements and because most coastal countries are expected to double their populations within the next 50 to 100 years.

Changing Planet


Meet the Author
Marine ecologist Dr. Enric Sala is a National Geographic Explorer-in-Residence who combines science, exploration and media to help restore marine life. Sala’s scientific publications are used for conservation efforts such as the creation of marine protected areas. 2005 Aldo Leopold Leadership Fellow, 2006 Pew Fellow in Marine Conservation, 2008 Young Global Leader at the World Economic Forum.