As on land, so at sea: the extinction of marine life

We’re having a big conversation about species loss in the face of growing environmental problems. And a lot of numbers are being thrown around — 40% of birds, hundreds of mammals, at times it seems like no one even knows what we’re losing and things feelĀ almost unimaginable. To some extent, that’s true. We didn’t know every single species that existed in the first place, and many have vanished without a trace. Some are likely extinct, but we can’t be sure. Other populations are in critical condition, but it might be possible to save them with extensive conservation efforts. It’s hard to say what’s going to happen on land in the coming years as we face up to the consequences of what we are doing to the planet.

But the Earth is called the blue marble for a reason, and it’s because the majority of the planet is covered in oceans. While oceans may seem empty and vast, unfathomable and too large to even contemplate, they are in fact rich with life. Animals inhabit every level of the sea column, living in the deep and deadly waters by hydrothermal vents as well as the shallow realms of continental shelves. They’re part of robust and complicated ecosystems, they live out lives entirely in darkness and murky waters — many ocean creatures are never seen by humans, which is why we’re always discovering weird new ones, and they vanish without notice also.

Defaunation, as it’s called, of marine animals has been occurring steadily over the last few centuries, but there’s been a significant uptick in the speed and severity — in fact, the disappearances of marine animals in significant numbers began before those of land animals. For illustration, think of how whales were pursued to the brink of extinction, how lobster used to be so plentiful that it was cheap bar food, how oysters were once a food for the poor, how cod was once so dense in Atlantic Waters that it was virtually a trash fish. These examples all illustrate the human role in marine defaunation, but it’s more complicated than that.

Yes, humans have been disrupting marine animals through harvesting and poor fisheries management. Climate change has also been a factor, as changes in ocean temperature irreparably damage marine habitat. It’s entirely possible that we may see a spike in extinction rates as a sort of tipping point is reached and pressures on the marine environment become too much to bear. We’ll never know what’s been lost, given that so much of the ocean remains unexplored and we’re still trying to learn about all of the animals that lurk beneath the waves — when you can find new species in relatively well-known and trafficked areas of the ocean, who knows what lies beneath other regions where humans fear to tread.

This will undoubtedly be a particularly acute problem in regions like the poles, where a very complex food web could be destabilised very quickly by ice melt, creating a cascade effect that would harm animal populations relying on the icy waters surrounding Antarctica and the Arctic for food and shelter — and this includes not just marine fauna, but also seals, polar bears, penguins, and others who live above the ice but survive on fish and other ocean inhabitants. Likewise, equatorial regions are likely to suffer heavily as a result of climate change, with tropical reefs heating to unbearable temperatures for both corals and the animals that depend on them for habitat, shelter, and a place to build community.

The thought of losing a tremendous amount of marine life is, on its face, a very sad and terrible one. Ocean animals are pretty cool, whether we’re talking about massive and majestic whales, or wicked intelligent octopuses, or dolphins, or angler fish, or other bizarre and wonderful and fascinating marine life — there’s a reason the ocean is a thing of legend and that the creatures who live under it are a subject of myriad creative works and studies. The ocean is, flatly, amazing, and everything that lives in it is strongly interconnected in a very complex series of relationships resembling nothing so much as a game of Jenga — which block would you like to pull out?

Which brings us to the problem with what we’re doing to the ocean. Humans rely heavily on the ocean as a source of food, and not always in the ways you think. Yes, humans eat fish across a variety of cultures, and make an assortment of foods (like fish sauce) from fish products. But more than that, fish furnishes supplies for a number of industrial processes and ingredients, fish are used for fertilizer, and fish play a key role in numerous aspects of life. Without fish, or with a greatly reduced number of them, we face a number of shortages and social problems — and thus, marine defaunation is a serious problem that we need to address.

We need better fisheries management. We need better control of marine environments. We need to start thinking about how to change our dependency on the ocean and our relationship to it, and we need to start thinking about how we can conserve and preserve delicate marine species and the relationships between them. Because if we don’t, the consequences will be dire.

Vanishing species on land get a great deal of attention, as do flashy and big marine species like mammals. But it may be krill, or some tiny fish, or tube worms that ultimately brings us down.

Photo: Humpback Whale, Gregory ‘Slowbirdr’ Smith, Flickr