For years, I’ve been trying to hammer the point that we have depopulated our oceans:
When is the last time, in those habitats, you have seen enough fish (and minnow-sized fish don’t count) to justify this strategy? What many people don’t realize is that these habitats, until a couple of centuries ago were teeming with wildlife; in terms of productivity, these habitats are marine equivalent of Iowa farm soil. In Maine, lobster, in shallow habitats, were so plentiful, they were used to fertilize soil–and feeding lobster to servants, slaves or orphans in the 1600s was illegal (it was considered feeding people cockroaches). Ditto the fish.
Needless to say, we’ve changed those environments. Despite those changes, it’s safe to say these habitats and most of their species still exist, though many species have probably altered their behavior and physiology to compensate for human activity (e.g., cod reproduce at smaller sizes to produce offspring before being caught)…
Whether or not coral reefs will become extinct doesn’t seem to be the right question. The real issue is one of massive alteration: are a decrease in coral reef size, altering of animals (e.g., cod), and the loss of biodiversity–locally on reefs and globally by species extinction–acceptable? Will (or how many) species go the way of the bison or passenger pigeon? Will coral reef ecosystems be confined to small isolated, habitat islands? And is this good for us?
No one alive truly understands what we have done to oceans–that they could be so teeming with life is completely alien. There simply isn’t any place where one can find this concentration of marine organisms (unless you’re in the middle of a school of fish). We have created a barren desert.
Well, it’s not just oceans anymore (boldface mine):
Scientists have begun to speak of functional extinction (as opposed to the more familiar kind, numerical extinction). Functionally extinct animals and plants are still present but no longer prevalent enough to affect how an ecosystem works. Some phrase this as the extinction not of a species but of all its former interactions with its environment — an extinction of seed dispersal and predation and pollination and all the other ecological functions an animal once had, which can be devastating even if some individuals still persist. The more interactions are lost, the more disordered the ecosystem becomes. A 2013 paper in Nature, which modeled both natural and computer-generated food webs, suggested that a loss of even 30 percent of a species’ abundance can be so destabilizing that other species start going fully, numerically extinct — in fact, 80 percent of the time it was a secondarily affected creature that was the first to disappear. A famous real-world example of this type of cascade concerns sea otters. When they were nearly wiped out in the northern Pacific, their prey, sea urchins, ballooned in number and decimated kelp forests, turning a rich environment into a barren one and also possibly contributing to numerical extinctions, notably of the Stellar’s sea cow…
In addition to extinction (the complete loss of a species) and extirpation (a localized extinction), scientists now speak of defaunation: the loss of individuals, the loss of abundance, the loss of a place’s absolute animalness. In a 2014 article in Science, researchers argued that the word should become as familiar, and influential, as the concept of deforestation. In 2017 another paper reported that major population and range losses extended even to species considered to be at low risk for extinction. They predicted “negative cascading consequences on ecosystem functioning and services vital to sustaining civilization” and the authors offered another term for the widespread loss of the world’s wild fauna: “biological annihilation.”
It is estimated that, since 1970, Earth’s various populations of wild land animals have lost, on average, 60 percent of their members. Zeroing in on the category we most relate to, mammals, scientists believe that for every six wild creatures that once ate and burrowed and raised young, only one remains. What we have instead is ourselves. A study published this year in the Proceedings of the National Academy of Sciences found that if you look at the world’s mammals by weight, 96 percent of that biomass is humans and livestock; just 4 percent is wild animals.
Realistically, I’m not sure we’ll do much about this: we can’t even do simple things like upzoning building codes by 20 feet in urban areas. So maybe this post is just further cataloging of the apocalypse, but at least more people are starting to be aware of defaunation.