Jellygate: extract of a paper, sent by Cynthia

And, of course, the end of fish would disrupt marine ecosystems to an extent that we are only now beginning to appreciate. Thus, the removal of small fish in the Mediterranean to fatten bluefin tuna in pens is causing the “common” dolphin to become exceedingly rare in some areas, with local extinction probable. Other marine mammals and seabirds are similarly affected in various parts of the world. Moreover, the removal of top predators from marine ecosystems has effects that cascade down, leading to the increase of jellyfish and other gelatinous zooplankton and to the gradual erosion of the food web within which fish populations are embedded. This is what happened off the coast of southwestern Africa, where an upwelling ecosystem similar to that off California, previously dominated by fish such as hake and sardines, has become overrun by millions of tons of jellyfish.

Jellyfish population outbursts are also becoming more frequent in the northern Gulf of Mexico, where the fertilizer-laden runoff from the Mississippi River fuels uncontrolled algae blooms. The dead algae then fall to a sea bottom from which shrimp trawling has raked all animals capable of feeding on them, and so they rot, causing Massachusetts-sized “dead zones.” Similar phenomena--which only jellyfish seem to enjoy--are occurring throughout the world, from the Baltic Sea to the Chesapeake Bay, and from the Black Sea in southeastern Europe to the Bohai Sea in northeastern China. Our oceans, having nourished us since the beginning of the human species some 150,000 years ago, are now turning against us, becoming angry opponents.

That dynamic will only grow more antagonistic as the oceans become warmer and more acidic because of climate change. Fish are expected to suffer mightily from global warming, making it essential that we preserve as great a number of fish and of fish species as possible, so that those which are able to adapt are around to evolve and propagate the next incarnations of marine life. In fact, new evidence tentatively suggests that large quantities of fish biomass could actually help attenuate ocean acidification. In other words, fish could help save us from the worst consequences of our own folly--yet we are killing them off. The jellyfish-ridden waters we’re seeing now may be only the first scene in a watery horror show.