Krill, Baby, Krill

January 17, 2009

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At Grytviken I met a pair of young British researchers studying marine life on and around South Georgia. One focused on seals, the other on the tinier sea creatures. They were just beginning what seemed a pretty good, two-and-a-half-year long gig. Year-round there are fewer than twenty residents here, some doing science, others watching after the museum, so it requires a fair amount of self-sufficiency at least in keeping your mind occupied.

Though new to the assignment the young marine biologists had already identified one important statistic, which could have major impact on the future of South Georgia and all its animal and fish life, the apparent sharp decline in the one thing all life depends on out here: Krill.

Swarms of life-supporting krill can cover 175 square miles of Southern Ocean

The tiny, shrimp-like crustacean dominates the invertebrate community in the seas that surround South Georgia, lunching on the abundant phytoplankton and in turn forming the diet of most of South Georgia’s whales, squid, fish, seals and sea birds.

It’s estimated there are 650 million tons of krill in the Southern Ocean, more than the weight of all humans on earth put together (that’s a lot!). They form huge swarms a half-mile across, sometimes accompanied by a frenzy of predators. The largest swarms can cover 175 square miles and contain more than two million tons of krill. Those colossal numbers make it THE lynchpin in the Antarctic ecosystem and the ecology of krill is crucial to understanding the wealth of wildlife on and around South Georgia.

Krill are the main food for whales and several species of seals and seabirds, including fur seal, black-browed albatross and macaroni penguin. Krill are also eaten by many species of fish and squid, so even those species of whales, seals and birds that don’t eat krill themselves, ultimately depend on them because they live off krill-eating prey.

I’ve suggested in previous postings that Antarctica is all about the ice; now I’ve recalculated to suggest it may all be about the krill.

The incredible abundance of krill has always been linked to the cold average annual temperatures and the dynamics of the southern ocean currents. Today’s warmer winters, resulting in far less sea ice, results in far less krill.

It’s estimated since the 1970s that the krill population has dropped by eighty percent … Eighty percent! … due primarily to the loss of winter sea ice in the Antarctic Peninsula region. Another factor impacting its population is fishing. Russians and Japanese catch them for both a luxury commodity and staples for animal feed and aquaculture and each season the take grows.

I talk all the time about how man’s incredibly consumptive demands on the wildlife in the seas may be the end of the ocean, as we know it. Here even the tiny krill, far tinier than a fingernail, may soon pay the ultimate price.