甲壳类动物在北半球更繁盛

Freshwater ecosystems in northern regions are home to significantly more species of water fleas than traditionally thought, adding to evidence that regions with vanishing waters contain unique animal life. The new information on water fleas -- which are actually tiny crustaceans（甲壳类） -- comes from a multi-year, international study that was published Feb. 24 in the journal Zootaxa.

The researchers scoured the globe seeking the creatures and found them inhabiting northern lakes and ponds in locations from Alaska to Russia to Scandinavia.

After analyzing the anatomy（解剖学） and genetic makeup of many different specimens, the team conclusively determined that at least 10 species of the crustaceans existed -- five times as many as thought for much of the last century.

More than half the diversity was found in northern latitudes, where rapid freshwater habitat loss is occurring due to melting permafrost（永久冻土） , increased evaporation and other changes tied to climate change.

"It is well known that parts of Alaska and Siberia have suffered a huge reduction in freshwater surface area, with many lakes and ponds disappearing permanently in the past few decades," said Derek J. Taylor, a University at Buffalo biologist and member of the research team. "What we're now finding is that these regions with vanishing waters, while not the most diverse in the world, do contain some unique aquatic（水生的） animals."

"Some of these subarctic ponds that water fleas inhabit are held up by permafrost, so when this lining of ice melts or cracks, it's like pulling the plug out of a sink," Taylor said. "When you see the crop circle-like skeletons of drained ponds on the tundra you can't help but wonder what animal life has been lost here."