By Robert A. Vella
Krill are small invertebrate shrimp-like crustaceans no bigger than your little finger. They feed primarily on phytoplankton (i.e. bacterial algae, or cyanobacteria) which bloom in huge numbers particularly in the Southern Ocean waters surrounding Antarctica during summertime. Together, these organisms form the productive base of a food-chain ecosystem of great diversity and importance. Many species of whales, seals, penguins and other birds, as well as other marine life in the Antarctic and beyond, are dependent upon the krill for their survival.
But, this ecosystem is beginning to falter and krill populations – along with their predators – are in decline. The cause appears to be climate change which is shortening the duration of the winter sea ice season that is crucial for the krill’s survival when its phytoplankton food supply isn’t blooming.
Watch the 1 hour video here, from PBS/NOVA – Mystery Beneath the Ice:
Tiny, transparent, and threatened, krill are crucial to the Antarctic ecosystem. But the population of krill is crashing for reasons that continue to baffle the experts. A leading theory says that krill’s life cycle is driven by an internal body clock that responds to the waxing and waning of the Antarctic ice pack, and as climate change alters the timing of the ice pack, their life cycle is disrupted. To test it, NOVA travels on the Polarstern, a state-of-the-art research vessel, to the frigid ice pack in the dead of winter. From camps established on the ice, scientists dive beneath the surface in search of the ice caves that shelter juvenile krill during the winter. There, they hope to discover what’s causing the krill to vanish and, ultimately, how the shifting seasons caused by climate change could disrupt ecosystems around the world.