Krill, the amazing euphausiid (actually called Euphausiia superba) are the biological engine that drives the Antarctic ecosystem, both on land and especially in the water. As goes krill, so go the whales, penguins, elephant seals, leopard sharks, Weddell seals, and fish of myriad kinds, some of them with antifreeze in their blood.
So krill counts are important for every other denizen of the southern continent and its adjacent island communities, as well. A possible large decline (hard to confirm) has been noted; it might not be so bad as first thought, because there's still a lot of krill. But as these articles note, further declines wouldn't be good and monitoring is important - even in this era of budget cuts.
Here's an article about the krill fishery management effort from NOAA:
License to krill
"Ice cover is important for krill, which take shelter under the ice and feed on algae that grow there. As winter ice cover has declined in extent and duration, the krill population has declined as well. By some estimates, krill abundance has dropped by as much as 80 percent since the 1970s.
With ice cover retreating, fishing has picked up in winter. The AMLR team, after 25 years of summer surveys, has shifted to winter as well. Reiss and his colleagues conducted their first wintertime krill survey last year, and preliminary data indicate that as fishing activity shifts to winter, there is the potential for competition between fishing vessels and winter-resident animals such as gentoo penguins and several species of seals."
And another one from the New York Times:
Team tracks a food supply at the end of the world
"The western Antarctic Peninsula is warming faster than most of the rest of the earth. Winter temperatures have shot up roughly 11 degrees Fahrenheit over the past 60 years, reducing sea ice cover. Those and other effects of climate change have caused Antarctic krill populations to plummet 40 to 80 percent in the last three decades around the South Shetland Islands near the tip of the peninsula, according to research published last May in The Proceedings of the National Academy of Sciences.
The research, led by Wayne Z. Trivelpiece of the National Oceanic and Atmospheric Administration, also showed that populations of Adélie and chinstrap penguins, which rely heavily on krill, declined more than 50 percent in the northern peninsula, where krill fishing vessels concentrate."