Krill Oil decline

Antarctic krill is the keystone species of the Antarctica ecosystem, and provides an important food source for whales, seals, Leopard Seals, fur seals, Crabeater Seals, squid, icefish, penguins, albatrosses and many other species of birds. Crabeater seals have even developed special teeth as an adaptation to catch this abundant food source: its most unusual multilobed teeth enable this species to sieve krill from the water. Its dentition looks like a perfect strainer, but how it operates in detail is still unknown. Crabeaters are the most abundant seal in the world; 98% of their diet is made up of E. superba. These seals consume over 63 million tonnes of krill each year.
Leopard seals have developed similar teeth (45% krill in diet). All seals consume 63-130 million tonnes, all whales 34-43 million tonnes, birds 15-20 million tonnes, squid 30-100 million tonnes, and fish 10-20 million tonnes, adding up to 152-313 million tonnes of krill consumption each year.

The next size step in the food chain to the whales is also enormous, a phenomenon only found in the Antarctic ecosystem. E. superba lives only in the Southern Ocean. In the North Atlantic, Meganyctiphanes norvegica and in the Pacific, Euphausia pacifica are the dominant species.

Biomass and production

The biomass of Antarctic krill is estimated to be between 125 to 725 million tonnes,[16] making E. superba the most successful animal species on the planet. It should be noted that of all animals visible to the naked eye some biologists speculate that ants provide the largest biomass (but this speculation adds up hundreds of different species) whilst others speculate that it could be the copepods, but this too would be the sum of many hundreds of species that exist over the planet. To get an impression of the biomass of E. superba against that of other species: The total non-krill yield from all world fisheries, finfish, shellfish, cephalopods and plankton is about 100 million tonnes per year whilst estimates of the Antarctic krill production are between 13 million to several billion tonnes per year.

The reason Antarctic krill are able to build up such a high biomass and production is that the waters around the icy Antarctic continent harbor one of the largest plankton assemblages in the world, possibly the largest. The ocean is filled with phytoplankton; as the water rises from the depths to the light-flooded surface, it brings nutrients from all of the world's oceans back into the photic zone where they are once again available to living organisms.

Thus primary production - the conversion of sunlight into organic biomass, the foundation of the food chain - has an annual carbon fixation of between 1 and 2 g/m² in the open ocean. Close to the ice it can reach 30-50 g/m². These values are not outstandingly high, compared to very productive areas like the North Sea or upwelling regions, but the area over which it takes place is just enormous, even compared to other large primary producers such as rainforests. In addition, during the Austral summer there are many hours of daylight to fuel the process. All of these factors make the plankton and the krill a critical part of the planet's ecocycle.

Decline with shrinking pack ice

after data compiled by Loeb et al. 1997[17] - temperature and pack ice area - the scale for the ice is inverted to demonstrate the correlation - the horizontal line is the freezing point - the oblique line the average of the temperature - in 1995 the temperature reached the freezing point

There are concerns that the overall biomass of Antarctic krill has been declining rapidly over the last few decades. Some scientists have speculated this value being as high as 80%. This could be caused by the reduction of the pack ice zone due to global warming.[18] The graph on the right depicts the rising temperatures of the Southern Ocean and the loss of pack ice (on an inverted scale) over the last years 40 years. Antarctic krill, especially in the early stages of development, seem to need the pack ice structures in order to have a fair chance of survival. The pack ice provides natural cave-like features which the krill uses to evade their predators. In the years of low pack ice conditions the krill tend to give way to salps,[19] a barrel-shaped free-floating filter feeder that also grazes on plankton.

Ocean acidification

Another challenge for Antarctic krill, as well as many calcifying organisms (corals, bivalve mussels, snails etc.), is the Acidification of the oceans caused by increasing levels of carbon dioxide.[20] Krill exoskeleton contains carbonate, which is susceptible to dissolution under low pH conditions. Little is currently known about the effects that ocean acidification could have on the krill but it is feared[who?] that it could significantly impact on its distribution, abundance and survival as it appears to have effects on its ability to moult and grow or its behavioural patterns.[21]

The above was sourced from

http://en.wikipedia.org/wiki/Antarctic_krill

Krill populations decline 80% - National Geographic

All the consumers taking krill oil supplements need to think twice about what they're doing: Krill populations have plummeted 80 percent across the world's oceans, and because krill are a major food source for marine mammals, whales populations may already be impacted by the non-sustainable harvesting of krill.

The bottom line is that if you take krill oil supplements, you are harming whales. This is one reason why so many are switching to green-lipped mussels for a sustainable, eco-friendly source of marine omega-3 fatty acids.

From National Geographic: "Krill feed on phytoplankton, microscopic, single-celled plants that drift near the ocean's surface and live off carbon dioxide and the sun's rays. They in turn are the main staple in the diets of literally hundreds of different animals, from fish, to birds, to baleen whales. Simply put, without krill, most of the life forms in the Antarctic would disappear. Alarmingly, there are recent studies that show Antarctic krill stocks may have dropped by 80 percent since the 1970s..."

It has been brought to my notice that the 80% decline figure is suspect.. Please check out the below

http://wattsupwiththat.com/2010/07/31/walking-the-plank-ton/