By moving from the surface of the sea down to deeper layers, Antarctic krill transport carbon down from the surface to the depths of the ocean. Scientists from the British Antarctic Survey (BAS) and Scarborough Centre of Coastal Studies at the University of Hull have now discovered that Antarctic krill venture between the surface and the deep sea several times per night. Earlier, they were believed to do so only once per night. The more times they head for the deep with their bellies filled, the more carbon they will remove form the surface, so this is interesting news for anyone worried about too much carbon in the atmosphere and upper ocean. According to Dr Geraint Tarling from BAS, Antarctic krill transport an amount of carbon equivalent to the annual emissions of 35 million cars.

Krill swims to the surface to feed on phytoplankton (which must stay fairly close to the surface since they rely on photosynthesis) but they do not spend all their time close to the surface because that would make them easy targets for predators. Instead, krill regularly sink down to greater depths where the risk of being eaten is lower. When krill excrete carbon rich waste products at such depths, the waste will sink down to the ocean floor.

Other studies have shown that adding iron to the water could allow the krill populations to increase in size which would cause them to remove more CO2 from the atmosphere. Adding iron can also help trigger algae growth that further removes CO2 from the atmosphere and can help fight global warming. We do however know too little about the potential side effects of adding iron to the water to make it a viable alternative at this time.

According to an article published by The Guardian, scientists believe that krill have declined 80 per cent since the 1970s. Why this has happened remains unknown, but it might be due to global warming. According to estimates made by the British Antarctic Survey (BAS), there is roughly 100 million tonnes krill left, while krill harvesting companies place the figure at 400-500 million tonnes. The Convention on the Conservation of Antarctic Marine Living Resources allows 4 million tonnes of krill to be caught in the Southern Ocean per year. Until now, this number has seldom been reached; in a normal year, less than 20 percent of the permitted 4 million tonnes have been caught.

Today, the emerging interest in health products such as Omega 3 oil and Omega 3 fortified food is causing a boom in krill fishing. A majority of the fished krilled is used to produce Omega 3 oil and other health supplements, or as fish-farm feed. So called “suction harvesting” is now used to meet the demand for krill.

So, why care about a tiny crustacean? The truth is that entire ecosystems depend on krill and krill are also able to help us remove carbon dioxide from the atmosphere. Some species, such as the gigantic Blue Whale, feeds directly on krill. Other species, such as penguins and seals, are indirectly depending on krill since they feed on animals that feed on animals that eat krill.

If you want to learn more about krill and hear different experts explain their view on the current situation, read the full article at The Guardian: http://www.guardian.co.uk/environment/2008/mar/23/fishing.food