Monday 8 October 2012

Antarctic Krill

  1. ANTARCTIC KRILL                                                                                                 By:Regina

Description

One of the most abundant organisms in Antarctic waters, the Antarctic krill is a ‘keystone species’ of the Southern Ocean ecosystem, playing a crucial role within the food chain as the main prey for a wide variety of predators, including fish, penguins, seals and whales . A small crustacean which is relatively shrimp-like in appearance, the Antarctic krill has a hard, calcified exoskeleton which is divided into three sections: the head and the thorax (which are fused into what is known as the cephalothorax), and the abdomen. Each section is further divided up into individual segments, with many of the...

Habitat

  • The Antarctic krill inhabits a variety of habitats throughout its life cycle, with adults more often associated with deeper waters, especially during winter, while juveniles are usually found at the surface of inshore waters, beneath the sea ice. The Antarctic krill is also commonly found in dense aggregations, where surface currents bring together many individuals to form patches or swarms, although groups are capable of migrating up and down the water column. These large groupings can span from a few square metres to more than 100 square kilometres, and are most often associated with islands, continental shelves and slopes, and zones of mixing water.

    Status

    This species has yet to be classified by the IUCN

    Threats

    Although the Antarctic krill population is currently estimated to have an incredible total mass of between 100 and 500 million tonnes, over the last 30 years the abundance of krill has seriously declined . Several threats to Antarctic krill have been identified, including increasing commercial demand for krill oil and meal for the aquaculture, medical and cosmetic industries, as well as advancing technologies which enable much greater catches and quicker processing. Over recent years, the Antarctic region has also seen significant increases in temperature as a result of climate change, which is affecting the extent and duration of the winter sea ice on which successful krill reproduction is so dependent.
    An additional concern is that Antarctic krill is the main food source for many predators, which are increasingly having to compete with fisheries that target krill aggregations on island shelves close to breeding sites. Over-fishing of these vital food sources will alter the whole Antarctic ecosystem, with localised depletions likely to have a severe knock-on effect for many predator populations

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