Invasions of voracious predatory crabs due to global warming could threaten the unique continental-shelf ecosystems of Antarctica, according to newly published findings.
"King crabs are ecologically important predators and form the basis of economically significant commercial fisheries," said Dr Sven Thatje, an evolutionary ecologist at the University of Southampton's School of Ocean and Earth Science (SOES), which is based at the National Oceanography Centre in Southampton.
Thatje and graduate student Sally Hall studied how water temperature influences the distributions of king crab species in the Southern Ocean, which has some of the coldest waters on Earth.
King crabs are cold blooded, their body temperature being determined largely by that of the surrounding environment. Although many of them live in cold, deep-sea habitats, experiments have shown that their larvae fail to mature in water temperatures below around half a degree Celsius, even after only brief exposure.
"We tested the hypothesis that the king crab species of the Southern Ocean only thrive above a critical minimum temperature and that it is this thermal barrier that determines their biogeographical distributions in the Southern Ocean," said Thatje.
To do this, Thatje and Hall carefully studied the distribution of seventeen species of king crab living at depths between around 500 and 1600 metres in the Southern Ocean. They collated data from published records, museum collections, commercial fishing records, and reports from scientific research cruises. They then compared these records to water temperatures measured at a range of relevant depths and geographical latitudes.
Consistent with their hypothesis, they found that king crabs occur mostly at locations where the polar water temperature is relatively warm. The coldest waters in which king crabs have been found are between 0.4 and 0.5C in the Ross Sea, suggesting that this ind
|Contact: Dr. Rory Howlett|
National Oceanography Centre, Southampton (UK)