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,” says Dr Sven Thatje, an evolutionary ecologist at the University of Southampton's School of Ocean and Earth Science (SOES). Dr 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, says an SOES press release.
Dr Thatje says: “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.”
To do this, the researchers carefully studied the distribution of 17 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. They found that king crabs occur mostly where the water temperature is relatively warm.
