QINGDAO, Sept. 28 (Xinhua) -- An international team of researchers has reported that Antarctic krill, a key species in the Southern Ocean food web, has taken refuges from climate change that degraded its original habitat.
Based on data from Chinese icebreaker Xuelong and other databases, the researchers reported in the journal Limnology and Oceanography that due to ocean warming and ice loss, the original habitat of Antarctic krill supports fewer krill than before, but the species has been seeking refuges in other regions which probably will hold more krill than they did a century ago.
Antarctic krill, a krill species about six centimeters in length and weighing over a gram, has been given credit for helping keep the balance in the ecosystem around the Antarctic as few animals can survive in such harsh conditions, and is commercially exploited.
The Southern Ocean, also called the Antarctic Ocean, refers to the sea surrounding Antarctica, consisting of parts of the southern Atlantic, Pacific, and Indian oceans. Scientists estimate that there are about 500 million tonnes of Antarctic krill in the Southern Ocean.
The Atlantic part of the Southern Ocean has long been thought to host the world's largest Antarctic krill population. In recent years, the region is one of the fastest-warming ocean regions on Earth, raising alarms for the conservation of Antarctic krill.
Scientists have been debating whether the krill stocks have declined, and the question also poses a challenge for the fishery industry.
The new study draws together researchers from the Institute of Oceanology under the Chinese Academy of Sciences, Plymouth Marine Laboratory in Britain, the British Antarctic Survey, the Anton Dohrn Zoological Station in Italy, and the University of Messina in Italy.
The data from the 30th Chinese National Antarctic Research Expedition by icebreaker Xuelong between 2013 to 2014 played a significant part in the study. The Chinese voyage sampled a ring of 103 stations around Antarctica.
The researchers analyzed sampling data from Xuelong along with a database of krill spanning from 1926 to 2016 and a large amount of data for zooplankton collected over the last 100 years.
They said that although conditions for Antarctic krill deteriorated rapidly in the Atlantic sector, the Indian and Pacific sectors of the Southern Ocean have become refuges for the species and may even hold more Antarctic krill than before.
The researchers said that the study provides a broader perspective on Antarctic krill stocks and shows there is an increasing need to take a circumpolar-scale view for effective management and conservation in the Southern Ocean.
According to Rod Downie, Chief Polar Advisor at the World Wildlife Fund, krill is on the frontline of the climate crisis. They feed huge populations of wildlife, from penguins to blue whales. They sequester millions of tonnes of carbon every year into the deep ocean, helping to maintain a stable climate for life on Earth.
"This study highlights new areas which may serve as safe havens for krill in the future as Antarctica feels the heat," he said.
Angus Atkinson, co-author of the research and Senior Ecologist at Plymouth Marine Laboratory, said in a press release that the study is a great example of how the different nations working around Antarctica can combine their ideas and data.
"A spirit of cooperation is essential for a joint approach to management and conservation around Antarctica," he noted. Enditem
Guang Yang, Angus Atkinson, Simeon L. Hill, Letterio Guglielmo, Antonia Granata, Chaolun Li (2020) Changing circumpolar distributions and isoscapes of Antarctic krill: Indo-Pacific habitat refuges counter long-term degradation of the Atlantic sector. Limnology and Oceanography, doi: 10.1002/lno.11603.
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