The population of Antarctic krill, the favourite food of many whales, penguins, fish and seals, has shifted southward during a recent period of warming in their key habitat, new research shows.
Antarctic krill are shrimp-like crustaceans which occur in enormous numbers in the cold Southern Ocean surrounding Antarctica. They have a major role in playing a significant role in the transport of atmospheric carbon to the deep ocean.
Important krill habitats are under threat from climate change, and this latest research – published today (Jan. 21, 2019) in Nature Climate Change – has found that their distribution has contracted towards the Antarctic continent. This has major implications for the ecosystems that depend on the krill.
An international team of scientists, led jointly by Dr Simeon Hill at the British Antarctic Survey and Dr Atkins Atkinson at Plymouth Marine Laboratory, analyzed data on the amount of krill caught in nets during scientific surveys. The data covered the Scotia Sea and Antarctic Peninsula – the region where krill are most abundant. The team found that the center of the krill distribution shifted towards the Antarctic continent by about 440 km (4 ° latitude) over the last four decades.
The team took great care to account for noise in the data. Many factors, in addition to long-term change, the amount of krill caught in any one net. Even after these factors the team found a consistent trend across the data, indicating a significant change in the krill population over time.
The study provides support for a proposed mechanism behind these changes – an increasingly unfavorable climate leading to younger krill replenishing the population. This has led to a small population dominated by older and big krill.
Dr Hill said: "Our analysis reveals a species facing increasing difficulty in replenishing itself and maintaining high numbers at the northern edge of the Southern Ocean."
"These northern waters have warmed and conditions throughout the Scotia Sea have become more hostile, with stronger winds, warm weather and less ice." This is bad news for young krill. "
Dr Atkinson added: "This is a nice example of international cooperation in the Antarctica It is only when we look at the huge scales of space and how to learn how populations of key polar species are responding to rapid climate change. "
Dr. Hill continued: "The surveys which provided this data were not about a large scale spatial scales or over 90 years.While we see a signal among all this noise is a sign of how much the population has changed over time changes. "The continuous preautionary management of the krill fishery is important, but is not substitute for global action on climate change."
Materials provided by British Antarctic Survey. Note: Content may be edited for style and length.