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Climate change pushes Arctic marine predators northward

The seas surrounding the Arctic are major ecological regions and fisheries. Unfortunately, they are also among the areas most affected by climate change, which leads to warming waters and loss of sea ice, affecting ecosystems in often unpredictable ways. 

To better understand the impact of climate change on Arctic biodiversity and ecology, a team of scientists led by Hokkaido University in Japan has examined Arctic-wide and regional changes in species richness, composition, and potential species associations, and discovered that recent changes in biodiversity were driven by pervasive poleward species range expansions.

“We used data on the occurrences of 69 species of apex predators and mesopredators in eight Arctic areas from 2000-2019,” said study lead author Irene Alabia, a postdoctoral fellow in Marine and Fisheries Science at Hokkaido. “We combined this information with climate and productivity data across the same period to map species-specific habitat distributions.”

For each of the eight Arctic areas, the experts computed the species richness, community composition, and co-occurrences between species pairs in order to infer potential species associations. 

The analyses revealed that species richness (the number of different species) has increased over the past two decades, a phenomenon largely driven by the northward migration of apex predators such as sharks, whales, and seabirds. By contrast, mesopredators like fish and crabs showed a relatively limited degree of northward expansion. 

According to the scientists, these Arctic biodiversity changes caused alterations in potential species associations due to habitat overlap between taxa from various marine communities during a period of unprecedented changes in temperature and sea ice extent.

“Our findings revealed that changes in climate and species richness in the Arctic vary across different large marine areas and highlight potential regions of climate and productivity hotspots, and emerging areas of species gain. This information is relevant for strengthening conservation and management efforts for the sustainable use of resources under the expanding footprints of climate change in the Arctic,” Alabia concluded.

The study is published in the journal Nature Scientific Reports.

By Andrei Ionescu, Staff Writer

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