New predictions reveal how global warming may shift the geographic distribution of 686 marine species that inhabit North America's Atlantic and Pacific continental shelves, according to a study published May 16, 2018 in the open-access journal PLOS ONE by James Morley of Rutgers University, United States, and colleagues.

In response to warming seas, some marine species have already moved north or south to more favorable habitats, or to deeper, cooler waters. These changes pose challenges for resource management, such as conflicts over fisheries catch allocation between neighboring regions. Further shifts are expected, and predictions for individual species could help inform conservation and management efforts.

To that end, Morley and colleagues used data from long-term ecological surveys to develop statistical models of thermally preferable habitats for each of 686 North American continental shelf species. Then, for each species, they applied 16 different ocean circulation models under future scenarios of low or high greenhouse gas emissions to see how their preferred habitat might change during the 21st century.

The analysis predicted that climate change will alter the location and size of suitable habitats for many species, with all 16 circulation models projecting similar changes for two thirds of the 686 species. Habitats generally tended to shift north along the coastline in the model predictions, but these shifts varied depending on specific species' requirements, seafloor characteristics, and continental shelf width.

The models predicted that the total area of some species' suitable habitat may increase, but habitats for other species, such as East Coast sheepshead, may shrink significantly. Species off the U.S. and Canadian West Coast may move the farthest, with some, such as West Coast canary rockfish, shifting over 1000 kilometers under a high greenhouse gas emissions scenario.

The researchers note that their predictions do not account for finely detailed knowledge of every species, and the 16 circulation models disagreed strongly for about 20 percent of the species. However, unlike previous studies that focused on narrow geographic regions or took a low-resolution global approach, this study provided fine-grained analysis over a broad geographic range.

"We found a major effect of carbon emissions scenario on the magnitude of projected shifts in species habitat during the 21st century," says James Morley. "Under a high carbon emissions future we anticipate that many economically important species will expand into new regions and decline in areas of historic abundance."