Climate change will reshuffle marine ecosystems in unexpected ways – “Like putting marine biodiversity in a blender”

Large predatory fish are expected to lag temperature changes due to food web dynamics.

A sophisticated model reveals how predator-prey relationships affect species ranges.

According to a new study from Rutgers, warming oceans due to climate change will mean fewer productive fish species to catch in the future.

The new study, published in the journal Proceedings of the Royal Society B, presents a mixed picture of the health of the oceans. Not only will large species and commercially important fisheries move out of their historic ranges as the climate warms, they are unlikely to be as abundant even in their new geographic ranges. For example, a cod fisherman in the Atlantic might still find fish 200 years from now, but in far fewer numbers.

“Warming coupled with food web dynamics will be like putting marine biodiversity in a blender.” — Malin Pinsky

“What this suggests from a fisheries perspective is that while the species we catch today will be there tomorrow, they won’t be there in the same abundance. In such a setting, overfishing becomes easier because population growth rates are low,” said study co-author Malin Pinsky, an associate professor in the Department of Ecology, Evolution and Natural Resources at Rutgers. “Warming coupled with food web dynamics will be like putting marine biodiversity in a blender.”

Previous studies of changes in habitat ranges have focused on the direct impacts of climate change on individual species. While these “one-at-a-time” species projections offer insight into the composition of ocean communities in a warming world, they have largely failed to consider how food web interactions will affect the rate of change.

The new study looked at trophic interactions – the process by which one species feeds at the expense of another – and other food web dynamics to determine how climate change affects species ranges.

Using sophisticated computer models, the researchers determined that predator-prey interactions cause many species, especially top predators, to shift their ranges more slowly than the climate.

“These dynamics will not just be in one place but on a global scale. This does not bode well for marine life, and it is not a widely recognized effect. — Malin Pinsky

“The model suggests that over the next 200 years of warming, species will continually reshuffle and be shifting their ranges,” said lead author EW Tekwa, a former Rutgers postdoc in ecology, evolution, and natural resources now at the University of British Columbia. “Even after 200 years, marine species will still lag behind temperature changes, and this is especially true for those at the top of the food chain.”

As the climate warms, millions of species are moving towards the poles in a dramatic reorganization of life on earth. However, our understanding of these dynamics has largely ignored a key feature of life: animals and other organisms must eat. The researchers filled this knowledge gap by examining how the basic need for food affects the movements of species.

“That dynamic won’t just be in one place but on a global scale,” Pinsky said. “That doesn’t bode well for marine life, and it’s not a widely recognized effect.”

Reference: “Body size-food web interactions mediate species range shifts under warming” by EW Tekwa, James R. Watson, and Malin L. Pinsky, April 12, 2022, Proceedings of the Royal Society B Biological Sciences.
DOI: 10.1098/rspb.2021.2755

Funding: Gordon and Betty Moore Foundation, Hakai Postdoctoral Fellowship, National Science Foundation, National Science Foundation, National Science Foundation