Warming seas may fundamentally shift marine ecosystems, says study

Larger marine predators were observed to shift their geographical ranges slower than climate change progressed, a new research showed, as larger-bodied predators typically stay in historical habitats for longer than smaller prey. Photo: Jakob Owens/Unsplash

Rising global temperatures spurred by human-induced greenhouse gas emissions may destabilise the marine food chain and disallow fish – especially predators – from keeping up with a rapidly-shifting ecosystem, researchers said.

The Rutgers University study, published in Proceedings of the Royal Society B, created a model that analysed the interactions of predators and prey over a course of 200 years of warming.

It found larger predators especially struggled as more abundant fish moved out of their historical ranges to attempt to adapt to warming seas.

Those same fish targeted by commercial fisheries are also unlikely to be as abundant in their new geographical locations, the research showed, potentially posing a threat to the market.

"What that suggests from a fisheries perspective is that while the species we fish today will be there tomorrow, they will not be there in the same abundance," study coauthor Malin Pinsky, an associate professor in Rutgers' Department of Ecology, Evolution and Natural Resources, said in a release.

"In such a context, overfishing becomes easier because the population growth rates are low. Warming coupled with food-web dynamics will be like putting marine biodiversity in a blender," added Pinsky.

By both accounting for climate change and parameters for marine life, such as metabolism and body size, the researchers were able to see how food-web interactions were hampered by climate change.

Larger predators were observed to shift their geographical ranges slower than climate change progressed, the new research showed, as larger-bodied predators typically stay in historical habitats for longer than smaller prey.

"These dynamics will not only be in one place but globally," added Pinsky. "That does not bode well for marine life, and this is not an effect that has been widely recognised."

The Rutgers researchers said while previous studies have focused on how climate change impacts individual species, food-web interactions are seldom studied.

A 2020 study found algae bloomed in greater abundance in warmer conditions while some fish species dwindled in numbers – creating difficulties for predators.The latest findings suggested a disrupted food chain will emerge as temperatures insidiously rise.

"The model suggests that over the next 200 years of warming, species are going to continually reshuffle and be in the process of shifting their ranges," said lead author E.W. 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 be lagging behind temperature shifts, and this is particularly true for those at the top of the food web." – Tribune News Service