Winter warming will rapidly alter fish diversity

Experts have used mathematical modeling inspired by social media to evaluate the future impacts of global warming on the world’s fisheries. The study revealed that winter warming has the most profound influence on fish biodiversity.

Study lead author Dr. Nicholas Clark is a researcher in the University of Queensland School of Veterinary Science.

“Usually, when modeling ecosystems to understand how nature is changing, we build models that only focus on the effects of the environment,” said Dr. Clark. “But it’s just not accurate enough.”

“Newer models – commonly used in social media to document people’s social interactions – offer an exciting way to address this gap in scientific knowledge.”

“These innovative network models give us a more accurate picture of reality by incorporating biology, allowing us to ask how one species responds to both environmental change and to the presence of other species, including humans.”

The team applied this modeling technique to analyze fish populations in the Mediterranean Sea, a biodiversity hotspot that is threatened by rapidly warming waters.

“Experts from fisheries, ecology and the geographical sciences have compiled decades of research to describe the geographical ranges for more than 600 Mediterranean fish species,” said Dr. Clark.

“We put this information, along with data from the Intergovernmental Panel on Climate Change’s sophisticated climate models into our network model.”

The analysis revealed that warming seas have widespread effects on fish biodiversity, particularly during the winter. Study co-author Professor Ceridwen Fraser noted that winter warming is often overlooked when considering the impacts of climate change.

“A great deal of research and media attention has been on the impacts of extreme summer temperatures on people and nature, but winters are getting warmer too,” said Dr. Fraser. “Interestingly, coastal water temperatures are expected to increase at a faster rate in winter than in summer.”

“Even though winter warming might not reach the extreme high temperatures of summer heatwaves, this research shows that warmer winters could also lead to ecosystem disruption, in some cases more than hotter summer warming will.”

“Our results suggest that winter warming will cause fish species to hang out together in different ways, and some species will disappear from some areas entirely.”

The researchers hope the study brings attention to the urgent need to understand and address climate change.

“If fish communities are more strongly regulated by winter temperatures as our model suggests, this means that fish diversity may change more quickly than we previously thought,” said Dr. Clark.

“Catches for many bottom-dwelling and open-ocean fishery species in the Mediterranean Sea have been steadily declining, so any changes to fish communities may have widespread economic impacts.”

“For the sake of marine ecosystems and the people whose livelihoods depend on them, we need to gain a better understanding of how ocean warming will influence both species and economies.”

The study is published in the journal Nature Climate Change.

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By Chrissy Sexton, Earth.com Staff Writer