Warming UK seas could ‘fundamentally reshape marine ecosystems’ – report

The seas around the British isles, particularly the southern North Sea, have been identified as marine climate hotspots, one of 20 globally to have warmed the fastest over 50 years. Under a scenario of 3C warming by 2100, the study found that while fish and seabed invertebrates may become more diverse by mid-century, key plankton groups lower in the food chain were likely to decline.

Food web imbalance

The projections highlight a predator-prey imbalance that could fundamentally reshape marine ecosystems in unforeseen ways. By mid-century, fish and seabed invertebrate diversity could increase by about 12%, whereas phytoplankton and zooplankton diversity could decline by about 3% and 7%, respectively.

Ecosystem consequences

This imbalance, the authors warned, could disrupt marine food webs and weaken the health and resilience of ocean ecosystems. Previous research suggested warming would result in climate winners, such as anchovies, seabass and sardines, while being less suitable for losers like Atlantic cod, haddock and coley.

If predator diversity rises while prey diversity falls, that has the potential to disrupt the food chain, said Lily Greig, a marine ecologist at Cefas who also co-led the study. Our results show that climate change could reshuffle marine biodiversity unevenly across the food web, and that gains in some groups do not necessarily mean the ecosystem as a whole is becoming more resilient.

Policy implications

The study, published in Science Advances and involving an international team of researchers, could provide an early warning system of potential ecosystem change. The work has already been submitted to the government's review of marine protected areas, which is looking at fishery management measures.

Policymakers have a mandate to try to preserve or even increase biodiversity, said Couce. What we are trying to tell them is climate change is already changing biodiversity, and you need to take that into account before you can make other management plans. The scientists used multiple long-term datasets and advanced machine-learning techniques to predict climate-driven biodiversity change until 2100.