Warming seas around the UK and the wider north-east Atlantic could destabilise marine food webs, weaken ocean health and jeopardise food security by 2050, according to a four-year study. Scientists who projected the impact of climate breakdown on four key groups of marine life crucial to maintaining ocean ecosystems in the region said their results challenged assumptions that in middle latitudes, such as the UK, marine biodiversity was likely to increase across the board. Instead, their projections highlight a predator-prey imbalance that could “fundamentally reshape marine ecosystems” in unforeseen ways, they said.
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. The new predictions, under a scenario of 3C (5.4F) of warming by 2100, 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. This imbalance, the authors of the report said, could disrupt marine food webs and weaken the health and resilience of ocean ecosystems.
The research, led by Cefas and published in Science Advances, involved an international team of researchers from the University of East Anglia, the Marine Biological Association, UiT the Arctic University of Norway, the Royal Netherlands Institute for Sea Research and the Technical University of Denmark. So we expected diversity to go up, because you get species from the south that are more diverse than the species you lose to the north.” Previous Cefas research looking at key fish species suggested warming in north-western European waters would result in climate “winners”, such as anchovies, seabass and sardines. Such conditions, however, are less suitable for climate “losers”, including Atlantic cod, haddock and coley.
The current study, focusing on ecosystems in UK waters and the wider north-east Atlantic including Ireland and France, found that 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 by 2050. The work has already been submitted to the government’s review of marine protected areas, which is looking at fishery management measures.
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