Coastal ecosystems are disrupted by small temperature changes

New research led by ecologists at the University of Plymouth has found that temperature increases of about 1.6°C – just below the maximum target established by the Paris Agreement in 2017 – could severely impact algal populations and animal species living in coastal ecosystems.

“Marine rocky intertidal organisms are amongst those most affected by climate change with regional distributional changes observed for many species,” wrote the study authors. 

“Although often ascribed to increased sea surface temperatures, precise assessment of the local habitat conditions underpinning observed and predicted changes in community assembly is lacking.”

The scientists examined how increases in rock surface temperature were affecting the quantity and behavior of animal and plant species currently found in the UK on the shorelines of Cornwall and Devon. 

The study was focused on two areas of the region’s north coast (Bude and Croyde), and two on the south coast (Bantham and South Milton Sands), all of which have deep gullies with both north- and south-facing surfaces. The average annual temperatures recorded on the south-facing surfaces were 1.6°C higher than those on the north-facing ones. 

These differences in temperature were strongly correlated with species abundance. During the summer of 2018, the researchers found 45 different species on the north-facing sites compared to 30 on the south-facing ones. During the winter, the figures were 42 and 24 respectively, with species such as red seaweed and sea cauliflower being restricted to north-facing surfaces. 

Temperature differences were also found to have a significant impact on the breeding patterns of animals in these coastal ecosystems. For instance, five times more dog whelk eggs were found on the north-facing surfaces than on the south-facing ones.

“We have all heard for some time about the importance of limiting average global temperature increases to 1.5°C, and it will undoubtedly be one of the key topics discussed at the forthcoming COP26 conference,” said study senior author Mick Hanley, an associate professor of Plant-Animal Interactions at Plymouth. 

“This study shows the impact even that kind of increase could have on important species that contribute to the health and biodiversity of our planet. As such, it does add to overwhelming evidence of the threats posed by human-induced climate change.”

The study is published in the journal Marine Environmental Research.

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By Andrei Ionescu, Earth.com Staff Writer