An increase in temperature of around 1.5 Â° C – just below the maximum target agreed at the COP23 meeting in Paris in 2017 – can have a marked impact on algae and animal species living on UK coasts , according to new research.
The study, conducted by environmentalists at the University of Plymouth, examined how increasing rock surface temperatures affected the amount and behavior of species commonly found on the shores of Devon and Cornwall.
It focused on two sites on the region’s north coast (at Bude and Croyde) and two on the south coast (Bantham and South Milton Sands), all of which have deep ravines with north and south facing surfaces. .
Their results showed that the mean annual temperature on surfaces exposed to the south at low tide was 1.6 Â° C higher than those exposed to the north and that the temperature extremes (i.e.> 30 Â° C) were six times more frequent on the faces exposed to the south.
At the four sites, these differences had a significant effect on species abundance with 45 different species found at the north-facing sites during the summer of 2018 versus 30 on the south-facing ones.
In winter, the numbers were 42 and 24, respectively, while some species – including the red algae Plumaria plumosa and sea cauliflower (Leathesia marina) – were limited to surfaces exposed to the north.
The different temperatures also had an impact on the reproduction patterns of species with five times more whelks (Nucella lapillus) eggs found on surfaces exposed to the north than those exposed to the south.
And while limpet reproduction generally occurred earlier on south-facing surfaces, these major grazers also exhibited higher stress levels.
The research, published in Marine environment research, is the first to explore the association between temperature and site geography on the abundance, physiology and reproductive behavior of species in coastal areas.
Its authors say it provides evidence of how local-scale temperature variation can affect species while providing insight into how future changes in global temperatures could negatively impact over the next few years. decades.
The research was led by Dr Axelle Amstutz as part of her doctorate, in collaboration with Associate Professor of Marine Ecology Dr Louise Firth, Professor of Marine Zoology John Spicer and Associate Professor of Plant-Animal Interactions Dr Mick Hanley.
Dr Hanley, lead author of the study, said: ‘We have all heard for some time now about the importance of limiting the global average temperature rise to 1.5 Â° C, and it will be without any doubt one of the key topics discussed at the next COP26 conference. This study shows the impact that even this type of increase could have on important species that contribute to the health and biodiversity of our planet. As such, it adds to the overwhelming evidence of threats posed by human-induced climate change.
âHowever, more than that, it shows how the pressure on different species can change even within individual sites. For example, we recorded a temperature of 42.5 Â° C on a south-facing area in Croyde at the same time as 22.5 Â° C was measured on the opposite face to the north. We believe this shows that these sites can be used as a “natural laboratory” to inform and predict how species and habitats might respond to climate change in the coming decades . “