An increase in marine heatwaves due to global climate change in the coming decades will have a significant impact on lifeforms in this environment, including those at the bottom of the food chain, according to a paper published in Estuarine, Coastal and Shelf Science by Brazilian researchers working in Brazil, Norway and the United States,
Marine heatwaves are periods of more than five days with water temperatures more than 90% above the historical average for the region. Projections point to a rise of 35% in the frequency of marine heatwaves by the year 2100 for the Santos-São Vicente area (coast of São Paulo state, Brazil) in which the study reported by the paper was conducted. It is important to distinguish between marine and atmospheric heatwaves, the latter typically being more intense but affecting mainly terrestrial environments, including cities.
The researchers evaluated the potential impact of marine heatwaves on planktonic larvae of the Atlantic mangrove fiddler crab Leptuca thayeri. “Although the larvae survived a rise in the acidity of the water, a rise of 2 °C in sea surface temperature during the first three to four days of their lives led to a 15% drop in the survival rate compared with larvae at the average temperature for the region. A rise of 4 °C led to a 34% rise in mortality,” said Murilo Zanetti Marochi, first author of the paper. The study was conducted while he was on a postdoctoral research fellowship at the Institute of Biosciences of the São Paulo State University’s Coast Campus (IB-CLP-UNESP) in São Vicente.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (via EurekAlert!), 18 January 2023. Press release.
