Ocean warming slows growth of even hardy Caribbean coral species

A long -term study studying the growth of corals in the Caribbean in the last century has shown that even species of tolerant corals with stress have difficulty adapting to increasing ocean temperatures and other factors induced by humans such as coastal pollution and overfishing.

An international team of scientists led by researchers from Freie Universität Berlin has revealed a reduction that gives reflection on the coral calcification rates, a development that will have deep consequences on marine and coastal ecosystems. Their study, “The emerging skeletal growth responses of Sideratrea Siderea Corals with multidennial anthropogenic impacts in Martinique, Caribbean Sea”, was recently published in Scientific relationships.

Tropical corals find it difficult to build solid reef structures. Even these species formerly considered to be particularly resilient now show signs of decline. In a new study, researchers have rebuilt more than a hundred years of growth in coral corals Siderea Siderea using samples taken off the coast of Martinique.

The results reveal a regular drop in calcification rates for most of the 20th century, with a net slowdown starting in the 1980s as marine heat laundry – caused by the climate change caused by humans – are more frequent.

One of the most worrying results of the study is the sharp drop in coral skeletal density between 2010 and 2020 – a decrease of 10.5%. This indicates a structural weakening caused by multiple stressors of interaction. Signs of decline have been visible since the 1950s, when reef growth rates began to slow down. At the time, scientists mainly linked the trend to local pressures such as coastal development and water pollution.

“Our study shows that if local protection measures remain important, they will not be enough,” explains Gabriel Cardoso, a coral researcher at the Institute of Geological Sciences in Freie University and the first author of the study. “Without a significant reduction in world CO₂ emissions, even the most resilient coral species – and the reefs they build – will be very long -term.

“The consequences could be serious. Coral reefs help protect themselves against coastal erosion, provide habitats for countless marine organizations and support the means of subsistence by fishing and tourism.”

The coral reefs are largely trained by the progressive growth of corals, which build their skeletons by depositing layers of calcium carbonate, a process called “calcification”. These layers create annual growth strips – a bit like rings in a tree trunk – which can be visible using X -ray imaging and digitally analyzed.

For this study, the research team has examined the growth of corals in the south of Martinique, using data collected from twelve drilled kernels taken from four different reef sites. The samples extend over the period from 1912 to 2020 and provide a detailed recording of the way in which coral growth and calcification rates have changed over time.