Coral reefs begin to disappear, not in the last 30-40 years, given the ongoing climate changes, and in the 50-ies of the last century. To such conclusion scientists have come, having studied the long-term dynamics of populations of the corals Acropora palmata and Acropora cervicornis on the Islands and mainland parts of the coast of the Caribbean sea. Possible causes of such events researchers call over-fishing, and the penetration of agricultural fertilizers into the ocean from surface runoff. The results of a study published in the journal Science Advances.
The disappearance of coral reefs — one of the main environmental problems of the XXI century. These unique communities have high productivity and ensure the biodiversity of ocean ecosystems, but have strict requirements to environmental conditions and are sensitive to such changes. It is believed that the global threat to corals occurred with increasing temperature and acidification of ocean waters with excess carbon dioxide, but these communities any dangerous pollution of the environment — even the use of sunscreens on the beaches. A living cover of reef-building corals of the Caribbean since the beginning of its environmental monitoring in the late 1970-ies has declined by 50 percent.
Scientists led by Katie Kramer (Katie L. Cramer) from Arizona state University studied the dynamics of populations of the corals Acropora palmata and Acropora cervicornis in the Caribbean sea during the period from the end of the Pleistocene (about 125 thousand years ago) in our time (2011) to identify the critical point of human impact on these communities and compare it with the crises of the past geological epochs.
The authors of the study examined the ratios and the age of the dead and live weight, dominance and abundance of species and population structure of Acropora palmata on data from 629 test sites, and similar indices for Acropora cervicornis 2468 sites. For this, they used the observations of global network monitoring of coral reefs (GCRMN) and older data, government reports and peer-reviewed studies conducted in more than 30 countries on the territory of the Large and lesser Antilles, Gulf of Mexico and the mainland coast of Central and South America.