The corals of the species Diploria labyrinthiformis , which, due to their peculiar arrangement, are known as brain corals, form circular structures that can reach two meters in diameter. They live in shallow waters and, despite their size, only a thin outer layer is made up of living tissue. Most of these colonial animals, which are made up of numerous identical individuals, consist of a kind of skeleton made of calcium carbonate. Thus, when they die, the remains of these corals contribute to the development of new reefs. However, they can live for hundreds of years.
Precisely, the study of a 130-year-old specimen has revealed that the impact of nitrogen from some fertilizers, a pollutant that, when it reaches the ocean, can be deadly for marine fauna, is less than what had been believed until now, when less in the North Atlantic. To determine this, a team of researchers from different institutions coordinated by Xingchen Wang, from the Department of Geosciences at Princeton University, measured the levels of this element in the coral skeleton. “Surprisingly, we found no evidence that there had been an increase in pollution over the past decades,” Wang said in a statement.
The experts, who describe the finding in an article published in the journal Proceedings of the National Academy of Sciences , did not expect these results, mainly because in similar work previously carried out in the South China Sea they had observed that this type Pollution was very high in that area, and that this corresponded to a significant increase in coal production and the use of fertilizers that had occurred in the Asian giant in the last twenty years.
Control measures
On this occasion, the scientists focused on an area near Bermuda Island, which is receiving large amounts of nitrogen from the US, related to emissions from vehicles and power plants. Although they could not verify that the effect caused by human activities was greater than in the past , they did observe variations that corresponded to the influence of a natural phenomenon known as the North Atlantic Oscillation. This, as indicated on its website by the State Meteorological Agency, is a large-scale fluctuation in the atmospheric mass located between the zone of high subtropical pressures and the low polar in the North Atlantic basin that determines the variability of the winter climate throughout the region.
In any case, Wang and his team emphasize that the results contrast with computer models that predicted a notable increase in nitrogen pollution and that it could be an indication that the measures taken to limit emissions and that they reach the sea are giving its fruits.
Reference: Natural forcing of the North Atlantic nitrogen cycle in the Anthropocene . Xingchen T. Wang et al. PNAS (2018) .
Image: Xingchen T. Wang et al.
