2023-07-04 17:00:14
The plastic pollution it is a growing problem in all the seas of the planet, but its distribution is not homogeneous. Plastics tend to accumulate in certain areas, due to the effect of ocean currents. At the same time, seabirds are distributed heterogeneously, visiting more frequently those areas where their prey is concentrated, also taking into account the influence of winds.
A new study has cross-referenced information on the distribution of plastics and ocean birds, to see where there is greater overlap and therefore greater risk of interaction. The research, which has been led by BirdLife International, has been published in Nature Communications.
The Spanish subsidiary SEO/BirdLife has participated in the work, which has provided data on the Balearic shearwater (P. mauretanicus), Mediterranean Cinderella (puffinus yelkouan) and Atlantic (C. borealis). Institutions such as the Center for Advanced Studies of Blanes (CEAB-CSIC), the Doñana Biological Station (EBD-CSIC) and the University of Barcelona, among others, have also collaborated.
Plastics give off dimethyl sulfate when they decompose, the same substance that plankton emit and that these birds use to locate food
Research has focused on the petrels and shearwaters (procellarids), one of the most endangered groups of birds on the planet. These birds are distributed throughout the seas, both in coastal and oceanic areas, and for this reason they are excellent indicators of the state of conservation of the marine environment. Studying the incidence of plastics on this group can help to better understand the impacts of this threat on the ecosystem as a whole.
According to the study, several species of shearwaters and petrels ingest this material regularly, either by confusing them with their prey, or by ingesting them through them. The risk is increased by the fact that plastics give off dimethyl sulphate when they decompose, the same substance that plankton emit and that these birds use to locate, from a considerable distance, areas of greater productivity (and, therefore, food).
In the case of larger plastics, their ingestion and accumulation can cause problems of digestive system obstructioneven causing suffocation or starvation, although it seems to be a problem that affects few specimens.
These birds regularly ingest plastics, either by mistaking them for their prey, or by eating them through them.
The problem of microplastics
On the other hand, the ingestion of small plastics (microplastics) is more widespread, and recent studies suggest that it could have significant deleterious effects. These pollutants are becoming more abundant, since in addition to reaching the sea directly as residue from some products (such as cosmetics), their number also increases due to the decomposition and fractionation of larger plastics into smaller and smaller particles.
Map of overlap between distribution of plastics and of petrels and pardeles globally, indicating areas of highest risk, among which the Mediterranean stands out. / SEO/BirdLife
critically endangered species
In total, data on the distribution of 7,137 specimens of petrels and shearwaters, of 77 different species worldwide. With the available data, the Mediterranean and the Black Sea stand out as the highest risk areas identified by the study.
This implies that the species of this basin are the most exposed to the problem of plastics, with the Mediterranean and Balearic shearwaters leading the way, both globally threatened and classified as vulnerable and critically endangered, respectively.
“The results of the study show the relevance of the problem of plastics for species of our direct competition, especially the endemic Balearic shearwater”, highlights Pep Arcos, Coordinator of the SEO/BirdLife Marine Program and one of the co-authors of the article.
In total, distribution data of 7,137 petrels and shearwaters, of 77 different species, have been analyzed
“So far we know that there is a high incidence of plastics in the three species of shearwaters typical of the Mediterranean, but in view of the results of this article we must intensify our efforts to understand its real impact,” he adds.
For his part, asuncion ruiz, executive director of SEO/BirdLife and also co-author of the article, affirms that “the study is another scientific evidence of the urgent need to change the model of production and consumption. Our seas and oceans are highly polluted and plastic is one of the highest risk factors for wildlife. Science provides knowledge and it is essential to continue betting on it; but we must ensure that it finds its way into decision-making so that the necessary measures are applied to put an end to models that put our authentic heritage, nature, at risk”.
Reference:
Bethany Clark et al. “Global assessment of marine plastic exposure risk for oceanic birds”. Nature Communications (2023)
Rights: Creative Commons.
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