92% of coral reefs are affected by plastic – 07/12/2023 – Environment

Plastic already reaches about 92% of the shallow coral reefs on the planet, reveals a new study published this Wednesday (12) in the scientific journal Nature, one of the most important in the world.

According to the research, which was coordinated by the Brazilian Hudson Pinheiro, from Cebimar (Center for the Study of Marine Biology) at USP, and with the participation of researchers from 30 countries and territories, the amount of plastic present in the oceans affects organisms that live both in environments close to coastal regions, where there is high population density, but also in those far away and in remote regions, such as isolated islets in the middle of the Pacific.

“By surveying the species present in many of these mesophotic corals [como são chamados os de profundidade até 150 m]we also decided to quantify the amount of plastic waste found, and we saw waste in 77 of the 84 (91.7%) locations studied,” said the biologist, who is also an associate researcher at the California Academy of Sciences in San Francisco, to Sheet.

“Remains of nets, fishing lines and longlines are of concern as they show that these ecosystems, although further from the coast and at greater depths, are not safe from overfishing and human activity”, he explains.

Still, the study identified four risk factors associated with greater exposure to plastic, namely: greater depth; highest population density within a radius of ten kilometers from the site; proximity to areas of fishing activity (markets); and proximity to marine protection units.

Recently, another study indicated that seabirds that migrate during the reproductive period and access isolated islands are at risk of finding plastic waste in the oceans.

The problem of plastic waste in the oceans is growing and there is a lack of global public policies that try to circumvent the inappropriate disposal of waste, evaluates the researcher.

Although most of the plastic waste found in the study in the deepest parts of the ocean originates from fishing activities (73%), there is also a high concentration of plastic in coastal areas associated with human consumption, such as plastic packaging.

The idea of ​​measuring the amount of plastic found in the oceans came about by chance, explains Pinheiro. Since 2014, he and colleagues had been researching the biodiversity present in mesophotic reefs in the Philippines, when they saw that there was a very large accumulation of waste in these areas.

They then mapped 84 reef zones in 25 locations in the Atlantic, Pacific and Indian oceans and made exploration lines that extended for 20 meters (called transects). In the end, they had a kind of grid where it was possible to extrapolate the concentration of plastic per square kilometer in the explored area. Reefs were also evaluated according to their distance from densely populated regions on the coast (in population per km^two).

Among the places with the highest concentration are the Philippines, the Comoros islands and the oceanic region of Brazil. In the Comoros islands, the highest concentration of garbage was observed, with 520 plastic waste found in an area equivalent to a football field (1.08 ha).

Pinheiro explains that the Philippines is one of the most diverse places for marine life in the world, where dozens of species of fish, corals, anemones, and other organisms that only live there are known, but the region of the Amazon coast, as in the reef at the mouth of of the Amazon, may harbor a still unknown diversity.

“There are areas that should be considered for use [exploração] and priority areas for conservation, and the mouth of the Amazon should be a priority for conservation”, he says, mentioning the area that is at the center of the discussion of a drilling request for oil research by Petrobras.

As coastal coral reefs are, in general, subject to tidal movements and sea currents, the deposition of plastics usually does not occur in these places as often.

This partly explains why there was a greater concentration of plastic waste in deeper places in the ocean and close to the so-called ocean gyres, areas of intense maritime activity that end up concentrating “bubbles” of plastic pollution.

The study found even in remote locations, where there is not a significant population density, the impact of human activity.

“In one of the most remote marine areas in Brazil, in the São Paulo archipelago, we saw a hag shark at a depth of 130 m with a fishing line in its mouth. So we are in a place, in the middle of the Atlantic Ocean, far from the coast and with this pressure on ecosystems due to human activity”, he concludes.

PLASTIC ALSO ACCUMULATES IN LAKES

In another article also published this Wednesday (12) in the journal Nature, researchers looked for microplastic present in 38 lakes and freshwater reservoirs present in 23 countries in the Northern Hemisphere.

In the study, led by Veronica Nava, a researcher from the Department of Earth Sciences and the Environment at the University of Milan-Bicocca (Italy), the scientists saw that the lakes can serve as “traps” and store high concentrations of plastic waste throughout of time.

The result was surprising because some of the sampled places had higher concentrations of plastic even than the ocean, known to be the hardest hit by aquatic plastic pollution.

“It is more surprising what we find in the great lakes, with high concentrations [de microplástico] and the fact that they were present in all the places studied”, the researcher told Sheet.

One such location was Lake Lugano, Italy, with 11.5 plastic particles per million (ppm). Others include the Maggiore (also in Italy), the Tahoe (California, US) and the Avery (Michigan, US).

Most of the plastic found was composed of fibers (49.5%) and fragments (41%), which may have been released either as a by-product of washing clothes or by decomposition of plastic packaging and fabric.

Although the concentrations and type of material varied from place to place, the scientists identified two patterns in the places with the most plastic waste, the first being the deeper and wider the lake and thus the greater the volume of water found, and the second the impact of human activity.

As many of the places studied use the lakes for leisure or human consumption, the researchers make an appeal: this amount of microplastics can affect the system present there.

“Providing reliable data on plastic contamination in the environment is essential in order to understand the impacts, considering that it is a very complex class of different polymers, as well as environmental data to understand the level at which organisms are exposed”, he completes.