Microplastics threaten marine filter-feeders, study reports

New research shows that, if nothing is done, microplastics could cause many ocean filter feeders to go extinct.
By Joseph Scalise | Feb 07, 2018
A group of international researchers has found that if more research is not done on the impact plastic pollution has on rays, whales, and sharks, many of the large marine species could die off in the near future.

Microplastic pollution is one of the biggest threats to ocean life, and the team in the recent study has found evidence that it hits larger species particularly hard. The researchers discovered that large marine animals are swallowing hundreds of tiny bits of plastic every day, a trend that could greatly reduce many filter feeder populations.

Even so, despite that risk there is very little research being done on the topic. To try and change that trend, the team analyzed a range of studies and found that the Gulf of Mexico,the Mediterranean Sea, the Bay of Bengal, and the Coral Triangle all need to be better monitored for the presence of microplastics.

The small particles are dangerous because, once ingested, they can damage the digestive system and lead to toxin exposure. That could then affect many biological processes, including growth and production. While the plastics affect many species, filter feeders -- which swallow hundreds of cubic meters of water a day -- are particularly susceptible to ingesting them. That is problematic because the larger species are a key part of many ecosystems.

"Our studies on whale sharks in the Sea of Cortez and on fin whales in the Mediterranean Sea confirmed exposure to toxic chemicals, indicating that these filter feeders are taking up microplastics in their feeding grounds," said study co-author Maria Fossi, a professor at the University of Siena in Italy, according to BBC News. "Exposure to these plastic-associated toxins pose a major threat to the health of these animals since it can alter the hormones, which regulate the body's growth and development, metabolism, and reproductive functions, among other things."

Whale sharks feeding in an important breeding ground at the Sea of Cortez off Mexico's Baja Peninsula are estimated to ingest under 200 pieces of plastic per day. In addition, fin whales in the Mediterranean Sea likely swallow closer to 2,000 microplastic particles per day.

The new research hopes to stem those issues by highlighting several key coastal regions for future research and monitoring. Whale sharks and other flagship species may act as a the center point for such study, especially in countries that rely on wildlife tourism. Many large filter feeding species are on the edge of extinction, and the team hopes more awareness could stem the tide and help prevent them from disappearing altogether.

"It is worth highlighting that utilizing these iconic species, such as whale sharks, manta rays and whales to gain the attention of and engage with communities, policy makers and managers will go far to enhance stewardship of entire marine ecosystems," said Elitza Germanov, a PhD student at Murdoch University.

The new research is published in the journalTrends in Ecology and Evolution.


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