The global impact of debris on marine life revealed

A recent study conducted by researchers at Plymouth University has revealed the extent of the global impact that marine debris has on marine life. In the most comprehensive impact study in more than a decade, nearly 700 species of marine animal have been recorded as having encountered man-made debris such as plastic and glass.

Authors of the study, Professor Richard Thompson and Sarah Gall, conducted an extensive literature search of 340 original publications to review the current state of knowledge on the effects of marine debris on marine organisms. Collated from a wide variety of sources on instances of entanglement, ingestion and physical damage to ecosystems, these publications reported that 693 species have encountered marine debris, nearly 400 involving entanglement and ingestion, with plastic materials accounting for 92% of cases. Plastic fragments showed to be the highest recorded substance for ingestion, with the green sea turtle and northern fulmar, the Laysan albatross, the Californian seal lion, the Atlantic puffin, and the greater shearwater among the worst affected species. These incidents have been reported globally, but were most commonly reported off the east and west coasts of North America, as well as Australia and Europe.

Co-author Professor Richard Thompson, who is acknowledged as one of the world’s leading experts on microplastics in the marine environment, also showed that at least 10% of the species encountering marine debris had ingested microplastics. These microplastics are tiny particles which measure 1mm or smaller, their size resulting from the physical breakdown of larger plastic items and have been shown to act as a vector for the transfer of pollutants and additive chemicals1.

Through comparison with the IUCN Red List, the study also found that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened, including the Hawaiian monk seal, the loggerhead turtle and sooty shearwater.

“The impact of debris on marine life is of particular concern, and effects can be wide reaching, with the consequence of ingestion and entanglement considered to be harmful.” says co-author Sarah Gall. “Reports in the literature began in the 1960s with fatalities being well documented for birds, turtles, fish and marine mammals.”

“We found that all known species of sea turtle, and more than half of all species of marine mammal and seabird had been affected by marine debris — and that number has risen since the last major study,” said Sarah. “And in nearly 80 per cent of entanglement cases this had resulted in direct harm or death.”

The situation regarding the abundance of anthropogenic debris found in the marine environment has become a widely discussed topic within environmental and scientific communities in recent years, with the major concerns relating to the time period that various debris items take to decompose in the ocean and the physiological and ecological impacts that this waste can have on marine life. It is thought that about 6.4 million tons of marine litter are disposed in the oceans and seas each year. According to other estimates and calculations, some 8 million items of marine litter are dumped in oceans and seas every day, approximately 5 million of which (solid waste) are thrown overboard or lost from ships. Furthermore, it has been estimated that over 13,000 pieces of plastic litter are floating on every square kilometre of ocean today 2.

The paper titled The impact of debris on marine life, published in Marine Pollution Bulletin, reports that while only four per cent of cases involving ingestion were known to have caused harm, further study of sub-lethal impacts are needed, with areas of concern around the impact upon metabolism and reproduction. Professor Richard Thompson says:

 “Encounters with marine debris are of particular concern for species that are recognised to be threatened, and with 17 per cent of all species reported in the paper as near threatened, vulnerable, endangered or critically endangered on the IUCN Red List, it is evident that marine debris may be contributing to the potential for species extinction.”

Article Source: S.C. Gall, R.C. Thompson. The impact of debris on marine life. Marine Pollution Bulletin, 2015; DOI: 10.1016/j.marpolbul.2014.12.041

Photo Header Credit: PlasticOceans.net

Additional References: 

Microplastic moves pollutants and additives to worms reducing functions linked to health and biodiversity Mark A. Browne, Stewart J. Niven, Tamara S. Galloway, Steve J. Rowland, Richard C. Thompson Current Biology, December, 2013

 UNEP, 2005 – http://www.unep.org/regionalseas/marinelitter/publications/docs/anl_oview.pdftter/publications/docs/anl_oview.pdf

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