Even though plastic pollution has not been studied a lot, it is known to be a health hazard for marine ecosystems around the globe. Jacob González Solís points out that “this is the first evaluation of plastic ingestion in Mediterranean seabirds. The Mediterranean Sea has been identified as an exceptionally sensitive ecosystem because its shores are highly industrialized, there is a lot of shipping activity and it contains a large degree of floating plastic in some areas.”
Endangered Mediterranean seabirds
The research is built upon the examination of 171 birds accidentally caught by fishing boats in the Catalan coast from 2003 to 2010. The UB science group analyzed plastic ingestion in nine particularly endangered seabird types: Cory’s shearwater (Calonectris diomedea), Yelkouan Shearwater (Puffinus yelkouan), Balearic Shearwater (Puffinus mauretanicus), gannet (Morus bassanus); Audouin’s gull (Ichthyaetus audouinii), Mediterranean Gull (Ichthyaetus melanocephalus), yellow-legged gull (Larus michahellis), black-legged kittiwake (Rissa tridactyla) and great skua (Catharacta skua).
From humans to the seabirds’ stomach.
Floating waste can cause entanglement, inflammatory conditions, infections and death to aquatic animals. They mostly consume them by mistake due to the plastic fragment resemblance of their natural food items, but in some situations, plastic comes from consuming prey with the substance already in their stomach. The most ingested pieces are from filaments, plastic spheres, laminar plastic, and industrial pellets.
Analysis revealed that 66% of seabirds had at least one fragment of plastic in their stomachs. Cory’s shearwaters were the most affected, with 93% of them containing plastic peaces (15 on average). In the study Balearic shearwaters and Yelkouan shearwaters, 70% had plastic remnants in them.
“The findings are disturbing,” Gónzalez Solís points out. “All three of the most affected are of conservation importance, especially the Balearic shearwater, which is indexed as seriously endangered by the International Union for Conservation of Nature (IUCN). It is a Balearic native species; there are only around 3,200 breeding pairs in the whole world. We do not understand its total impact but it is urgent to research it if it affects populations in a negative aspect.”
Chicks are the most vulnerable.
Seabird chicks are really endangered by plastic ingestion because they cannot vomit as mature individuals do. The small amount of plastics in gulls probably is an outcome from their better ability to vomit any hard parts. The research proves that plastic garbage is introduced to the oceans’ food chain and may grow into a new threat for seabirds and aquatic ecosystems. Seabirds are part of the many affected animals by that kind of pollution.
The sea is not a garbage bin
Accidental plastic consumption is a worldwide issue that affects different species as the Laysan Albatros (Phoebastria immutabilis) in the Hawaiian Islands and the Northern Fulmar (Fulmarus glacialis rogdgersii).
“Plastic stays above water and is hard to biodegrade,” added González Solís. “In the end, all debris which are not destroyed on land reach the sea. The restriction and regulations over the plastic products and their transportation on a corporation level should tighten up, even though there was a slight improvement over the course of time. Right now things still seem not satisfying enough, as dumping more and more waste becomes a growing problem that needs urgent measures. There is also the need to prohibit ships’ discharge into the water.”
González Solís is the co-author of a research – currently published on the journal PLOS ONE – about the circulation of flavivirus – viruses account for several infectious diseases that affect humans and different species – among with Western Mediterranean seabird populations. The research discovers that yellow-legged gulls (Larus michahellis), commonly seen along the Mediterranean coast, may be potential containers for these pathogens. Therefore, it is crucial to improve health surveillance on these Mediterranean inhabitants.