When discussing the pollution of earth’s oceans we often get the impression that the repercussions are yet to come. The waste is, however, already there and it is affecting lifeforms right now – and with that, it is affecting us. A study published in April (http://www.nature.com/articles/srep14340) this year has found evidence that the there is a certain percentage of unnatural waste in the fish we eat. And it is not a low percentage.
The team of scientists looked at the content of the digestive tract of fish and bivalve samples from markets from Indonesia, Makassar and California (U.S.A.). In 28% of the individual fish from Indonesia anthropogenic debris (that means human made, not natural debris) was found. Overall, anthropogenic debris was found on 55% of all the Indonesian species the researchers examined. The results for California are similar: 67% of the species looked had man-made debris in their digestive organs. The amount of anthropogenic debris found inside these fish species was on average 33%.
These are not random fish species – they were meant to be sold for human consumption. All marine animals in the study were bought from markets and fisherman, where many other people purchase heir seafood. As ocean waste can be found almost anywhere from coral reefs to shallow bays, estuaries, the open ocean and the deep sea, a variety of marine life is affected. Researchers Van Cauwenberghe and Janssen found in an earlier study that even commercially grown mussels and oysters, sold in supermarkets contain anthropogenic debris.
Organisations like the National Centre for Ecological Analysis and Synthesis, United National Environment Programme, United States Environmental Protection Agency, Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection and National Oceanic and Atmospheric Administration have long been concerned about the affect this might have on our health.
It may seem as of these concerns can be easily dismissed, considering we rarely eat fish organs, however the debris found contains toxins which are absorbed into other parts of the fish. Shellfish of course we usually eat along with their organs – and apparently a good bit of our own waste. This is can pose a serious health threat to us. Physical damage leading to cellular necrosis, inflammation and lacerations of tissues in the gastrointestinal (GI) tract have been shown to be caused by the kind of debris, often consisting of plastic and other non-degradable pollutants, found in our seafood.
Previously there have been concerns when it was discovered that hard plastic does in fact partially break down in the ocean and releases Bisphenol A. A research team in 2010 team analyzed sand and seawater mainly from Southeast Asia and North America. They found amounts of Bisphenol A ranging from 0.01 parts per million (ppm) to 50 ppm. This compound, which acts like a hormone in our body, has been correlated to serious health issues like hyperactivity, disrupted sex development in male babies and a declining sperm count in men. However, there is an ongoing debate in the scientific community about the validity of these results.
The species tested included skipjack tuna (Katsuwonus pelamis), Indian mackerel (Rastrelliger kanagurta), silver-stripe round herring (Spratelloides gracilis), Pacific anchovy (Engraulis mordax), Pacific mackerel (Scomber japonicus), striped bass (Morone saxatilis), Chinook salmon (Oncorhynchus tshawytscha) and albacore tuna (Thunnus alalunga) amongst many more. You can find a full list of all the fish tested in the paper itself.
The kind of anthropological debris found inside the fish varies from country to country, showing which kinds of waste make it into the ocean in each nation. In Indonesia, all the debris was plastic, while the debris found in the fish from the U.S. consisted mainly of fibre (from both cotton and synthetic fabrics) and only 20% of stomach contents were found to be plastic.
Of course this is just one more repercussion of one of many a harmful human practices. In 1999 Australia recognized in its Protection and Biodiversity Conservation Act that ‘Injury and fatality to vertebrate marine life caused by ingestion of, or entanglement in, harmful marine debris’ is one of the biggest threats for many endangered species. Not all marine life survives the consumption of ocean waste. Many die before they are ever caught. However, enough survive so that we now end up eating the waste we tried to get rid off by throwing it into the ocean or water ways. A prime example of dramatic irony that has been long predicted by the scientific community.
Foto Credit to: Waterkeeper Alliance Inc.