Source: Al Jazeera
Scientists and experts are alarmed at amount of plastic debris and growing ‘dead zones’ in the world’s oceans.
A drumbeat of recent scientific studies emphasises an increasingly alarming convergence of crises for Earth’s oceans.
The amount of plastic floating in the Pacific Gyre – a massive swirling vortex of rubbish – has increased 100-fold in the past four decades, phytoplankton counts are dropping, over-fishing is causing dramatic decreases in fish populations, decreasing ocean salinity is intensifying weather extremes, and warming oceans are speeding up Antarctic melting.
One warning of humanity’s increasingly deleterious impact on the oceans came from prominent marine biologist Jeremy Jackson of the Scripps Institute of Oceanography.
In a 2008 article published in Proceedings of the National Academy of Sciences, Jackson warned that, without profound and prompt changes in human behaviour, we will cause a “mass extinction in the oceans with unknown ecological and evolutionary consequences”.
The statement might sound extreme, until one considers what science journalist Alanna Mitchell has written about the oceans: “Every tear you cry … ends up back in the ocean system. Every third molecule of carbon dioxide you exhale is absorbed into the ocean. Every second breath you take comes from the oxygen produced by plankton.”
These and other issues will be discussed at the Rio 20 United Nations Conference on Sustainability, which will be held between June 20 and 22 in Rio de Janeiro, Brazil.
But marine biologists, oceanographers, and others who study the seas are telling Al Jazeera of the deepening impact humans are having on the oceans, and, from what they are saying, now is the time to listen.
Plastic, plastic everywhere…
The most obvious impact humans are having on the world’s oceans is pollution. Though it can take myriad forms, pollution is now most shockingly evident in the seas in the form of giant, swirling gyres of plastic.
Scientists recently investigated the North Pacific Subtropical Gyre, known as the “Great Pacific Garbage Patch”, and found an “alarming amount” of refuse, much of it comprising individual pieces of very small size. The eastern section of the spiralling mass, between Hawaii and California, is estimated to be around twice the size of Texas, and is having ecosystem-wide impacts, according to their study released May 8.
Miriam Goldstein, a graduate student researcher at Scripps Institution of Oceanography at University of California San Diego, and the lead author of the study, told Al Jazeera that by adding this amount of plastic to the oceans, humans could be causing large-scale change to the ocean’s ecological system.
“We found eggs on the pieces of plastic, and these were sea-skater [insect] eggs,” Goldstein said. “Sea skaters naturally occur in the gyre and are known to lay their eggs on floating objects. So we found that the amount of eggs being laid had increased with the amount of plastic.”
Goldstein is also concerned by the findings because, “Our work shows there could be potential effects to the ocean ecosystem that we can’t expect or predict. There are five subtropical gyres, one in each ocean basin, and they are natural currents. They are vast areas of the oceans; together they comprise the majority of the area of the oceans. So altering them on a large scale could have unexpected results on all kinds of things.”
The study shows how an increase in pollution, in this case an immense amount of plastic, may have dire consequences for animals across the entire marine food web.
This Scripps study follows another report by colleagues at the institution that showed nine per cent of the fish collected during the trip to study the gyre had plastic waste in their stomachs.
Published in Marine Ecology Progress Series, that study estimated that fish at intermediate ocean depths in the North Pacific Ocean could be ingesting plastic at the staggering rate of 12,000 to 24,000 tonnes per year.
Dr Wallace J Nichols, a research associate at the California Academy of Sciences, told Al Jazeera he finds plastic on every beach he visits across the globe, and added, “Probably every sea turtle on the planet interacts with plastic at some point in its life.”