Our oceans are at risk from a combination of acidification, warming waters and decreasing oxygen. According to scientists this could lead to a mass extinction of key species.
On Thursday October 3, Scientists from the International Programme on the State of the Ocean (IPSO) published their biennial State of the Oceans report. The oceans are more acidic now than they’ve been at any time in the last 300 million years. In addition to the alarming findings in this study indicating that current levels of acifification are “unprecedented” the survey also states that the overall health of the ocean is declining much faster than expected.
“We are entering an unknown territory of marine ecosystem change, and exposing organisms to intolerable evolutionary pressure,” the report states. “The next mass extinction may have already begun.”
Ocean acidification has far reaching impacts on marine ecosystems, and coral in particular which are essential measures of aquatic health and vital nurseries for young fish. According to the study if temperatures rise by 2 degrees C, coral may
stop growing and at 3 degrees C they may begin to dissolve.
In addition to impacts on coral acidification is also harmful to shellfish larvae and in the Arctic tiny sea snails that are crucial sources of food for many birds, fish and whales. In the Antarctic, krill are being threatened, which is a vital part of the food chain.
The report stated that ocean oxygen, caused by climate change and nutrient runoff (mostly from agriculture) is expected to decline of between 1 and 7 percent by 2100. This will increase the number and size of ocean dead zones which have doubled every decade. Decreasing habitat for large ocean predators such as tuna and marlin that have high oxygen requirements.
According to the study, current efforts are insufficient as there is a time lag of several decades between levels of atmospheric CO2 and dissolved CO2 in the ocean. Governments must take fast action to ensure temperatures don’t rise past 2 degrees C.
The survey found that overfishing is still a major problem leading to declines in key ocean species. At least 67 percent of fish stocks are being over-fished. The report advocates stricter oversight and monitoring of commercial fishermen and giving more control of fisheries to local communities.
However, there has been some progress on this front with some local governments successfully stopping depletion of fish in local waters. To illustrate the point when one Mexican town banned fishing, it saw its marine biomass increase by 463 percent while fishing improved in regions outside the preserve.
“Ultimately, however, [these measures] must be undertaken within a wider re-evaluation of the core values of human society and its relationship to the natural world on which we all rely,” the report states. “The future of humanity and the future of the ocean are intertwined.”
With wide ranging ecosystem impacts, including the important fishing and shellfish industries, there has never been more urgency to protect our oceans from human impacts.
Click here to go to the 2013 ISPO State of the Oceans Report.
© 2013, Richard Matthews. All rights reserved.
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