Avoiding the Next Mass Extinction
by Gabriel Cross
A recent report by the International Programme on the State of the Ocean (IPSO), which was highlighted in a Reuters/Science story late last month, came to a startling conclusion: human beings may be on the brink of causing a globally significant extinction event in our oceans. As shocking as this may be, to those who have paid attention to the various studies sited by the report it may come as no surprise. In the last few decades, we have seen massive dead zones at every bay and estuary due to Eutrophication of our rivers and streams, threats to essential species on the bottom of the food chain due to Ocean Acidification, and dramatically declining populations of many species due to Over Fishing.
As the human population continues to grow, the cumulative effects of our actions have a greater and greater impact on our world. For generations, we didn’t have the tools to measure this effect, and were ignorant to it. Now, for decades, we have had the tools but many of us just can’t believe that it is true. I am certain that there is a very small minority of people who understand that those effects are real and choose to deny them publicly and spread misinformation for profit, but I honestly feel that most people want to do the right thing, and simply have not been convinced that these issues are real.
In April of 2009 PBS produced a fantastic special called Poisoned Waters which told very much the same story as the IPSO report (it is available in full for free online and very much worth your time). But still, many people don’t believe, and the response to the Reuters story was split between shock and total dismissal. Why is it that people refuse to believe that our actions have consequences? Why do we so deeply distrust scientific, evidence based, peer reviewed research? Why is it that most Americans assume that anything preceded by “International” is a thin veil for a communist plot to end our freedom? The facts are actually quite clear, so why is it that people are not getting the facts?
Eutrophication is a fancy word for too much food (it comes from a Greek word meaning “adequate nutrition”). Simply put, our waste is adding some fantastic algae food to our streams and rivers, and the algae is really digging it. The problem is that when the algae is over grown, it sucks all of the oxygen out of the water and everything else that needs oxygen to live suffocates. There are only two things that algae needs to run amok in a waterway: nitrogen and phosphorus. When level of these two nutrients reach a certain threshold, algae blooms, oxygen is used up, and all other organisms die. We used to be adding the nitrogen and phosphorus directly through our waste water, but regulations now require American cities to remove most of the nutrient load from sewage before returning it to waterways. Now, most of the excess N and P come from fertilizers and concentrated animal feeding lots.
Ocean acidification is a byproduct of our excess CO2 emissions. Even if you deny global warming, you cannot deny that we are burning lots of stuff and there is more CO2 in the air than before. Some of that CO2 is absorbed by the ocean in a process called deposition, but it doesn’t just disappear at that point, it alters the chemical make-up of the water near the ocean’s surface. In short, it lowers the pH, making the water slightly more acidic. The change is small, but according to a lot of very good scientific research, it could be enough within a decade or two to make those waters unfit for a number of organism that are an essential part of the ecosystem. The species that are affected adversely by acidification are those that require a hard, calcium based shell to survive; at a certain acidity, the water deteriorates their shells. There are several families of oceanic species that require a hard calcium based shell, and some of them, such as krill, are a primary food source for everything from penguins to whales. Disrupting the population of a whole family of ocean species is likely to have profound impacts on ocean ecology.
Over fishing is self explanatory: for certain species, we are taking fish out of the ocean faster than it can replenish them. The problem is complicated, however, by the fact that much of it occurs in the “high seas,” areas that are beyond the waters controlled by any nation, so implementing rules is a complex international affair. Also at issue is how certain species reproduce: some fish species only reach sexual maturity after many years of life, making catch limits or controls somewhat difficult to set. Salmon live in the open ocean, but only reproduce in streams far inland. In the Atlantic, mismanagement of streams and over fishing completely decimated the population (though recent efforts have seen improvements), but in the Pacific better practices (and a more sparsely distributed human demography) have ensured a thriving salmon population.
The problems are severe, but some of the solutions are actually quite simple and well understood. Though we may have little hope of stopping the major driver of ocean acidification (anthropogenic CO2 emissions), we can quite easily control over-fishing and eutrophication. These two issues have well understood and documented methods of control, which if implemented could go a long way to halting the next mass extinction.
Establishing large, contiguous “no fish” zones in the high seas, in other words aquatic nature preserves, will allow fish populations to bounce back. There have been several test cases that prove this method, and in some cases even allowing intensive fishing right along the edges of the no-fish zones the populations remained stable. In some instances, both the population and the total catch of a species has gone up significantly after establishing a no-fish zone.
Nutrients like Nitrogen and Phosphorus are already considered pollutants, and regulated by the EPA, but because of the way the rules are written, the EPA has no ability to enforce the rules unless the polluters are literally dumping the excess nutrient loads directly into a receiving stream (as was the case with civil waste water). Re-writing the rules to give the EPA authority to stop anyone from allowing excess nutrients to leach into our waterways is absolutely essential for maintaining the health of our bays and estuaries, and maintaining a strong fishing economic sector.
The means are known, understood, documented, even tested and proven. All that we lack is the political will to get the job done. What we have to realize is that it not just some fish at stake; with over a fifth of the worlds population getting a significant percentage of their protein from sea food, it is us who have the most to benefit from a healthy ocean.
Spreading Dead Zones and Consequences for Marine Ecosystems, Robert J. Diaz, and Rutger Rosenberg, Science, August 15, 2008
Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms, James C. Orr, et. al., Nature, September 29, 2005
Historical Overfishing and the Recent Collapse of Coastal Ecosystems, Jeremy B. C. Jackson, et. al., Science, July 27, 2001