We are all, ultimately, creatures of the sea. We carry our ocean origins in our bodies, in the salt levels of our blood, which match closely those of the ancestral oceans from which our ancestors emerged so many hundreds of millions of years ago.
The world ocean — and it is a single ocean, despite the names we use to parse it — is the great engine of our climate, the source of our rain, and the vast, complex ecosystem which provides humans with the primary source of animal protein.
But the ocean is dying, and we have only ourselves to blame.
From Marlowe Hood of Agence France-Presse:
Pollution and global warming are pushing the world’s oceans to the brink of a mass extinction of marine life unseen for tens of millions of years, a consortium of scientists warned Monday.
Dying coral reefs, biodiversity ravaged by invasive species, expanding open-water “dead zones,” toxic algae blooms, the massive depletion of big fish stocks — all are accelerating, they said in a report compiled during an April meeting in Oxford of 27 of the world’s top ocean experts.
Sponsored by the International Programme on the State of the Ocean (IPSO), the review of recent science found that ocean health has declined further and faster than dire forecasts only a few years ago.
These symptoms, moreover, could be the harbinger of wider disruptions in the interlocking web of biological and chemical interactions that scientists now call the Earth system.
All five mass extinctions of life on the planet, reaching back more than 500 million years, were preceded by many of the same conditions now afflicted the ocean environment, they said.
“The results are shocking,” said Alex Rogers, an Oxford professor who heads IPSO and co-authored the report. “We are looking at consequences for humankind that will impact in our lifetime.”
The global oceanic collapse results from three primary factors:
- Rising global temperatures
- Increased ocean acidity resulting from rising carbon dioxide levels
- Human created dead zones, resulting from declining levels of ocean oxygen
“We have underestimated the overall risks, and that the whole of marine degradation is greater than the sum of its parts,” Rogers said. “That degradation is now happening at a faster rate than predicted.”
The massive rise in the use of fossil fuels accompany the industrial revolution poured vast amounts of carbon dioxide into the earth’s atmosphere and from there at least a quarter of the total ends up in the seas into the seas through rainwater and runoff. Add carbon dioxide to water and you get carbonic acid.
As Hood reports, the rate of oceanic carbon absorption has new topped the levels present during the last great marine die-off 55 millions ago when half of all oceanic life was rendered extinct during the Paleocene-Eocene Thermal Maximum.
Another major factor has been the swill we humans dump into the oceans, ranging from the vast quantities of nitrogen-based fertilizer on which modern industrial agriculture depends, a host of other chemical capable of knocking biological endocrine systems out of whack, and an endless barrage of microbes, sewage, and other noxious byproducts of our way of life.
Add to this endless overfishing of dwindling reserves of food fish and the stage is set for the greatest biological disaster we’re ever likely to witness, one likely to reach a peak within the next 40 years.
Of vanishing sharks and populous jellyfish
Barry Estabrook, writing at The Atlantic, tells about the dire effects of human’s on one of the key critters in the ocean ecology, killed off because of an Asian craving for soup and a Western fear inspired by a Spielberg blockbuster :
Sharks the world over are in deep trouble. [Juliet] Eilperin, a reporter at The Washington Post, points out that within the last few decades, 99 percent of smooth hammerhead, dusky, and bull sharks have been wiped out, often caught on long lines intended for more valuable food species. Other species are faring little better: Tiger sharks and scalloped hammerheads are down by 97 percent, silky sharks by 90 percent, white thresher sharks in the northwest Atlantic by 75 percent. Oceanic white tip sharks may once have been the most abundant large animal on earth. But since the 1950s their population in the Gulf of Mexico has declined by 99 percent. By exterminating 90 percent of the oceans top predators, Eilperin says, humans are conducting a massive, uncontrolled experiment on the oceans.
Iinitial results from that experiment are frightening in part because bad news for top predators is great news for their prey. Off the East Coast, the demise of sharks has resulted in a population explosion of cownose rays. The bottom-feeding rays in turn have decimated scallop, oyster, and clam populations to the point where North Carolina had to close its once lucrative scallop fishery. The oceans are suddenly awash in explosions of jellyfish, which devour young food species. Some scientists think the absence of sharks may be one explanation for out-of-control jellyfish populations.
Next, ponder this warning from earlier this year from Voice of America’s Roseanne Skirble via The Cutting Edge:
By 2050, small fish could dominate the oceans because of the rapid decline of larger, predator fish.
In a new report, the U.N. Food and Agriculture Organization finds that one-third of the world’s fisheries are overexploited, depleted or recovering and in urgent need of rebuilding. At a recent meeting of the American Association for the Advancement of Science meeting in Washington, University of British Columbia fisheries expert Villy Christensen predicted the eventual preponderance of small fish.
Twenty years ago, Christensen designed a computer tool called Ecopath to study complex marine ecosystems. Now Ecopath has 6,000 users in 155 countries.
Christensen used 200 marine models from the Ecopath database for the analysis released at the Washington meeting. “We are estimating that the predatory fish, the large fish that eat other fish, have declined by two-thirds in the 100 years and the decrease is accelerating. In the last 40 years alone, 54 percent of that decline occurred.”
Over the same 100-year period, Christensen says, prey fish like anchovies, herring and sardines have more than doubled. “We’ve never had numbers like that before. We expected it might be the case, now we have numbers documenting it. What has happened here really is that we’ve changed the wild ocean. We’ve removed the big fish.”
More prey and fewer predators could throw the ecosystem out of balance, Christensen says. That could promote the growth of algal blooms which deplete oxygen in the water column. Christensen fears that marine animals and plants would then begin dying off in huge numbers. “If we look ahead we are going to see less stable ecosystems in the oceans. There would be forage fish and very few of the organisms that control our ecosystem. We need the predators to keep the populations healthy of all the prey fish. That will continue unless we change the way we manage the oceans.”
What’s driving these trends? Jacqueline Alder, coordinator of the Marine and Coastal Ecosystem Branch of the United Nations Environment Program, believes it is overfishing and pollution, complicated by global climate change. She says the future health of the ocean depends on fishing less, reducing wasteful by-catch, and taking action on multiple threats to marine ecosystems.
Those ever-proliferating jellyfish
And as for those jellyfish, another key species now undergoing a radical population change, here’s Michael Viney, writing for the Irish Times:
Population explosions among the world’s jellyfish menace not merely human swimmers but the aquaculture industry and ocean ecosystems as a whole. Marine scientists from Cork and Swansea universities are collaborating in the urgent EcoJel study project, funded by the EU. They also joined the team, drawn from both islands and headed by Dr Christopher Lynam, that tackled the obvious question in a paper published in Global Change Biology: “Have jellyfish in the Irish Sea benefited from climate change and overfishing?” Their answer backs the global consensus: jellyfish numbers may respond to warming seas, but overfishing can give them an exponential boost.
In the Irish Sea, the decline of herring (which filter-feed on animal plankton, also the food of jellyfish) produced “a cascading regime shift” during the 1980s. Since then, the team says, “sea temperatures have increased, the fish community has altered, and jellyfish abundance has risen such that jellyfish and haddock may now play an increasingly important role in the ecosystem”.
Threats to this island’s aquaculture were shown dramatically in 2007, when great swarms of the mauve stinger, Pelagia noctiluca, a warm-water species proliferating off Spain, destroyed an entire fish farm’s stock of salmon in Co Antrim. Experiments at University College Cork’s Coastal Marine Research Centre have now shown that even the “harmless” moon jelly, Aurelia aurita, familiar on every Irish coast, can cause severe gill problems in marine-farmed fish, even when shredded through the nets.
And from Enric Sala of National Geographic News, more on the impact of the global jellyfish population explosion:
A new study by Robert Condon of the Virginia Institute of Marine Science and collaborators found that jellyfish blooms can wreak havoc by disrupting ocean food webs – and indirectly adding carbon dioxide to seawater.
Jellyfish eat the tiny plankton at the base of the ocean food chain. By doing so in large volumes, they can reduce the amount of food that goes up the food chain to feed larger animals. Because few animals are able to eat such massive amounts of jellyfish, this may mean a dead-end for food going up the food chain.
What the new research found is that jellyfish release organic matter that dissolves in seawater. In other words, jellyfish “sweat” large amounts of carbon to the water surrounding them. This dissolved carbon is then used by a rare type of marine bacteria, that turns it into carbon dioxide. So there you have it: jellyfish add carbon dioxide to seawater – eventually turning the ocean more acidic.
And then consider this from The Guardian’s Tracy McVeigh:
Dr Carol Turley, a scientist at Plymouth University’s Marine Laboratory, said the research highlighted the growing problem of ocean acidification, the so-called “evil twin” of global warming. “Oceans have been taking up 25% of the carbon dioxide that man has produced over the last 200 years, so it’s been acting as a buffer for climate change. When you add more carbon dioxide to sea water it becomes more acidic. And already that is happening at a rate that hasn’t occurred in 600 million years.”
The acidification of the oceans is already predicted to have such a corrosive effect that unprotected shellfish will dissolve by the middle of the century.”
Think of it. Marine shellfish, from the tiniest of critters all the way up to those giant clams, gone by 2061.
And then there’s the run-off
In previous posts we’ve noted how the mercury has contaminated the fish of San Francisco Bay to the point where they’re now inedible. And we’ve written about agricultural chemicals that are causing horrible mutations among amphibians, as well as pollution of waterways and seas by prescription drugs that results in suicidal shrimp.
But our greatest impacts on sea life may result from the vast amounts of fertilizers on which modern agriculture depends.
Consider this from GulfCoastMaritime.com:
The Gulf of Mexico experiences an annual “dead zone” of oxygen-depleted waters as summer storms in the Mississippi River watershed carry a surge of agricultural fertilizer runoff, animal waste, municipal sewage, and other contaminants downstream to the river’s mouth. Once the contaminant-laden runoff flows into the warm environment of the Gulf, marine phytoplankton, or algae, respond to the sudden influx of nutrients with large blooms of excessive growth. The algae themselves consume oxygen, and they also create large amounts of organic matter that eventually sink deep into the water column and to the sea floor. There, bacteria break down the organic matter in a process that further absorbs oxygen. The end result: low oxygen levels in the surrounding waters, which can suffocate fish and other marine animals and force others to escape by abandoning their habitat. So, while tiny phytoplankton form a critical component of the ocean food chain, their runaway growth in response to agricultural and municipal runoff can create a hypoxic wasteland in the marine environment along the Gulf Coast and up to 60 miles out to sea.
This year, scientists predict that the dead zone may be the largest yet recorded, at between 8,500 and 9,400 square miles, or approximately the size of Lake Erie. This is due to enhanced runoff from the rain-drenched and flooded Mississippi River watershed.
According to Dr. Nancy Rabalais, of the Louisiana Universities Marine Consortium, the 2011 dead zone likely will exceed the 2002 zone, the largest known to date, by some five to ten percent. Dr. Rabalais has studied the dead zone effect since 1985 and is considered a leading expert on the phenomenon.
But with the basis of human life itself under threat, here’s our valiant president, leading us deeper into the morass of endless wars fought again regimes which control vital resources needed to keep the whole polluting machine afloat.
How’s that for Hope™ and Change™?