The Fate of the Ocean
Page 11 of 12
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As matters stand, we miss many messages, even those that wash ashore. Walk any beach these days and you’ll likely find miniature SOS signals littering the tide line: seabirds drowned in fishing nets, plastic flotsam, globules of oil, castaway cargo from containers lost overboard. Seek in the waters just offshore and you may well find male fish bearing eggs or ovary tissue, the unfortunate results of living near sewage outflows, where chemicals, including the copious quantities of pharmaceuticals inhabiting our bodies, flow to the sea. Despite the ocean’s fetch, there is no place on it where our impact is not seen, felt, or heard.
Noise is our newest assault, including the low-frequency active (LFA) sonar used by the military to detect submarines and by the oil and gas industry to search for fossil fuels. The loudest sound ever put into the seas, LFA sonar could soon be deployed across 80 percent of the world ocean, at an amplitude of 230 decibels, strident enough to kill whales and dolphins and already causing mass strandings and deaths in areas where navies conduct exercises [see “Collateral Damage”]. A few people, misfortunate enough to be in the water near LFA sonar tests, have suffered lung vibrations, seizures, disorientation, and nausea. No one knows what effects these extreme noises have on the majority of marine life that “see” underwater with their acoustical senses.
Meanwhile, plastic pollutants masquerade as familiar marine objects. David Barnes of the British Antarctic Survey finds that invertebrates that normally hitch rides on floating wood or pumice are increasingly grabbing lifts on floating plastics; the presence of so many new “boats” has doubled the spread of exotic species in the subtropics and more than tripled it at high latitudes, threatening biodiversity worldwide. Furthermore, fish and invertebrates commonly mistake the ubiquitous pellets of partially degraded plastic, known as nurdles, for zooplankton, and ingest them, poisoning themselves and all who eat them, while sea turtles and marine mammals perish from consuming plastic bags, which resemble jellyfish.
Increasingly, persistent organic pollutants (POPs) such as DDT and PCBs are being found in such high levels in marine animals that some living creatures meet our definitions of toxic waste, including many whales, dolphins, and seals. Female mammals off-load POPs in their breast milk, lessening their own toxic load while poisoning their children. Perhaps consequently, killer whale calves from Puget Sound and the Canadian Southwest are dying in the first year; adult male orca, which have no off-loading capabilities, are also dying off. In 2005, the National Marine Fisheries Service listed this population as endangered. Currently, there is no such listing for the people who rely on marine mammal meat, even though the accumulation of POPs in the tissues of Greenland Inuits has nearly reached levels known to suppress the immune system.
The problems facing the world ocean are virtually all human-induced, and many are beginning to cross-pollinate. Jellyfish populations expand in response to red tides and hypoxia, as well as to the depletion of their competitors, such as menhaden [see “Net Losses,”]. This, combined with the virtual extinction of jellyfish-eating sea turtles (leatherbacks have declined 97 percent in 22 years), leaves more food for those jellies that prey mostly upon other jellyfish. Thus the nearly independent jelly web is expanding—and increasing its impact on human fishers, including forcing the closure of the Gulf of Mexico shrimp fishery in 2000, when 25-pound jellyfish native to Australia swarmed so heavily that shrimpers were unable to retrieve their nets.
In a similar vortex of cause and effect, researchers from NASA and the U.S. Geological Survey forecast that Alaskan earthquakes will increase in the wake of retreating glaciers, triggering more tsunamis, as happened dramatically in similar warmer epochs of the past. Freed of the immense weight of these rivers of ice, tectonic stresses are released, sometimes for the first time in millennia. Many scientists also believe that a warmer ocean is making hurricanes bigger, faster growing, and stronger, with 2005’s Hurricane Wilma prompting a call for a new Category 6 on the Saffir-Simpson scale, or a new scale altogether. And because bigger storms destroy more coastal wetlands and mangrove forests, they also incidentally reduce the land’s natural buffering against storms and earthquake-generated tsunamis.
