Thursday, October 19, 2006

Ocean "Dead Zones"

At the Second Intergovernmental Review Meeting (IGR-2) of the Global Programme of Action for the Protection of the Marine Environment from Land-Based Activities in Beijing, scientists reported that there may now be as many as 200 "dead zones" in the world's oceans. "Dead zones" are areas of the ocean environment in which oxygen depletion makes it difficult to sustain the normal diversity of marine life. As a press release from the United Nations Environment Programme (UNEP) puts it,

De-oxygenated zones are areas where algal blooms, triggered by nutrients from sources including fertilizer run off, sewage, animal wastes and atmospheric deposition from the burning of fossil fuels, can remove oxygen from the water.

The low levels of oxygen in the water make it difficult for fish, oysters and other marine creatures to survive as well as important habitats such as sea grass beds.

The Gulf of Mexico, which receives large inputs of nitrogen from agricultural lands in the Mississippi River Valley via the Mississippi, contains one of the best known "dead zones."

Meanwhile, here in Malibu there are concerns that faulty septic systems may be the cause of chronically contaminated ocean water. Los Angeles County officials plan to use DNA testing to determine whether the waste washing into Santa Monica Bay from area streams is human or animal. If human, inspection of septic systems will likely follow in an effort to pinpoint the sources of Malibu's marine pollution.