Links
Dead zones a coastal threat
Dead zones increased dramatically in U.S. waters over the past 50 years, threatening ecosystems and fisheries nationwide, according to a sweeping report Friday by the federal Office of Science and Technology Policy.
The multiagency assessment said that incidents of hypoxia–a condition in which oxygen levels drop so low that fish and other animals are stressed or killed–have risen nearly 30-fold since 1960 due in part to man-made pollutants.
It called for renewed efforts to reduce water pollutants that lead to low levels of dissolved oxygen and improve strategies to protect marine food sources.
A dead zone in San Diego Bay, first documented in the 1980s, was part of the analysis. Scientists have used it for years as an example of an oxygen-starved area where runoff from cities contributes to hypoxic conditions.
"There are reasons to worry about San Diego Bay, but hypoxia hasn't been studied as rigorously here as it has in other places like the Chesapeake Bay, where it is a much bigger problem," said Brian Hentschel, a biology professor at San Diego State University who studies bottom-dwelling organisms such as worms, clams and shrimps.