Controlling fertilizer runoff into the Chesapeake Bay is paying off. As Conservation Magazine highlights, new research tracking the dead zone in the bay—where the oxygen level in the water is so low that most life cannot survive—shows that both size and duration have declined.
Looking at water data for the past 60 years, scientists have determined that "the size of the dead zone in mid to late summer has decreased steadily since the late 1980s and that the duration...is closely linked each year to the amount of nutrients entering the bay."
What causes the dead zone? Each spring increases in run off from fertilizer, farm animal waste, and water treatment plant discharge, triggered by spring rains, go into the bay. This in turn triggers algae blooms, which, when they die, sink to the bottom and are consumed by bacteria—which in turn end up consuming the available oxygen.
Similar situations exist at hundreds of places around the planet, perhaps most notably for many TreeHugger readers in the Gulf of Mexico. Scientists say that climate change is likely to markedly increase the number of ocean dead zones around the world.