Water sampling done in early June by the Department of Natural Resources found dissolved oxygen levels too low to be suitable for fish, crabs and shellfish in just 12 percent of the bay, according to the department's "Eyes on the Bay" website.As you may recall, about this time last year scientists correctly predicted the bad summer for anoxia in the Bay. The variations of summertime anoxic area in the bay are largely determined by the extent and timing of rains in late winter and spring. These rains bring in the nutrients which fuel the algae blooms, which rot to use up the oxygen in the deep water, and the excess fresh water which forms a layer of less dense water on the surface, which makes it more difficult for winds to mix the bottom water with the surface water, and prevents the restoration of oxygen to the bottom.
That's well below the long-term average since 1985 of 17.1 percent of the Chesapeake experiencing low oxygen levels. It's also a dramatic improvement over last year, when a third of the bay's waters was starved of the oxygen that fish, crabs and shellfish need to breathe.
Oxygen levels in the bay's deepest waters decline every spring as warming temperatures spur algae to grow, fed by the glut of nutrients in the water from sewage, fertilizer runoff and air pollution. Those thick algae blooms then consume the oxygen in the water as they die, sink to the bottom and decay.
State scientists say favorable weather most likely is responsible for healthier bay water so far this year, just as unfavorable weather has been blamed for last year's record large dead zone. Drier, warmer conditions from February through April this year meant less pollution washed off the land to feed the algae growth, while wetter, cooler weather in late spring helped keep low-oxygen conditions from setting in. Last year, by contrast, an extremely wet spring helped flush more nutrients into the water.
After a few years of such predictions, it begins to feel a bit like kabuki dancing, a stylized drama we go through annually. The second act it is the various bay report cards, in which various agencies and non-profit breathlessly report how the condition of the Bay (and it's various tributaries) actually turned out, and whether it represents an improvement or a step back from the year before. Sometimes they even acknowledge that the weather played an important role in how that year turned out.
They never acknowledge that there is enormous annual variations in the bay, in anoxia and in many other parameters linked to it, which, are in fact, largely driven by weather and climatic variations, and the noise in the system is far greater than the signal, and that decades more data will be necessary to see if the Bay is actually improving through the noise.