The Heat Is On
High Summer Temperatures Impact the Bay
August 2006 -- A hot, steamy summer has settled on the Bay watershed, bringing scorching temperatures and high electric bills. The news has been filled with reports of poor air quality and power outages, and we still have over a month of summer left.
But high temperatures affect a lot more than our sweat glands and wallets; they impact the Chesapeake as well. Although it is America's largest estuary, the Bay is surprisingly shallow, with an average depth of about 21 feet. (By contrast, Lake Michigan has an average depth of 279 feet.) Because of its shallow nature, the Bay suffers large seasonal fluctuations in temperature.
As summer water temperatures rise, it lessens the water's capacity to hold dissolved oxygen, which is vital to a host of creatures, from blue crabs to striped bass. The warmer the water gets, the less oxygen it contains. When combined with tons of nutrients and sediments, the heat spells trouble for the Bay in the form of numerous anoxic “dead zones.” These areas are becoming an annual summer problem in the Bay's deep channels.
High water temperatures may also affect underwater grass beds. Last year, warmer than average water temperatures may have caused the large scale loss of eelgrass in Tangier Sound. And while high temperatures can negatively affect SAV, they aid in the growth of something not so desirable: algae. These tiny plants flourish in the hot summer sun, soaking up rays and nutrients, but often multiplying to unhealthy proportions. These harmful algae blooms can block out sunlight needed by SAV, or produce toxins that kill fish and sicken humans.
If you are interest in ways to combat the problems facing the Bay, check out the Bay Program's Ways You Can Help. Maryland DNR also offers the latest information on harmful algae blooms.