|
|
A large algal bloom in Baltimore 's Inner Harbor , comprised mainly of the algae Prorocentrum minimum, was observed at the DNR Fort McHenry continuous monitoring station between May 26th -28th (see Figure.1) leading to a fish kill reported on June 3 rd . Maryland Department of the Environment reported that approximately 7,000 fish were killed, consisting primarily of adult menhaden but also including croakers, white perch, and pumpkinseed sunfish. Dissolved oxygen was measured at 3mg/l from the surface to a depth of 12ft in the Inner Harbor with readings as low as .3mg/l being taken in the Canton area (5mg/l is considered the minimum needed for most aquatic life to flourish). Algal blooms routinely occur in the Inner Harbor during the spring and summer months and occur when excess nutrients occurring in the harbor allow for algal growth to increase exponentially eventually leading to a collapse when the nutrients are depleted. The dying algal cells are decomposed by bacteria which lead to a rapid drop in available dissolved oxygen and possible fish kills if fish are trapped by the anoxic water.
Figure1. Graph showing a rapid increase in chlorophyll indicating an algal bloom is occurring between May 26th and 28th . DNR will continue to monitor this and other blooms, and all information will be posted at MDDNR's Eyes on the Bay website.
|
