Algal blooms in the Chesapeake Bay became increasingly frequent from 1991 to 2008, according to new research from
the University of Maryland. Driven by runoff containing excess nitrogen and other nutrients, algal blooms can severely deplete oxygen levels and release significant amounts of toxins in the water, killing fish and altering food webs. Harmful algal blooms have long been plaguing the Chesapeake Bay and its tributaries, but water quality data from the Maryland Department of Natural Resources show that the events roughly doubled in the 1991-2008 period. Major blooms of one type of microscopic algae, Kalrodinium veneficum, increased from fewer than five per year in 2003 to more than 30 per year in 2008. That type of bloom produces a toxin implicated in fish kills in the Chesapeake Bay and with oyster spawning and development problems.