Problems can result from large changes in phytoplankton abundance.
For example, excessive reproduction of phytoplankton, usually caused by enhanced levels of nutrients, results in algae blooms. The oxygen depletion accompanying eutrophication can suffocate other aquatic organisms and generally degrade the environment. Conversely, a shortage of phytoplankton depletes the food supply of primary and higher consumers such as oysters, shrimp, fish, and birds. Phytoplankton research in Galveston Bay began in the late 1950s and peaked in the 1970s with Trinity Bay impact studies related to cooling water discharges of the Cedar Bayou electrical power generating station. Most of these studies had limited spatial and temporal coverage, and no documented phytoplankton studies have been conducted on the bay since 1985.