THE LIFE AND DEATH OF A GULF COAST ESTUARY

Perdido Bay is a small (<130km²) estuary located in the central Gulf Coast of the United States. As with other neighboring estuaries, its origin can be traced to flooding of an ancient stream valley that formed by sea level rise that began in the late Pleistocene. Written accounts describe the bay as an original freshwater system that contained an abundant submerged aquatic vegetation and fauna. The opening of a pass through the barrier island system into the Gulf of Mexico in the early 20th century created the present saltwater (brackish) environment. Prior to the 1940's, the bay was a nearly pristine habitat and was characterized by clear water, a white sand bottom, and a diverse biota which included many species of fish and shellfish. This diversity and abundance, however, has been severely impacted by the activities of man. Municipal and urban development has created stress in the bay and a significant impact has been clearly traced to a paper manufacturing mill that has been discharging into the bay for over 60 years. Riparian property owners have expressed a particular concern about large quantities of a fine grained, black material (described by residents as “black mayonnaise”) that is especially common in the upper bay. This material has been frequently washed on to adjacent residential properties during storms and abnormally high tides and has been observed by divers as occurring as a several inch thick, “flocculant clay-colloidal layer” that floats just above the sediment-water interface. This substance is also characterized by anomalous levels of a number of heavy metals (arsenic, aluminum, chromium, lead, iron, manganese, zinc, etc.), adsorbable organic halides (AOX compounds), organic carbon, nitrogen, and dioxins. The discharge of this material has had a devastating effect on the biota and the upper bay has now been described as a “biologcal desert.” While wetlands adjacent to the upper bay have not yet been demonstrably affected by the mill's activities, this too may change if the mill gains permission from the State to divert present discharge directly into the Tee Lake-Wicker Lake system that lies near the head of the bay.