Abstract
Oyster harvesting in Florida began long before Ponce de Leon arrived at its shores in 1513 in search of the fountain of youth. In fact, the economies of some of Florida’s earliest Native American societies may not only have been estuarine based but may also have partially relied on the mass collection of oysters and oyster reef animals as a means of subsistence (Quitmyer and Massaro 1999). After the European invasion,
oysters became the basis for a thriving industry in Florida’s major estuaries; however, the industry was well into a decline by the 1940s (Ingle and Smith 1949).
The story of oystering in Chesapeake Bay is much better known. Changes in land use instigated by settling Europeans soon brought changes in water quality (Cooper and Brush 1993), and by the end of the 19th century oysters were being harvested at an unsustainable rate. The removal of these filter feeders from the Bay further affected water quality, so that today, oyster populations represent only 1 percent of their former abundance in spite of a substantial effort at restoration.
Whether in Florida or along the Chesapeake Bay, overharvesting and changes in water quality are the explanations most often given for this decline; however, these two impacts are not mutually exclusive. Oysters have the capacity to strain large quantities of water through their gills as they feed, clearing the water of small particles and anything attached to the particles, in the process. This filtering function helps maintain good water
quality in estuaries, where the amount of suspended particles present can otherwise be quite high. Overharvesting, therefore, not only results in increasingly fewer oysters, but it also reduces the ability of an estuary to filter its own water. As a result of these changes in water quality, even after harvesting has long
ceased, efforts at oyster restoration may still be unsuccessful (Jackson et al. 2001). Fixed to the bottom and exposed to the elements as they feed, oysters are on the front line in a defense against pollutants, disease organisms, and ever changing environmental conditions, including salinity. As such, they can serve as sentinels of estuarine health by responding to these changes in water quality.
At Florida Gulf Coast University in Southwest Florida, we have turned to the Caloosahatchee River and Estuary, among others, to examine the relationships between oyster communities and both watershed development and water management. Inasmuch as oysters are not only affected by the quality of the water in which they live but also influence the water quality around them, they are ideal candidates for use as an indicator species. According to Newell (1988) of the University of Maryland Center for Environmental Science, “An increase in the oyster population by management and aquaculture could significantly improve water quality by removing large quantities of particulate carbon.”