Cassiopea xamachana is a scyphozoan jellyfish that harbors endosymbiotic algae know as zooxanthellae. The uptake of dissolved inorganic phosphates (DIP) by Cassiopea requires a symbiotic relationship with zooxanthellae of the genus Symbiodinium. Animals were collected from Florida Bay, Key Largo, Florida for analysis. Pre-exposure to high levels (2uM and greater) of DIP in hospite caused a decreased rate of phosphate uptake. The animals continued to show a decreased rate of uptake for up to 5 hours after being removed from elevated DIP levels. This suggested a suitability fo ruse of Cassiopea xamachana as a bioindicator of DIP in seawater. Subsequent field studies involved placing animals on a fore reef, a patch reef, and nearshore in Florida Bay. Animals that were farther from shore exhibited significantly greater (p<0.05) rates in DIP uptake after 4 days than those in nearshore Florida Bay, suggesting that DIP levels decrease significantly with distance from shore.