Abstract

Objective: To determine the presence of consistent spatial or temporal patterns to the abundance of Pyrodinium bahamense (P. bahamense) in Mosquito Bay, Vieques, Puerto Rico. Methods: Measurements of dissolved oxygen, pH, salinity, water temperature, tide level, wind speed, and density counts of P. bahamense were taken at six sites in the bay over approximately one year. The data were analyzed statistically to determine if spatial or temporal patterns were present. Results: There were statistically significant patterns of P. bahamense seasonally, which was similar to other studies done in other subtropical locations with phytoplankton. Also, trends were seen that rain events caused short-term increases in abundance and shallow areas of the bay had lower abundance than that of deeper areas. The average number of organisms from 736 samples was 26.8 per mL. The average water temperature was 29.0 °C, the average salinity was 36.8 ppt, the average pH was 8.11, and the average dissolved oxygen level was 4.27 mg/L. Conclusions: The abundance of P. bahamense varies seasonally over shorter time periods. The abundance also varies over a few meters in small coastal bays. This information indicates that economically important bioluminescent bays are vulnerable to changes in freshwater input, water temperature, water circulation patterns and possibly the nutrient inputs from the land surrounding such bays.

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