Carbon dynamics of Florida Bay: spatiotemporal patterns and biological control.

Carbon dynamics of Florida Bay is manifested by wide ranges of pH (7.65-8.61), dissolved inorganic carbon (DIC, 929-3223 μM) and partial pressure of CO2 (pCO2, 50-1313 μatm) observed over seven years. Despite the seasonal variation, a decline of -0.0066 pH per year was observed as a result of ocean acidification and the spatiotemporal patterns were consistent with known biological processes in the bay. Microbial respiration of organic matter produced high pCO2, resulting in Florida Bay being a CO2 source to the atmosphere during winter and spring. In summer, cyanobacteria blooms developed in the north central bay drew down pCO2, causing bloom waters to become a CO2 sink while the nonbloom waters shrunk but remained a CO2 source. The maxima local CO2 fluxes were 36.4 ± 10.5 and -14.0 ± 5.6 mmol m(-2) d(-1) for the source and sink region, respectively. Cyanobacteria blooms modulated the interannual variation in bay-wide CO2 net flux, which averaged 7.96 × 10(9) ± 1.84 × 10(9) mol yr(-1). Extensive cyanobacteria blooms in 2009 resulted in a 50% reduction in the net CO2 flux as compared with 2010 when a minimal cyanobacteria bloom occurred.