Seasonal patterns in bacterioplankton abundance and production in Narragansett Bay, Rhode Island, USA

Bacterial abundance and production were measured weekly for 34 mo consecutively at 2 stations in Narragansett Bay, Rhode Island, a well mixed temperate estuary. Data from the more centrally located Station were used to describe the relationship between temperature, bacterial abundance and bacterial production over the annual cycle. During the entire sampling period, temperature ranged from -1.0 to 22.6degreesC, bacterial abundance varied by a factor of 16 and bacterial production by a factor of 101. Significant correlations of temperature on bacterial abundance and production (p < 0.05) highlight the strong seasonality of bacterial activity in the bay. After controlling for temperature, both bacterial abundance and production were significantly higher in the spring than in the fall, suggesting that the relationship between temperature and the populations present is different during these 2 seasons. No significant relationships were found between the bacterial bulk parameters and concentrations of chl a. Data from both stations were used to calculate annual net bacterial production values of 83 and 68 g C m(-2) yr(-1) for the mid- and lower bay, respectively. Gross bacterial carbon demand (production + respiration) at the mid-bay station was estimated at similar to237 g C m(-2) yr(-1), which is roughly 94% of previous estimates of bay-wide, net phytoplankton primary production.