| This thesis describes the seasonal dynamics of the bacterioplankton in the bay using a weekly sampling regime. Sampling occurred between September 1999 and June 2002. Over the entire sampling period, temperature ranged from −1.0 to 22.6°C and significant correlations of temperature on bacterial abundance and production (p < 0.05) highlight the strong seasonality of bacterial activity in the bay. No significant relationships were found between the bacterial bulk parameters and concentrations of chlorophyll a. Gross bacterial production at the mid-bay station was 237 g C m−2yr −1, roughly 94% of previously reported estimates of bay-wide net phytoplankton primary production, indicating the importance of bacterial activity to the carbon budget of the bay.; Denaturing gradient gel electrophoresis was used to observe bacterial community structure during two successive winter-spring periods. Each sample (n = 48) contained 10 to 32 discernable bands (phylotypes). Eight to 14 phylotypes appeared to be present in all or almost all of the samples collected in each year and many were present in both years. Others could be grouped into winter, early spring, late spring, and summer phylotypes based upon the temporal pattern of their presence/absence within the sample set. Temperature alone appears to be a poor indicator of the timing of transitions in bacterial community structure. Distinct transitions did coincide with changes in phytoplankton community structure, suggesting that the bacterial community changes in response to changes in phytoplankton activity and community composition.; Bay-wide sampling showed that between 47 and 63% of the phylotypes present on each date were present at every location sampled indicating that about half of the dominant phylotypes in the bay have wide distributions. Sequencing results suggest that at least some of the ubiquitous members of the bacterioplankton community are related to previously cultured groups (α and γ Proteobacteria and Flavobacteriacea). |
