Abstract: To decipher the relative importance of temperature and substrate supply in regulating the spatial patterns of bacterial production and specific growth rates, field surveys in the continental shelf of the East China Sea and on board substrate (dissolved free amino acids) enrichment experiments were conducted in December 1997 and March 1998. The results suggested that there was a shift from temperature dominance inside the mid-shelf to substrate supply dominance outside the mid-shelf controlling the spatial variability of bacterial growth during the cold seasons. The Q(10) values for bacterial specific growth rates (B mu) derived from the winter (Q(10) = 3.4 +/- 0.3) and the spring (Q(10) = 3.3 +/- 0.3) were very similar and comparable with the values derived from other estuarine and coastal ecosystems (Q(10) = 3.1 to 3.4). Such a consistent relationship between temperature and B mu allows one to use sea-surface temperature (SST) and depth-integrated bacterial biomass to model depth-integrated bacterial production (IBP) inside the mid-shelf of the East China Sea. The B mu versus temperature curve, InB mu = -0.42 + 0.122 (+/- 0.02) x SST, derived from a previous study in the southern East China Sea was used to simulate IBP. The total difference between the measured IBP and the simulated IBP is <20%.