The coupling of bacterial production and hydrography in the southern East China Sea: Spatial patterns in spring and fall

Heterotrophic bacterial biomass, production and turnover rates were investi gated in a transect across the continental shelf of the southern East China Sea during spring and fall. The sampling area covered different water type s including nutrient-rich coastal and upwelling waters as well as oligotrop hic Kuroshio waters. On area basis, bacterial biomass (IBB; 350-1200 mgC m( -2)), production (IBP; 28-329 mgC m(-2) d(-1)) and averaged turnover rates (mu = IBP/IBB; 0.09-0.22 d(-1)) in the coastal and upwelling areas were at least 2-fold of those in the Kuroshio waters. IBB, IBP and mu were positive ly correlated with primary production (IPP; 90-2133 mgC m(-2) d(-1)) and pa rticulate organic carbon (IPOC; 1415-4682 mgC m(-2)) but showed a negative trend with temperature in the outer shelf area. While in the inner shelf (< 20 degrees C), IBP and mu were positively correlated with temperature; the Q(10) value for bacterial mu was 3.12. These indicated that the spatial pat terns of IBB, IBP and mu were more likely to be controlled by substrate sup ply and temperature interactively. Values of IBP : IPP ratio ranged 6-42% w ith an average of 22 +/- 10%. Under the assumption of a growth efficiency o f 20%, shelf bacteria might consume carbon equivalent to almost 100% of the in situ daily particulate IPP. Dissolved organic carbon from non-phytoplan kton and allochothonous sources might play a significant role in supporting bacterial carbon demand in the shelf area of the East China Sea, (C) 2000 Elsevier Science Ltd. All rights reserved.