Uncoupling of bacteria and phytoplankton during a spring diatom bloom in the mouth of the Yellow Sea

Abstract

Bacterial abundance, production, and environmental parameters were investigated to study the distribution of bacterial variables and interrelationships between bacteria and phytoplankton along a transect from the southwestern tip of the Korean Peninsula to the axis of the Yellow Sea in April 1991 The study area showed a tidally induced turbidity maximum in the middle region of the transect. The turbidity maximum had lower phytoplankton abundance, primary production, and bacterial production than the adjacent waters. Diatom blooms were observed in the inner bay and in waters outside of the turbidity maximum. Bacterial abundance and production showed relatively large variations along the transect from 3 to 32 X 10' I-' and from undetectable to 11.9 pg C 1" d-l, respectively. Bacterial and phytoplankton variables did not correlate significantly (p z 0.12). Further, depth-integrated bacterial production over the euphotic zone comprised less than 4 O/o of primary production, suggesting that bacteria and phytoplankton were not closely coupled during the study period. The uncoupling seemed to be unrelated to phytoplankton community structure. Strong tidal mixing, which would mix the organic matter produced in the euphotic zone into the deeper water column, possibly coupled with mass sinking of phytoplankton to the bottom seemed to cause low substrates level and unbalanced growth for bacteria in the euphotic zone and thereby the observed uncoupling of bacteria from phytoplankton. Further, strong tidal mixing seemed to facilitate the bacterial use of sinking carbon in the aphotic zone.

Seasonal and vertical distribution of planktonic bacteria and heterotrophic nanoflagellates in the middle Adriatic Sea

“…An uncoupling between bacteria and phytoplankton in coastal areas has been reported to be due to a response to alochtonous inputs at specific times of the year (Kepkay et al 1993), seasonal changes (Pomeroy et al 1991), and variations in hydrodynamic conditions (Cho et al 1994). Since KaÐtela Bay receives large quantities of nutrients throughout the year (Barić et al 1996;Bogner et al 1998), this location shows conditions in which substrate concentrations are almost always above the saturation level.…”

Comparative analysis of bacterioplankton and phytoplankton in three ecological provinces of the northern South China Sea

“…Recent studies in the southern ECS suggest the importance of dissolved organic carbon from non-phytoplankton and allochthonous sources in supporting bacterial carbon demand (Shiah et al 2000 and high rates of microbial plankton respiration . Further north, in the Yellow Sea, bacteria are also uncoupled from phytoplankton, apparently because strong tides mix the organic matter produced in the euphotic zone into the deeper water column (Cho et al 1994). In both the SCS and ECS, it therefore appears that bacteria are coupled to phytoplankton most strongly in the offshore biome in a pattern stereotypic for open ocean waters (Ducklow 1992).…”

Bacterial abundance, production and ectoproteolytic activity in the Strait of Magellan

“…Moriarty et al 1997, Talbot & Bianchi 1997 or other regions of the Southern Ocean , Ducklow & Carlson 1992. With values of bacterial densities exceeding 106 cells ml-l, the waters of the Strait of Magellan appear closer to temperate or tropical offshore, or even coastal, than to Antarctic waters (Cho S1 Azam 1990, Cho et al 1994, Caron et al 1995.…”