Distribution and activity of bacterio-plankton in the marginal ice zone of the Weddell-Scotia Sea during austral spring

Abstract

The distribution and metabolic actlvity of bactenoplankton were examined in relabon to b~ologlcal, chemical and physlcal factors in the marginal ice zone south of the confluence of the Weddell-Scotia Sea during austral spring 1983 Melt water produced by the seasonal retreat of the Ice edge resulted in regions of water wlth reduced salinity and increased vertical strabf~catlon, w h~c h in turn increased average irradiance levels for phototrophic growth The enhanced stability of the water column apparently influenced &stributions of blomass and physiological activlt~es of both autotrophs and heterotrophs Elevated biomass and productivity of phytoplankton and bactenoplankton coincided spatially with maxlma occurring from 100 to 250 km seaward of the ice edge Bacterial abundance and biomass in ice-covered and open water regions averaged 0 7 X 10" cells m-3 and 1 8 mg C m-3 and 1 6 X 10" cells m-3 and 3 7 mg C m-3 respectively Bactenal biomass represented only about 3 % of the total particulate organlc carbon but bacterial productlon integrated over the euphotic zone averaged about 11 % of pnmary production Our results suggest that bacteiloplankton productlon In the marginal ice zone of the Weddell-Scotia Sea contnbutes signlf~cantly to the enhanced biological actlvlty of the region

Spatial distribution of microbial biomass and activity (bacterivory and bacterial production) in the northern Weddell Sea during the austral summer (January 1994)

“…We found an inverse pattern between these variables (compare Fig. 5 of Sullivan et al 1990 with Fig. 4 in this study).…”

“…In contrast, we found low values for abundance of heterotrophic microorganisms (bacteria and HNF) and BHP in this zone, compared to the other study zones (Table 1). Sullivan et al (1990) found higher heterotrophic microbial activity and biomass in the ice edge surrounding waters up to 200 km northward. These authors also found a significant correlation between bacterioplankton and phytoplankton (activity and biomass) along a transect from the IEZ to the open sea.…”

“…However, microbial productivity and indeed the importance of the microbial food web can vary depending on the physico-chemical characteristics of the water column in different areas of the Southern Ocean. Thus, temperature, distribution of organic and inorganic nutrients, photosynthetically available radiation (PAR), and the presence of ice are also significant factors in controlling the rates of microbial processes (Sullivan et al 1990, Kang et al 1997. Large spatial and seasonal variability in microbial productivity and biomass has been found in different geographical locations (open sea, continental shelves, coastal embayments, pack ice, etc.).…”

“…Veth et al 1992, Lancelot et al 1993, AMERIEZ (e.g. Nelson et al 1989, Sullivan et al 1990, and RACER (e.g. Bird & Karl 1990).…”

Microbial processes in cold oceans. I. Relationship between temperature and bacterial growth rate

“…Low-temperature suppression of bacterial growth has not been universally observed. For example in Antarctica, bacterial growth rates of ca 0.01 to 2 d-' have been reported at -1.5"C (Hanson et al 1983, Kottmeier et al 1987, Kottmeier & Sullivan 1988, Cota et al 1990, Rivkin 1991. In the North Bering and Chukchi Seas, bacteria grew at 0.1 to 0.54 d-' at < l°C (Anderson 1988) and in Resolute, NWT, Canada, sea ice bacterial growth rates were 0.02 to 0.25 d-' at -1.7"C (Smith et al 1989, Smith & Clement 1990.…”