Sea Ice Microbial Communities: Distribution, Abundance, and Diversity of Ice Bacteria in McMurdo Sound, Antarctica, in 1980

Abstract

An abundant and diverse bacterial community was found within brine channels of annual sea ice and at the ice-seawater interface in McMurdo Sound, Antarctica, in 1980. The mean bacterial standing crop was 1.4 x 1011 cells m-(9.8 mg of C m-); bacterial concentrations as high as 1.02 x 101cells m3 were observed in ice core melt water. Vertical profiles of ice cores 1.3 to 2.5 m long showed that 47% of the bacterial numbers and 93% of the bacterial biomass were located in the bottom 20 cm of sea ice. lce bacterial biomass concentration was more than 10 times higher than bacterioplankton from the water column. Scanning electron micrographs showed a variety of morphologically distinct cell types, including coccoid, rod, fusiform, filamentous, and prosthecate forms, dividing cells were commonly observed. Approximately 70% of the ice bacteria were free-living, whereas 30% were attached to either living algal cells or detritus. Interactions between ice bacteria and microalgae were suggested by a positive correlation between bacterial numbers and chlorophyll a content of the ice. Scanning and transmission electron microscopy revealed a close physical association between epibacteria and a dominant ice alga of the genus Amphiprora. We propose that sea ice microbial communities are not only sources of primary production but also sources of secondary microbial production in polar ecosystems. Furthermore, we propose that a detrital food web may be associated with polar sea ice.

Enzymes from psychrophilic organisms

“…Up to now, most of them originate from bacteria and fish living in polar regions and especially in Antarctic sea water which represents a permanently cold and constant temperature habitat (0°C _+ 2) exerting on endemic species a highly selective pressure. In this environment, bacterial communities are particularly successful since density of cells as high as 105/ml and 106/ml have been recorded, respectively, in the water column and in the sea ice [7,8].…”

Epiphytic bacteria on the Antarctic ice diatom Amphiprora kufferathii Manguin cleave hydrogen peroxide produced during algal photosynthesis

“…A major part of the bacterial community in Antarctic sea ice is represented by members of the Bacteriodetes, especially in SIMCOs with a high abundance of diatoms from the genus Amphiprora (Bowman et al 1997). Amphiprora species seem to carry more epiphytic bacteria than other diatoms and over 50% of all attached living bacteria were reported to be on Amphiprora (Sullivan & Palmisano 1984). The reason for the accumulation of bacteria in the SIMCO is not known ).…”

Production of exopolysaccharides by Antarctic marine bacterial isolates

“…In the Antarctic marine environment, annual sea ice is a microhabitat for a complex community of marine bacteria often in close association with phytoplankton. These assemblages are essential components of carbon and energy transfers in the southern ocean (Sullivan and Palmisano 1984). Abundant bacterial populations have been found in thick annual pack ice with psychrophilic bacteria being particularly common in samples of brown ice and pore waters (Delille 1992).…”

“…Abundant bacterial populations have been found in thick annual pack ice with psychrophilic bacteria being particularly common in samples of brown ice and pore waters (Delille 1992). Bacterially produced EPS may provide a means by which bacteria can adhere to the microalgal cells (Sullivan and Palmisano 1984). During ice formation microalgal cells are scavenged by sea-ice crystals floating up to the sea surface (Gleitz and Thomas 1993) and bacteria attached to algal cells may be incorporated into new ice in conjunction with some algal species (Grossmann and Dieckmann 1994).…”