Abundance and variability of microorganisms and transparent exopolymer particles across the ice-water interface of melting first-year sea ice in the Laptev Sea (Arctic)

Abstract

The distribution and abundance of transparent exopolymer particles (TEP) was determined in and below pack ice of the Laptev Sea from July to September 1995. Samples were collected from the lowermost 10 cm of icē oes and at 10 cm below the ice±water interface. Abundance of bacteria, protists and TEP was determined, and the sea ice±water boundary layer was characterized using temperature, salinity and molecular viscous shear stress. TEP, with a distinct size distribution signal, were found in highest concentrations inside the sea ice, ranging from not detectable to 16 cm 2 l )1 (median: 2.9 cm 2 l )1 ). In the water, concentrations were one order of magnitude lower, ranged from below detection to 2.7 cm 2 l )1 (median: 0.2 cm 2 l )1 ) and decreased after the middle of August, whereas abundances of autotrophic¯agellates (AF), diatoms, heterotrophic¯agellates (HF) and ciliates increased. The abundance of TEP decreased with its size in all samples following a power law relationship. The relation of TEP to the microbial community diered between the sea ice and water, being positively correlated with bacteria and diatoms in the ice and negatively correlated with HF in the sea water. The presence of a pycnocline signi®cantly in¯uenced the abundance of organisms, diatom composition and TEP concentrations. Pennate diatoms dominated by Nitzschia frigida were most abundant inside the ice. Though bacteria have the potential to produce exopolymeric substances (EPS), the results of this study indicate that the majority of TEP at the ice±water interface in ®rst-year Arctic summer pack ice are produced by diatoms.

Abundance, size distribution and bacterial colonization of exopolymer particles in Antarctic sea ice (Bellingshausen Sea)

“…Krembs & Engel (2001) At all stations, maximum EP concentrations occurred in layers coinciding with the maxima of bacterial and algal biomass. At Stns 113 and 114, the EP and biomass maxima were located in a layer of porous ice (of intermediate granular/columnar or granular texture) approximately 10 cm below the freeboard of the ice floes.…”

“…High concentrations and characteristic size distributions of EP were found in all samples. The determination of EP in sea ice, however, is subject to methodological difficulties (Krembs & Engel 2001). Melting of ice causes salinity changes, which may affect the stainability of EP with the cationic dye Alcian Blue.…”

“…There is currently a substantial interest in the role of EPS in marine habitats, and recent studies have shown high concentrations of EPS in Arctic fast and pack ice (Krembs & Engel 2001, Krembs et al 2003, Meiners et al 2003. Riebesell et al (1991) showed that aggregate formation is a characteristic property of Antarctic sea ice algae, and other authors proposed that Antarctic sea ice may contain large amounts of EPS (Herborg et al 2001).…”

Transparent exopolymer particles (TEP) in aquatic environments

“…The exponent b of the size distribution can therefore be used as an indicator for the degree of aggregation. In sea ice, observed TEP size distributions have an average b of 1.9, with larger values occurring in the water directly below the ice (Krembs & Engel, 2001), suggesting a differing formation mechanism (see below). As well as aggregation, other processes such as bacterial utilization or zooplankton activity will affect the size distributions of TEP ; activities of copepods, for example, result in the formation of larger TEP, and shift the size distribution upward (Prieto, Sommer, Stibor, & Koeve, 2001).…”

Abundance and size distribution of transparent exopolymer particles (TEP) in a coccolithophorid bloom in the northern Bay of Biscay

“…Transparent exopolymer particles (TEP) merge the two properties of (1) being retained onto 0.4 mm membrane filters and (2) being stainable by Alcian Blue, a specific dye for acidic (-COO À ) or sulphated (-O-SO 3 À ) reactive groups of carbohydrates (Alldredge et al, 1993). Several studies indicate that TEP are natural constituents of the bulk particulate matter in marine (Passow and Alldredge, 1995b;Mari and Kiorboe, 1996;Krembs and Engel, 2001;Garcia et al, 2002;Engel, 2004;Brussaard et al, 2005;Radic et al, 2005;Shackelford and Cowen, 2006;Prieto et al, 2006;Sugimoto et al, 2007) (Logan et al, 1995;Grossart et al, 1997;Berman and Viner-Mozzini, 2001;Arruda-Fatibello et al, 2004) ecosystems. Most of the field sites where TEP have been described so far were dominated by diatoms, dinoflagellates or cyanobacteria.…”