Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 6
items per page: 25 50 75
Sort by:

Abstract

In general, Antarctic marine bacteria are small, with biovolumes ranging from 0.139 to 0.204 μm-3 cell-1, but their total biomass in seawater is considerable due to relatively high numbers that approximate to 1020 cells km-3. Bacterial biomass becomes more concentrated closer to land. Our multi-year Antarctic studies demonstrated an average total bacterial biomass of 504 tons in Admirality Bay (24 km3) or 21 tons per 1 km3, versus 6.4 tons per 1 km3 in the open ocean. Strikingly, bacterial biomass reached 330 tons per 1 km3 of seawater at the sea-ice edge, as sampled in Goulden Cove in Admiralty Bay. Bacterial biomass in Admirality Bay, which we believe can be enriched by halotolerant and thermotolerant fresh water bacteria from glacial streams, is equal to or even exceeds that of the standing stock of krill (100-630 tons per bay) or other major living components, including phytoplankton (657 tons), flagellates (591 tons), and ciliates (412 tons). However, the bacterial biomass is exceeded by several orders of magnitude by non-living organic matter, which constitutes the basic bacterial carbon source. Factors regulating high bacterial abundance in the vicinity of land are discussed.
Go to article

Abstract

Total count (TC) of bacteria in drifting annual pack-ice in austral spring fluctuated between 2.8-106 and 2,09-109 dm3. TC of bacteria was lowest in the upper layer of a large pack-ice fragment, emersed above water surface and almost completely free of diatoms; it was comparable to TC of bacteria in surrounding sea water, which was very low at this time (1,92- 106 — 5.8-106 dm -3). TC of bacteria increased in the deeper layers of pack-ice, attaining a maximum in the middle layer characterized by a high count of diatoms. TC of bacteria was highest in small pack-ice pieces 10—20 kg in being and densely overgrown with diatoms. Bacterial population in pack-ice was dominated by rods (62%), and it contained filamentous bacteria (2.4%) and prosthecate forms (4,8%), rarely present in deep sea. Mean volume of bacterial cell (0,206/μm3) was small, only slightly exceeding that of cells of free-living bacteria in sea water in summer.
Go to article

Abstract

Water samples were collected at 12 oceanographic stations from six standard depths ranging from 0 to 100 and 150 m. The number of bacteria and concentration of organic components were expressed in adequate units per 1 litre of sea water and in the form of the integrated values for the whole water column under I m2 of sea of organic components were expressed in adequate units per 1 litre of sea water and in the form of the integrated values for the whole water column under 1 m2 of sea surface. Total numbers of bacteria (TC) ranged from 0.16 to 7.31 x 107/1 and 1.74 — 5.67 x 10, 2/m2 saprophytic bacteria (CFU) 0.10 — 46.85 x 103/1 and 0.62 — 27.7x 108/m2. contents of particulate organic carbon (РОС) 0.02 — 0.25 mg/1 and 3.5 — 20.0 g/m2 dissolved organic carbon (DOC) 0.07 — 3.02 mg/1 and 53.5 — 207.9 g/m2, dissolved free amino acids (DFAA) 0 — 1.8965 μmol/1 and 2.7 -151.5 mmol/m2, dissolved combined amino acids (DCAA) 0 2.9366 μmо1/1 and 16.5— 163.5 mmol/m2, particulate combined amino acids (PCAA) 0 — 3.0215 μmо1/1 and 3.7 — 249.0 mmol/m2. Total numbers of bacteria and РОС, DOC and DCAA concentrations, widely differentiated in the investigated area, were on the average much lower than the values obtaine in previous years. The saprophytic bacteria content and DFAA and PCAA concentrations were at a similar level to that in the past years. Higher TC and CFU values were observed in the areas with high concentrations of phytoioplankton to the NW of Anvers I. and around Clarence I.
Go to article

Abstract

Since 1978 the retreat of Ecology Glacier in the vicinity of Henryk Arctowski Station has opened new ice-free areas for colonization by terrestrial organisms initiated by pioneer microbes. Samples were collected from the soil surface, at 0, 5 and 20 cm below surface close to glacier front, then stored at below -20°C . Total bacterial count (TC), estimated by epifluorescence microscopy, reached high values, of 1010 g-1 dry wt. Healthy looking bacterial cells of mean volume 0.0209 µm3 at 0 cm to 0.0292 µm3 at 20 cm made up from 7% at 0 cm , to 30% at 20 cm of total bacterial population. The number of colony forming units (CFU) accounted for only 0.02% of TC. Taxonomically they belonged to the a, b, g subdivisions of the proteobacteria and to the Cytophaga-Flavobacterium-Bacteroides (CFB) group. Morphophysiologically CFU bacteria were diverse, from Gram variable short coccal forms to very long rods or filaments. Randomly selected CFU colonies were characterized by low sugar assimilation and high esterase/lipase activity. Spore forming bacteria – absent from 0 and 5 cm , formed a small fraction of 175 cells g-1 dry wt at the 20 cm depth. Filamentous fungi were relatively abundant and represented mainly by oligotrophs.
Go to article

Abstract

There are hardly any data concerning the vertical micro−distribution of protozoa in water column in cryoconite holes on the glacier surface. Such comparisons can provide insights into the ecology of protozoa. The present research was made on Ecology Glacier (South Shetland Islands, Antarctic); vertical microzonation of c iliates in relation to physical and chemical parameters in cryoconite holes was studied. The density and biomass of protozoans significantly differed between the studied stations (cryoconite holes), with the lowest numbers in the surface water and the highest in the bottom water. The surface waters were dominated by mixotrophic and omnivorous taxa, whe reas the deepest sampling level has shown the increase of the proportion of bacterivore species . Ordination analysis indicated that TN and P−PO 4 can strongly regulate the abundance and species composition of protozoa. The redundancy analyses (RDA) showed that the ciliate communities can be separated into two groups. The first group included species associated with surface water: Halteria grandinella and Codonella sp. The second group included species that are associated with bottom water: Prorodon sp. , Holosticha pullaster , Stylonychia mytilus −complex and small scuticociliates.
Go to article

This page uses 'cookies'. Learn more