Microbial diversity and function in Antarctic freshwater ecosystems

Ellis‐Evans, J. Cynan

doi:10.1007/bf00051985

Cited by 98 publications

(54 citation statements)

References 100 publications

(139 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As pointed out by Vincent (2000), the extreme environmental conditions of Antarctica (low temperature, short variations in light intensity and photoperiod and short ice-free growing season) exert a strong selection pressure on the propagules. Ellis-Evans (1996) and Laybourn-Parry et al (2001) suggested that such extreme conditions constrain plankton diversity in Antarctic freshwater ecosystems. Our microscopic observations also support this view.…”

Section: Discussionmentioning

confidence: 99%

Nanoplankton assemblages in maritime Antarctic lakes: characterisation and molecular fingerprinting comparison

Unrein

Izaguirre²,

Massana³

et al. 2005

Aquat. Microb. Ecol.

View full text Add to dashboard Cite

The composition of planktonic eukaryotes in the size fraction 3-20 µm of 10 maritime Antarctic lakes was studied by denaturing gradient gel electrophoresis (DGGE). Microscopic observations were also carried out to compare the results obtained by this molecular fingerprinting technique with morphological data. Six lakes from Hope Bay (Antarctic Peninsula) and 4 from the Potter Peninsula (King George Island) were sampled during the austral summer of 2003. These lakes were of different trophic status and covered a wide range of limnological features. Previous studies of the planktonic communities of these lakes revealed high nanoflagellate abundance and biomass, but their taxonomic identification was usually uncertain due to their similarity in size and shape. Here, the application of DGGE allowed both a comparison of the structure of the nanoplanktonic communities and an identification of the dominant populations through sequencing of the most prominent DGGE bands. The most important organisms in these lakes were the Chrysophyceae, represented in the DGGE gel by 5 different band positions and identified by microscopy in 5 different morphotypes, including uniflagellated and biflagellated naked organisms: 1 sequence belonged to the Chrysosphaerales, 2 closely related bands (likely 2 species from the same genus) belonged probably to the Ochromonadales (unicellular biflagellates), while the other 2 bands could not be assigned to any defined chrysophyte group. Sequences related to Chlorophyceae, Bacillariophyceae and probably Cercozoa were also retrieved. A Dictyochophyceae belonging to the order Pedinellales is reported for the first time in freshwater Antarctic ecosystems. Microscopic observations suggest that this phytoplanktonic organism most likely corresponds to Pseudopedinella. Most of the lakes shared several common sequences, such as 2 chrysophyte bands, which suggests the existence of well-adapted nanoplanktonic species dispersed throughout the Antarctic lakes. However, some sequences appeared exclusively in specific lakes, which seems to be related to the trophic status of the water bodies and probably also to the local conditions of the maritime Antarctic regions sampled. KEY WORDS: Freshwater nanoplankton · Antarctic lakes · DGGE · 18S rDNAResale or republication not permitted without written consent of the publisher Aquat Microb Ecol 40: 269-282, 2005 Signy Island, this fraction contributes between 49 and 69% of carbon fixation (Ellis-Evans 1991). In addition, bacterivory by heterotrophic nanoflagellates may remove between 0.1 and 32% of the bacterial production per day (Laybourn-Parry et al. 1995, Bell & LaybournParry 2003, while mixotrophic nanoplanktonic algae are able to remove up to 16% of the bacterial biomass, equivalent to >100% of in situ bacterial production (Bell & Laybourn-Parry 2003).Flagellated algae dominate the nanoplanktonic fraction of the phytoplankton community in Hope Bay lakes (Antarctic Peninsula) (Izaguirre et al. 1993, 2003. In particular, Chrysophyceae dominate algal...

show abstract

Section: Discussionmentioning

confidence: 99%

Nanoplankton assemblages in maritime Antarctic lakes: characterisation and molecular fingerprinting comparison

Unrein

Izaguirre²,

Massana³

et al. 2005

Aquat. Microb. Ecol.

View full text Add to dashboard Cite

show abstract

“…A microbial presence in the water column can be inferred from existing accreted ice data and from studies of cold aquatic environments elsewhere (Vincent, 2000;Ellis-Evans, 1996;Priscu et al, 1999b). Microbes favour colonizing surfaces and environments with strong chemical gradients, and significant colonization of the lake sediments seems likely.…”

Section: Implications For Life In Subglacial Lakesmentioning

confidence: 99%

“…The vast majority of microbes isolated from Antarctic soils, freshwater, marine, and air samples to date are psychrotolerant rather than psychrophilic (Ellis-Evans, 1996;Fritsen and Priscu, 1998;Vincent, 2000), which implies that selection pressures for optimal growth at low temperature are often less important than other constraints in these extreme environments. Psychrophilic forms are more prevalent in permanently cold environments, such as sea ice and the marine abyssal, but the influence of temperature in subglacial environments may prove to be primarily manifested in dampening of overall rates of activity.…”

Section: Implications For Life In Subglacial Lakesmentioning

confidence: 99%

“…Solar radiation through photosynthesis is, directly or indirectly, the major source of energy for most organisms on Earth, and a major driver of processes in surface Antarctic lake ecosystems (Ellis-Evans, 1996). In its absence, microbes in subglacial lakes would have to utilize chemical energy to power biological processes.…”

Section: Implications For Life In Subglacial Lakesmentioning

confidence: 99%

See 1 more Smart Citation

The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes

Siegert

Tranter

Ellis‐Evans

et al. 2002

Hydrological Processes

View full text Add to dashboard Cite

Abstract:Our understanding of Lake Vostok, the huge subglacial lake beneath the East Antarctic Ice Sheet, has improved recently through the identification of key physical and chemical interactions between the ice sheet and the lake. The north of the lake, where the overlying ice sheet is thickest, is characterized by subglacial melting, whereas freezing of lake water occurs in the south, resulting in ¾210 m of ice accretion to the underside of the ice sheet. The accreted ice contains lower concentrations of the impurities normally found in glacier ice, suggesting a net transfer of material from meltwater into the lake. The small numbers of microbes found so far within the accreted ice have DNA profiles similar to those of contemporary surface microbes. Microbiologists expect, however, that Lake Vostok, and other subglacial lakes, will harbour unique species, particularly within the deeper waters and associated sediments. The extreme environments of subglacial lakes are characterized by high pressures, low temperatures, permanent darkness, limited nutrient availability, and oxygen concentrations that are derived from the ice that provides the meltwater.

show abstract

“…Due to low temperatures, extended periods of ice-cover, a short growing season and extremes in irradiance, Antarctic lakes have simple food webs that are generally dominated by the microbial loop (Laybourn-Parry et al, 2002). Most lakes are oligotrophic or ultraoligotrophic, and nutrient deficiency is common unless lakes are subject to the influence of marine birds and mammals (Ellis-Evans, 1996;Borghini and Bargagli, 2004).…”

Section: Introductionmentioning

confidence: 99%

Temporal variation in the water chemistry of northern Victoria Land lakes (Antarctica)

et al. 2008

View full text Add to dashboard Cite

Concentrations of major ions, silicate and nutrients (total N and P) were measured in samples of surface water from 28 lakes in ice-free areas of northern Victoria Land (East Antarctica). Sixteen lakes were sampled during austral summers 2001/02, 2003/04, 2004/05 and 2005/06 to assess temporal variation in water chemistry. Although samples showed a wide range in ion concentrations, their composition mainly reflected that of seawater. In general, as the distance from the sea increased, the input of elements from the marine environment (through aerosols and seabirds) decreased and there was an increase in nitrate and sulfate concentrations.Antarctic lakes lack outflows and during the austral summer the melting and/or ablation of ice cover, water evaporation and leaching processes in dry soils determine a progressive increase in water ion concentrations. During the five-year monitoring survey, no statistically significant variation in the water chemistry were detected, except for a slight (hardly significant) increase in TN concentrations. However, Canonical Correspondence Analysis (CCA) indicated that other factors besides distance from the sea, the presence of nesting seabirds, the sampling time and percentage of ice cover affect the composition of water in Antarctic cold desert environments.

show abstract

Microbial diversity and function in Antarctic freshwater ecosystems

Cited by 98 publications

References 100 publications

Nanoplankton assemblages in maritime Antarctic lakes: characterisation and molecular fingerprinting comparison

Nanoplankton assemblages in maritime Antarctic lakes: characterisation and molecular fingerprinting comparison

The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes

Temporal variation in the water chemistry of northern Victoria Land lakes (Antarctica)

Contact Info

Product

Resources

About