Temporal plankton dynamics in an oligotrophic maritime Antarctic lake

Butler, Helen G.; Edworthy, M.G.; Ellis‐Evans, J. Cynan

doi:10.1046/j.1365-2427.2000.00542.x

Cited by 33 publications

(30 citation statements)

References 48 publications

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“…Although Pseudopedinella, another genus of Dictyochophyceae, is commonly found in high latitude oligotrophic lakes of the northern hemisphere (Isaksson et al 1999, Hobbie et al 2000, this class had never been reported from Antarctic freshwater lakes. Butler et al (2000) observed the presence of small motile species, and they suggested that they could belong to the genus Pseudopedinella, although its presence was not confirmed. In our samples, organisms resembling Pseudopedinella (with a radial symmetry, 3 to 6 chloroplasts and 5 to 8 µm in diameter) were observed under light microscopy in Esperanza, Flora and Encantado Lakes.…”

Section: Discussionmentioning

confidence: 95%

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

Unrein

Izaguirre²,

Massana³

et al. 2005

Aquat. Microb. Ecol.

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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...

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Section: Discussionmentioning

confidence: 95%

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

Unrein

Izaguirre²,

Massana³

et al. 2005

Aquat. Microb. Ecol.

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“…In these studies, natural nutrient enrichment has resulted in significantly higher nitrate, phosphate and chlorophyll a concentrations, higher bacterioplankton population densities, higher heterotrophic nanoflagellate and phototrophic nanoflagellate abundances, dramatic shifts in species composition within the phytoplankton and high productivities creating seasonal anoxia under ice. In addition to these changes, Laybourn-Parry et al (1996), Butler (1999a, b) and Butler et al (2000) were able to show that significant changes in the protozooplankton community structure could occur over relatively short periods of time.…”

Section: Introductionmentioning

confidence: 89%

Significant changes in the bacterioplankton community structure of a maritime Antarctic freshwater lake following nutrient enrichment

et al. 2005

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Nutrient enrichment is known to increase bacterioplankton population density in a variety of Antarctic freshwater lakes. However, relatively little is known about the associated changes in species composition. In this study, the bacterioplankton community composition of one such lake was studied following natural nutrient enrichment to investigate the resistance of the system to environmental change. Heywood Lake is an enriched freshwater maritime Antarctic lake, with nitrogen and phosphorus concentrations significantly higher than its more oligotrophic neighbours (by at least an order of magnitude). This major change in lake chemistry has occurred following large increases in the fur seal population over the last 30 years. Using analysis of 16S rRNA gene fragments, fatty acid methyl ester analysis, denaturing gradient gel electrophoresis and fluorescence in situ hybridization, significant changes are reported in lake microbiology which have resulted in a distinct bacterioplankton community. In comparison to its more oligotrophic neighbours, nutrient-enriched Heywood Lake has a high bacterioplankton population density, reduced species richness and an increasing evenness among key groups. Only 42?3 % of the clones found with >97 % similarity to a named genus were also present in adjacent oligotrophic lakes, including three of the dominant groups. Critically, there was an apparent shift in dominance with trophic status (from the b-Proteobacteria to the Actinobacteria). Other key observations included the absence of a dominant group of Cyanobacteria and the presence of marine bacteria. The significant impact of natural nutrient enrichment on the microbiology of Heywood Lake, therefore, suggests that low-temperature oligotrophic freshwater lake systems might have low resistance to environmental change.

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“…Blue excitation was used to confirm the presence or absence of red fluorescing chloroplasts. Taxonomic identification of phytoplankton was based on Findlay andKling (1979), CanterLund andLund (1995) and Wehr and Sheath (2003) on specimens viewed at 1,0009. Heterotrophic protists were poorly identified using the above references, but they were separated by shape and size, and diversity estimates were based on the separate categories.…”

Section: Microscopymentioning

confidence: 99%

“…The aim of the present study was to identify and compare the contribution of different phytoplankton to the protist community structure of three limnologically contrasting High Arctic lakes using 18S rRNA gene surveys, classic microscopic observations and pigment analyses. Given the previous records based on microscopy from Arctic (Welch 1973;Panzenböck et al 2000;Bonilla et al 2005), Subarctic (Forsström et al 2005) and Antarctic (Butler et al 2000;Unrein et al 2005) lakes, a second objective was to examine the detailed phylogeny of the chrysophytes in the different lakes. Heterotrophic protists have been little examined in such waters although heterotrophic nanoflagellates have been identified as an important food web component ).…”

Section: Introductionmentioning

confidence: 99%

Chrysophytes and other protists in High Arctic lakes: molecular gene surveys, pigment signatures and microscopy

2011

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Microscopic analysis of the phytoplankton and other protist communities in High Arctic lakes has shown that they often contain taxa in the Chrysophyceae. Such studies have been increasingly supported by pigment analysis using high-performance liquid chromatography (HPLC) to identify the major algal groups. However, the use of 18S rRNA gene surveys in other systems indicates that many protists, especially small heterotrophs, are underreported or missed by microscopy and HPLC. Here, we investigated the late summer protist community structure of three contrasting lakes in High Arctic polar desert catchments (Char Lake at 74°42 0 N, Lake A at 83°00 0 N and Ward Hunt Lake at 83°05 0 N) with a combination of microscopy, pigment analysis and small subunit 18S ribosomal RNA gene surveys. All three methods showed that chrysophytes were well represented, accounting for 50-70% of total protist community biomass and 25-50% of total 18S rRNA gene sequences. HPLC analysis supported these observations by showing the ubiquitous presence of chrysophyte pigments. The clone libraries revealed a greater contribution of heterotrophs to the protist communities than suggested by microscopy. The flagellate Telonema and ciliates were common in all three lakes, and one fungal sequence was recovered from Char Lake. The approaches yielded complementary information about the protist community structure in the three lakes and underscored the importance of chrysophytes, suggesting that they are well adapted to cope with the low nutrient supply and strong seasonality that characterize the High Arctic environment.

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Temporal plankton dynamics in an oligotrophic maritime Antarctic lake

Cited by 33 publications

References 48 publications

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

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

Significant changes in the bacterioplankton community structure of a maritime Antarctic freshwater lake following nutrient enrichment

Chrysophytes and other protists in High Arctic lakes: molecular gene surveys, pigment signatures and microscopy

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