Characteristics and classification of the lakes of Signy Island, South Orkney Islands, Antarctica

Heywood, R. B.; Dartnall, H. J. G.; Priddle, J.

doi:10.1111/j.1365-2427.1980.tb01179.x

Cited by 53 publications

(30 citation statements)

References 7 publications

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“…Though not officially named, they will be referred to as Heywood and Moss Streams respectively. Full descriptions of the lakes are given in Heywood et al (1980). Moss Lake is oligotrophic, occupying a barren catchment comprising mostly ice and bare rock.…”

Section: Standing Crop Estimations Study Sitesmentioning

confidence: 99%

Photosynthesis in thick cyanobacterial films: a comparison of annual and perennial antarctic mat communities

Hawes¹

1993

Hydrobiologia

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Annual and perennial cyanobacterial mats from streams on Signy Island, Antarctica, show similar area1 concentrations of chlorophyll-a and area1 rates of photosynthesis. Maximum rates of photosynthesis were temperature dependant over the range O-14 C, with a Q10 of approximately 2.5. Rates of photosynthesis per unit chlorophyll-a were comparable to other Antarctic mat communities but low compared to phytoplankton from upstream lakes. Areal rates of photosynthesis were however much higher than for phytoplankton.Low chlorophyll-specific rates of photosynthesis are interpreted as the effect of self shading within the mats. It is hypothesised that these mats rapidly attenuate incoming radiation and that photosynthesis in most of the mat is effectively light-limited. This situation is likely to occur in all thick periphyton films.

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Section: Standing Crop Estimations Study Sitesmentioning

confidence: 99%

Photosynthesis in thick cyanobacterial films: a comparison of annual and perennial antarctic mat communities

Hawes¹

1993

Hydrobiologia

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“…These small shallow lakes have formed following progressive deglaciation of Signy Island (Hawes, 1990). Most are oligotrophic (Heywood et al, 1980), but several are enriched and of these Heywood Lake is the best known and most extensively studied (Fig. 1a).…”

Section: Methodsmentioning

confidence: 99%

“…So Heywood Lake, although adjacent and physically similar to the oligotrophic Moss and Sombre Lakes, is different principally because its catchment is accessible to seals, which contribute considerable amounts of organic matter to the water. Unlike its more oligotrophic neighbours, there is evidence of high levels of nutrient input from seal activity over 33 % of the catchment area, and up to 1 % from bird activity, so that the total annual carbon gain in Moss Lake is less than an eighth of that in Heywood Lake (catchment data from Heywood et al, 1980;Ellis-Evans, 1982and Fogg, 1998). Butler (1999a) obtained values of 0?7-5?1 mg dissolved organic carbon l 21 and 0?8-6?4 mg total organic carbon l 21 for Heywood Lake.…”

Section: Methodsmentioning

confidence: 99%

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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“…This causes turbulence and the rapid introduction of oxygen to the upper region of the underlying winter water body, but general mixing does not occur until ice cover is lost (Hawes, 1983b) when the effects of strong winds (annual mean is 6 m s -I Heywood et al ., 1980)) ensure complete mixing .…”

Section: Locationmentioning

confidence: 99%

“…The rate of chemical weathering in the maritime Antarctic is relatively slow compared to a temperate environment (Campbell & Claridge, 1987) and the cation balance in the lakes of Signy Island is more characteristic of the marine environment due to exposure to sea spray (Heywood et al ., 1980) . These factors would have caused the ratio of the concentrations of dissolved sodium and calcium to be, increased with respect to the study lakes of other workers .…”

Section: Composition Of Aggregatesmentioning

confidence: 99%

Origin and composition of settling iron aggregates in oligotrophic Sombre Lake, Signy Island, Antarctica

Caulkett

Ellis‐Evans

1996

Hydrobiologia

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Sediment traps were deployed in an oligotrophic, seasonally anoxic maritime Antarctic lake for 15 months . Immediately after the onset of the inflow in spring many iron oxyhydroxide aggregates were collected in the traps . Image analysis, scanning electron microscopy and energy dispersive X-ray analysis were used to examine the aggregates .The aggregates consisted of primary particles that persisted in the aggregates . The mean diameter of the aggregates was constant with depth . The aggregates consisted predominantly of iron, phosphorus and oxygen but calcium was also an important constituent . Significant concentrations of manganese and sodium were also detected . The molar ratio Fe :P remained constant at 4 :1 as did the ratio Fe :Ca at 52 :1 . The concentration of iron, phosphorus and calcium in the aggregates increased with depth, whilst the concentration of manganese decreased with depth in parallel with a gradient of increasing anoxia .The stable water column formed under ice cover and the temporal and spatial data provide evidence that the Fe :P and Fe :Ca ratios are constant and characteristic of the aggregates, whilst the overall composition of the aggregates is more dynamic and dependant on redox conditions and water chemistry .

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Characteristics and classification of the lakes of Signy Island, South Orkney Islands, Antarctica

Cited by 53 publications

References 7 publications

Photosynthesis in thick cyanobacterial films: a comparison of annual and perennial antarctic mat communities

Photosynthesis in thick cyanobacterial films: a comparison of annual and perennial antarctic mat communities

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

Origin and composition of settling iron aggregates in oligotrophic Sombre Lake, Signy Island, Antarctica

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