Exploration of Ellsworth Subglacial Lake: a concept paper on the development, organisation and execution of an experiment to explore, measure and sample the environment of a West Antarctic subglacial lake

Antarctic subglacial lakes have, over the past few years, been hypothesised to house unique forms of life and hold detailed sedimentary records of past climate change. Testing this hypothesis requires in situ examinations. The direct measurement of subglacial lakes has been considered ever since the largest and best-known lake, named Lake Vostok, was identified as having a deep water-column. The Subglacial Antarctic Lake Environments (SALE) programme, set up by the Scientific Committee on Antarctic Research (SCAR) to oversee subglacial lakes research, state that prior exploration of smaller lakes would be a “prudent way forward”. Over 145 subglacial lakes are known to exist in Antarctica, but one lake in West Antarctica, officially named Ellsworth Subglacial Lake (referred to hereafter as Lake Ellsworth), stands out as a candidate for early exploration. A consortium of over 20 scientists from seven countries and 14 institutions has been assembled to plan the exploration of Lake Ellsworth. An eight-year programme is envisaged: 3 years for a geophysical survey, 2 years for equipment development and testing, 1 year for field planning and operation, and 2 years for sample analysis and data interpretation. The science experiment is simple in concept but complex in execution. Lake Ellsworth will be accessed using hot water drilling. Once lake access is achieved, a probe will be lowered down the borehole and into the lake. The probe will contain a series of instruments to measure biological, chemical and physical characteristics of the lake water and sediments, and will utilise a tether to the ice surface through which power, communication and data will be transmitted. The probe will pass through the water column to the lake floor. The probe will then be pulled up and out of the lake, measuring its environment continually as this is done. Once at the ice surface, any water samples collected will be taken from the probe for laboratory analysis (to take place over subsequent years). The duration of the science mission, from deployment of the probe to its retrieval, is likely to take between 24 and 36 h. Measurements to be taken by the probe will provide data about the following: depth, pressure, conductivity and temperature; pH levels; biomolecules (using life marker chips); anions (using a chemical analyzer); visualisation of the environment (using cameras and light sources); dissolved gases (using chromatography); and morphology of the lake floor and sediment structures (using sonar). After the probe has been retrieved, a sediment corer may be dropped into the lake to recover material from the lake floor. Finally, if time permits, a thermistor string may be left in the lake water to take time-dependent measurements of the lake’s water column over subsequent years. Given that the comprehensive geophysical survey of the lake will take place in two seasons during 2007–2009, a two-year instrument and logistic development phase from 2008 (after the lake’s bathymetry has been assessed) makes it possible that the exploration of Lake Ellsworth could take place at the beginning of the next decade.     

Inorganic carbon promotes photosynthesis,growth, and maximum biomass of phytoplankton in eutrophic water bodies

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The status of research on the mammals of Sulawesi,Indonesia

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Ecological influences on larval chironomid communities in shallow lakes: implications for palaeolimnological interpretations

1. To correctly interpret chironomid faunas for palaeoenvironmental reconstruction, it is essential that we improve our understanding of the relative influence of ecosystem variables, biotic as well as physicochemical, on chironomid larvae. To address this, we analysed the surface sediments from 39 shallow lakes (29 Norfolk, U.K., 10 Denmark) for chironomid head capsules, and 70 chironomid taxa (including Chaoborus) were identified. 2. The shallow lakes were selected over large environmental gradients of aquatic macrophytes, total phosphorus (TP) and fish communities. Redundancy analysis (RDA) identified two significant variables that explained chironomid distribution: macrophyte species richness (P < 0.001) and TP (P < 0.005). Generalised linear models (GLM) identified specific taxa that had significant relationships with both these variables. Macrophyte percentage volume infested (PVI) and species richness were significant in classifying the lake types based on chironomid communities under twinspan analysis, although other factors, notably nutrient concentrations and fish communities, were also important, illustrating the complexities of classifying shallow lake ecosystems. Lakes with plant species richness >10 all had relatively diverse (Hill’s N2) chironomid assemblages, and lakes with Hill’s N2 >10 all had TP <250 μg L⁻¹ and total fish densities <2 fish per m². 3. Plant density (PVI), and perhaps more importantly species richness, were primary controls on the distribution of chironomid communities within these lakes. This clearly has implications for palaeoenvironmental reconstructions using zoobenthos remains (i.e. chironomids) and suggests that they could be used to track changes in benthic/pelagic production and could be used as indicators of changing macrophyte habitat. 4. Measuring key biological gradients, in addition to physicochemical gradients, allowed the major controls on chironomid distribution to be assessed more directly, in terms of plant substrate, food availability, competition and predation pressure, rather than implying indirect mechanisms through relationships with nutrients. Many of these variables, notably macrophyte abundance and species richness, are not routinely measured in such studies, despite their importance in determining zoobenthos in temperate shallow lakes. 5. When physical, chemical and ecological gradients are considered, as is often the case with palaeo‐reconstructions rather than training sets chosen to maximise one gradient, complex relationships exist, and attempting to reconstruct a single trophic variable quantitatively may not be appropriate or reliable.     

The use of systems analysis methods in the sustainable management of wetlands

The management of the utilisation of natural resources from wetland ecosystems is a multiobjective and complex task. The creation of innovative decision making tools for sustainable wetland resource utilisation is an important challenge for the future. This is particularly crucial in the light of the growing shortages for high quality freshwater and the vanishing habitat for a large number of wetland fauna and flora species. Because wetlands combine attributes of both aquatic and terrestrial ecosystems, wetlands are often at the crossroads of a number of disciplines with no specific discipline of its own. Therefore, management programmes require a multidisciplinary approach founded on a systematic monitoring of key biological and physical parameters. A European Commission DG XII research project dedicated to the development of management tools for wetland resources in Latin America is being developed by a multidisciplinary team of researchers from eight universities, located in four EU member states, Argentina and Brazil. The study sites that will be utilised for this analysis are two shallow lakes in Northeast Argentina within the large (13000 km²) wetland `Esteros del Ibera'. Continuous and periodic in-situ monitoring instrumentation has been installed in a long term monitoring programme of hydrological and meteorological factors, coupled with monthly biological and ecological data gathering. Potential future scenarios for wetland resource use are being discussed in a series of public meetings with key provincial and local actors (teachers, university professors, clergymen, local business persons and politicians). These meetings address both the small scale modifications of wetland use (water extraction for agriculture, tourism, controlled hunting) as well as regional projects related to the creation of large scale economic development (forestation, modification of nearby waterways for hydroelectric production and increased river transportation). Models are developed relating the chemical, physical, biological and ecological parameters monitored. These models will be dedicated to analysing the effects of development on wetland functions and resource quality. An economic model will be created to evaluate potential modifications in wetland functions in the local and regional socio-economic context. Evaluation instruments are developed and tested which include; qualitative models using loop analysis, goal functions based on the aquatic trophic web and the overall energy flux in the lagoon, and a geographical information system utilising satellite images. The purpose of these instruments is to examine the overall impacts of development alternatives on resource quality and ecosystem integrity, as well as demonstrating key parameters that should be more closely monitored. The final package will include an evaluation of the potential impacts of the development scenarios proposed by the key actors, recommendations to reduce specific impacts through alternative technologies, together with a monitoring programme and analysis tools for improved decision making in wetland resource management.     

Novel Aerobic Methylotrophic Isolates from the Soda Lakes of the Southern Transbaikal Region

Twenty-one bacterial associations isolated from the soda lakes of the southern Transbaikal region were found to be able to actively grow at pH 9–10 on methanol as the source of carbon and energy. Two alkalitolerant facultatively methylotrophic strains, Bur 3 and Bur 5, were obtained in pure cultures. Both strains represent gram-negative, nonmotile, bean-shaped, encapsulated cells that reproduce by binary fission. The strains are able to grow at temperatures ranging from 6 to 42°C, with an optimum growth temperature of 25–29°C (strain Bur 3) and 35–37°C (strain Bur 5) and at pH between 6.5 and 9.5, with an optimum pH value of 8.0–8.5. At pH 9.0, strain Bur 3 exhibits an increased content of phosphatidylglycerol and a decreased content of phosphatidylethanolamine. Strains Bur 3 and Bur 5 are similar in the G+C content of their DNAs (66.2 and 65.5 mol %, respectively) and in the type of the dominant ubiquinone (Q ₁₀). Unlike Bur 5, strain Bur 3 is able to grow autotrophically in an atmosphere of CO₂+ O₂+ H₂. The strains oxidize, by the respective dehydrogenases, methanol to CO₂, which is assimilated by the ribulose bisphosphate pathway. Ammonium ions are assimilated in the glutamate cycle and by the reductive amination of -ketoglutarate. The strains are highly homologous to each other (92%) and are much less homologous (at a level of 28–35%) to representatives of the genus Ancylobacter, A. aquaticusATCC 25396^Tand A. vacuolatumDSM 1277. Based on the results obtained, both strains are assigned to a new species, Ancylobacter natronumsp. nov.     

Microbial cycling of iron and sulfur in sediments of acidic and pH-neutral mining lakes in Lusatia (Brandenburg, Germany)

A vast number of lakes developed in the abandoned opencast lignite mines of Lusatia (East Germany) contain acidic waters (mmolSm^–2a^–). Potential Fe(III) reduction measured by the accumulation of Fe(II) during anoxic incubation yielded similar rates in both types of sediments, however, the responses towards the supplementation of Fe(III) and organic carbon were different. Sulfate reduction rates estimated with ³⁵S-radiotracer were much lower in the slightly acidic sediment than in the pH-neutral sediment (156 v.s. 738mmolSO₄ ^2–m^–2a^–1). However, sulfate reduction rates were increased by the addition of organic carbon. Severe limitation of sulfate-reducing bacteria under acidic conditions was also reflected by low most probable numbers (MPN). High MPN of acidophilic iron- and sulfur-oxidizing bacteria in acidic sediments indicated a high reoxidation potential. The results show that potentials for reductive processes are present in acidic sediments and that these are determined mainly by the availability of oxidants and organic matter.     

Accelerated molecular evolution in halophilic crustaceans

In contrast to the stable ionic composition of the oceans, inland waters show striking diversity, possessing salt concentrations varying from I mM to 5 M. Although species diversity is highest in fresh water, some lineages have colonized hypersaline environments where they encounter elevated levels of both ultraviolet (UV) radiation and osmotic stress. This study compares rates of evolution in halophilic and freshwater taxa for two groups of microcrustaceans, anostracans and daphniids, from Australia and North America. The results establish that halophilic species show consistent rate acceleration, involving elevated levels of both insertion/deletion events and of nucleotide substitutions. The elevated pace of molecular evolution does not appear to be linked to selection or to other agents that are known to influence the supply rate of mutations, such as UV exposure, generation length, or shifts in metabolic rate. However, variance in ionic strength, which is known to have potent effects on DNA-protein interactions as well as on the structural properties of DNA and proteins, might account for the lowered fidelity of DNA replication in life from hypersaline settings. Regardless of its cause, the consistent rate acceleration in halophiles suggests that past efforts to employ sequence divergences to date events, such as the age of asexual lineages in Artemia, have resulted in serious overestimates. More generally, the results indicate that coordinated shifts in rates of molecular evolution may occur in lineages exposed to extreme environmental conditions.     

Phytoplankton of the extremely acidic mining lakes of Lusatia (Germany) with pH ≤3

Most of the flooded, open-cast lignite mining lakes of Lusatia (Germany) impacted by the oxidation of iron sulphides (pyrite and marcasite) are extremely acidic. Of 32 lakes regularly studied from 1995 to 1998, 14 have a pH <3 (median pH 2.3–2.9). These lakes are typically buffered by high concentrations of Fe (III) and have high conductivity (1000–5000 S cm^–1). Concentrations of dissolved inorganic carbon (DIC) and phosphorus are typically extremely low. These factors result in a very different environment for algae than found in neutral and acid-rain impacted lakes. The planktonic algal flora is generally dominated by flagellates belonging to genera of Chlorophyta (Chlamydomonas), Heterokontophyta of the class Chrysophyceae (Ochromonas, Chromulina), Cryptophyta (Cyathomonas) and Euglenophyta (Lepocinclis, Euglena mutabilis). Near-spherical non-motile Chlorophyta (Nanochlorum sp.), Heterokontophyta of the class Bacillariophyceae (Eunotia exigua, Nitzschia), Dinophyta (Gymnodinium, Peridinium umbonatum), other Chlorophyta (Scourfieldia cordiformis) and Cryptophyta (Rhodomonas minuta) are also found.