Large East African Rift lakes have been changing rapidly during the last decades. They typically ... more Large East African Rift lakes have been changing rapidly during the last decades. They typically have a relatively high productivity compared to large temperate lakes and have active fisheries providing local populations with a relatively cheap source of proteins. However, human-induced changes, including climate change, can have significant effects on primary production of these lakes, as shown for Lake Tanganyika. It is likely that these decreases in primary production have affected secondary producers and fisheries, but, before being able to predict the extent of the primary productivity changes and how they affect whole ecosystem production, an improved understanding of ecosystem function and food web processes is required.
Antarctic soils are known to be oligotrophic and of having low buffering capacities. It is expect... more Antarctic soils are known to be oligotrophic and of having low buffering capacities. It is expected that this is particularly the case for inland high-altitude regions. We hypothesized that the bedrock type and the presence of macrobiota in these soils enforce a high selective pressure on their bacterial communities. To test this, we analyzed the bacterial community structure in 52 soil samples from the western Sør Rondane Mountains (Dronning Maud Land, East Antarctica), using the Illumina MiSeq platform in combination with ARISA fingerprinting. The samples were taken along broad environmental gradients in an area covering nearly 1000 km(2) Ordination and variation partitioning analyses revealed that the total organic carbon content was the most significant variable in structuring the bacterial communities, followed by pH, electric conductivity, bedrock type and the moisture content, while spatial distance was of relatively minor importance. Acidobacteria (Chloracidobacteria) and Ac...
Sub-Antarctic South Georgia is a key region for studying climate variability in the Southern Hemi... more Sub-Antarctic South Georgia is a key region for studying climate variability in the Southern Hemisphere, because of its position at the core of the Southern Hemisphere Westerly Wind belt and between the Antarctic Circumpolar Current and the Polar Frontal Zone. Here, we present a 5.8-m long high-resolution pollen record from Fan Lake on Annenkov Island dominated by local sub-polar vegetation, with Acaena and Poaceae being present throughout the last 7000 years. Palynological and sedimentological analyses revealed a warm late Holocene ‘climate optimum’ between 3790 and 2750 cal. yr BP, which was followed by a gradual transition to cool and wet conditions. This cooling was interrupted by slightly warmer environmental conditions between 1670 and 710 cal. yr BP that partly overlap with the Northern Hemisphere ‘Medieval Climate Anomaly’. Increases in non-native and long-distance pollen grains transported from South America (e.g. Nothofagus, Podocarpus) indicate that stronger Southern Hemi...
Components of the pelagic food web in four eutrophic shallow lakes in two wetland reserves in Bel... more Components of the pelagic food web in four eutrophic shallow lakes in two wetland reserves in Belgium (‘Blankaart’ and ‘De Maten’) were monitored during the course of 1998–1999. In each wetland reserve, a clearwater and a turbid lake were sampled. The two lakes in each wetland reserve had similar nutrient loadings and occurred in close proximity of each other. In
Large East African Rift lakes have been changing rapidly during the last decades. They typically ... more Large East African Rift lakes have been changing rapidly during the last decades. They typically have a relatively high productivity compared to large temperate lakes and have active fisheries providing local populations with a relatively cheap source of proteins. However, human-induced changes, including climate change, can have significant effects on primary production of these lakes, as shown for Lake Tanganyika. It is likely that these decreases in primary production have affected secondary producers and fisheries, but, before being able to predict the extent of the primary productivity changes and how they affect whole ecosystem production, an improved understanding of ecosystem function and food web processes is required.
Antarctic soils are known to be oligotrophic and of having low buffering capacities. It is expect... more Antarctic soils are known to be oligotrophic and of having low buffering capacities. It is expected that this is particularly the case for inland high-altitude regions. We hypothesized that the bedrock type and the presence of macrobiota in these soils enforce a high selective pressure on their bacterial communities. To test this, we analyzed the bacterial community structure in 52 soil samples from the western Sør Rondane Mountains (Dronning Maud Land, East Antarctica), using the Illumina MiSeq platform in combination with ARISA fingerprinting. The samples were taken along broad environmental gradients in an area covering nearly 1000 km(2) Ordination and variation partitioning analyses revealed that the total organic carbon content was the most significant variable in structuring the bacterial communities, followed by pH, electric conductivity, bedrock type and the moisture content, while spatial distance was of relatively minor importance. Acidobacteria (Chloracidobacteria) and Ac...
Sub-Antarctic South Georgia is a key region for studying climate variability in the Southern Hemi... more Sub-Antarctic South Georgia is a key region for studying climate variability in the Southern Hemisphere, because of its position at the core of the Southern Hemisphere Westerly Wind belt and between the Antarctic Circumpolar Current and the Polar Frontal Zone. Here, we present a 5.8-m long high-resolution pollen record from Fan Lake on Annenkov Island dominated by local sub-polar vegetation, with Acaena and Poaceae being present throughout the last 7000 years. Palynological and sedimentological analyses revealed a warm late Holocene ‘climate optimum’ between 3790 and 2750 cal. yr BP, which was followed by a gradual transition to cool and wet conditions. This cooling was interrupted by slightly warmer environmental conditions between 1670 and 710 cal. yr BP that partly overlap with the Northern Hemisphere ‘Medieval Climate Anomaly’. Increases in non-native and long-distance pollen grains transported from South America (e.g. Nothofagus, Podocarpus) indicate that stronger Southern Hemi...
Components of the pelagic food web in four eutrophic shallow lakes in two wetland reserves in Bel... more Components of the pelagic food web in four eutrophic shallow lakes in two wetland reserves in Belgium (‘Blankaart’ and ‘De Maten’) were monitored during the course of 1998–1999. In each wetland reserve, a clearwater and a turbid lake were sampled. The two lakes in each wetland reserve had similar nutrient loadings and occurred in close proximity of each other. In
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