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Testate Amoebae as Proxy for Water Level Changes in a Brackish Tidal Marsh

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Ooms M., Beyens L., Temmerman S.

Acta Protozoologica

2012

vol. 51

issue 3

Few studies have examined testate amoebae assemblages of estuarine tidal marshes. This study investigates the possibility of using soil testate amoebae assemblages of a brackish tidal marsh (Scheldt estuary, Belgium) as a proxy for water level changes. On the marsh surface an elevation gradient is sampled to be analyzed for testate amoebae assemblages and sediment characteristics. Further, vegetation, flooding frequency and soil conductivity have been taken into account to explain the testate amoebae species variation. The data reveal that testate amoebae are not able to establish assemblages at the brackish tidal marsh part with flooding frequencies equal to or higher than 36.5%. Further, two separate testate amoebae zones are distinguished based on cluster analysis. The lower zone’s testate amoebae species composition is influenced by the flooding frequency (~ elevation) and particle size, while the species variability in the higher zone is related to the organic content of the soil and particle size. These observations suggest that the ecological meaning of elevation shifts over its range on the brackish tidal marsh Testate amoeba assemblages in such a brackish habitat show thus a vertical zonation (RMSEP: 0.19 m) that is comparable to the vertical zonation of testate amoebae and other protists on freshwater tidal marshes and salt marshes.

The Distribution of Soil Testate Amoebae under Winter Snow Cover at the Plot-scale Level in Arctic Tundra (Qeqertarsuaq/Disko Island, West Greenland)

100%

Tsyganov A. N., Temmerman S., Ledeganck P., Beyens L.

Acta Protozoologica

2012

vol. 51

issue 2

Understanding the spatial distribution of soil protozoa under the snow cover is important for estimation of ecosystem responses to climate change and interpretation of results of field experiments. This work explores spatial patterns of soil testate amoebae under the snow cover at the plot scale (the range of metres) in arctic tundra (Qeqertarsuaq/Disko Island, West Greenland). To explain spatial patterns in abundance, species diversity and assemblage composition of testate amoebae, we measured microtopography, snow depth and substrate density. The results indicate that the abundance of active testate amoebae under the snow cover was quite low. The empty shell assemblage was characterised by the presence of linear spatial trends in the species composition across the site, whereas no patterns were detected within the plot. The distribution of the abundance and the species diversity were unstructured. The linear trends in the species composition corresponded to the site microtopography and were controlled by the topography-related soil moisture. Snow depth also affected the linear trends presumably by controlling soil temperatures. Overall, the results suggest that population processes do not generate spatial patterns in protozoan assemblages at the plot scale so that protozoan distribution can be considered random at macroscopically homogeneous plots.

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2 Acta Protozoologica

2 2012

2 Beyens L.

2 Temmerman S.

1 Ledeganck P.

1 Ooms M.

1 Tsyganov A. N.

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Testate Amoebae as Proxy for Water Level Changes in a Brackish Tidal Marsh

The Distribution of Soil Testate Amoebae under Winter Snow Cover at the Plot-scale Level in Arctic Tundra (Qeqertarsuaq/Disko Island, West Greenland)