Meiobenthic response to river‐borne benthic particulate matter – a microcosm experiment

Abstract

1. Benthic communities inhabiting river-lake interfaces are confronted with temporal variation in the import of river-borne material to the associated littoral zone. The primary objective of this study was to evaluate the exposure to river-borne benthic particulate matter as a force shaping the meiofauna of the river-lake interface. 2. In a 2 · 2 factorial design, combinations of strongly and weakly river-influenced communities (near or far from the river mouth) with and without river-borne benthic particulate matter enrichment were studied in laboratory microcosms to assess the response of the heterotrophic meiobenthos to river-borne matter. 3. Nematodes dominated both habitat types and were the only meiofaunal taxon that responded to the enrichment. 4. A strong interactive effect between experimental enrichment and location of site was observed. Whereas nematodes from the littoral habitat close to the river mouth responded to the enrichment only marginally, nematodes from the remote site were strongly affected in the presence of river-borne particulate matter. 5. In the non-enriched samples of the remote site, the number of nematodes increased greatly over time. Among nematode feeding types, deposit feeders dominated over chewers at the beginning of the experiment but both types were equally abundant at the end. In the presence of river-borne matter the increase of chewers ceased and a shift in feeding type composition did not occur. 6. It was shown that for river-lake interface meiofaunal assemblages in relative proximity, the same taxon might respond differently if exposed to an external pressure, e.g. riverborne components. These components may have a stronger influence on taxa with longer life cycles.

Diversity, Abundance, Spatial Variation, and Human Impacts in Marine Meiobenthic Nematode and Copepod Communities at Casey Station, East Antarctica

“…A 32 µm sieve was used to retain the meiofauna size fraction. Meiofauna were extracted through a modified gravity gradient centrifugation technique (Heip et al, 1985;Pfannkuche et al, 1988) using a% solution of Ludox HS40 and Ludox AS in distilled water (Witthoft-Muhlmann et al, 2005). Ludox is a silica sol (a colloidal solution of Si02) which causes no plasmolysis.…”

Nematodes of Lake Constance, Germany, with special reference to littoral communities of a river mouth area

“…The influence can be stronger on taxa with longer life cycles (Witthöft-Mühlmann et al, 2005b). Having recognised the importance of interactions between river-borne components and the wind (e.g., resuspension and re-allocation of sediments, import/export with the pelagic zone) this study set out to address the following questions: i) does nematode feeding type composition vary from site to site within a river mouth?…”

Extreme Benthic Communities in the Age of Global Change

“…A 32 µm sieve was used to retain the meiofauna size fraction. Meiofauna were extracted through a modified gravity gradient centrifugation technique Pfannkuche et al, 1988) using a% solution of Ludox HS40 and Ludox AS in distilled water (Witthoft-Muhlmann et al, 2005). Ludox is a silica sol (a colloidal solution of Si02) which causes no plasmolysis.…”