Investigation on the diversity and function of microphytes and protists in the food web of marine and limnic sediments
This thesis aimed at achieving a deeper understanding of the dynamics and structure of microbenthic communities with a focus on protists. The most important discovery concerning protozoa in recent years is the fact that they play a much more important role in for example carbon and energy flow in na...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Universität Bremen
2006
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| Online Access: | https://media.suub.uni-bremen.de/handle/elib/2237 https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000103494 |
| Summary: | This thesis aimed at achieving a deeper understanding of the dynamics and structure of microbenthic communities with a focus on protists. The most important discovery concerning protozoa in recent years is the fact that they play a much more important role in for example carbon and energy flow in nature than previously believed. In this thesis several studies were presented which focus on the seasonal dynamics and the spatial distribution of components of the small benthic community in marine and freshwater environments in temperate and arctic climates and which aim at establishing a generalised model of relationships and controlling factors in small benthic food webs. Samples of the upper 3 mm of the surface of soft sediment were collected in coastal freshwater and marine sites in Germany, USA and North East Greenland. The abundance and biomass of bacteria, cyanobacteria, diatoms and nanoflagellates (phototrophic and heterotrophic) were enumerated by means of epifluorescence microscopy. Ciliate species and meiofauna were enumerated with the help of light microscopy after QPS (quantitative protagol staining). Environmental data, such as temperature, salinity, sediment water content, grain size distribution, total and organic carbon- and nitrogen content as well as chlorophyll-a values were determined in order to study their influence on the community structures and total biomass. The investigation of a habitat in a mudflat in Dorum (Germany) revealed that the benthic microbial food web varied with the season with a primacy of bottom-up control during winter and spring, an increasing influence of top-down forces mainly by meiofauna grazing towards summer, decreasing again towards autumn, accompanied by a recovery of microphytobenthos.Investigations of soft sediment communities in different climate and geographic positions of freshwater and marine sites in Germany, North America (USA; Pennsylvania, New Jersey) and in North East Greenland were carried out. The results revealed considerable differences in the ... |
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