Functional and compositional responses of stream microphytobenthic communities to multiple stressor increase and decrease
Microphytobenthos represents the main autochtonous source of organic matter in stream ecosystems, and is characterised by a rich organismal diversity. Diatoms are arguably the best-studied organisms in these communities: compositional differences of their assemblages along diverse environmental gradients, including anthropogenic stressors, have been described in a range of systems. Effects of anthropogenic stressors upon photosynthetic fitness and performance of stream microphytobenthic communities have also been studied (though less frequently).
An integrative characterisation of community reorganisations and changes in photosynthesis-related traits accompanying stressor load and release under highly controlled conditions has, however, rarely been attempted. This project aims, on the one hand, to fill this gap by assessing compositional responses (by microscopy and DNA metabarcoding) in parallel with functional changes (in photosynthesis-related traits) of microphytobenthos to stressor increase and release in the ExStream experiments of RESIST.
Second, participating in the field activities of the CRC by characterizing field microphytobenthic communities in an analogous manner, the project will assess to what extent differences in these communities reflect differences in land use (in the Kinzig network) and differing time periods since stream restoration (in the Emscher/Boye localities). Beyond establishing community ecological foundations for benthic microalgae (and other protists) in the study sites, the first project phase will mainly address the hypothesis that photosynthesis related traits are largely decoupled from community composition under moderate stressor levels.
Complementing results of other RESIST projects, our data sets will contribute to comparative analyses among different organismal groups within the synthesis activities in the frame of Z03. At this level, the data from this project will help to address the hypothesis that because of their larger population sizes and resulting better dispersability, microphytobenthos shows faster recovery than communities of macroscopic organisms do.
Serge Mayombo (University of Duisburg-Essen)
Functional and compositional responses of stream microphytobenthic communities to multiple stressors increase and decrease
Microphytobenthos form a key group of autochthonous primary producers in stream ecosystems. Microphytobenthic communities occur at the base of all aquatic food webs and play an important role in the transfer of energy to higher trophic levels. Diatoms are arguably the best‐studied organisms in these communities, e.g. changes in their community structures against environmental gradients, including a combination of anthropogenic stressors, in a range of systems. Diatom assemblages are widely used for biomonitoring of various environmental conditions and paleoecological reconstruction.
This is possible because the species composition of diatom communities reflects directly the influence of the specific combination of long-term environmental factors prevailing in their thriving ecosystems. Inside the framework of RESIST, our goal is to investigate the effect of multiple stressors on microphytobenthos, mainly diatoms, and photosynthesis-related traits. Very few studies reported the effects of anthropogenic stressors upon photosynthetic fitness and performance of stream microphytobenthic communities up to date. An integrative characterisation of community reorganisations and changes in photosynthesis‐related traits accompanying stressor load and release under highly controlled conditions has been very seldom attempted.
This study, on the one hand, aims to fill this gap by assessing compositional responses of benthic diatoms (using digital microscopy and DNA metabarcoding) in parallel with functional changes (in photosynthesis‐related traits) of microphytobenthic communities to stressor (flow, salinity and temperature) increase and release in the large-scale ExStream mesocosm experimental setting. On the other hand, field samplings taken on two anthropogenically impacted river catchments, aim to characterise field microphytobenthos assemblages in a similar manner, in order to assess to what extent differences in these communities reflect changes in adjacent land-use (along the Kinzig network) and differing time periods since urban stream restoration (in the Emscher/Boye localities).
First Supervisor: Prof. Dr. Bánk Beszteri (University of Duisburg-Essen, Phycology)
Second Supervisor: Prof. Dr. Daniel Hering (University of Duisburg-Essen, Aquatic Ecology)
Mentor: Dr. Julia Förster (LANUV NRW)