Preface: Patterns and processes of meiofauna in freshwater ecosystems.

Never heard of harpacticoids, ostracods, gastrotrichs or microturbellarians? This is no surprise, they are so tiny! Yet these taxa and many others more famous (nematodes, rotifers, or tardigrades) show complex behaviours and extraordinary physiologies that allow them to colonize inland waters worldwide. This exuberant fauna is better known as the meiofauna (or meiobenthos). Meiofaunal organisms have been fascinating study objects for zoologists since the seventeenth century and recent research has demonstrated their intermediate role in benthic food webs.

Selective grazing behaviour of chironomids on microalgae under pesticide pressure.

The herbicide diuron and the insecticide imidacloprid are amongst the most frequently detected pesticides in French rivers, and each is known to affect many aquatic organisms. However, the question of whether and how both pesticides together might induce multi-stress conditions, which could induce indirect effects such as the modification of biological interactions within freshwater microbial communities has not received much attention. This study was undertaken to determine the effect of diuron and imidacloprid alone and in combination on the feeding behaviour of chironomid larvae.

Flatworm mucus as the base of a food web.

Background: By altering their habitats, engineering species can improve their own fitness. However, the effect of this strategy on the fitness of coexisting species or on the structure of the respective food web is poorly understood. In this study, bacteria and bacterivorous nematodes with short (Caenorhabditis elegans) and long (Plectus acuminatus) life cycles were exposed to the mucus secreted by the freshwater flatworm Polycelis tenuis.

Analyzing life-history traits and lipid storage using CARS microscopy for assessing effects of copper on the fitness of Caenorhabditis elegans.

Lipid storage provides energy for cell survival, growth, and reproduction and is closely related to the organismal response to stress imposed by toxic chemicals. However, the effects of toxicants on energy storage as it impacts certain life-history traits have rarely been investigated. Here, we used the nematode Caenorhabditis elegans as a test species for a chronic exposure to copper (Cu) at EC20 (0.

Depth-Related Effects on a Meiofaunal Community Dwelling in the Periphyton of a Mesotrophic Lake.

Periphyton is a complex assemblage of micro- and meiofauna embedded in the organic matrix that coats most submerged substrate in the littoral of lakes. The aim of this study was to better understand the consequences of depth-level fluctuation on a periphytic community. The effects of light and wave disturbance on the development of littoral periphyton were evaluated in Lake Erken (Sweden) using an experimental design that combined in situ shading with periphyton depth transfers.

Life-History Traits of the Model Organism Pristionchus pacificus Recorded Using the Hanging Drop Method: Comparison with Caenorhabditis elegans.

The nematode Pristionchus pacificus is of growing interest as a model organism in evolutionary biology. However, despite multiple studies of its genetics, developmental cues, and ecology, the basic life-history traits (LHTs) of P. pacificus remain unknown.

Free-living nematodes in the freshwater food web: a review.

Free-living nematodes are well-recognized as an abundant and ubiquitous component of benthic communities in inland waters. Compelling evidence from soil and marine ecosystems has highlighted the importance of nematodes as trophic intermediaries between microbial production and higher trophic levels. However, the paucity of empirical evidence of their role in freshwater ecosystems has hampered their inclusion in our understanding of freshwater food web functioning.

Predator effects on a detritus-based food web are primarily mediated by non-trophic interactions.

Predator effects on ecosystems can extend far beyond their prey and are often not solely lethally transmitted. Change in prey traits in response to predation risk can have important repercussions on community assembly and key ecosystem processes (i.e.

Selective feeding of bdelloid rotifers in river biofilms.

In situ pigment contents of biofilm-dwelling bdelloid rotifers of the Garonne River (France) were measured by high performance liquid chromatography (HPLC) and compared with pigment composition of surrounding biofilm microphytobenthic communities. Among pigments that were detected in rotifers, the presence of carotenoids fucoxanthin and myxoxanthophyll showed that the rotifers fed on diatoms and cyanobacteria. Unexpectedly, while diatoms strongly dominated microphytobenthic communities in terms of biomass, HPLC results hinted that rotifers selectively ingested benthic filamentous cyanobacteria.