Dataset supporting the use of nematodes as bioindicators of polluted sediments

Schenk J, Höss S, Brinke M, Kleinbölting N, Brüchner-Hüttemann H, Traunspurger W. Dataset supporting the use of nematodes as bioindicators of polluted sediments. Data in Brief. 2020;32: 106087.We provide the dataset supporting the research article “Nematodes as bioindicators of polluted sediments using metabarcoding and microscopic taxonomy” [1]. Nematodes are frequently used as bioindicators and the NemaSPEAR[%] is an validated index that is originally based on morphological data. The index was compared to molecular sequence data for the 28S rDNA, 18S rDNA and COI gene for 7 locations. This dataset includes chemical analyses of the sediments for 33 different substances. The sequence data for OTU-based analyses for the 28S rDNA, 18S rDNA and COI gene is given, together with the read distribution during bioinformatics processing. We furthermore include alternative ASV data, based on a cluster-independent approach. The morphological data is presented, including the biomass for each species, as well as an overview about whether the species is represented in the NCBI database. Furthermore, rarefaction analysis is given for the morphological data, and furthermore NMDS plots for the species and genus level based on morphological and molecular data. The correlation between the mean PEC-Q and the NemaSPEAR[%] values is given in order to compare the efficiency of the index, based on morphological and molecular data

Deflection of phototactic microswimmers through obstacle arrays

We study the effect of inhomogeneous environments on the swimming direction of the microalgae \textit{Chlamydomonas Reinhardtii} (CR) in the presence of a light stimulus. Positive or negative phototaxis describe the ability of microorganisms to bias their swimming towards or away from a light source. Here we consider microswimmers with negative phototaxis in a microfluidic device with a microfabricated square lattice of pillars as obstacles. We measured a mean deflection of microswimmers that shows an interesting nonlinear dependence on the direction of the guiding light beam with respect to the symmetry axes of the pillar lattice. By simulating a model swimmer in a pillar lattice and analyzing its scattering behavior, we identified the width of the reorientation distribution of swimmers to be also crucial for the nonlinear behavior of the swimmer deflection. On the basis of these results we suggest in addition an analytical model for microswimmers, where the pillar lattice is replaced by an anisotropic scattering medium, that depends only on a scattering rate and the width of the reorientation distribution of swimmers. This flexible and handy model fits the experimental results as well. The presented analysis of the deflection of light guided swimmers through pillar lattice may be used for separating swimmers having different reorientation distributions