ENCENTRUM ESSEXIS SP. N. (MONOGONONTA: DICRANOPHORIDAE), A NEW ROTIFER INHABITING STREAM BENTHOS FROM EAST ENGLAND

A new species of Rotifera belonging to the genus Encentrum (Monogononta, Dicranophoridae) is described from benthos of the Blackwater River, East Anglia, Essex, England, UK. Encentrum essexis sp. n. is characterised by the in dorsal view more or less conical toes having three elongate drop-shaped, light-refracting bodies leading to the tip of the toe. Trophi of Isoencentrum-type; outline of rami hexagonal; intramallei extended towards trophi axis into long spiniform process; inner margin of basal rami chambers with short tooth

Examining the diet of meiofauna: a critical review of methodologies

Majdi N, Schmid-Araya JM, Traunspurger W. Examining the diet of meiofauna: a critical review of methodologies. Hydrobiologia. 2020;847(12):2737-2754

Preface: Patterns and processes of meiofauna in freshwater ecosystems

Majdi N, Schmid-Araya JM, Traunspurger W. Preface: Patterns and processes of meiofauna in freshwater ecosystems. Hydrobiologia. 2020;847(12):2587-2595

Biomass and production of freshwater meiofauna: a review and a new allometric model

Schmid-Araya JM, Schmid PE, Majdi N, Traunspurger W. Biomass and production of freshwater meiofauna: a review and a new allometric model. HYDROBIOLOGIA. 2020;847:2681–2703.Freshwater meiofauna occupies a central role in stream food webs, not always as intermediary but also as top consumers. Consequently, the meiofauna's transient dynamical patterns and turnover are vital to understand its contribution to the overall production and energy flow within benthic freshwater systems. Here, we revise the current methodological procedures used to estimate production in benthic meiofauna, and compare their biomass and production data (a) to other benthic taxa, (b) in different habitats and systems, and (c) at the species level. Given the phyla diversity and when including temporary meiofauna (i.e. small insect larvae), care must be taken in selecting a production method and/or relying on published generation times. A handful of studies demonstrate that meiofaunal production values are well within the range displayed by macrofauna. We show that temperature-adjusted production and biomass of meiofaunal species from lakes, wetlands, and streams display a positive linear relationship with an exponent around 0.9, whereby biomass explains 90% of the variation in production. Further studies on meiofauna production should test the validity of our proposed allometric model for stream ecosystems and, thus, its possible generality

Scaling in stream communities.

Scaling relationships between population density (N) and body size (W), and of their underlying size distributions, can contribute to an understanding of how species use resources as a function of size. In an attempt to resolve the controversy over the form of scaling relationships, an extensive dataset, comprising 602 invertebrate species, was obtained from two geographically separate stream communities (Seebach in Austria and Mynach in Wales). We analysed the temporal consistency of the N-W relationship, which was subjected to ordinary least squares (OLS), bisector (OLS(BIS)) and quantile regressions, and species-size spectra with seasonally collated data. Slopes of seasonal OLS(BIS) regressions did not depart from -1 in either community, indicating a seasonally convergent scaling relationship, which is not energetically constrained. Species-size spectra may scale with habitat complexity, providing an alternative explanation for the observed body-size scaling. In contrast to the right-skewed species-size frequency distributions of single-species assemblages, the size spectra of these benthic communities exhibited 'central tendencies', reflecting their phyletic constitution. The shape of species body-mass spectra differed between the two communities, with a bimodal and seasonally convergent pattern in the Seebach community and a seasonally shifting unimodality in the Mynach community. The body-size spectra of large, mostly insect, species (greater than or equal to 1 mm) scaled to seasonal variations in habitat complexity (i.e. fractal D), suggesting that habitat structure constrains the community organization of stream benthos

Appendix A. Intrinsic rate of population increase per day and generation times in days of ciliate and meiofaunal species from the Lone Oak stream and the Pant stream, grown in laboratory cultures.

Intrinsic rate of population increase per day and generation times in days of ciliate and meiofaunal species from the Lone Oak stream and the Pant stream, grown in laboratory cultures