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

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.