Spotlight on meiofauna

Posted on May 26, 2009

Meiofauna are aquatic invertebrates less than 1 mm in size.  Although they may account for over 80% of the total number of species in freshwater streams, their ecological role is unclear, partly because the sieves used for the routine collection of benthic invertebrates have a mesh size of 0.5 mm, and don’t retain small meiofauna.  Because of its influence on the availability of oxygen and food, and the removal of waste products, substrate particle size probably has an important influence on the density and distribution of meiofauna.  In a study ofArkansasheadwater streams, substrate size successfully predicted the densities of most of the main meiofauna taxa.  Copepods and nematodes were associated with silt and fine sand.  Rotifers occurred in fine sand but avoided coarse sand.  Hydrachnids avoided silt.  The study showed that meiofauna can be abundant and diverse in headwater streams, and that meiofaunal communities are likely to be affected by accumulations of fine particles typically associated with human disturbance.

Reference: Radwell, A.J. & Brown, A.V.  2008.  Benthic meiofauna assemblage structure of headwater streams: density and distribution of taxa relative to substrate size.  Aquatic  Ecology 42, 405–414.