The role of meiofauna in the energy transfer in a Mediterranean seagrass bed (Calvi, Corsica)

Meiofaunal communities of five different habitats characterised by different qualities of macrophytodetritus were sampled in a Mediterranean seagrass bed. Two different kinds of meiofauna communities were distinguished amongst the five habitats. A benthic community of meiofauna living on a sediment substrate or in highly fragmented macrophytodetritus and a foliar, epiphytal community associated with seagrass leaves and low fragmented macrophytodetritus leaves. The diversity index amongst these communities was comparable, but the composition in harpacticoid copepods families was different. Trophic biomarkers such as stable isotopes and fatty acids were combined to identify the major sources of organic matter contributing to the diet of these marine invertebrates. Harpacticoid copepods are very likely to feed on the biofilm on the plant material and hence, copepods use the seagrasses and detritus merely as substrate.
In addition to the field data, an experimental setup was conducted where detritus biofilm was enriched with 13C stable isotopic carbon. Harpacticoid copepods and Gammarus aquicauda amphipods were inserted in the incubation to observe their interaction and difference in uptake. No interaction between the two invertebrates was observed. The amphipods preferably feed on the detritus. The harpacticoid copepods on the other hand preferred and assimilated more biofilm than the amphipod.