Preliminary results of a nitrogen freeze-coring methodology for determining the vertical distribution of benthic invertebrates from the lowland River Babingley, UK

Summary

A Nitrogen freeze-coring method was used to sample the benthic invertebrate fauna of the river Babingley, UK to a depth of 70 cm. The fauna was stunned in situ using 700 V, 50 Hz AC prior to the removal of the core, a technique modified from Bretschko & Klemens (1986). Eighty-five percent of the total epigeic fauna appeared to dominate the surface 10 cm of the hyporheic zone, the rest was restricted to a depth of around 50 cm. Certain species showed preferences for different zones within the substrate e.g. Hydropsychidae was only to be found in the surface 10 cm Elminthidae was found between 0 and 30 cm. Conversely, Valvatidae showed a distinct avoidance of surface substrate and was only to be found at a depth of 30 — 40 cm.