The species listed under this fidelity scores have been derived from surveys of the Diptera of sandy exposed riverine sediments (ERS). Species surveyed were allocated to ERS fidelity classes:
- Fidelity score 1: total fidelity (11 species)
- Fidelity score 2: strong fidelity (20 species)
- Fidelity score 3: moderate fidelity (54 species)
The two principal microhabitats sampled during the surveys were bare wet margins and drier, higher deposited material with sparse ruderal vegetation. Other micro-habitats that were sampled were more densely vegetated deposits or the actual river banks, any obvious variations in particle size (sand, pebbles, organic silt), position on large bars (upstream, edge, downstream, by backwater channels), and isolated ponds within the river’s channel.
The fidelity scores were first proposed based on on work in Devon (Bell, D., Sadler, J.P., and Drake, C.M. 2004. The invertebrate fauna of exposed riverine sediments in Devon: a survey report. Unpublished report to The Environment Agency and Devon County Council) and were subsequently expanded based on more extensive sampling of 18 rivers in England, Wales and Scotland (see link below).
For more information see: Drake, C.M., Godfrey, A., Hewitt, S.M., and Parker, J. 2007. Fly Assemblages of Sandy Exposed Riverine Sediment. Buglife.