Seasonal distribution and life histories of Ephemeroptera in a Northumbrian River

Abstract

SUMMARY. The life histories of twelve abundant species in the River Coquet are given together with notes on certain scarce species. The life histories are compared with those recorded for other river systems and major differences in findings between studies are related to geographical location and temperature. Catastrophic mortalities noted for some populations coincided with the presence of slush‐ice in the river bed and subsequent winter spates caused by meltwaters. Extended hatching periods are apparently adaptive and compensate for such losses. Life histories are also compared along the length of the R. Coquet. Hatching periods, growth rates and emergence periods show regional differences which are apparently dependent on altitudinal variations in temperature regime.