Low flows and recovery of macroinvertebrates in a small regulated chalk stream



The ecological effects of, and subsequent recovery from, a protracted drought exacerbated by groundwater abstractions on a small English chalk stream are described. Preliminary data from 15 sites showed significant physical and biotic changes between two surveys (in 1992 and 1993) and between ‘upland’ and ‘lowland’ sectors. At the end of the drought (1992) the macroinvertebrate community was severely reduced in the upland sector—with low abundances and species richness—but recovery was dramatic with the return of normal flows. In contrast, relatively little change was observed in the lowland sector. The observed faunal differences are discussed in relation to information on the impact of previous droughts and recovery rates.