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 cha lk stream are described. Preliminary data from 15 sites showed signifi cant physical and biotic changes between two surveys (in 1992 and 1993 ) and between 'upland' and 'lowland' sectors. At the end of the drough t (1992) the macroinvertebrate community was severely reduced in the u pland sector-with low abundances and species richness-but recovery was dramatic with the return of normal flows. In contrast, relatively lit tle change was observed in the lowland sector. The observed faunal dif ferences are discussed in relation to information on the impact of pre vious droughts and recovery rates.