Response of benthic invertebrates to disturbance from stream restoration: the importance of bryophytes

The response of benthic invertebrates to disturbance from stream restoration was studied in the Reinikankoski rapids, central Finland. I hypothesized that stream bryophytes could act as a refugium for invertebrates. The restoration procedure destroyed nearly half of the bryophytes present at the study reach, and invertebrate densities decreased sharply immediately after the restoration. Within 2 weeks, invertebrates had recolonized the disturbed reach, and within 1 month peak numbers were attained. Invertebrates showed a clear association with bryophytes, especially after the restoration. My study shows that invertebrate recovery can be relatively fast in winter, and underlines the importance of stream mosses as invertebrate habitat and refugia. They should be taken in consideration in stream restoration projects by leaving patches of stream bottom intact.