Re-colonization by the Macroinvertebrate Community after a Drought Period in a First-Order Stream (Agüera

The effect o f a drought on the inacroinvertebrate coinni~inity was studied in a 1st order tributary of the Agüera stream (iiorth-ern Spain), from Noveiiiber 1995 to May 1996. During the dry period taxa richness was very low. Chironomidae, Ceratopogonidae, Odonata, Oligochaeta and Mollusca were recorded in the streambed. Non-flying taxa were dominant in den-sity and biomass at the beginning of the re-coloniaation process, indicating that these taxa are more resistant to drought than flying taxa. Thereafter, tlying taxa became more abundant. Taxa hatching in winter (Capnioneura and Glossosomatidae) seem to be less affected by the drought and developed dense populations. lnvertebrate density and biomass increased significantly over time, becoming a quite diverse coinmunity by the end of the study period