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Distribution and microhabitat selection of Hydropsyche exocellata Dufour (Trichoptera, Hydropsychidae) in a Mediterranean river affected of organic pollution: the Guadaira River (S. Spain)

2007; Volume: 26; Issue: 1 Linguagem: Inglês

10.23818/limn.26.08

2660-8537

Alfonso Gallardo-Mayenco, Antonio Ruíz,

Aquatic Invertebrate Ecology and Behavior

Distribution and microhabitat selection of Hydropsyche exocellata Dufour (Trichoptera, Hydropsychidae) in a Mediterranean river affected of organic pollution: the Guadaira River (S. Spain)During the wet season, floods in the Guadaira river can reach up to 2000 m 3 /s flow, whereas during dry season the river only receives crude domestic sewage effluents and periodical industrial effluents from olive oil factories.In this study, the distribution of Hydropsyche exocellata along the watercourse of the Guadaira river during the flood and drought periods and its preferences for the available microhabitats were studied.H. exocellata was the only hydropsychid found along the river, except at one site at the headwater where it was found coexisting with H. infernalis Schmid Its higher abundances were found at the start of the dry period (June) and at its end (October).From the IBMWP values obtained at the sampling sites, we found that the highest densities of H. exocellata were coincidental with ranks of this index characterizing moderately polluted waters, whereas it was not found at sites where pollution reached highest levels.Thus, it seems it avoids sites extremely polluted in the study area.From the stepwise multiple regression analysis and microhabitat selection results, we can infer that to get a successful population size it requires an environment basically consisting of fast water current velocity and firm substrate (stones).