Recovery of the macroinvertebrate community below a wastewater treatment plant input in a Mediterranean stream

Abstract

We sampled chlorophyll a, benthic organic matter, and benthic macroinvertebrates in June 2001 in La Tordera stream (Catalonia, NE Spain), receiving a wastewater treatment plant (WWTP) input. Samples were collected in six equidistant transects in three reaches located upstream (UP), few m below (DW1), and 500 m below the WWTP input (DW2). Our first objective was to assess the effects of the point source on the structure and functional organization of the benthic macroinvertebrate community. Our second objective was to determine if the self-purifying capacity of the stream implied differences between the communities of the DW1 and the DW2 reaches. The WWTP input highly increased discharge, nutrient concentrations, and conductivity and decreased dissolved oxygen. At the DW1 and the DW2 reaches, taxa richness, EPT taxa (Ephemeroptera, Plecoptera, and Trichoptera), and Shannon diversity decreased and gatherer relative density increased relative to the UP reach. At the UP reach, CPOM and FPOM standing crops were similar, whereas at the DW1 and the DW2 reaches CPOM was two times higher than FPOM. Detailed analysis showed that major changes in the benthic community occurred abruptly between 80 and 90 m downstream of the point source (middle of the DW1 reach). At this location, chlorophyll a concentration, density of macroinvertebrates, taxa richness, and scraper relative density increased, whereas gatherer relative percentage decreased. The macroinvertebrate community at the DW2 reach was comparable to that at the second middle of the DW1 reach (DW1B). The macroinvertebrate community at the DW1B and the DW2 reaches were quite similar to that at the UP reach, indicating that the recovery capacity of the stream from nutrient enrichment was high.

Environmental effects and urban impacts on aquatic macroinvertebrates in a stream of central Brazilian Cerrado

“…Generalist organisms such as the collectors have wider range of feeding resource acceptability than the specialists; hence they are more tolerant to pollution since they are capable of modifying the availability of certain feeding sources (Cummins and Klug 1979). A similar response has been observed in other studies (Ortiz et al 2005;Roy et al 2003).…”

Effects of a waste water treatment plant on organic matter dynamics and ecosystem functioning in a Mediterranean stream

“…This result indicates a higher temporal variation of FBOM standing crop downstream of the WWTP. Due to the fact that WWTPs emit particulate organic matter (Rauter et al 2005, Ulseth & Hershey 2005 an increase of FBOM standing crop was expected in DW (but see Ortiz et al 2005). The seston concentration reported above for DW, and some very high seston concentrations (e.g.…”

Macroinvertebrates as Indicators of Water Quality in Running Waters: 10 Years of Research in Rivers with Different Degrees of Anthropogenic Impacts

“…The importance of using macroinvertebrates as bioindicators of the water quality of rivers has already been highlighted by several authors (Alba-Tercedor et al, 2002;Alonso, 2006;Bonada et al, 2000;Ortiz et al, 2005;Oscoz et al, 2006). The importance of this group is also reflected in this study because we were able to evaluate the conservation status of these rivers and assess the degree of impact that they are subjected to, whether by pollution or the construction of hydroelectric power stations.…”

“…In Spain, in recent years such studies have increased considerably and several papers studying these types of impacts in different regions of the country have been published. Amongst them we highlight Alonso (2006) in Madrid, Bonada et al (2000) and Ortiz et al (2005) in Catalonia, García Criado & Fernández Aláez (2001) in León, or Marqués et al (2003) in the Basque Country.…”