Abstract
AIMS: The aims of this study are to evaluate the effects of spatial and temporal variability of the macroinvertebrate fauna in drift and in the substrate of a mountain stream. METHODS: The study site is located in Achiras stream (Central, Argentina). This is an endorheic fluvial course whose headwaters are located in the southern extreme of Los Comechingones Mountains. Three replicate Surber samples were collected from benthos with 300 µm, 0.09 m² nets. Three drifting fauna samples were collected using drift nets, 1 m long, 300 µm and 0.0192 m². The taxonomic identification of specimens was performed according to the lowest possible taxonomic level. In order to characterize the drifting and benthic fauna, total abundance, taxonomic richness, Shannon and evenness indices were estimated and they were tested with two-way analysis of variance (ANOVA). In order to assess the distribution patterns of drift and benthos samples, we performed Canonical Correspondence Analysis (CCA). RESULTS: A total of 61 taxa were identified in drift and 82 in benthos. A 26.3% taxonomic similarity between the two assemblages was observed, according to the Jaccard index. In drift and benthos, Arthropoda presented higher abundance and Insecta contributed with more taxa and it was also the most abundant. The most abundant orders were Ephemeroptera, Trichoptera and Diptera. In the present study, Anacroneuria sp. (Perlidae) and Podonominae (Chironomidae) were first recorded for benthic community of Achiras stream. CONCLUSION: In this study we found that the structural organization of the drifting and benthic macroinvertebrate community shows different patterns of variation at spatial and temporal scales.
Highlights
Rivers and streams unidirectional flow continuously transport benthic invertebrates downstream (Waters, 1965; Hynes, 1970)
Headwaters are in the southern extreme of Los Comechingones mountains, which are located in the southwest of Córdoba province (Central Argentina)
Our findings for the composition of the constant drift and benthic community of Achiras stream are consistent with existing data reported for other fluvial courses of medium order in the province of Córdoba, Central Argentina (Gualdoni et al, 1991; Principe and Corigliano, 2006)
Summary
Rivers and streams unidirectional flow continuously transport benthic invertebrates downstream (Waters, 1965; Hynes, 1970). The organisms that temporarily leave the streambed and do not resist the drag strength constitute the drift fraction. One important property of drift is the fact that it homogenizes genetically different populations and facilitates the repopulation of areas partially or totally denuded by floods, drought or contamination (Svendsen et al, 2004). Drift components differ from the benthic components because not all organisms have the same predisposition to drifting. The drift composition reported for temperate regions indicates that Ephemeroptera, Diptera larvae, Plecoptera and some Trichoptera (those which build nets or light cases) dominate the drift fraction in this order. Isopods and oligochaetes are present (Allan, 1995)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
