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          Institute: MPI für Evolutionsbiologie     Collection: Tropical ecology     Display Documents

ID: 293394.0, MPI für Evolutionsbiologie / Tropical ecology
Physical pollution: effects of gully erosion on benthic invertebrates in a tropical clear-water stream
Authors:Wantzen, Karl M.
Date of Publication (YYYY-MM-DD):2006
Title of Journal:Aquatic Conservation: Marine and Freshwater Ecosystems
Journal Abbrev.:Aquatic Conserv: Mar. Freshw. Ecosyst.
Issue / Number:7
Start Page:733
End Page:749
Review Status:not specified
Audience:Not Specified
Abstract / Description:1. Many tropical streams are situated in geologically old, weathered landscapes that are prone to erosion. Permanent or seasonally pulsing inputs of eroded material into the streams may have significant effects on benthos and habitats, even if chemical water quality remains unaltered.
2. This study presents data from the Cerrado Region, Brazil, where the semideciduous forests have been largely converted into agricultural areas with considerable erosion problems. In order to quantify impacts of erosion on the benthic community, a simple, inexpensive, standardized artificial substrate was exposed on the stream bed above and below the mouth of an erosion gully in two experiments at the beginning and at the end of the rainy season.
3. While the abundance and biomass of most of the biota in the reference sites did not change during the rainy season, it decreased significantly at the impact sites below the mouth of the erosion gully. It was the combination of rainfall-driven flood pulses and increased load of suspended particles from erosion which caused the decline of the benthic colonization in these streams rather than the hydrological disturbance alone.
4. Site-to-site comparisons revealed a highly significant reduction in density, biomass and taxon richness of the benthic invertebrates caused by siltation. All benthic insect taxa studied showed the same pattern, indicating a general impact of erosion on habitat quality and food sources. Semi-aquatic insects adapted to shifting habitat conditions, terrestrial food sources and aerial respiration were the most resistant invertebrate group.
5. Restoration schemes for the stream catchments are urgently needed to reduce local population extinctions due to impassable stream sections.
Free Keywords:siltation; impact; artificial substrates; aquatic invertebrates; Cerrado; Brazil
External Publication Status:published
Document Type:Article
Communicated by:Brigitte Lechner
Affiliations:MPI für Limnologie/AG Tropenökologie
External Affiliations:Limnology Institute, University of Konstanz, Postfach M659, 78467 Konstanz, Germany
Identifiers:ISSN:1052-7613 [Print]
ISSN:1099-0755 [Online]
DOI:10.1002/aqc.813 [ID-No:3]
LOCALID:2518/S 38636 [Listen-Nummer/S-Nummer]
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