Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams.

MESA LETICIA; REYNAGA CELINA; CORREA MARCELA; SIROMBRA MARTIN

IHERINGIA. SéRIE ZOOLOGIA

FUNDACAO ZOOBOTANICA RIO GRANDE SUL

Lugar: Porto Alegre; Año: 2013 vol. 103 p. 342 - 349

0073-4721

THE NATURE OF THE RIPARIAN AND SURROUDING LANDSCAPEHAS BEEN MODIFIED BY ANTHROPOGENIC ACTIVITIES., WHICH MAY SUBSEQUENTLY ALTER THE COMPOSITION AND FUNCIONAL STRUCTURE OF MACROINVERTEBRATE ASSEMBLAGES. THE EFFECTOF THESE CHANGES ON FUNCTION OF BENTHONIC FAUNA IS DIFFICULT TO ASSESS DUE TO THE SCARSE KNOWLEDGEN ON FUNCTIONAL STRUCTURES IN TROPICAL STREAMS. IN THIS STUDY WE EVALUATE WHETHER SITES IMPACTED AND UNIMPACTED BY ANTHROPOGENIC ALTERATIONS DIFFERED IN ASSEMBLAGE COMPOSITION AND DENSITY, RICHNESS AND DIVERSITY OF EACH FUNCTIONAL FEEDING GROUP. THE SELECTION OF SITES WAS RELATED TO THEIR DISTINCT RIPARIAN CHARACTERISTICS, FOLLOWING THE QBRY RIPARIANQUALITY INDEX. COLLECTOR-GATHERER WAS THE DOMINANT FUNCTIONAL FEEDING GROUP, COMPRISING 91% OF TOTAL DENSITY, WHEREAS THE PROPORTION OF SHREDDERS WAS VERY LOW, REPRESENTING LESS OF 0,5 OF TOTAL DENSITY. ASEMBLAGE CO POSITION OF MACROINVERTEBRATES DIFFERED BETWEEN IMPACTED AND UNIMPACTED SITES. PREDATORS WERE DOMINANT IN TAXA NUMBER, REPRESENTING ABOUT 60% OF TOTAL TAXA RICHNESS. IN ADDITION, THE DIVERSITY AND RICHNESS OF COLLECTOR-GATHERERS DIFFERED SIGNIFICANTLY BETWEEN DEGRADED AND UNIMPACTED SITES, REFLECTING THE SENSITIVITY OF THIS GROUP TO ENVIRONMENT CHANGES AND THE UTILITY TO BE USED IN THE ASSESSMENTBN OF ANTHROPOGENIC MODIFICATIONS. THE RESULTS OF THIS STUDY REINFORCE THE IDEA THAT RIPARIAN CORRIDOR MANAGEMENT IS CRITICAL FOR THE DISTRIBUTION OF MACROINVERTEBRATEASSEMBLAGES AS WELL AS FUNCTIONAL ORGANIZATION OF LOTIC STREAM.