Correspondance between Stream Benthic Macroinvertebrate Assemblages and Ecoregions in Northwestern Argentina

EDGARDO JAVIER IGNACIO PERO; HANKEL, G. E.; MOLINERI, C.; DOMÍNGUEZ, E.

Freshwater Science

University of Chicago Press

Lugar: Chicago; Año: 2019 vol. 38 p. 64 - 76

2161-9565

The use of ecoregions to classify stream and riverenvironments has been extensively tested in North America and Europe, but fewsuch studies have been conducted in South America. In this study we testedwhether taxonomic richness, composition, and organism abundance within benthicmacroinvertebrate assemblages were associated with ecoregions in northwesternArgentina at the genus and family levels. We included 3 ecoregions and theirrespective sub-ecoregions in this study: the Yungas subtropical cloud forest,the Western Chaco subtropical dry forest, and the Monte xeric shrublands. Weused non-metric multidimensional scaling, analysis of similarity, andrank-abundance curves to assess how assemblages varied among ecoregions andsub-ecoregions. We used principal components analysis to describe howenvironmental factors varied among sites and regions. Most aspects ofinvertebrate assemblages were associated with both ecoregions andsub-ecoregions. The structure of themacroinvertebrate assemblages was generally concordant with ecoregionalclassification at the genus level, although concordance was not evident at thesub-ecoregion level of resolution, especially for family level data. Thesegregation of assemblages was most strongly related to environmental variablesassociated with topography and less strongly related to physiochemicalvariables. Our results confirm that ecoregions mayeffectively predict the invertebrate biota inhabiting streams in northwesternArgentina, but it was difficult to delineate discrete assemblages. Future workshould assess the effectiveness of modeling approaches that would betteraccount for the gradual changes in assemblage composition that occur alongenvironmental gradients, and test how well both classification and modeling approachespartition biotic variation in other parts of South American.