The relative influence of geographic location and reach-scale habitat on benthic invertebrate assemblages in six ecoregions

Abstract

The objective of this study was to determine the relative influence of reach-specific habitat variables and geographic location on benthic invertebrate assemblages within six ecoregions across the Western USA. This study included 417 sites from six ecoregions. A total of 301 taxa were collected with the highest richness associated with ecoregions dominated by streams with coarse substrate (19-29 taxa per site). Lowest richness (seven to eight taxa per site) was associated with ecoregions dominated by fine-grain substrate. Principle component analysis (PCA) on reach-scale habitat separated the six ecoregions into those in high-gradient mountainous areas (Coast Range, Cascades, and Southern Rockies) and those in lower-gradient ecoregions (Central Great Plains and Central California Valley). Nonmetric multidimensional scaling (NMS) models performed best in ecoregions dominated by coarse-grain substrate and high taxa richness, along with coarse-grain substrates sites combined from multiple ecoregions regardless of location. In contrast, ecoregions or site combinations dominated by fine-grain substrate had poor model performance (high stress). Four NMS models showed that geographic location (i.e. latitude and longitude) was important for: (1) all ecoregions combined, (2) all sites dominated by coarse-grain substrate combined, (3) Cascades Ecoregion, and (4) Columbia Ecoregion. Local factors (i.e. substrate or water temperature) seem to be overriding factors controlling invertebrate composition across the West, regardless of geographic location.

Can bottom-up procedures improve the performance of stream classifications?

“…Ideally, stream classifications should group locations with similar taxonomic composition into a small number of easily understood classes using a restricted set of environmental variables (Heino and Mykra 2006;Munn et al 2008). However, increasing the number of classes and including a wider range of environmental variables may increase the performance of classifications (i.e., the extent to which classes group sites having similar taxonomic composition; e.g., Leathwick et al 2010).…”

Development of a benthic multimetric index for the Serra da Bocaina bioregion in Southeast Brazil

“…1997. Other studies, like our own, found macroinvertebrate fauna more associated with local aquatic habitat or to land-use adjacent to the stream than with strict ecoregional classification (Waite et al, 2000, Mykrä et al, 2004, Frimpong et al, 2005, Munn et al, 2009. It is logical to suppose that these differences, if they exist, they would result in biological indices as well.…”

Analysis of benthic macroinvertebrates biodiversity of Cunas river by means of environmental indicators, Junin-Peru

“…Este tipo de presión reduce la estabilidad térmica de la columna de agua, incrementa la frecuencia de sedimento y de macrofitas acuáticas y, facilita la entrada de contaminantes a los cuerpos de agua (Scalley y Aide, 2003). Entre las consecuencias más importantes de esta presión es el deterioro de la calidad del agua y la reducción de la biodiversidad (Corbacho et al, 2003;Bonada et al, 2006), debido a la destrucción del hábitat de muchos estadios adultos de la entomofauna acuática (Munn et al, 2009;Egler et al, 2012).…”