Ecological filters and variability in stream macroinvertebrate communities: do taxonomic and functional structure follow the same path?

Abstract

We examined the community-environment relationships of lotic macroinvertebrates in near-pristine headwater streams, and the correlation between patterns in taxonomic and functional structure at two regional extents. The across-ecoregion scale comprised five ecoregions spanning all of Finland, while the within-ecoregion scale comprised of north boreal and middle boreal ecoregions. We expected that taxonomic structure should exhibit stronger relationships than functional structure to spatial gradients, while the reverse should be true for local environmental factors. We found some support for this notion, because spatial variables were marginally more important for taxonomic than functional structure. Furthermore, within the two ecoregions, local environmental variables were slightly more important for functional than taxonomic structure. Geographical location (i.e. spatial variables) was more influential at the across-ecoregions extent than within the two ecoregions. Largely the same local environmental variables accounted for variation in both taxonomic and functional structure, including water pH, nutrients, colour, and stream size. Similar responses to local environmental features likely contributed to the significant correlation between patterns in taxonomic and functional structure. It has been suggested that functional traits may be rather insensitive to natural variation, yet our functional categorization showed distinct variation along local environmental, catchment, and spatial gradients across nearpristine streams. Thus, natural ecological filters should be accounted for prior to the examination of the effects of anthropogenic filters on stream macroinvertebrate community composition.

Caddisflies (Trichoptera) as good indicators of environmental stress in mountain lotic ecosystems

“…diversity measures) indicate various environmental stresses. Analysis of functional composition of caddisflies resulted in similar patterns like their taxonomic composition despite the lower number of functional groups comparing to number of taxonomic units, which is in agreement with observations within smaller regions (e.g., Heino et al 2007). However, it explained even more variability among variously impacted sites, which corresponds to studies sug-gesting that the proportion of variance explained by environmental variables is greater for metrics than for taxa (Johnson & Goedkoop 2002;Feld & Hering 2007).…”

Zooplankton communities are good indicators of potential impacts of Athabasca oil sands operations on downwind boreal lakes

“…The total amount of variation explained by both local and regional factors was modest in the present study (24%), but comparable to other zooplankton surveys using ordination techniques to quantify the explainable variation in species composition (e.g., Pinel-Alloul et al 1995;Stemberger and Miller 1998;Kurek et al 2011) when the differences in spatial extents and sample sizes are taken into account (Heino et al 2007). As most of the unexplained variation in these analyses may represent lack of fit to the models implicit in ordination methods, we placed more emphasize on the relative fractions of explained variation (Legendre and Legendre 1998;Økland 1999).…”

Measurement of the Ecological Integrity of Cerrado Streams Using Biological Metrics and the Index of Habitat Integrity

“…The BMWP was correlated to three other metrics considered important for water monitoring, especially the richness of EPT [3] and richness of families [52]. In addition, the EPT fauna and the richness of families have been considered to be highly congruent with the community; in other words, they can be representative of the community diversity [32,53]. Thus, its information cannot be ignored despite the high abiotic quality of most of the streams, and it should be considered in the evaluation of environmental quality of aquatic ecosystems of low order in Northern Brazil’s Cerrado.…”