Determinants of macroinvertebrate diversity in headwater streams: regional and local influences

Abstract

Summary1. Multiscale determinants of diversity and the relationship between regional (RSR) and local richness (LSR) have recently attracted increased attention, yet such studies on stream organisms remain scarce. We studied the relationships among RSR, β -diversity, LSR and local environmental variables in 120 headwater streams in Finland. Approximately similar-sized areas of eight drainage systems were defined as regions, and 15 stream riffles (= locality) per region were sampled. 2. RSR showed a strong positive relationship with mean LSR ( R 2 = 0·686), and there was no sign of curvilinearity within the observed range of RSR. RSR was also positively, although non-significantly, related to β -diversity ( r = 0·662). 3. In stepwise regression, RSR was the first variable to enter the model, and a model incorporating RSR and stream width explained 32·5% of variation in LSR. If RSR was omitted from the model, then stream width emerged as the most important variable, followed by water pH, which together accounted for 20·6% of variation in LSR. 4. At the within-region scale, different variables were important in accounting for variation in LSR. Factors correlated with LSR reflected either stream size, spatial heterogeneity, adverse water chemistry conditions (pH), or a limiting resource base for macroinvertebrates (nutrient concentrations). 5. The major role of RSR in setting the upper limit to LSR suggests that macroinvertebrate assemblages of boreal headwater streams are unsaturated. This finding is supported by evidence from experimental studies, where it has been shown that competitive interactions among stream macroinvertebrates are effective only at very small spatial scales, and competitive exclusion is prevented typically by frequent disturbances. However, although RSR was generally the most influential variable contributing to LSR, it is far from clear whether RSR consistently sets the limits to LSR, or vice versa. For instance, uniformly adverse water chemistry conditions across a region may lead to low levels of local richness and low species turnover among sites, leading eventually to an impoverished regional species pool. 6. These findings do not deny the importance of local factors, but emphasize that understanding the organization of stream benthic communities requires simultaneous examination of factors prevailing at multiple spatial scales.

Concordance between Ephemeroptera and Trichoptera assemblage in streams from Cerrado – Amazonia transition

“…These kinds of behaviors happening in synchrony between both orders probably contributed to our results. Heino et al (2003) agree that concordant patterns verified in fall-water season can be related to morphological, physiological adaptations, and especially, behavioral adaptations of these insects to hydrological instability.…”

“…However, same author reports a negative correlation between species richness of Plecoptera and other organisms, because stoneflies have different requirements for water temperature and dissolved oxygen. In a second study, Heino et al (2003) found low concordance in species richness of larvae from four groups in headwater streams (Ephemeroptera, Trichoptera, Plecoptera, and Chironomidae) in Finland, other studies often found low concordance in the structure and species richness in freshwater ecosystems, especially at small spatial scales (e.g. within basin Allen et al, 1999;Paavola et al, 2003;Tolonen et al, 2005).…”

Environmental and spatial processes determining Ephemeroptera (Insecta) structures in tropical streams

“…Sattler et al (2010), studying three different communities (spiders, bees and birds), and Nogueira et al (2011, unpublished thesis), for Trichoptera at the same sub-basins of this study (Corrente, Pindaı´ba and Suia´-Missu), found effects only of environmental variables. On the other hand, Heino et al (2003) have studied macroinvertebrate diversity and have found only influence of spatial variables, further suggesting the abandonment of the traditional local approach, and suggesting processes "within" streams as sole or primary regulators of local diversity.…”

Taxonomic, phylogenetic and functional diversity of leeches (Hirudinea) and their suitability in biological assessment of environmental quality

“…The type of response may be dependent (among the others) on the level of taxonomic identification (Wright et al, 1995;Wright and Ryan, 2016), type of stressor (Gutiérrez-Cánovas et al, 2013) and spatial scale of an analysis (Heino et al, 2003). Determining which type of response is responsible for relationships between EQ at a sampling site and the diversity of different groups of benthic animals is important from the point of view of biological assessment.…”