Environmental variables interact across spatial scales to structure trichopteran assemblages in Ouachita Mountain rivers

Abstract

An important goal in aquatic ecology is to determine the interacting variables that regulate community structure; however, complex biotic and abiotic interactions coupled with the significance of scale have confounded the interpretation of community data. We evaluated stream and riparian habitat features in southeastern Oklahoma, USA at a range of spatial scales from local, in-stream variables to largescale, regional characteristics to address the following questions: (1) How much variation in trichopteran community composition can be attributed to local, regional, and spatial variables? and (2) What environmental variables are most important in determining trichopteran community structure? We collected data on caddisfly community structure, local and regional environmental variables, and spatial location on the landscape from 25 sites in four rivers. We analyzed these data using canonical correspondence analysis (CCA) and variation partitioning. Our analysis explained approximately 60% of the variation in caddisfly community composition. We found that local and regional environmental variables were near equal in importance in governing caddisfly communities, with each accounting for approximately a quarter of the explained variation. Although pure spatial variables were less important, the amount of variation shared among spatial variables and local and regional variables was substantial, indicating that biogeographic history is also key to understanding caddisfly distributions. We also found a strong influence of human landuse (i.e., percent of land in agriculture, distance to roads) on caddisfly community composition. Our study indicated that communities are influenced by factors across scales, and that bioassessments should focus on not only local habitat conditions, but also incorporate largerscale factors.

Formation of groupings of mayfly larvae (Ephemeroptera) in the area of small hydrological structures, in the streams of the Kamienica Nawojowska river basin (the Sądeckie Beskids, Poland)

“…According Törnblom et al (2011), mayflies do not show in this regard any clear preferences -at most, the willingly inhabit streams whose basins are agricultural in character (extensive agriculture). Mayflies have a greater environmental tolerance than stoneflies and caddisflies, when it comes to the type of coverage of the basin area (Hughes, 2006;Galbraith et al, 2008;Medhurst et al, 2010). It was confirmed in this study.…”

“…The taxonomic diversity and abundance of specimens in the betnhos of watercourses are influenced by trophic state index of water, which is shaped, by, among others, the nature of the development of the river basin and coastal areas (Kopacz, Twardy, 2006;Galbraith et al, 2008). According Törnblom et al (2011), mayflies do not show in this regard any clear preferences -at most, the willingly inhabit streams whose basins are agricultural in character (extensive agriculture).…”

The influence of environmental factors on the structure of caddisfly (Trichoptera) assemblage in the Nišava River (Central Balkan Peninsula)

“…The caddisfly larvae are among the best indicator groups of macroinvertebrates for assessing water quality, as they have limited mobility and a relatively long life span; different species vary in sensitivity to various types of pollution and are easily sampled (Dohet, 2002). Temporal and spatial distribution patterns of lotic larval caddisfly assemblages in relation with environmental variables have been investigated extensively in the past (Huryn and Wallace, 1988;Schmera, 2004;Hughes, 2006;Galbraith et al, 2008). Among the environmental variables that have a strong impact on the distributional pattern of aquatic organisms are the geomorphology of the stream bed (Reid et al, 2010;Skuja and Spungis, 2010), land-use (Hughes, 2006;Helms et al, 2009), substrate type (Buss et al, 2004;Urbanič et al, 2005), hydraulic conditions (Statzner and Dolédec, 2011), and water temperature (Townsend et al, 1997;Hughes, 2006;Fengqing et al, 2012).…”

Chironomidae (Insecta, Diptera) from Alto Paranapanema Basin, southeastern Brazil

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The usual conclusions in such studies focus on the negative aspect of the conversion of riparian forest to agricultural land (Cetra and Petrere 2007;Galbraith et al 2008). Their presence is important for the maintenance of temperature equilibrium, as continous food supply for aquatic animals, as source of organic material and stabilization of stream banks (Marinho Filho and Reis 1989;Rodrigues 1992;Aguiar et al 2002).

Because of their widespread distribution and the sensitiveness to pollution observed for some species, chironomids are used worldwide as biological indicators of environmental quality (Bacey and Spurlock 2007;Chessman et al 2007; Smith et al.

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“…The usual conclusions in such studies focus on the negative aspect of the conversion of riparian forest to agricultural land (Cetra and Petrere 2007;Galbraith et al 2008). Their presence is important for the maintenance of temperature equilibrium, as continous food supply for aquatic animals, as source of organic material and stabilization of stream banks (Marinho Filho and Reis 1989;Rodrigues 1992;Aguiar et al 2002).…”