Relationship between current velocity, depth and the invertebrate community in a stable river system

Abstract

The relationship between invertebrate densities, current velocity and water depth was studied in the Dan River, northern Israel. Maximum current preferences ranged from 5-120 cm set -', and depth preferences ranged from 5-60 cm. Thirty-five taxa of invertebrates were collected by means of colonization cages. Larval and adult stages of 3 Elmidae (Coleoptera) species were treated separately: Limnius letourneuxi, Grouvellinus caucasicus and Elmis rioloides. Differences in current preference were observed between larval and adult stages of the same species of Elmidae. Taxa were also grouped according to preference for turbulence. Wide ranges of depth and current velocity preferences were observed. Most of the taxa were found at between 80-100 cm set -I and at depths of less than 30 cm. A correlation between species diversity and current velocity was established. Velocities of 60-80 cm set-' contained the greatest overlap of faunal preference. The sensitivity of selected species to stream flow reduction is discussed.

Microhabitat type selection of caddisfly larvae (Insecta: Trichoptera) in a shallow lowland stream

“…Collector-gatherer Psychomyia pusilla and scraper Goera pilosa were mainly found on cobbles in deep water (30 cm). Degani et al (1993) reported the same depth preference for P. pusilla. The community of marginal habitats contained most major feeding types including shredders (Limnephilus lunatus), filterers (Hydropsyche modesta, Neureclipsis biomaculata), predators (Oecetis notata, Athripsodes cinereus, Cyrnus trimaculatus) and piercer (Orthotrichia angustella).…”

“…Most latter studies, that have reported species-specific microhabitat preferences (Gore & Judy, 1981;Orth & Maughan, 1983;Rutt et al, 1989, Degani et al, 1993Voelz & Ward, 1996), infer the relationships between species and environment from community composition data and associated microhabitat measurements. However, of these, only a few studies have concerned caddisflies (e.g.…”

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

“…This makes sense since local habitat variables are the ones that individual organisms experience directly (Johnson & Goedkoop, 2000). Like other studies that have examined caddisfly community structure and local environmental variables, we found measures that quantify stream reach characteristics (i.e., depth and bank slope, water chemistry) to be important (Minshall 1984;Degani et al, 1993;Voelz et al, 1994;Townsend et al, 1997). We also found evidence of habitat preferences among certain genera based on these environmental variables.…”

“…This problem arises due to the fact that the processes that regulate stream communities vary across spatial and temporal scales, and range from local biotic interactions to large-scale biogeographic history (Tonn, 1990;Poff, 1997). The role of local, instream environmental variables (e.g., depth, substrate size, current velocity) in structuring stream communities has been well studied (Minshall, 1984;Degani et al, 1993;Voelz et al, 1994;Townsend et al, 1997;Fairchild & Holomuzki, 2002). In recent years, researchers also have begun focusing on how larger scale regional and landscape-scale factors (e.g., annual discharge patterns, watershed area, landuse) influence aquatic communities (Corkum, 1992;Richards et al, 1997;Sandin & Johnson, 2000;Parson et al, 2003;Weigel et al, 2003).…”

Effect of current velocity and case adaptations on the distribution of caddisfly larvae (Glossosoma, Trichoptera)

“…A number of studies have reported a relationship between water current velocity and the distribution of rheophilic insects (Kovalak 1976;Rabeni and Minshall 1977;Degani et al 1993;Hoffman et al 2006). Glossosoma species are generally rheophilic and are distributed in fast riffles.…”