Community structure of caddisflies along a temperate springbrook
McCabe, D.J.; Sykora, J.L.
published: Apr 14, 2000
ArtNo. ESP141014802009, Price: 29.00 €
In an in-depth analysis of zonation patterns we examined the seasonal distribution of caddisfly larvae from 22 sites along the 420 m length of an Appalachian springbrook. We used a Wilcoxin signed rank test to determine whether each species was clumped at a particular location or randomly distributed along the length of the brook. This approach permitted objective characterization of observed distribution patterns. Of the 27 species of caddisfly larvae collected during this study, 2 had upstream distributions (Apatania blacki and Lepidostoma frosti) and 4 had downstream distributions (Diplectrona modesta, Dolophilodes distinctus, Hydropsyche ventura and Paranyctiophylax nephophilus) in at least 1 season. With the exception of Parapsyche apicalis, most filtering-collector species were clustered downstream. In 2 out of 4 seasons, trichopteran species richness peaked at an intermediate distance along the springbrook. Evenness of the trichopteran community increased downstream in September, December, and June, when Apatania blacki dominated the trichopteran community at the upstream sites. Spring restricted species (Apatania blacki and Lepidostoma frosti) ranged farther downstream in September and December than in March or June. The upper distributions of downstream species fluctuated from season to season, but the changes were not consistent among species. The results illustrate that zonation patterns in springbrooks are not fixed but have a strong seasonal component.