Relative Importance of Substrate Particle Size and Detritus to Stream Benthic Macroinvertebrate Microdistribution

Abstract

Manipulative field experiments were conducted in Carnation Creek, British Columbia, to determine whether particle-size composition of the stony substrate influenced macroinvertebrate microdistribution if substrate detritus was standardized. A standardized quantity of alder (Alnus rubra) detritus was added to five substrate mixtures ranging from homogeneous gravel to a heterogeneous gravel, pebble, and cobble mixture, and the substrates imbedded in a riffle to allow macroinvertebrate colonization. Densities and biomasses of most macroinvertebrate taxa (16 of 19) were not significantly different among the wide range of substrate types containing the standardized alder detritus, even though surface area, intra-substrate current velocity, and interstitial space varied significantly between treatments. However, in the treatment that did not have the standardized detritus, the biomasses and densities of nine taxa, and the totals of all taxa combined, were significantly lower than in an identical substrate mixture that contained the detritus. We concluded that the differential colonization of substrates demonstrated for many macroinvertebrate taxa in previous studies was more likely related to differences in organic sedimentation. Although detritus is a major determinant of detritivore microdistribution, substrate composition may be an important factor to other trophic groups such as filter-feeders.

The relative influence of geographic location and reach-scale habitat on benthic invertebrate assemblages in six ecoregions

“…Substrate has long been recognized as a major controlling factor for benthic invertebrates in that it commonly explains much of the invertebrate assemblage composition and distribution of populations (Rempel et al 2000;Richards et al 1993). The importance of substrate in controlling benthic invertebrates is related to organic matter retention (Culp et al 1983), biotic interactions of predation and competition (Lancaster et al 1990), and providing in-stream flow refugia from hydraulic stress (Lancaster and Hildrew 1993). The role of substrate in our study was shown by the importance of percent CG in the ecoregion specific analysis for four of the ecoregions.…”

Factors Affecting Macroinvertebrate Richness and Diversity in Portuguese Streams: a Two‐Scale Analysis

“…In a manipulative experiment with baskets containing sediments differing in heterogeneity and detritus content, WILLIAMS, (1980) showed that higher biomass and numbers of invertebrates were attained in treatments with more detritus, independently of substratum heterogeneity. In another manipulative experiment, CULP et al, (1983) andDAVIES, (1985) reported that the addition of organic material to inorganic sediments of several particle sizes generally resulted in an increase in the number of individuals and/or in total invertebrate biomass. Detritus accumulation may enhance habitat heterogeneity, but several manipulative experiments have shown that the food value of coarse particulate organic matter, and not heterogeneity, is a main determinant of preferential colonization of substrate by invertebrates (RICHARDSON, 1992;GRAÇA and PEREIRA, 1995).…”

Change does not happen overnight: a case study on stream macroinvertebrates

“…In our fieldwork study, the only difference found in terms of community composition and environmental variables was represented by the "mean riverbed substrate diameter" variable, which was relevant when considering the daytime data. The dependence of community structure on riverbed typology is a matter of constant debate (e.g., Culp et al, 1983;Barnes et al, 2013;Laini et al, 2014), although features like size, constitution or complexity have often been shown to influence macroinvertebrate diversity, structure or preferences in different streams and regions (e.g., Gayraud and Philippe, 2001;Graça et al, 2004;Barnes et al, 2013;Fu et al, 2015).…”