How do substrate types affect the seasonal richness and functional feeding groups variation of benthic insects in an arid region (northeastern Algeria)?

Abstract

The diversity of bottom substrates is a primary driver of taxonomic richness and species abundance patterns of freshwater benthic insects in space and time. Here, we examine the in uence of substrate composition on the seasonal patterns of benthic insect communities in streams of arid regions. Benthic insects were sampled monthly over a year at three sampling sites distributed along the Bouilef stream within the Belezma biosphere reserve (Algeria). Different substrate types (sand, gravel, pebbles, boulders, and emergent macrophytes) were sampled in the rainy and dry seasons. During the 2 studied seasons, a total of 8599 insects belonging to 6 orders, 26 families, and 39 genera/species were sampled and identi ed. Student's t-test analysis showed that season in uences signi cantly the mean abundance of benthic insects, which increases in the rainy season. However, the season does not affect taxa richness. Substrate types in uence taxa composition and variation of benthic insect communities. The results showed that pebbles and boulders are the most populated by gathering and ltering collectors in terms of taxa abundance. Emergent macrophytes are more favorable for herbivores shredders. Principal Coordinates Analysis ''PCoA'' also showed that pebbles and boulders differed signi cantly from other substrates, whereas sand and gravel substrates exhibited similar taxa mean abundance. Such assessments can help propose conservation measures needed to successfully safeguard these fragile ecosystems.