Relationships Between Benthic Organic Matter and Invertebrates in Sand Substrates of Northern Michigan Streams

Relationships between benthic organic matter (BOM) and macroinvertebrates have been well studied in streams with coarse substrates, but such relationships have been little studied in sand habitats, despite the abundance of sand in many streams. These relationships were investigated in sand habitats of 15 streams in three watersheds of the Ottawa National Forest, Michigan. BOM size composition and macroinvertebrate biomass in sand habitats differed among the three watersheds. However, at this broad spatial scale, BOM quantity and quality had little effect on invertebrate community metrics in sand habitats. Sand-dwelling invertebrates were dominated by gathering- collectors, primarily Chironomidae, in all streams. A 32-day colonization experiment demonstrated that at a local scale BOM content of sand significantly affected macroinvertebrate abundance, biomass, and functional feeding group composition. BOM content of sand habitats likely represents one factor, among many components of this dynamic habitat, which shapes overall macroinvertebrate communities.