macroinvertebrate

Macroinvertebrate is a term used for invertebrates that are large enough to be seen without a microscope and that are commonly found in aquatic ecosystems. In freshwater biology, macroinvertebrates include insects, crustaceans, mollusks, and segmented worms. They inhabit streams, rivers, lakes, ponds, and wetlands, and may be found in surrounding leaf litter and soil as well.

Common groups include aquatic insects such as mayflies, stoneflies, caddisflies, dragonflies and damselflies; crustaceans like amphipods and crayfish; mollusks such as snails and freshwater mussels; and annelid worms including leeches and aquatic oligochaetes. Many insect taxa have aquatic larval or nymphal stages that live in water, while adults may be terrestrial or aerial.

Macroinvertebrates play multiple ecological roles. They act as detritivores, shredders, grazers, and filter feeders, contributing to the breakdown of organic matter and nutrient cycling. They also form a crucial food source for fish, amphibians, and other wildlife. Because their presence and community composition respond to water quality, they are widely used in bioassessment and biomonitoring.

Monitoring often involves sampling with kick nets or Surber samplers to collect representatives from different habitats, followed by analysis using indices such as the EPT (Ephemeroptera, Plecoptera, Trichoptera) richness or BMWP scores to gauge ecological condition.

Threats to macroinvertebrate communities include habitat alteration, pollution, sedimentation, invasive species, and climate change, which can reduce diversity and disrupt ecosystem functions.