Macroinvertebrate communities in central Platte River wetlands: Patterns across a hydrologic gradient

Wetlands provide critical wildlife habitat in the central Platte River basin of Nebraska, USA, but little is known about their macroinvertebrate communities or how factors such as hydrology affect them. In 1997, we quantified macroinvertebrate abundance, biomass, and community structure and organic matter resources in four natural wetlands that represented a gradient from ephemeral to permanent flooding. All four wetlands had abundant macroinvertebrate communities when flooded, and we observed unique taxa at all sites. Mean annual macroinvertebrate abundance and biomass increased with hydroperiod length, but taxon richness and diversity were greatest in intermittent sites. Non-insect groups, mostly crustaceans, annelids, and mollusks, were important at all sites, and their taxonomic composition shifted across the hydrologic gradient. Insect communities were dominated by dipterans (mostly Chironomidae and Ceratopogonidae) and Coleopterans (mostly Hydrophilidae and Dytiscidae), and these also varied across the hydrologic gradient. Collector-gatherers, scrapers, and predators were the dominant functional groups in terms of biomass, and biomass was most evenly distributed among these groups in intermittent sites. Macroinvertebrate communities in these riparian wetlands vary across natural hydrologic gradients, and diversity peaks in intermittent sites. Patterns of abundance, biomass, and diversity, along with seasonal patterns, suggest that, at a landscape level, a diversity of wetland habitats with different hydrologic regimes will maximize abundance and diversity of freshwater macroinvertebrate communities in this region.