Wetland Invertebrate Community Responses to Varying Emergent Litter in a Prairie Pothole Emergent Marsh

Plant litter produced in the interior of dense emergent stands may directly or indirectly influence invertebrate communities. Low litter may provide structure and refuge to invertebrates while high litter may displace vegetation and decrease oxygen concentration. Within an emergent stand, an edge-to-interior transect study and an interior litter treatment study were performed to investigate the impact of increasing litter densities on the invertebrate community. The interior had more litter, lemnid biomass, and hypoxia than the edge but did not differ in total invertebrate abundance. Low and moderate litter plots in the interior treatment study experienced higher lemnid biomass and greater total invertebrate abundance than the high litter plots, but the high litter plots were characterized by higher invertebrate diversity. There was a significant negative relationship between litter and invertebrate abundance in July and August. Invertebrate patterns were driven primarily by amphipod abundance and may be related to the use of lemnids as habitat. Hypoxic-tolerant and semi-aquatic taxa were associated with high litter, while several algal-feeding taxa were associated with the edge. High litter can reduce abundant invertebrates that support higher trophic levels and shift invertebrate communities. These findings underscore the importance of understanding long-term litter accumulation dynamics in wetland systems.