Interaction of climate variability and landscape modification on trophic structure and amphipod populations in prairie wetlands: Implications for waterbird habitat conservation

Waterbirds breeding at wetlands in North Dakota forage mostly on aquatic invertebrates. Historically, productivity and abundance of aquatic invertebrates primarily was driven by inter-annual hydrological dynamics (i.e., wet-dry cycles). Wetland drying allows for nutrient cycling and a subsequent pulse of productivity when wet conditions return. However, abundance and quality of wetlands in North Dakota has declined due to landscape modifications, primarily agriculture. Consolidation drainage, a practice of draining less permanent wetlands into larger more permanent ones, is common in North Dakota and it increases connectivity and stabilizes water levels among remaining wetlands. For the effective management and restoration of wetland habitats targeted to species of conservation priority, it is critical that we understand how drainage and consolidation of wetlands and upland disturbances ultimately influence productivity in wetlands, but also how they might interact with inter-annual hydrological dynamics of wetlands. Moreover, understanding connections between inter-annual hydrological dynamics and landscape modifications is prerequisite step to modeling the effects of climate change on the hydrological function and productivity of prairie wetlands. In prairie wetlands, the abundance of amphipods (scuds) are indicators of both wetland and water quality because they are sensitive to contaminants, disturbances in uplands, and invasive species. In 2004–2005 amphipod abundance was low across the upper-Midwest (including North Dakota), perhaps due to landscape modifications. However, most of the prairies were in a drying period in 2004–2005, after relatively long stable high-water conditions, so amphipod numbers could have been low due to a period of little inter-annual variation. In 2009 wet conditions returned to prairie wetlands, following a period of sustained moderate to severe drought in North Dakota. We will compare amphipod densities from wetlands throughout North Dakota in 2010 and 2011 (pulse years in cycle) to those from there in 2004 and 2005 (drying years in cycle), this should provide, 1) estimates for upper- and lower-bounds of amphipod densities for this landscape, 2) an ability to tease apart how position in hydrological cycle and landscape modification influence amphipod abundance, and 3) an ability to examine how landscape modification influences interannual variation in wetland hydrology and ultimately wetland productivity. Higher more stable water regimes with more connected basins may favor invasive species because native communities were evolved in a dynamic and isolated system, and provides colonization corridors for invasive species (e.g., fish and cattail) that threaten natural functions of prairie wetlands. In 2004–2005, fish and cattails apparently were more prevalent in prairie wetlands than they were historically, having implications for the abundance and quality of both forage and habitat structure for waterbirds. Therefore, it also is important to understand how landscape modifications have influenced the abundance and distribution of fish and cattail in prairie wetlands of North Dakota. Programs to protect and restore wetlands have historically focused on restoring wet conditions, because there is not enough information to structure these programs to restore ecosystem function and improve or restore productivity. This study will provide information to managers about drivers of productivity and function in wetlands in relation to natural, climate, and anthropogenic influences. Specifically, this study will provide 1) an understanding of how drainage and consolidation of wetlands and upland disturbances ultimately influence productivity in remaining wetlands, 2) how those disturbances might interact with inter-annual hydrological dynamics of wetlands, and 3) provide a basis for modeling hydrological and productivity changes of wetlands in relation to climate change forecasts.

Principal Investigator(s):

Michael J Anteau

Project Status:

Completed

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