Diagram depicting aquatic-terrestrial subsidies.

Many insects spend most of their lives as aquatic larvae/nymphs and emerge as adults to reproduce. These adults subsidize terrestrial food webs when terrestrial predators like birds and spiders consume them. In regions with low terrestrial productivity, these subsidies can be highly important to sustaining terrestrial food webs. Despite this, we know very little about what conditions structure subsidy biomass, quality, and distance-decay (from a given stream) in the Great Basin, the driest region in North America. My PhD work looks to inform our understanding of these regional subsidies through examining how conditions like drought, hydrological regime, and management decisions can affect subsidy characteristics. 

While understanding dynamics within a given reservoir is important (see above), it's also critical to understand how ecosystem level processes and overall function may vary between years in a given system. This is especially true for reservoirs, which serve as a primary drinking water source for many communities in the central U.S. By leveraging multi-year buoy data from three large reservoirs in central/eastern Kansas (Tuttle Creek Lake, Marion Reservoir, Clinton Lake), we're developing a clearer picture of how consistent (or inconsistent) reservoir ecosystem function is year-to-year. With this design, we are also better understanding large scale influences (land use, reservoir morphology, annual weather patterns) on lake metabolism.

Real-time monitoring buoy deployed on Marion Reservoir, KS. Photo by Chris Frazier 

Andrew Karlin (center) and Taylor Conley (right) examining large branchiopod communities in our field mesocosms, Lawrence, KS. Photo by Chris Frazier.

Taxa found in ephemeral wetland communities can generally be split into two categories: colonizers and residents. Resident taxa are dominated by large branchiopods (fairy, clam, and tadpole shrimp), while colonizers are typically insects (beetles, dragonflies, bugs) that prey upon or directly compete with the branchiopods. Under the pretense of climate change, source populations of colonizing aquatic insects will likely become fewer and more distant from isolated temporary wetlands; what does this mean for the branchiopods? We investigated this concept using an insect-excluding treatment in mesocosms with rehydrated playa sediment. We found that while insect colonization did not change community composition, it did change population-level characteristics, including mean body size, time to maturity, and abundance, and did so differently for two species of fairy shrimp. This means that the effects of isolation and cutoff from colonization will have taxon-specific consequences that may change the ecosystem function contribution of those taxa.

Sunset on Clinton Lake, KS. Photo by Chris Frazier

Reservoirs are the dominant lentic habitat type in the American Great Plains but our understanding of their ecology and function is lacking, despite the critical link between ecology, water quality, and their capacity as a major drinking water source. Through the study of lake metabolism, or the balance between gross primary production (GPP) and ecosystem respiration (ER), we can simultaneously gather information about ecosystem function and ecology in lentic ecosystems. Using an array of real-time monitoring buoys on Clinton Lake, Kansas, we studied how lake metabolism varies over the course of a year and across space, and what environmental conditions drive overall metabolism and its components (GPP, ER). We found that stratification strength is a major driver of these patterns, likely associated with blooms of buoyant cyanobacteria that dominate during periods of strong stratification but struggle to photosynthesize when the reservoir mixes.

Studies of hydrology's influence on macroinvertebrate community composition are often restricted to comparisons of geographically close wetlands of drastically different hydrologic regimes. We're currently investigating the inverse: how do wetland communities vary under similar hydrologic regimes across vast differences? Our forthcoming publication examines communities from North Dakota through Texas in terms of taxonomic and functional composition and diversity.

A large ephemeral wetland on Padre Island, TX. Photo by Chris Frazier.

Bison at Konza Prairie, Manhattan, KS. Photo by Chris Frazier.

If you've ever had the opportunity to watch a herd of bison, you'll notice they love to take dust baths. A byproduct of 1000+ lbs. of ungulate writhing on the prairie is the formation of shallow depressions with substrate packed tightly enough to hold water. In analogous systems in Africa and Europe created by large mammals (elephants and boar, respectively), these habitats offer prime conditions for large branchiopods (fairy, clam, tadpole shrimp; Anostraca, Spinicaudata/Laevicaudata, Notostraca, respectively). We found that sediment in bison wallows contains viable clam shrimp and tadpole shrimp eggs, but the spatial arrangement and density of these eggs within wallows is highly stochastic. 

Sand dunes along the eastern shore of Lake Michigan have long been a case study for ecological succession, but this framework had historically been limited to the terrestrial dune habitat. In the low-lying areas between dune crests are a globally-imperiled, highly dynamic wetland habitat type known as interdunal wetlands. We studied how these habitats and communities change through time with a space-for-time approach: wetlands nearer the lakeshore represent younger habitat, while those further inland are older. Along this gradient there are dramatic shifts from high wind, low nutrient, and few macrophytes in the open dunes to sheltered, high nutrient, macrophyte-dense wetlands beyond the treeline. This change in habitat conditions begets strong variation in community composition, both in terms of taxonomic and trait assemblage. Younger wetlands have low diversity and are characterized by traits centered around opportunistic development (multiple generations per year, strong dispersal capability), while communities in older wetlands capitalize on hydrological stability and trophic resource diversity (longer lived macroinvertebrates and increased trophic strategy diversity).

Schriever lab studying interdunal wetlands at Sleeping Bear Dunes National Lakeshore, MI. Photo by Tiffany Schriever.