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Increasing biodiversity and habitat complexity in invaded wetlands

Project Abstract: 
Biodiversity and ecological functions in species-rich Great Lakes coastal wetlands are threatened by aggressive invasive cattails, Typha spp. Presently, invasive cattails are the most common, spreading, and ecologically detrimental aquatic invasive plant in the St. Marys River, Les Cheneaux Islands, and Michigan’s northern lower peninsula, an area of the US Great Lakes harboring the highest quality remaining coastal wetlands. Results from 2010-2013 GLRI-funded adaptive restoration research clearly demonstrated that mechanical harvesting of invasive cattail increases plant species diversity in northern Great Lakes coastal wetlands. Here, we propose to implement this proven cattail harvesting technique to measure how cattail removal affects aquatic species diversity. We will evaluate the effectiveness of including aquatic connectivity and structural complexity treatments to harvested areas to increase fish, macroinvertebrate, and herpetofauna diversity. This work will reduce invasive plant abundance at ecologically significant locations, promote biodiversity of multiple taxa, and advance the science and practice of restoration.
Methods: 
Fish and larval amphibian communities will be monitored at the treatment wetlands three to four times throughout the growing season (spring through early fall) using two to four minnow traps and larval fish light traps per site. During each sampling period, nets and traps (net size and type will depend on the range of water depths at the site) will be set in four treatment plots at each treatment wetland over one to three nights. Fish and larval amphibians will be identified to species and enumerated. We will sample aquatic macroinvertebrates (>0.5mm) and amphibian larvae using 0.5-mm mesh, Dframe dip nets. Macroinvertebrate samples will be collected in late July-early August, when emergent plants typically reach maximum annual biomass and late instars of most aquatic insects are present and easy to identify. Larval amphibians will be sampled three to four times from early spring to summer. Where standing water is present, we will collect at least four replicates per plot that will consist of dip net sweeps at the water surface, mid-depth, and at the substrate surface. In the field, we will empty nets into white pans and pick macroinvertebrates and amphibians. In the laboratory, organisms will be sorted into the finest taxonomic class possible and richness and abundance metrics will be estimated. During fish and macroinvertebrate sampling, we will also measure basic water quality parameters in order to relate taxa richness and abundance with abiotic conditions. These parameters include: water depth, temperature, dissolved oxygen, turbidity, pH, conductivity, total N, total P, nitrate-N, ammonium-N, soluble reactive phosphorus, and chlorophyll a. We will evaluate substrate characteristics visually.
Funding agency: 
EPA: GLRI (subaward through Loyola University)