Biology
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Item A BIODEGRADABLE POT TECHNIQUE, AND EMERGY ANALYSIS TO IMPROVE RESTORATION OUTCOMES OF POTAMOGETON PERFOLIATUS L.(2018) Zinecker, Elizabeth Kirsten; Kangas, P. C.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Potamogeton perfoliatus (L.) (P. perfoliatus), is a species of submersed aquatic vegetation (SAV) in mesohaline Chesapeake Bay that provides important ecosystem services but has been in decline. Efforts to restore its populations have met with mixed success. While the challenges to healthy SAV growth such as inadequate light for photosynthesis, poor water quality, and site disturbance have been well documented, studies using microcosms have failed to specifically examine other factors such as propagule type and seed storage duration, source population, plant growth response to a fully characterized substrate, and planting techniques, for the duration of an entire simulated growing season. Also, no studies have conducted an environmental cost accounting to assess the sustainability of a given restoration approach. This research investigated the growth and reproductive responses of P. perfoliatus propagules to various substrates and planting techniques; and conducted an emergy analysis case study, a type of environmental cost accounting, to compare two restoration techniques. P. perfoliatus net primary productivity and reproductive potential was highest when grown in sediment cores taken from SAV beds (~1.0gDW/m2/day, 18% stems with inflorescences), with peat/oyster shell being the next most desirable substrate choice for propagation (~0.86 gDW/m2/day, 4% stems with inflorescences). Seeds grown in biodegradable pots grew no differently than seeds grown in control polyethylene pots, or seeds planted by hand onto the bare sediment surface of the microcosm, (although hand-planting required multiple attempts to keep buoyant, germinated seeds in place). Seeds grown from harvests four years apart also showed no differences in yield (~0.56 gDW/m2/day). Biodegradable pots lost on average 60 percent of their mass over 12 weeks, and degraded more in brackish vs. fresh SAV bed sediments in the field. Emergy analysis indicated that planting seed-filled biodegradable pots resulted in 97% more area (m2) SAV bed restored than hand transplanting sods, and was more ecologically sustainable. These results indicate that appropriate substrates for propagation and restoration sites, and the ability to securely place propagules in the sediment, may be critical to P. perfoliatus establishment and success, thereby enhancing SAV habitat in Chesapeake Bay.Item Alternate state theory and tidal freshwater mudflat experimental ecology on Anacostia River, Washington, D.C.(2007-11-13) may, peter; Kangas, Patrick; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The concept that multiple community states may alternately exist for some ecosystems has been the subject of controversy for decades. This theory is tested and applied to the mudflats of the low/middle marsh intertidal zone of two restored freshwater tidal marshes on the Anacostia River. It is believed that experimental exclosures exposed strong species interactions and provided a window with which to view the potential alternate existence of two structurally different systems, intertidal mudflat and emergent marsh. The occurrence, persistence and community composition of the two ecosystem states are examined through experimental exclosures at the two marsh restoration study areas. The power of large grazers to deflect the goals of wetland restoration practitioners is studied in the context of alternate state theory. Initially unvegetated mudflat, native marsh vegetation emerged within exclosure study areas at two restoration sites. Resident Canada geese (Branta canadensis maxima) decimated planted areas of restored marsh left open to grazing, returning marsh to unvegetated mudflats. Data from exclosures are presented on macrophyte community composition, sediment elevation, bird, fish, invertebrate and algae associations from two separate sets of Anacostia River experimental exclosure sites, one covering 588 m2, the other covering 2,700 m2. Results support the hypothesized alternate existence of the two system states in the same space and relative time, each dependant upon the access of a critical mass of large grazers. A description of the mudflat biotic community and its interconnectivity is discussed as an important feature of the Anacostia River system. An emergy analysis of each state and an accounting of fisheries energy flow is conducted. Information collected relating to the pre-restoration (tidal mudflat) and post-restoration (emergent marsh) physical and biological conditions are detailed and analyzed. A determination of the emergy inputs for a large-scale marsh restoration project are calculated and as a final analysis, economic (emdollar) equivalents are developed to compare the yield of fisheries production supplied by mudflats vs. a restored and mature emergent freshwater tidal marsh. Through these studies support is given to valuing mudflats as important system components of Anacostia River.