Tuesday, June 6, 2017
14:00 - 15:45

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14:00 - 14:15: / 301B INTEGRATING HYDROLOGY, PLANT COMMUNITIES, AND MICROBIAL COMMUNITIES TO ENHANCE MITIGATION OF GREENHOUSE GAS FLUXES IN WETLANDS

6/06/2017  |   14:00 - 14:15   |  301B

INTEGRATING HYDROLOGY, PLANT COMMUNITIES, AND MICROBIAL COMMUNITIES TO ENHANCE MITIGATION OF GREENHOUSE GAS FLUXES IN WETLANDS To better manage wetland ecosystem services for carbon sequestration, nitrogen removal, and reduced greenhouse gas (GHG) production, a deeper understanding of management impacts on microbial communities facilitating those processes is needed. These microbially mediated biogeochemical processes are dependent on soil hydrology and redox status, which determines electron acceptors available for respiration. Since plants can transport gas to and from soils, measuring plant influences on GHG fluxes is also critically important. Using a mesocosm design, we manipulated duration and hydrologic condition (i.e. stable dry, stable flooding, and interim) to induce soil redox changes. One mesocosm represents a wetland ecosystem, where half of the mesocosm included plants and the other half was absent of plants. We characterized total bacterial communities using targeted amplicon sequencing, soil physicochemical properties, redox potential, and GHG rates. Microbial community functional response to hydrology is more dynamic across a wider redox gradient and is also possibly buffered by the presence of plants. By integrating plant, microbial, and soil physicochemical responses to hydrology, we quantified how contemporary hydrologic change on wetland microbes relates to greenhouse gas emissions.

Regina Bledsoe (Primary Presenter/Author), East Carolina University, bledsoer15@students.ecu.edu;


Ariane Peralta ( Co-Presenter/Co-Author), East Carolina University, peraltaa@ecu.edu;


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14:15 - 14:30: / 301B THE INFLUENCE OF DATASET SPECIFICATIONS AND ANALYSIS PROTOCOLS ON STREAM-WETLAND CONNECTIVITY IN A COASTAL PLAIN, MARYLAND WATERSHED

6/06/2017  |   14:15 - 14:30   |  301B

THE INFLUENCE OF DATASET SPECIFICATIONS AND ANALYSIS PROTOCOLS ON STREAM-WETLAND CONNECTIVITY IN A COASTAL PLAIN, MARYLAND WATERSHED Distance-based metrics often serve as fundamental indicators when assessing stream-wetland hydrological connectivity, but whose quantification is subject to variation arising from dataset resolution, analysis methodology, and geographic scale. Evaluating this variation is needed to inform regulatory and management programs that assess wetland status based on distance. We investigate and show how differences in digital elevation model resolution, stream network definition and resolution, method of distance calculation, and watershed scale influence measured stream-wetland connectivity. Median distances between geographically isolated wetlands (GIWs) and downstream waters were 52% longer when measured via flowpaths as compared to Euclidean distance. Including riparian wetlands as part of the stream network resulted in decreased distances between GIWs and the stream network of 35-50% when comparing flowpath and Euclidean based distance approaches respectively. Altering elevation resolution did not result in differences in calculated flowpath length, but affected channel course. At a subwatershed scale, measured differences in stream density, wetland density and flowpath distance highlight the influence of landscape variability on connectivity. Disclaimer: The authors views expressed here do not necessarily reflect views or policies of USEPA or USFWS.

Jason Todd (Primary Presenter/Author), U.S. EPA, todd.jason@epa.gov;


Laurie Alexander ( Co-Presenter/Co-Author), U.S. EPA, alexander.laurie@epa.gov;


Megan Lang ( Co-Presenter/Co-Author), U.S. FWS, megan_lang@fws.gov;


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14:30 - 14:45: / 301B RESPONSE OF AQUATIC MACROINVERTEBRATE COMMUNITIES TO DISTURBANCE IN TEMPORARY WOODLAND POOLS

6/06/2017  |   14:30 - 14:45   |  301B

RESPONSE OF AQUATIC MACROINVERTEBRATE COMMUNITIES TO DISTURBANCE IN TEMPORARY WOODLAND POOLS Temporary woodland pools are common throughout the Pennyroyal Plain north of Clarksville, Tennessee. We studied the effects of disturbance on aquatic macroinvertebrate community structure in these wetlands. Our objective was to determine correlations, if any, between community structure and landscape. We used canopy density, canopy height, and vegetative buffer as disturbance metrics. Mean maximum water level was also measured as an estimate of hydroperiod. Macroinvertebrates were collected from ten sites using activity traps and substrate sampling. Identified specimens were grouped as active or passive dispersers. Significant associations were indicated between disperser ability and site (X2=2927.626, p=0.0001), which is best explained by variation in maximum water level and vegetative buffer. Mean maximum water level was negatively correlated with the proportion of active dispersers (p=0.0064) and positively correlated with passive dispersers (p=0.0078). Mean vegetative buffer and mean maximum water level were negatively correlated (p=0.0075). These findings suggest that well-buffered sites are more ephemeral, likely due to decreased runoff. More ephemeral study sites were found to have more unique communities. Disturbance impacts temporary woodland pools, including increased permanence and decreased biodiversity.

Brandy Schnettler (Primary Presenter/Author), Austin Peay State University, bschnettler@my.apsu.edu;


Steven W. Hamilton ( Co-Presenter/Co-Author), Austin Peay State University, hamiltonsw@apsu.edu;


Joseph R. Schiller ( Co-Presenter/Co-Author), Austin Peay State University, schillerj@apsu.edu;


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14:45 - 15:00: / 301B UNRAVELLING BENTHIC AND PELAGIC DECOMPOSITION PATHWAYS IN SHALLOW WETLANDS

6/06/2017  |   14:45 - 15:00   |  301B

UNRAVELLING BENTHIC AND PELAGIC DECOMPOSITION PATHWAYS IN SHALLOW WETLANDS Dead organic matter fuels shallow wetland food webs by serving as food source for microbes and invertebrates. Large amounts of plants decompose in a standing-dead position in the pelagic layer before the shoot material collapses to the benthic layer. The respective microbial and invertebrate community functioning in each layer is largely unknown. We hypothesized that shallow wetlands have different pelagic and benthic decomposition pathways due to an oxic-anoxic interface between the layers. We tested this hypothesis in 15 Dutch peat ditches (depth 50-70cm) between May and July 2016. We measured dissolved oxygen continuously, captured invertebrates, determined the functional bacterial community, and measured microbial and invertebrate decomposition rates using standard substrate DECOTABs. The results show that the relative contribution of microbial decomposition is high in the anoxic benthic layer (67% microbes vs. 33% invertebrates), whereas the invertebrate consumption is high in the oxic pelagic layer (26% microbes vs. 74% invertebrates). Hence, it can be concluded that the oxic-anoxic interface provokes a clear difference between benthic and pelagic ecosystem functioning, which has important implications for the monitoring and management of shallow wetlands.

Gea van der Lee (Primary Presenter/Author), Institute of Biodiversity and Ecosystem Dynamics, g.h.vanderlee@uva.nl;


Michiel Kraak ( Co-Presenter/Co-Author), Institute of Biodiversity and Ecosystem Dynamics, M.H.S.Kraak@uva.nl;


Ralf C.M. Verdonschot ( Co-Presenter/Co-Author), Wageningen Environmental Research, ralf.verdonschot@wur.nl;


Arie Vonk ( Co-Presenter/Co-Author), Institute of Biodiversity and Ecosystem Dynamics, J.A.Vonk@uva.nl;


Piet F.M. Verdonschot ( Co-Presenter/Co-Author), University of Amsterdam / Wageningen Environmental Research , piet.verdonschot@wur.nl;


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15:00 - 15:15: / 301B SUBSIDIES OF ESSENTIAL NUTRIENTS FROM AQUATIC TO TERRESTRIAL ENVIRONMENTS VIA AMPHIBIAN EMERGENCE

6/06/2017  |   15:00 - 15:15   |  301B

SUBSIDIES OF ESSENTIAL NUTRIENTS FROM AQUATIC TO TERRESTRIAL ENVIRONMENTS VIA AMPHIBIAN EMERGENCE Impacts of resource subsidies are not only a function of raw export, but also the relative scarcity in recipient habitats. Certain n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential in biochemical reactions, and active in critical aspects of physiology. Animals obtain LC-PUFAs from food or through de novo synthesis. Many cannot synthesize LC-PUFAs sufficient to meet physiological demands and thus benefit from consuming preformed EPA and DHA. LC-PUFAs are synthesized in great quantities by some algae and thus occur in higher amounts in aquatic habitats. LC-PUFAs can be transported across aquatic-terrestrial boundaries via emergences of animals with complex life cycles such as amphibians. We quantified n-3 LC-PUFAs transport from temporary wetlands via post-metamorphic amphibian emergence. Anurans exported a mean of 3862.3 mg of EPA, and 4925.4 mg of DHA from ponds, while salamanders exported a mean of 225.9 mg of EPA, and 99.0 mg DHA. Aquatic-origin nutrients such as LC-PUFAs may directly benefit animals foraging in and around wetland habitats, and such aquatic-terrestrial subsidies may have far-reaching effects on surrounding communities.

Kelley Fritz (Primary Presenter/Author), Southern Illinois University Carbondale, k.a.fritz@siu.edu;


Jesse Trushenski ( Co-Presenter/Co-Author), Department of Fish and Game, Eagle Fish Health LaboratoryEagle, Idaho, USA, saluski@siu.edu;


Matt Whiles ( Co-Presenter/Co-Author), Southern Illinois University, mwhiles@zoology.siu.edu;


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15:15 - 15:30: / 301B FROM SALAMANDERS TO GREENHOUSE GASSES: DOES UPLAND MANAGEMENT AFFECT WETLAND FUNCTION?

6/06/2017  |   15:15 - 15:30   |  301B

From salamanders to greenhouse gasses: Does upland management affect wetland function? While effects of forest management on watershed hydrology are recognized, little is known about how upland management impacts adjacent wetland hydrology and function. We simulated effects of upland tree basal areas and different upland management approaches on hydrology, biogeochemistry, and habitat functions of adjacent wetlands. Wetland inundation depth and duration were inversely related to upland basal area and associated forest water use. Wetlands were sinks of global warming potential, but this function increased with higher upland basal area, driven by lower methane production in drier wetlands. Amphibian habitat suitability decreased with increasing basal area due to reduced wetland inundation. Simulated 25-year management scenarios highlighted impacts of time-varying forest structure. Prescribed fire generated cyclic patterns in wetland hydrology and function, whereas pine plantations transitioned from wet to dry regimes. This work represents a first step to link upland management, wetland hydrology, and wetland function, highlighting opportunities to optimize forest management for landscape-scale function.

C. Nathan Jones (Primary Presenter/Author), Virginia Tech University, Department of Forest Resources and Environmental Conservation, cnjones@vt.edu;


Daniel McLaughlin ( Co-Presenter/Co-Author), Virginia Tech University, Department of Forest Resources and Environmental Conservation, mclaugd@vt.edu;


Kevin Henson ( Co-Presenter/Co-Author), University of Florida, kevinh1212@ufl.edu;


David Kaplan ( Co-Presenter/Co-Author), University of Florida, dkaplan@ufl.edu;


Carola Haas ( Co-Presenter/Co-Author), Virginia Tech, cahaas@vt.edu;


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15:30 - 15:45: / 301B HYDROLOGIC DRIVERS OF PEAT, VEGETATION, AND FIRE IN THE GREAT DISMAL SWAMP

6/06/2017  |   15:30 - 15:45   |  

HYDROLOGIC DRIVERS OF PEAT, VEGETATION, AND FIRE IN THE GREAT DISMAL SWAMP The forested peatlands of the Great Dismal Swamp have been greatly altered since colonial times. Drainage ditches were installed to lower water levels and allow timber harvesting. Current forest communities are largely comprised of the maturing remains from selective timber harvesting that ended in the early 1970’s. As a result, red maple has become the dominant tree species, homogenizing the mosaic of cypress-tupelo, pocosin, and Atlantic white cedar stands. Restoration efforts to repair water control structures in the ditches aim to control drainage to re-establish historic forest communities, reduce peat decomposition, and reduce fire vulnerability. We established transects where we measured water level and ecosystem attributes – i.e. vegetation composition, peat depths, and microtopography. We also tested peat samples for burn threshold moisture content to assess fire vulnerability. At wetter sites we found deeper peat, lower maple dominance, higher tree diversity and density, and higher burn threshold moisture contents. These data help explain hydrology’s effect on vegetation structure, maple dominance, fire vulnerability, and carbon storage ultimately guiding large-scale management and restoration for improved community composition and ecosystem function.

Morgan Schulte (Primary Presenter/Author), Virginia Tech, schulte@vt.edu;


Daniel McLaughlin ( Co-Presenter/Co-Author), Virginia Tech University, Department of Forest Resources and Environmental Conservation, mclaugd@vt.edu;


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