Wednesday, May 25, 2016
10:30 - 12:00

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10:30 - 10:45: / 315 UNDERSTANDING THE ECOLOGICAL COSEQUENCES OF DAM REMOVAL UTILIZING TRENDS IN MACROINVERTEBRATE COMMUNITY DATA

5/25/2016  |   10:30 - 10:45   |  315

UNDERSTANDING THE ECOLOGICAL COSEQUENCES OF DAM REMOVAL UTILIZING TRENDS IN MACROINVERTEBRATE COMMUNITY DATA Dam removals have increased rapidly in the last two decades, a trend that is expected to intensify on a global scale. Unfortunately this trend has not coincided with an increase in the number of published dam removal studies. Such studies are vital to assure that best practices are utilized when removals are decided and what should be expected in terms of ecological responses. It is well known that the installation of dams result in a press disturbance that can strongly alter the structure and dynamics of habitats and biota. The removal process results in a pulse disturbance that is suggested to have only short-term negative effects, followed by recovery to ecological conditions exceeding those prior to dam removal. In order to contribute to an improved understanding of the ecological response we conducted an investigation of macroinvertebrate responses in terms of biodiversity and indicators to dam removal utilizing a world-wide dataset including pre- and post-dam removal. Spatiotemporal trends in macroinvertebrate community metrics were shown to differ downstream of the dam, within the impoundment, and upstream of the impoundment.

Peter Carlson (Primary Presenter/Author), Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden, peter.carlson@slu.se;


Leonard Sandin ( Co-Presenter/Co-Author), Department of Aquatic resources, Swedish University of Agricultural Sciences , Leonard.Sandin@slu.se;


Erik Degerman ( Co-Presenter/Co-Author), Swedish University of Agricultural Sciences, erik.degerman@slu.se;


Claudia Von Brömssen ( Co-Presenter/Co-Author), SLU University, claudia.von.bromssen@slu.se;


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10:45 - 11:00: / 315 DAM REMOVAL INFLUENCES THE DIETS OF THE FILTER FEEDER STENOPSYCHIDAE SP. IN STREAM ECOSYSTEMS

5/25/2016  |   10:45 - 11:00   |  315

DAM REMOVAL INFLUENCES THE DIETS OF THE FILTER FEEDER STENOPSYCHIDAE SP. IN STREAM ECOSYSTEMS Aquatic insects are good bioindicators in stream ecosystems. The isotopic signals of its body and stomach contents show long-term diet assimilated and those are not digested, respectively. We hypothesized that isotopic signal of body and stomach contents can be used to infer the flow condition in the field. We collected Stenopsychidae sp. samples for analyzing stable isotopes at sites above (#1?#2) and below (#3?#4) the dam in the period before and after dam removal. The standard ellipse areas (SEA) were calculated to determine the isotopic niche. The results showed that the isotopic niches of the body and stomach contents were smallest at site #3 before dam removal. The niches were getting similar at all sampling sites after dam removal. This indicated that the food sources were less diverse below check dam before dam removal. And the food sources showed little difference after dam removal. In conclusion, the existence of check dam would make the ecosystem less diverse food sources below the dam and the food sources of stream ecosystems would be unimpeded after dam removal.

Hao-Yen Chang (Primary Presenter/Author), Department of Life Sciences, National Chung Hsing University, Taiwan ROC, peter710503@gmail.com;


Ming-Chih Chiu ( Co-Presenter/Co-Author), University of California, Berkeley, mcchiu@berkeley.edu;


Hsing-Juh Lin ( Co-Presenter/Co-Author), Department of Life Sciences, National Chung Hsing University, Taiwan ROC, hjlin@dragon.nchu.edu.tw;


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11:00 - 11:15: / 315 EFFECT OF WILDFIRES ON STREAM THERMAL REGIMES AND IMPLICATIONS FOR FRESHWATER FISH ACROSS THE PACIFIC NORTHWEST

5/25/2016  |   11:00 - 11:15   |  315

EFFECT OF WILDFIRES ON STREAM THERMAL REGIMES AND IMPLICATIONS FOR FRESHWATER FISH ACROSS THE PACIFIC NORTHWEST The magnitude of past year’s wildfire season in the Pacific Northwest emphasized the need for understanding the ecological implications of such disturbance events for freshwater ecosystems. The thermal regimes of streams and their resident fish communities are believed to be sensitive to wildfire effects, yet our current understanding of these impacts are limited to individual watersheds or burn events. In this talk, we report on the results of a broad-scale investigation of how stream thermal regimes across the Pacific Northwest have responded to wildfires, and explore the implications of these impacts for native Chinook salmon and nonnative smallmouth bass and northern pikeminnow. Our results demonstrate the spatial variability in streams response to fire, and illustrate how changes to the thermal regime can have disproportionate effects on the phenology and distribution of native and nonnative species. Predicted changes in wildland fire behavior as a result of climate change give precedence for research such as this to inform the science and management of fire as it affects freshwater systems across landscapes.

Elliot Koontz (Primary Presenter/Author), University of Washington, Seattle, ekoontz@uw.edu;


E. Ashley Steel ( Co-Presenter/Co-Author), PNW Research Station, US Forest Service, asteel.usfs@gmail.com;


Julian Olden ( Co-Presenter/Co-Author), University of Washington, olden@uw.edu;


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11:15 - 11:30: / 315 THE RESPONSES OF MACROINVERTEBRATES TO REMOVAL OF RIPARIAN RHODODENDRON UNDERSTORY IN SOUTHERN APPALACHIAN STREAMS

5/25/2016  |   11:15 - 11:30   |  315

THE RESPONSES OF MACROINVERTEBRATES TO REMOVAL OF RIPARIAN RHODODENDRON UNDERSTORY IN SOUTHERN APPALACHIAN STREAMS Southern Appalachian forests are in a time of change, as the eastern hemlock, once a dominant canopy species, is disappearing due to the parasite hemlock wooly adelgid. The void left by hemlock loss is being filled by a Rhododendron understory. Working in conjunction with the U.S. Forest Service at the Coweeta LTER, a manipulation of the riparian Rhododendron understory was conducted along 4 streams in the Wine Spring Creek basin in the Nantahala National Forest in western North Carolina. The sites were chosen based on the abundance of riparian rhododendron and prior hemlock abundance. The treatments for the riparian rhododendron involve differing levels of cutting and burning. We are performing pre- and- post treatment analyses following a BACI design. The study will measure the change in community assemblage, density, and functional traits of the macroinvertebrates in the streams. Preliminary multivariate analysis shows the 4 streams to have similar community composition pre-treatment, and seasonal changes.

Kevin Eliason (Primary Presenter/Author), Virginia Tech, eliasonk@vt.edu;


E.F. Benfield ( Co-Presenter/Co-Author), Virginia Tech, benfield@vt.edu;


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11:30 - 11:45: / 315 RECOVERY OF BENTHIC PRIMARY PRODUCERS TO FLOOD DISTURBANCE IN A TROPICAL SAVANNAH RIVER

5/25/2016  |   11:30 - 11:45   |  315

RECOVERY OF BENTHIC PRIMARY PRODUCERS TO FLOOD DISTURBANCE IN A TROPICAL SAVANNAH RIVER The recovery of benthic primary producers during prolonged dry season base-flow (June to November) to wet season (January to March) flood disturbances in the Daly River, northern Australia, is examined. A 3.3 km long reach comprising a pool-run-pool-run sequence was surveyed on four dates during the dry season for periphyton microalgae, visible Spirogyra, charophytes, and the vascular macrophyte Vallisneria nana. Benthic primary producers had low resistance to flood disturbance, with the exception of the perennial V. nana which survived through rhizomes and leaves. Micro- and macro-algae most likely colonize the riverbed from propagules from off-channel water bodies and low-order streams. The net total dry weight biomass of primary producers increased 30-fold between June and November. Charophytes and V. nana contributed most to the reach’s standing crop in November, but were negligible in June. Climate change and water resource developments will affect the resistance and resilience of benthic primary producers through altered flows. These impacts will vary between the plant groups examined and the flow scenario, and need to be understood within the context of naturally high inter-annual flow variability.

Simon Townsend (POC,Primary Presenter), Charles Darwin University, simon.townsend@nt.gov.au;


Julia Schult ( Co-Presenter/Co-Author), Department of Land Resource Management, julia.schult@nt.gov.au;


Michael Douglas ( Co-Presenter/Co-Author), University of Western Australia & Charles Darwin University, michael.douglas@uwa.edu.au;


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11:45 - 12:00: / 315 THE INFLUENCE OF SUCCESSIONAL STATE ON COMMUNITY RESPONSES TO DISTURBANCE IN POND MESOCOSMS

5/25/2016  |   11:45 - 12:00   |  315

THE INFLUENCE OF SUCCESSIONAL STATE ON COMMUNITY RESPONSES TO DISTURBANCE IN POND MESOCOSMS Communities undergo succession after a significant disturbance. Though we know that succession follows disturbance, we are still unsure how successional state impacts the response of a community to additional perturbation. The time interval between disturbances represents an opportunity for colonization, acclimation, and community-wide recovery, each of which can alter the structural components of a community that confer stability. Using pond mesocosms, we examined the effect of community age (analogous to time since last disturbance) on vulnerability to a drying disturbance. We recorded changes in community composition both immediately following disturbance and over a recovery period after pond re-filling, tracking changes in algae, zooplankton, and macroinvertebrates to quantify relative community resistance and resilience in ponds of different ages. We observed an interactive effect of drying disturbance and community age on multiple trophic levels and recovery patterns, suggesting that changes to community structure over the time between disturbances altered vulnerability to further disturbance . This research highlights the importance of integrating disturbance history and successional state into our understanding of community vulnerability.

Jessica Haghkerdar (Primary Presenter/Author), University of Maine, jessica.haghkerdar@maine.edu;


Jack McLachlan ( Co-Presenter/Co-Author), University of Maine, jack.mclachlan@maine.edu;


Emma Toth ( Co-Presenter/Co-Author), University of Maine, emma.toth@maine.edu;


Alexis Ireland ( Co-Presenter/Co-Author), Orono High School, alexisireland2017@rsu26.org;


Hamish Greig ( Co-Presenter/Co-Author), University of Maine, hamish.greig@maine.edu;


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