Monday, May 23, 2016
15:30 - 17:00

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15:30 - 15:45: / 311-312 EXPLORING RESPONSES TO RIVER RESTORATION WITH DYNAMIC FOOD WEB MODELS

5/23/2016  |   15:30 - 15:45   |  311-312

EXPLORING RESPONSES TO RIVER RESTORATION WITH DYNAMIC FOOD WEB MODELS Restoration is frequently aimed at the recovery of target species but also influences the larger food web within which these species participate. To help incorporate these complexities into restoration planning we constructed a dynamic river food web model. We present an application of this model to the Methow River, Washington (USA), a location of on-going restoration aimed at recovering salmon. Three restoration strategies were simulated: riparian vegetation planting, nutrient augmentation, and floodplain reconnection. Simulations suggest that floodplain reconnection may be the best strategy for salmon recovery at this location. However, modeled responses were strongly sensitive to changes in the food web. The addition of non-target fishes and exotic snails modified pathways of energy through the food web, which negated restoration improvements. This finding suggests that changes in food web structure, as might be expected with the spread of invasive species, could compromise restoration outcomes. By elucidating the direct and indirect pathways by which restoration impacts target species, dynamic food web models can improve restoration planning by fostering a deeper understanding of system connectedness and dynamics.

J. Ryan Bellmore (Primary Presenter/Author), Forest Service, Pacific Northwest Research Station, Juneau, AK, jbellmore@fs.fed.us;


Joseph Benjamin ( Co-Presenter/Co-Author), USGS Forest and Rangeland Ecosystem Science Center, Corvallis, OR, jbenjamin@usgs.gov;


Michael Newsom ( Co-Presenter/Co-Author), US Bureau of Reclamation, Portland, OR, mnewsom@usbr.gov;


Jennifer Bountry ( Co-Presenter/Co-Author), Bureau of Reclamation, jbountry@usbr.gov;


Daniel Dombroski ( Co-Presenter/Co-Author), Bureau of Reclamation, ddombroski@usbr.gov;


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15:45 - 16:00: / 311-312 THE ROLE OF AQUATIC CONSUMERS TO MACROINVERTEBRATES: A FIELD EXPERIMENT IN A PACIFIC NORTHWEST STREAM

5/23/2016  |   15:45 - 16:00   |  311-312

THE ROLE OF AQUATIC CONSUMERS TO MACROINVERTEBRATES: A FIELD EXPERIMENT IN A PACIFIC NORTHWEST STREAM Species interactions in food webs can vary in strength and direction depending on the spatial scale of observation. Species with strong impacts at a certain scale can be weak at another scale. Using a field manipulation experiment during seasonal low flow in 2014, we evaluated how different densities of stream consumers (fish and amphibians) affect abundances and sizes of macroinvertebrates at the patch and reach scale in a Pacific Northwest stream. Macroinvertebrates were compared among natural, elevated, and depleted consumer densities in 70-m reaches and 1m2 mesocosms. All macroinvertebrates were aquatic in origin and mostly insects. We hypothesized that macroinvertebrates will decrease in abundance and size when consumer density increases at the reach scale and that we will see the opposite effect when consumer densities decrease. At the patch-scale, we do not expect to capture the complete food web and hence, we may observe different responses to consumer manipulations than we see at the reach-scale. Our findings reveal the importance of the spatial scale of observation when evaluating the implications of changes in food webs.

Brooke Penaluna (Primary Presenter/Author), PNW Research Station, US Forest Service, brooke.penaluna@oregonstate.edu;


Alba Argerich ( Co-Presenter/Co-Author), University of Missouri, alba.argerich@oregonstate.edu;


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16:00 - 16:15: / 311-312 SPATIAL AND TEMPORAL VARIABILITY OF STREAM FUNCTIONAL PROCESSES IN RESPONSE TO AQUATIC CONSUMER MANIPULATIONS

5/23/2016  |   16:00 - 16:15   |  311-312

SPATIAL AND TEMPORAL VARIABILITY OF STREAM FUNCTIONAL PROCESSES IN RESPONSE TO AQUATIC CONSUMER MANIPULATIONS In an effort to improve our understanding of the relationship between ecosystem structure and function and aquatic consumers at different spatial scales, we tested the effect of manipulating densities of aquatic consumers on nutrient uptake and stream metabolism in 3 streams at the HJ Andrews Experimental Forest in the Pacific Northwest of the United States. In each stream, we selected three consecutive reaches to act as natural, depleted, and elevated densities that we delineated using block nets to avoid movement of consumers for approximately 40 days. Here we present the changes observed in primary producers, ammonium uptake, ecosystem respiration, and primary production at a reach and a patch scale, and we compare them to the results found one year before at one of the sites. Results from this study will help us understand the role of spatial and temporal scale when evaluating stream functional responses to changes in the food web.

Alba Argerich (Primary Presenter/Author, Co-Presenter/Co-Author), University of Missouri, alba.argerich@oregonstate.edu;


Brooke Penaluna ( Co-Presenter/Co-Author), PNW Research Station, US Forest Service, brooke.penaluna@oregonstate.edu;


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16:15 - 16:30: / 311-312 FIRE, FOOD AND FISH: FOOD-WEB RESPONSES TO WILDFIRE AT MULTIPLE SCALES IN TIME AND SPACE

5/23/2016  |   16:15 - 16:30   |  311-312

FIRE, FOOD AND FISH: FOOD-WEB RESPONSES TO WILDFIRE AT MULTIPLE SCALES IN TIME AND SPACE We investigated multi-scale consequences of wildfire for food-webs and productivity in wilderness streams of Idaho, USA. We combined 24 years of data and a short-term, paired-stream comparison with a multifactorial analysis of fish populations and environmental variables across 12 streams spanning gradients in fire history and recovery. Paired streams exhibited similar characteristics for 11 years preceding wildfire. After wildfire in 2000, one stream retained an open-canopy; the other regrew a closed-canopy. Over 14 years post-fire, the former exhibited ~3.2× more chl-a biomass, ~2.4× more invertebrate biomass, and exhibited greater interannual range in those values. Summer estimates (2014) showed 2–3× higher primary, invertebrate, and trout production in the open-canopy stream. Proportionately, disturbance adapted invertebrates (e.g. Baetidae) fueled ~2.5× more trout production in the open-canopy stream, while terrestrial invertebrates supported ~2.3× more in the closed-canopy stream. Across 12 streams, fish biomass was best explained by a model including invertebrate biomass, light, total nitrogen, and watershed area. Our observations suggest stream productivity is resilient to wildfire, and provide evidence of a productivity pulse persisting >10 years post-fire with mediation by riparian regrowth.

Matthew Schenk (Primary Presenter/Author), Idaho State University, schematt@isu.edu;


Colden Baxter ( Co-Presenter/Co-Author), Idaho State University, baxtcold@isu.edu;


G. Wayne Minshall ( Co-Presenter/Co-Author), Idaho State University , minswayn@isu.edu;


Mirjam Schärer ( Co-Presenter/Co-Author), Swiss Federal Institute of Aquatic Science and Technology, mirjam.schaerer@bluewin.ch ;


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16:30 - 16:45: / 311-312 CLIMATE CHANGE, WILDFIRE AND A MESSAGE OF RESILIENCE FROM THE “RIVER OF NO RETURN”

5/23/2016  |   16:30 - 16:45   |  311-312

CLIMATE CHANGE, WILDFIRE AND A MESSAGE OF RESILIENCE FROM THE “RIVER OF NO RETURN” The Salmon River, Idaho is among the longest free-flowing rivers remaining in the USA, and is largely in wilderness. It has experienced climate warming, shifts in hydrology and, like much of the west, a dramatic increase in wildfire such that the majority of the basin has burned in the past 35 years. If past ecologists had peered into this future, they would likely have predicted dire consequences for aquatic ecosystems and organisms, including a suite of endangered salmonid fishes. Thus far, however, this has not occurred. Rather, numerous lines of evidence point to responses of resistance, resilience, and even invigoration. A combination of long-term and intensive studies reveal that, while habitats are often dramatically changed, organisms in some streams rapidly return to pre-fire conditions, invertebrate diversity appears stable or may even increase, many streams exhibit prolonged pulses in productivity that appear to benefit endangered fish populations as well as downstream and riparian (via emergence) organisms, and salmon are spawning in the rubble of seeming catastrophes like debris flows. Indeed, such dynamism appears essential to the ecological character of the “River-of-No-Return.”

Colden Baxter (Primary Presenter/Author), Idaho State University, baxtcold@isu.edu;


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