6/06/2017  |   09:00 - 09:15   |  301A

RIPARIAN CANOPY HERBIVORY STIMULATES BIOFILM AUTOTROPHY AND HETEROTROPHY IN LIGHT-LIMITED STREAMS Western spruce budworms, the dominant defoliator of coniferous forests in western North America, subsidize forest canopy organic matter contributions to stream food webs. These subsidies leach compounds that contribute nutrients and/or dissolved organic matter for biofilm metabolism. We studied differences in biofilm activity in response to litter and frass leachate amendments under ambient and experimentally reduced light conditions. Regardless of light availability, heterotrophic respiration increased with frass leachate amendments expressed on an areal basis (P<<0.001), but respiration with frass and litter leachate inputs did not differ when expressed per unit biomass. Autotrophic production was higher under ambient light when expressed on an areal basis (P<<0.001), but frass or litter had no effect, suggesting that inorganic nutrients from leachates did not stimulate production. Leachates suppressed production on a biomass basis (P<<0.001), suggesting allelopathy from conifers and the possibility that leached coniferous organic matter could moderate increased autotrophy resulting from greater light availability through canopy thinning by herbivory. Results suggest that organic matter inputs to streams via budworm herbivory could alter trophic basis of production by stimulating respiratory activity in forested streams.

Clay Arango (POC,Primary Presenter), Central Washington University, arangoc@cwu.edu;


Sally Entrekin ( Co-Presenter/Co-Author), Virginia Tech, sallye@vt.edu;


Jennifer Lipton ( Co-Presenter/Co-Author), Central Washington University, liptonj@cwu.edu;


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6/06/2017  |   09:30 - 09:45   |  301A

Phosphorus availability in the source population influences response to dietary phosphorus quantity in a New Zealand freshwater snail Variation among populations in resource availability can shape ecological and evolutionary processes. We address whether variation among populations in availability of dietary phosphorus (P) is linked to heterogeneity in growth of Potamopyrgus antipodarum, a New Zealand snail, on a P-limited diet. In juvenile snails from lakes that vary in P availability, we quantified growth rate and alkaline phosphatase (AP) expression on high vs. low-P diets. We found that P. antipodarum exhibits wide intraspecific variation in response to P limitation and some of this variation is associated with P availability in the lake of origin. In particular, snails from lakes with relatively low P availability featured the most dramatic increases in growth on the high-P diet. By contrast, although AP expression varied substantially among lineages, overall AP expression was not affected by diet treatment and was not associated with the relationship between C:P in the lake of origin and sensitivity to P limitation. Together, our results demonstrate connections between variation in dietary resource availability among populations and organismal response to P limitation as well as evidence for intraspecific variation of AP expression in animals.

Maurine Neiman (Primary Presenter/Author), University of Iowa, krist@uwyo.edu;


Laura Bankers ( Co-Presenter/Co-Author), University of Iowa, laura-rice@uiowa.edu;


Katelyn Larkin ( Co-Presenter/Co-Author), University of Iowa, katelyn-larkin@uiowa.edu;


Michele Larson ( Co-Presenter/Co-Author), University of Wyoming, mlarso22@uwyo.edu;


Daniel Greenwood ( Co-Presenter/Co-Author), University of Wyoming, dgreenw2@uwyo.edu;


Marissa Dyck ( Co-Presenter/Co-Author), University of Wyoming, mdyck@uwyo.edu;


Maurine Neiman ( Co-Presenter/Co-Author), University of Iowa, maurine-neiman@uiowa.edu;


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6/06/2017  |   09:45 - 10:00   |  301A

LONG-TERM TRENDS IN ICHTHYOPLANKTON ASSEMBLAGE STRUCTURES IN A RECOVERING FRESHWATER TIDAL EMBAYMENT Tidal freshwater systems are utilized for spawning and larval development by anadromous and freshwater fish species. Historically polluted by wastewater treatment effluent, Gunston Cove, is an embayment of the Potomac River that has shown improvement in water quality since nutrient loadings were significantly reduced in the 1980s. This improvement facilitated a transition from a phytoplankton dominated ecosystem, to a system whose primary production is driven by submerged aquatic vegetation (SAV) in the last decade. This study aims to determine effects of observed trends in environmental quality on ichthyoplankton assemblage structures. Using data from ichthyoplankton tows conducted since 1993, we employed multivariate statistical approaches to explore relationships between assemblages and environmental variables associated with nutrient loading. We found a significant difference between assemblage structures sampled within the cove during phytoplankton and SAV dominated periods. Increases in abundance of fish species that utilize SAV for spawning were found to be significant and correlated with decreases in total nitrogen, total phosphorus and total suspended solids. Outcomes from this analysis help broaden the understanding of point source nutrient reduction in ecosystems undergoing recovery.

Amanda Sills (Primary Presenter/Author), George Mason University, asills@ectinc.com;


Kim de Mutsert ( Co-Presenter/Co-Author), George Mason University, kdemutse@gmu.edu;


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6/06/2017  |   10:00 - 10:15   |  301A

INSECT PHENOLOGICAL RESPONSES TO SPATIOTEMPORAL TEMPERATURE VARIABILITY IN HEADWATERS OF LOOKOUT CREEK, OREGON Climate change drives an interest in understanding environmental controls on timing of life-history events (phenology) within and among species. Differential phenological responses of aquatic insects to changing temperature regimes could result in trophic mismatch or local extinction of populations already near their physiological limits. We collected emerging insects April-July at six headwater streams in six consecutive years (2009-2014). Streams represented a range of natural temperature regimes across the topographically complex Lookout Creek watershed in the Oregon Cascades. One mayfly (Paraleptophlebia temporalis), one caddisfly (Dolophilodes dorcus), and two stoneflies (Moselia infuscata, Alloperla fraterna) were common enough spatiotemporally for phenological analysis. We detected three types of response across the four species: 1) direct response to degree-day accumulation across years and sites (Dolophilodes); 2) direct response to degree-day accumulation within sites, but variable responses among sites resulting in coordinated emergence despite inter-site temperature differences (Alloperla, Paraleptophlebia); 3) lengthy annual emergence periods across sites coordinating adult presence at all sites through the season (Moselia). Spatial environmental heterogeneity appears to integrate complex differences among species’ phenological responses, reminiscent of a “portfolio effect” of life-history diversity.

Debra Finn (Primary Presenter/Author), Missouri State University, dfinn@missouristate.edu;
Associate Professor Stream Ecology

William Gerth ( Co-Presenter/Co-Author), Oregon State University, william.gerth@oregonstate.edu;


Ivan Arismendi ( Co-Presenter/Co-Author), Oregon State University, Department of Fisheries & Wildlife, ivan.arismendi@oregonstate.edu;


Judy Li ( Co-Presenter/Co-Author), Oregon State University, judyli@comcast.net;


Sherri Johnson ( Co-Presenter/Co-Author), U.S. Forest Service, Pacific Northwest Research Station, sherrijohnson@fs.fed.us;


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6/06/2017  |   10:15 - 10:30   |  301A

JUVENILE COHO SALMON LIFE HISTORY VARIATION IN A SPRING-FED NORTHERN CALIFORNIA RIVER The Shasta River in northern California historically produced the largest populations of coho salmon in the Klamath River system. The river’s spring-dominated hydrology provides consistent inter and intra-annual flow and the thermal and chemical characteristics of the spring sources promote high primary and secondary productivity, resulting in rapid salmonid growth rates. However, surface water diversions and land use practices have degraded salmonid habitat. To describe current habitat utilization patterns and prioritize habitat restoration needs, we studied juvenile coho salmon movements using Passive Integrated Transponder (PIT) tags and a network of twenty PIT tag detection stations located at key locations throughout the Shasta River watershed. A variety of life history tactics were observed, likely resulting from favorable conditions provided by spring inflows and unfavorable conditions due to water use practices. We observed extensive downstream and upstream movements to access thermal refugia, and rapid growth resulting in apparent smoltification at age-0, which is atypical of coho salmon in adjacent watersheds. Understanding how life history variants contribute to population dynamics is critical for implementation of recovery efforts at appropriate temporal and spatial scales.

Christopher Adams (Primary Presenter/Author), Michigan Technological University, ccadams@mtu.edu;


Bill Chesney ( Co-Presenter/Co-Author), California Department of Fish and Wildlife, bill.chesney@wildlife.ca.gov ;


Caitlin Bean ( Co-Presenter/Co-Author), California Department of Fish and Wildlife, Caitlin.Bean@wildlife.ca.gov;


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