5/20/2015  |   10:30 - 10:45   |  103AB

INFLUENCES OF RIPARIAN FOREST STAND DEVELOPMENT ON STREAM PERIPHYTON, INVERTEBRATE AND VERTEBRATE POPULATIONS IN CASCADE MOUNTAIN STREAMS, OR. Riparian forests can influence ecosystem processes and biota in adjacent streams via controls on light availability, allochthonous organic matter input and large wood recruitment. Riparian forests are dynamic though. Their influence on light, organic matter or wood changes through time as a result of stand succession, disturbance events, and anthropogenic actions. In this study, we determine how approximately 40 years of riparian forest stand development has influenced vertebrate populations across five Pacific Northwest headwater streams. We also explore more broadly the relationships between forest structure, the stage of stand development (old growth vs. mid-seral), stream habitat, periphyton stocks, and stream vertebrate populations in 9 streams with paired old-growth/second-growth study reaches. In both the stand development study and the forest comparison study we found that canopy cover and light were closely associated with differences in periphyton accrual, fish biomass, and overall stream predator biomass over time and across streams. Canopy openness was significantly correlated with total vertebrate biomass (p= 0.002). In contrast (and somewhat surprisingly) neither large wood nor total pool area were significant predictors of trout and vertebrate biomass.

Matthew Kaylor (Primary Presenter/Author), Oregon State University, matthew.kaylor@oregonstate.edu;


Dana Warren (Co-Presenter/Co-Author), Oregon State University, dana.warren@oregonstate.edu;

5/20/2015  |   10:45 - 11:00   |  103AB

AQUATIC POLLUTION INCREASES USE OF TERRESTRIAL PREY SUBSIDIES BY STREAM FISH Freshwater and terrestrial food webs are spatially linked through cross-ecosystem movements of energy and nutrients, which can augment consumer abundance and alter distribution. Reliance of consumers on cross-ecosystem subsidies depends in part on in situ resource availability, which can be reduced by anthropogenic and natural stressors. We tested the research question that as trace-metal pollution in streams increased, and aquatic prey availability decreased, stream fish (mainly Salmo trutta and Salvelinus fontinalis) would increase consumption of terrestrial insect subsidies in 16 sub-alpine headwater streams in the Colorado Mineral Belt, USA. Salmonids, the dominant fishes in these systems, increased their reliance on terrestrial insect prey (up to 50% by dry mass) as stream metals increased and aquatic prey availability decreased. Salmonid densities were unrelated to metal concentrations in fish-containing streams. Stream fish have the potential to become more dependent on terrestrial prey as aquatic stressors that limit in situ food production increase, suggesting a link between preserving aquatic-terrestrial linkages and fish populations in stressed watersheds. Specifically, intact aquatic-terrestrial linkages are likely to be important for maintaining salmonid production in moderately metal-impacted streams.

Johanna Kraus (Primary Presenter/Author), United States Geological Survey, jkraus@usgs.gov;


Justin Pomeranz (Co-Presenter/Co-Author), Colorado Mesa University, jfpomeranz@gmail.com;
o Justin is an assistant professor of environmental science at Colorado Mesa University. He is a community ecologist with a special affinity for streams and benthic macroinvertebrates. Justin’s research is focused on understanding the variation in community biomass distributions from both natural and anthropogenic causes. He enjoys working with large datasets across scales and playing the banjo. Justin received a BS and MS from Colorado State University and a PhD from the University of Canterbury in New Zealand.

Andrew S. Todd (Co-Presenter/Co-Author), U. S. Geological Survey, Crustal Geophysics and Geochemistry Science Center, Denver, CO 80225, atodd@usgs.gov;


David Walters (Co-Presenter/Co-Author), United States Geological Survey, waltersd@usgs.gov;
Dr. David Walters is a Supervisory Research Ecologist at the Columbia Environmental Research Center. David has been a research ecologist with the USGS since 2008. Prior to that, he was an ecologist for the U.S. EPA, National Exposure Research Laboratory for 6 years. He is a freshwater ecologist with broad training in stream ecology, human impacts on aquatic ecosystems, and ecotoxicology. His current research topics include food webs and contaminant flux, aquatic-riparian linkages, stream fish ecology, land use and climate change, and invasive species.

Richard Wanty (Co-Presenter/Co-Author), U.S. Geological Survey, rwanty@usgs.gov;


Travis Schmidt (Co-Presenter/Co-Author), USGS WY-MT Water Science Center, tschmidt@usgs.gov;

5/20/2015  |   11:00 - 11:15   |  103AB

SPATIAL HETEROGENEITY IN RIVER TEMPERATURE ASYNCHRONIZES AQUATIC INSECT EMERGENCE, AND PROLONGS THE FOOD SUPPLY TO PREDATORS Many natural rivers encompass microhabitats with considerable spatial heterogeneity in patch- or reach-scale water temperatures, especially during summer low flow. This temperature variation may increase the trophic efficiency of cross-habitat exchanges, so subsidies support more predators. Ephemerella maculata is a mayfly that emerges from sunlit mainstem rivers, flies into dark, unproductive tributaries, oviposits, and dies. Their mass migration subsidizes tributary predators that would otherwise be food-limited. Experimentally reared E.maculata nymphs emerged earlier at warmer temperatures. Mayflies in nature emerged earlier from warmer sunlit mainstem habitats and later from cooler, shaded or upstream reaches. While the emergence from each thermally distinct habitat lasts only two weeks, the overall, asynchronized E.maculata emergence lasted four weeks, corresponding to the observed 4-week adult flight period in tributaries. Preliminary 34S isotope analyses indicate that adults that arrived earlier in tributaries originated from warmer downstream mainstem reaches, and later arrivals came from cooler upstream habitats. The spatial thermal heterogeneity that prolongs flight periods of E.maculata also increases the duration, hence the trophic efficiency, of the subsidy they deliver to tributary predators.

Hiromi Uno (Primary Presenter/Author), Center for Ecological Research, Kyoto University, hiromiuno1@gmail.com;


Keith Bouma-Gregson (Co-Presenter/Co-Author), University of California, Berkeley, kbg@berkeley.edu;
Dr. Mary E. Power is Professor in the Department of Integrative Biology at the University of California, Berkeley. She was awarded an honorary doctorate by Umea University, the Kempe Medal for distinguished ecologists, and the Hutchinson Award from the American Society of Limnologists and Oceanographers. She is a member of the California Academy of Science, the American Academy of Arts and Sciences, and National Academy of Sciences, USA. She has served on the Editorial Board of PNAS (2014 to present) and Science (2006-2009). Mary also served as President of the American Society of Naturalists, and of the Ecological Society of America. Since 1988, she has been the Faculty Director of the Angelo Coast Range Reserve, (one of the UC Natural Reserve System sites, a 3500 ha reserve protected for university teaching and research). She has studied food webs in temperate and tropical rivers, as well as linkages of rivers, watersheds and near-shore environments. Focal organisms include cyanobacteria, algae, invertebrates, fish, estuarine crustaceans and terrestrial grasshoppers, spiders, lizards, birds and bats. By studying how key ecological interactions depend on landscape and temporal contexts, her group hopes to learn how river-structured ecosystems will respond to changes over space and time in climate, land use, and biota. Her group also collaborates closely with Earth and atmospheric scientists in site-based research to investigate linkages among riverine, upland, and near-shore ocean ecosystems.

5/20/2015  |   11:15 - 11:30   |  103AB

VARYING PREY SUBSIDY QUALITY AFFECTS THE GROWTH RATE OF SUBSIDIZED TERRESTRIAL CONSUMERS The growth and development of subsidized consumers may be limited by prey nutrient quality. Significant interspecific variation of nutrient stoichiometry in prey species may create an imbalance in predator body stoichiometry. Due to this imbalance, predators may suffer losses of growth and development time, and/or differentially excrete or store excess carbon (C) or nutrients in order to maintain body stoichiometry. For this experiment, I tested how different diets of prey (Culex quinquefasciatus, Chironomus dilutus, and Drosophila melanogaster) of varying nutrient quality affected the growth and development of predatory terrestrial spiders (Tetragnatha sp.). Spiders fed on mosquitoes (Cx. quinquefasciatus) had significantly lower body nitrogen (N) and higher C-N ratio than spiders fed on midges (C. dilutus) or fruit flies (D. melanogaster). Although spiders fed on mosquito diet had lower growth rate during early instars, growth rate increased during later instars compared to spiders fed on other diets. Spiders fed mosquitoes had significantly lower δ 13C ‰ than mosquitoes they were fed on, while other treatments did not differ significantly in isotopic signature from their prey.

Steven Merkley (Primary Presenter/Author), University of California-Riverside, steven.merkley@email.ucr.edu;

5/20/2015  |   11:30 - 11:45   |  103AB

SHORELINE HARDENING ALTERS THE STRUCTURE AND FUNCTION OF LAND-WATER INTERFACES Shoreline hardening is a widespread anthropogenic activity at terrestrial-freshwater interfaces worldwide, and these altered shorelines might be considered ‘novel ecosystems’ that bear little resemblance to their natural counterparts. We compared morphology, organic-matter dynamics, and invertebrate communities in terrestrial and aquatic habitats of natural and riprap-hardened shorelines of Lake St. Clair (Michigan, U.S.A.). In terrestrial shoreline habitats, organic matter decomposed faster on natural shorelines than on riprap. In aquatic habitats, however, decomposition rates were similar between shoreline types. Natural shorelines contained 3.5x more wrack than riprap shorelines in summer, 6x more in fall, but similar quantities in spring. The finding that natural shorelines contained more wrack despite faster decomposition suggests that wrack retention is impaired by riprap. Invertebrate community composition also differed between terrestrial habitats of natural and riprap shorelines. Exotic taxa were abundant and included European isopods, Asian earthworms, cyanobacteria (Lyngbia), and Phragmites. Riprap shorelines were steeper, drier, and had larger sediments, differences that may mediate organic-matter dynamics. Overall, riprap-hardened shorelines differ greatly from natural shorelines, particularly in terrestrial habitats, and possess attributes that qualify them as novel ecosystems.

Stacey Wensink (Primary Presenter/Author), Oakland University, smwensin@oakland.edu;


Scott Tiegs (Co-Presenter/Co-Author), Oakland University, tiegs@oakland.edu;

5/20/2015  |   11:45 - 12:00   |  103AB

METAL CONCENTRATIONS DECLINE BY AN ORDER OF MAGNITUDE DURING METAMORPHOSIS IN THE MAYFLY (BAETIS TRICAUDATUS) Insect metamorphosis can reduce contaminant concentration and alter chemical tracers with potential consequences for food web and contaminant studies. We exposed larval mayflies (Baetis tricaudatus) to aqueous zinc in the lab (3 to 340 ug/L) and measured the change in zinc concentration and stable isotopes of larvae, subimagos, and imagos. Larval zinc concentrations varied ~9-fold across the gradient, but were only marginally related to aqueous zinc. Mayflies lost ~82% of their larval zinc during the transition to subimago. Zinc was also lost during the transition from subimago to imago, but only in high zinc environments. Further, ?15N increased during emergence, while ?13C declined. These results suggest substantial chemical changes during metamorphosis. Intriguingly, mayflies in high zinc environments required a two-stage depletion process in which most zinc is lost during metamorphosis from larva to subimago, and the rest is lost during metamorphosis from subimago to imago.

Charles Nearman (Co-Presenter/Co-Author), University of South Dakota, c_nearman32@hotmail.com;


David Walters (Co-Presenter/Co-Author), United States Geological Survey, waltersd@usgs.gov;
Dr. David Walters is a Supervisory Research Ecologist at the Columbia Environmental Research Center. David has been a research ecologist with the USGS since 2008. Prior to that, he was an ecologist for the U.S. EPA, National Exposure Research Laboratory for 6 years. He is a freshwater ecologist with broad training in stream ecology, human impacts on aquatic ecosystems, and ecotoxicology. His current research topics include food webs and contaminant flux, aquatic-riparian linkages, stream fish ecology, land use and climate change, and invasive species.

Travis Schmidt (Primary Presenter/Author), USGS WY-MT Water Science Center, tschmidt@usgs.gov;


Johanna Kraus (Co-Presenter/Co-Author), United States Geological Survey, jkraus@usgs.gov;


Richard Wanty (Co-Presenter/Co-Author), U.S. Geological Survey, rwanty@usgs.gov;


Craig A. Stricker (Co-Presenter/Co-Author), USGS, cstricker@usgs.gov;


William Clements (Co-Presenter/Co-Author), Colorado State University, william.clements@colostate.edu;