5/19/2015  |   13:30 - 13:45   |  101A

DENSITY DEPENDENCE OF HERBIVOROUS FISH IN STREAM MESOCOSMS Herbivorous fish can have strong effects on stream ecosystem function by consuming primary producers and excreting limiting nutrients. Thus, factors regulating their biomass and abundance might feedback to determine ecosystem function. We tested if populations of Central Stonerollers Campostoma anomalum exhibit density dependence across a range of typical densities found in Great Plains streams. We predicted that stocking density and fish growth would be negatively associated, while primary production and fish growth would show a positive relationship. Central Stonerollers were stocked across a range of densities in eight experimental stream units. Change in mass (production) was measured between the beginning of the experiment and after 41 days. Fish growth was compared to initial stocking biomass and primary production using regression analysis. Average growth of individuals was negatively associated with stocking density (r2=0.61; p=0.02). Contrary to our prediction, fish growth was not related to primary productivity (r2=0.001; p=0.93), thus density dependence occurred despite no apparent lack of food resources. We hypothesize that stoneroller growth was limited by competition for high quality algae or invertebrates, or behavioral interactions causing interference competition.

Casey Pennock (Primary Presenter/Author), The Ohio State University, pennock.17@osu.edu;


Keith Gido (Co-Presenter/Co-Author), Kansas State University, kgido@ksu.edu;

5/19/2015  |   13:45 - 14:00   |  101A

SCALING ECOSYSTEM RATES IN STREAM MESOCOSMS ALONG A GRADIENT OF CONSUMER DENSITIES Stream organisms that range in size from microbes to large predators are often patchily distributed, resulting in heterogeneous distributions of organic matter and ecosystem rates. Identifying how ecosystem properties scale from heterogeneous patches to reaches, segments and catchments is necessary to quantify critical stream ecosystem services of streams such as nutrient processing and retention. We measured ecosystem rates (gross primary productivity, net primary productivity and ecosystem respiration) at both the patch (10 cm x 10 cm basket) and reach (10 m) scales in experimental stream mesocosms that were stocked with nine densities of central stonerollers Campostoma anamolum ranging from zero to 25 g/m2. Patch and reach scale measurements of ecosystem rates were weakly related, highlighting difficulties in accurately sampling and extrapolating small-scale heterogeneity to larger scales. However, increasing densities of central stonerollers resulted in greater GPP at both patch and reach scales. The positive feedback between grazers and primary production is likely to apply at larger scales resulting in important consequences for ecosystem functioning of small streams.

Keith Gido (Primary Presenter/Author), Kansas State University, kgido@ksu.edu;


Casey Pennock (Co-Presenter/Co-Author), The Ohio State University, pennock.17@osu.edu;


Walter Dodds (Co-Presenter/Co-Author), Kansas State University, wkdodds@ksu.edu;

5/19/2015  |   14:00 - 14:15   |  101A

LIFE-HISTORY RESPONSES OF AMPHIDROMOUS FISH TO HYDROLOGIC VARIATION AMONG HAWAIIAN STREAMS Freshwater streams across the Hawaiian Archipelago are characterized by flashy flow regimes that appear to be shifting with climate change. Here, we summarize the intra-annual variability in daily stream flow on five islands, and examine how the geomorphic characteristics of catchments mediate hydrological variation. The most stable hydrologies were found in streams that drain small, steep, highly eroded catchments along the windward/rainy side of islands. More variable flow regimes were generally found on younger islands draining narrow catchments. To assess the biological consequences of hydrological complexity, we used otolith microchemistry to identify individual gobies (Awaous stamineus) that remained in the stream environment as larvae rather than going to sea. We found that the hydrologic variability was correlated to the proportion of the goby population that went to sea: the more variable the stream, the more likely that gobies are truly amphidromous. This life-history flexibility may be important for population resilience as stream flows are further altered by climate change and water abstraction for human use.

Peter J. Lisi (Primary Presenter/Author), University of Wisconsin, peter.j.lisi@gmail.com;


Peter B. McIntyre (Co-Presenter/Co-Author), Cornell University, pbm3@cornell.ecu;


James Hogan (Co-Presenter/Co-Author), Texas A&M University – Corpus Christi, james.hogan@tamucc.edu;


Michael Blum (Co-Presenter/Co-Author), Univ. Tennessee - Knoxville, mblum@utk.edu;


Jim Gilliam (Co-Presenter/Co-Author), North Carolina State Unv., jfgzo@ncsu.edu ;

5/19/2015  |   14:15 - 14:30   |  101A

ADULT RAINBOW TROUT HABITAT SELECTION IN THE HENRY'S FORK OF THE SNAKE RIVER, IDAHO The Henry’s Fork is a high-elevation, 4th-order, groundwater-dominated river with notable seasonal changes in aquatic habitat. Previous fisheries research has focused on factors limiting the rainbow trout population. As a result, management and restoration were directed toward increasing recruitment. With current population numbers now equal to historical highs, our research focus has shifted to adult rainbow trout ecology and behavior. Field work during the summers of 2013 and 2014 was conducted in order to quantify available aquatic habitat and link trout position to environmental variables. Detailed habitat surveys indicate that macrophyte cover substantially increases throughout the summer and is a strong determinant of in-stream habitat characteristics. Paired logistic regression shows that adult rainbow trout prefer greater depths. Water levels are highly dependent on macrophyte abundance at the reach scale, and available trout habitat increases through this interaction. However, when macrophyte abundance is high, adult trout show secondary preference for localized areas of lower macrophyte cover but otherwise show no selectivity for macrophyte cover, velocity, or substrate size.

Zach Kuzniar (Primary Presenter/Author), Grand Valley State University, kuzniarz@mail.gvsu.edu;


Rob VanKirk (Co-Presenter/Co-Author), Henry's Fork Foundation, robert.vankirk@humboldt.edu;


Eric Snyder (Co-Presenter/Co-Author), Grand Valley State University, snydeeri@gvsu.edu;


Mark Luttenton (Co-Presenter/Co-Author), Annis Water Resources Institute, Grand Valley State University, luttentm@gvsu.edu;

5/19/2015  |   14:30 - 14:45   |  101A

IS IT WORKING? USING FISH MOVEMENT TO ASSESS EFFECTS OF SMALL SCALE FISH HABITAT RESTORATION As part of a spawning habitat restoration we manipulated the benthic habitat of a river reach by removing fine sediments. We expected increases in fish habitat preference in the manipulated reach due to the documented negative effects of embedded substrates on salmonid populations. Prior to sand removal surficial stream substrates were nearly 100% sand in the manipulated reach as well as upstream and downstream reference reaches. Immediately after the manipulation the substrate consisted of unembedded coarse substrates in the removal reach and sand in the reference reaches. This condition was maintained throughout the year until pulse of sand bedflow embedded the manipulated substrates the following summer. We monitored brook trout (Salvelinus fontinalis) and sculpin (Cottus spp) fish movement and habitat use in each of these three phases of the substrate composition in order to test different metrics of fish habitat preference. We compared fish turnover rates, immigration rates, and densities with observed patterns of movement and use. We found immigration rate best matched expected patterns of habitat preference through time and among the different sites.

Tony Matthys (Primary Presenter/Author), Michigan Technological University, admatthy@mtu.edu;


Casey Huckins (Co-Presenter/Co-Author), Michigan Technological University, cjhuckin@mtu.edu;

5/19/2015  |   14:45 - 15:00   |  101A

SHIFTS IN FISH POPULATION DYNAMICS RELATED TO ENERGY DEVELOPMENT AND HYDROLOGY IN HEADWATER STREAMS OF THE WYOMING RANGE Natural gas development has expanded at an unprecedented rate and our understanding of how stressors associated with these activities affect aquatic ecosystems is limited. Stressors linked to natural gas development are proposed to have negative impacts to stream health unless best management practices are implemented. The objective of the study is to examine whether there have been shifts in fish population dynamics in relation to varying levels of energy development across years with differing hydrologic regimes (2012-2014). Specifically, we examined abundance and size-structure of mottled sculpin (Cottus bairdii), mountain sucker (Catostomus platyrhynchus), and Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus). Very few mottled sculpin and no cutthroat trout were collected from high energy development sites, though mountain suckers had higher abundances. At sites with low energy development, all species exhibited similar oscillating patterns in abundance that are potentially linked to differences in yearly hydrologic regimes. A better understanding of how energy development and hydrology interact to affect fish population dynamics can help guide management of these native fish species.

Richard Walker (Primary Presenter/Author), University of Wyoming, rwalker2442@gmail.com;


Annika Walters (Co-Presenter/Co-Author), University of Wyoming, awalter8@uwyo.edu;