Wednesday, May 20, 2015
10:30 - 12:00

<< Back to Schedule

10:30 - 10:45: / 102DE MACROINVERTEBRATE RESPONSES TO CLIMATIC EXTREMES FOLLOWING A LEGACY OF STREAM HYDROLOGIC ALTERATION

5/20/2015  |   10:30 - 10:45   |  102DE

MACROINVERTEBRATE RESPONSES TO CLIMATIC EXTREMES FOLLOWING A LEGACY OF STREAM HYDROLOGIC ALTERATION With stream restorations increasingly common, ecological data to guide these efforts are in demand. The lower Cache River (LCR) in southern Illinois suffers from reduced flow, hypoxia, and sedimentation associated with an upstream diversion ditch. Resource managers are considering a partial reconnection to its headwaters, the upper Cache River (UCR), to restore flow. We examined macroinvertebrate communities in the UCR and LCR for four summers with conditions ranging from record drought to flooding to gain insight on responses to flow variability and inform restoration and management actions. Community composition in both reaches differed significantly among years (p=0.0001). Mean body size was significantly higher in the UCR (p=0.002), and highest overall in 2011, a flood year (p=0.001). Body size of chironomids, which dominate the LCR assemblage, was positively correlated with monthly discharge in June of all years (p=0.008). Spatial variability of chironomids (calculated as biomass coefficient of variation, CV) was negatively correlated with mean discharge (p=0.04). Responses to hydrologic variation indicate restored flow in the LCR could affect food quality (invertebrate body size) and patchiness (CV) available to higher trophic levels.

Karen Baumann (Primary Presenter/Author), Murray State University, kbaumann1@murraystate.edu;


Eric Scholl (Co-Presenter/Co-Author), U.S. Geological Survey, escholl@usgs.gov;


Heidi Rantala (Co-Presenter/Co-Author), Minnesota Department of Natural Resources, heidi.rantala@state.mn.us;


Matt Whiles (Co-Presenter/Co-Author), University of Florida, mwhiles@ufl.edu;


10:45 - 11:00: / 102DE CONTRASTING RESPONSES OF BLACKFLY SPECIES (DIPTERA: SIMULIIDAE) TO EXPERIMENTAL STREAM WARMING

5/20/2015  |   10:45 - 11:00   |  102DE

CONTRASTING RESPONSES OF BLACKFLY SPECIES (DIPTERA: SIMULIIDAE) TO EXPERIMENTAL STREAM WARMING Mean global surface temperature has risen 0.89°C over the past century and may increase by an additional 3-5°C by 2100. How freshwater communities will respond is an important question, yet information allowing accurate predictions is lacking. We experimentally warmed a stream in Iceland by approximately 3.5°C using a geothermal heat exchanger, and examined the abundance, biomass, and production of two congeneric blackfly species in the warmed stream and a nearby reference stream for 1 year prior to warming and 2 years during warming. Warming had a positive effect on the abundance, biomass, and production of Simulium vittatum in the experimental stream relative to the reference stream, but had a negative effect on the abundance, biomass, and production of S. vernum. The contrasting responses of these two species likely resulted from fundamental differences in their thermal preferences and whether these species existed below or above their thermal optima before warming. Our results indicate that species-specific thermal tolerances will be important in predicting population- and community-level responses to climate change, and that even closely related species cannot be assumed to respond similarly.

Daniel Nelson (Primary Presenter/Author), University of Oklahoma, dnelson12@crimson.ua.edu;


Jonathan P. Benstead (Co-Presenter/Co-Author), The University of Alabama, jbenstead@ua.edu;


Alexander D Huryn (Co-Presenter/Co-Author), The University of Alabama, huryn@bama.ua.edu;


Wyatt Cross (Co-Presenter/Co-Author), Montana State University, wyatt.cross@montana.edu ;


James Hood (Co-Presenter/Co-Author), The Ohio State University, hood.211@osu.edu;


Philip Johnson (Co-Presenter/Co-Author), University of Alabama, pjohnson@eng.ua.edu;


James Junker (Co-Presenter/Co-Author), University of North Texas, james.junker1@gmail.com;


Gisli Mar Gislason (Co-Presenter/Co-Author), University of Iceland, gmg@hi.is;


Jón S. Ólafsson (Co-Presenter/Co-Author), Marine and Freshwater Research Institute, Iceland, jon.s.olafsson@hafogvatn.is;


11:00 - 11:15: / 102DE AQUATIC INSECT COMMUNITY STRUCTURE AND SECONDARY PRODUCTION IN SOUTHCENTRAL ALASKA STREAMS WITH CONTRASTING THERMAL AND HYDROLOGIC REGIMES

5/20/2015  |   11:00 - 11:15   |  102DE

AQUATIC INSECT COMMUNITY STRUCTURE AND SECONDARY PRODUCTION IN SOUTHCENTRAL ALASKA STREAMS WITH CONTRASTING THERMAL AND HYDROLOGIC REGIMES Streams along the Copper River Delta, southcentral Alaska, exhibit contrasting thermal and hydrologic variability associated with being primarily groundwater-fed (GWF) or surface water-fed (SWF). Groundwater-fed streams are predictable both thermally and hydrologically year round, whereas SWF streams are unpredictable and exhibit more variable thermal and hydrologic regimes. These differences may strongly influence aquatic insect community structure and secondary production. Four streams, two GWF and two SWF, were sampled twice monthly from late April 2013 through August 2013 and once seasonally in fall (September) and winter (November). Community structure differed markedly in both stream types. Diversity was significantly higher in SWF than in GWF streams. Principal components analysis of community structure revealed two distinct groups corresponding to GWF and SWF streams. Secondary production was higher in GWF than in SWF streams with Baetis sp. (Ephemeroptera) having the highest rates in both sets of streams. Results from this study have strong implications for aquatic insect communities in GWF and SWF streams because of differing susceptibilities of these systems to the potential effects of climate change.

Samantha Hertel (Primary Presenter/Author), Loyola University Chicago, shertel@luc.edu;


Martin B. Berg (Co-Presenter/Co-Author), Loyola University Chicago, mberg@luc.edu;


11:15 - 11:30: / 102DE GROUNDWATER INFLUENCE ON WINTER INVERTEBRATE COMMUNITIES IN SOUTHEASTERN MINNESOTA STREAMS

5/20/2015  |   11:15 - 11:30   |  102DE

GROUNDWATER INFLUENCE ON WINTER INVERTEBRATE COMMUNITIES IN SOUTHEASTERN MINNESOTA STREAMS Groundwater-fed streams, which remain ice-free in winter, provide ideal habitat for winter-active insects. Previous studies of these insects have focused on their thermal tolerance limits and emergence patterns; however, their relationships to groundwater input and the invertebrate community are not well-established. We documented invertebrate community composition and abundance in 36 groundwater-fed streams in southeastern Minnesota during the winters of 2010-2013. Hess samples were collected on three occasions at each site, with 12 sites sampled each winter. Dominant genera within the invertebrate communities included Baetis and Ephemerella (Ephemeroptera), Brachycentrus and Glossosoma (Trichoptera), Diamesa (Diptera: Chironomidae), and Gammarus (Amphipoda). Community composition patterns significantly varied among streams, with one or more of the dominant genera absent or nearly absent from each stream. Both invertebrate community composition and abundance were dynamic throughout the winter in each stream. Invertebrate abundance was significantly related to groundwater input, with average winter abundances ranging from 800 to nearly 10000 individuals per square meter of riffle habitat. Thus, we conclude that groundwater inputs within southeastern Minnesota's karst landscape significantly influence winter invertebrate dynamics in area trout streams.

Jane Mazack (Primary Presenter/Author), University of Minnesota, louws002@umn.edu;


Bruce Vondracek (Co-Presenter/Co-Author), Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota - Twin Cities, bvondrac@umn.edu;


Leonard C. Ferrington, Jr. (Co-Presenter/Co-Author), University of Minnesota, ferri016@umn.edu;


11:30 - 11:45: / 102DE CLIMATE WARMING AND AGRICULTURAL STRESSORS INTERACT TO DETERMINE STREAM MACROINVERTEBRATE COMMUNITY DYNAMICS

5/20/2015  |   11:30 - 11:45   |  102DE

CLIMATE WARMING AND AGRICULTURAL STRESSORS INTERACT TO DETERMINE STREAM MACROINVERTEBRATE COMMUNITY DYNAMICS Global climate change is likely to modify the ecological consequences of currently acting stressors, but potentially important interactions between climate warming and land-use related stressors remain largely unknown. Agriculture affects streams and rivers worldwide, including via nutrient enrichment and increased fine sediment input. We manipulated nutrients (simulating runoff), deposited fine sediment (simulating erosion) (2 levels each) and water temperature (8 levels, 0-6°C above ambient) simultaneously in 128 streamside mesocosms to determine the individual and combined effects of the three stressors on macroinvertebrate community dynamics (community composition and body size structure of benthic, drift and insect emergence assemblages). Changes in benthic community composition showed a complex interplay among habitat quality (with or without sediment), resource availability (with or without nutrient enrichment) and the behavioural/physiological tendency to drift or emerge as temperature rose. Of particular importance is that community measures of stream health routinely used around the world (taxon richness, EPT richness and diversity) all showed complex three-way interactions, with either a consistently stronger temperature response or a reversal of its direction when one or both agricultural stressors were also in operation.

Jeremy Piggott (Primary Presenter/Author), University of Otago, jeremy.piggott@otago.ac.nz;


Colin Townsend (Co-Presenter/Co-Author), University of Otago, colin.townsend@otago.ac.nz;


Christoph Matthaei (Co-Presenter/Co-Author), University of Otago, Dept of Zoology, New Zealand, christoph.matthaei@otago.ac.nz;


11:45 - 12:00: / 102DE HYPORHEIC COMMUNITY COMPOSITION IN A GRAVEL-BED HEADWATER STREAM OF NORTH-WEST ALGERIA: INFLUENCE OF HYDROLOGICAL EXCHANGE, SEDIMENT STRUCTURE AND PHYSICOCHEMISTRY

5/20/2015  |   11:45 - 12:00   |  102DE

HYPORHEIC COMMUNITY COMPOSITION IN A GRAVEL-BED HEADWATER STREAM OF NORTH-WEST ALGERIA: INFLUENCE OF HYDROLOGICAL EXCHANGE, SEDIMENT STRUCTURE AND PHYSICOCHEMISTRY The influence of hydraulic exchange patterns, subsurface sediment composition and interstitial physicochemistry on hyporheic invertebrate community composition was examined in four semi-arid headwater streams of North-West Algeria. We measured monthly, vertical hydrological gradient (VHG), dissolved oxygen, water temperature, PH and conductivity using mini-piezometers, each installed in a different upwelling or downwelling zone. Sediment samples and organic matter were taken along each piezometers on each date. The structure and functional organisation of hyporheic macroinvertebrate assemblages in pool and riffle bed streams were compared over summer and winter. Multivariate analyses revealed macroinvertebrate assemblages differed significantly between streams, geomorphology habitats and seasons. The hyporheos was numerically dominated by Cyclopoidae (permanent hyporheos), Gammaridae, Tubificidea, Chironomidae (occasional hyporheos), and subterranean asellidae isopods with high abundance. Species diversity (Shannon–Weaver) and taxonomic richness was significantly higer (P < 0.05) in down-welling zones than up-wellings, because more epigean taxa were present. Species diversity and taxonomic richness were lowest in up-wellings where hypogean animals dominated the hyporheic fauna.

Amina Taleb (Primary Presenter/Author), University of Tlemcen (ALGERIA), taleb_14@hotmail.com;


Nouria Belaidi (Co-Presenter/Co-Author), University of Tlemcen (ALGERIA), n_belaidi@mail.univ-tlemcen.dz;