SFS Annual Meeting

5/20/2019  |   09:00 - 09:15   |  250 DE

DEVELOPMENT AND APPLICATION OF THE “TROPHIC BASIS OF PRODUCTION” METHODOLOGY IN QUANTIFYING FOOD WEBS Attempts to describe food webs go back >100 years, but the vast majority have been qualitative (who eats whom). In contrast, “energy flow” studies (starting with Lindeman, Odums) were quantitative, but initially limited to flows between “trophic levels” rather than between taxa or functional groups. More detailed energy flow studies followed, especially during the years of the International Biological Program, often focusing on major taxa or function groups. A taxon-based approach using secondary production and quantitative gut analyses was developed in 1980 to estimate the “trophic basis of production” (TBP); i.e., how much individual foods contribute to production of individual taxa. This approach eventually led to estimating complex taxon-specific flow webs, as have now been demonstrated for entire communities (mostly freshwater) by many participants in this session. Unlike early energy flow studies, estimation of bottom-up flows with the TBP approach makes it possible to estimate top-down predator impacts and trophic position of all taxa within a community. I describe the history of how the approach was developed, how it compares with other attempts to quantify food webs, and why to date it has been limited to freshwater communities.

Arthur Benke (Primary Presenter/Author), University of Alabama, abenke@ua.edu;


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5/20/2019  |   09:15 - 09:30   |  250 DE

DEVELOPMENT AND APPLICATION OF THE “TROPHIC BASIS OF PRODUCTION” METHODOLOGY IN QUANTIFYING FOOD WEBS Attempts to describe food webs go back >100 years, but the vast majority have been qualitative (who eats whom). In contrast, “energy flow” studies (starting with Lindeman, Odums) were quantitative, but initially limited to flows between “trophic levels” rather than between taxa or functional groups. More detailed energy flow studies followed, especially during the years of the International Biological Program, often focusing on major taxa or function groups. A taxon-based approach using secondary production and quantitative gut analyses was developed in 1980 to estimate the “trophic basis of production” (TBP); i.e., how much individual foods contribute to production of individual taxa. This approach eventually led to estimating complex taxon-specific flow webs, as have now been demonstrated for entire communities (mostly freshwater) by many participants in this session. Unlike early energy flow studies, estimation of bottom-up flows with the TBP approach makes it possible to estimate top-down predator impacts and trophic position of all taxa within a community. I describe the history of how the approach was developed, how it compares with other attempts to quantify food webs, and why to date it has been limited to freshwater communities.

Arthur Benke (Primary Presenter/Author), University of Alabama, abenke@ua.edu;


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5/20/2019  |   09:30 - 09:45   |  250 DE

WHEN FLOW FOOD WEBS GET FISHY: SOME CHALLENGES AND OPPORTUNITIES Energy-flow food web (FFW) approaches were developed and principally applied to stream invertebrates. Extended to fishes they yield challenges and opportunities that we evaluate in the context of case studies. Challenges of perception occur with the fisheries discipline, and include the idea that the approach is too laborious, a lack of understanding of production measures, a drift-feeding framework driven by a focus on salmonid fishes, and an existing paradigm of single-species bioenergetic models that may not translate well to communities. Real challenges include the need to adapt FFW calculations to fishes whose net production efficiencies change with size/age, concerns regarding fish movement and spatial origin of food resources, weighing sources of error in population estimates vs. error in FFW calculations, and tension between instantaneous measures of species interactions versus those integrated over longer time-steps. Opportunities include potential to reveal foodweb mechanisms responsible for responses by fish populations to management actions, investigate the likelihood of food limitation of fish populations, estimate the distribution and dynamics of interaction strengths in food webs that include fishes, and test general ecological theory using more complete, complex freshwater food webs.

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


J. Ryan Bellmore (Co-Presenter/Co-Author), USGS Forest and Rangeland Ecosystem Science Center, Corvallis, OR, jbellmore@usgs.gov;


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


Robert O. Hall (Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana, bob.hall@flbs.umt.edu;


Ted Kennedy (Co-Presenter/Co-Author), USGS Southwest Biological Science Center, Grand Canyon Monitoring and Research Center, tkennedy@usgs.gov;


Amy Marcarelli (Co-Presenter/Co-Author), Michigan Technological University, ammarcar@mtu.edu;


James Paris (Co-Presenter/Co-Author), Stream Ecology Center, Dept. Biological Sciences, Idaho State University, parijame@isu.edu;


Emma Rosi (Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, rosie@caryinstitute.org;


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5/20/2019  |   09:45 - 10:00   |  250 DE

SCALING FROM THE LANDSCAPE TO RIVERINE FOOD WEBS A fundamental perspective in ecology is that physical habitat provides the template for ecological interactions. Within this framework, habitat heterogeneity (HH) is known to have a strong influence on ecological dynamics, including the structure and function of food webs. Both empirical and theoretical studies suggest that local HH can dampen strong destabilizing trophic interactions, particularly when habitats are coupled by mobile consumers. In large river ecosystems, HH may be expressed at spatial scales that are not immediately obvious (e.g., floodplain morphology, tributary confluences), yet, these features are likely critical for supporting and maintaining river diversity and production. Rivers are notable for their spatio-temporal heterogeneity across scales, making them ideal settings to investigate relationships between landscape-scale geomorphological processes, local patterns of HH, and energy flows through food webs. We examined spatial associations between benthic HH, geomorphic features, and flow food webs across large segments of the Missouri and Yellowstone rivers in Montana and North Dakota, USA. Using this approach, we present a road map for incorporating the spatial hierarchy of habitat-generating features into our understanding of energy flows through river food webs.

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


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


Addie Dutton (Co-Presenter/Co-Author), Montana Cooperative Fishery Research Unit, Montana State University , adeline.dutton@msu.montana.edu;


Christopher Guy (Co-Presenter/Co-Author), U.S. Geological Survey, Montana Cooperative Fishery Research Unit, Montana State University, cguy@montana.edu;


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5/20/2019  |   10:00 - 10:15   |  250 DE

SPATIAL HETEROGENEITY IN BIOMASS TURNOVER AND ENERGY-FLOW ACROSS A FLOODPLAIN FOODWEB MOSAIC The trophic basis of production and quantitative flow food web approaches hold potential to confront food web theory, and one under-realized possibility lies in using biomass turnover rates (P:B ratios) to examine characteristics of energy flow through freshwater meta-food webs. Recent studies illustrate that connections among spatially distinct sub-webs couple energy channels which differ in rates of energy flux due to differences in biomass turnover rates, and such coupling is predicted to confer stability to meta-food webs. However, these ideas have seen little empirically evaluation. In a spatially complex river-floodplain of the Methow River, WA, we found that biomass turnover rates of invertebrate and fish assemblages varied among sub-webs among habitat patches, and that biomass turnover and energy flow increased across a gradient of off-channel habitats as hydrologic connectivity with the main channel decreased. Because movements of materials and organisms connect these habitats and their distinct process rates, such a spatial arrangement of sub-webs may contribute to maintenance of biodiversity. These findings may improve our understanding of meta-foodweb architecture and dynamics in the shifting habitat mosaic of river-floodplains, and guide future investigation of heterogeneity in energy flow across landscapes.

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


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


James Paris (Primary Presenter/Author), Stream Ecology Center, Dept. Biological Sciences, Idaho State University, parijame@isu.edu;


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5/20/2019  |   10:15 - 10:30   |  250 DE

QUANTIFYING THE EFFECTS OF ALTERED HYDROLOGY AND FOOD-WEB STRUCTURE ON ECOSYSTEM CARRYING CAPACITY IN A FLOODPLAIN RIVER There is widespread evidence for a reduction in biomass of tertiary consumers such as large predatory fish in lowland rivers. These declines are caused by a myriad of factors such as overfishing, habitat loss, fragmentation, declining water quality and lost spawning cues. Recently research has also emphasized the role of altered food-webs and changes in energy production as factors that may limit the current carrying capacity of higher consumers in these systems. Here we present a novel ecosystem approach to quantifying the effects of altered hydrology and altered food-web structure on the carrying capacity of large-bodied native fish in the Murray River, southeastern Australia. We combine estimates of current and historical primary production with current and historic food-webs to estimate energy available to support native fish species such as Murray cod and golden perch. Our results suggest that river regulation and food-web changes have reduced energy fluxes to these native tertiary consumers by roughly 70% relative to historic levels, due to reduced production and the presence of trophic dead ends (notably carp). Both limitations will need to be addressed contemporaneously if carrying capacity of native fish is to be restored.

Nick Bond (Primary Presenter/Author), La Trobe University, n.bond@latrobe.edu.au;


Jian Yen (Co-Presenter/Co-Author), University of Melbourne, j.yen@unimelb.edu.au;


James Thomson (Co-Presenter/Co-Author), Monash University, Melbourne, Victoria, Australia, jim.thomson@delwp.vic.gov.au;


Keller Kopf (Co-Presenter/Co-Author), Charles Sturt University, rkopf@csu.edu.au;


Daryl Nielsen (Co-Presenter/Co-Author), CSIRO, Daryl.Nielsen@csiro.au;


Nicole McCasker (Co-Presenter/Co-Author), Charles Sturt University, nmccasker@csu.edu.au;


Paul Humphries (Co-Presenter/Co-Author), Charles Sturt University, PHumphries@csu.edu.au;


John Morrongiello (Co-Presenter/Co-Author), University of Melbourne, john.morrongiello@unimelb.edu.au;


David Crook (Co-Presenter/Co-Author), La Trobe University, David.Crook@latrobe.edu.au;


Paul Reich (Co-Presenter/Co-Author), DELWP, p.reich@delwp.vic.gov.au;


Mark Kennard (Co-Presenter/Co-Author), Australian Rivers Institute, Griffith University, m.kennard@griffith.edu.au;


Gavin Butler (Co-Presenter/Co-Author), NSW Dept of Primary Industries, gavin.butler@dpi.nsw.gov.au;


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