SFS Annual Meeting

6/06/2024  |   10:30 - 10:45   |  Freedom Ballroom H/G

Benchmarking river ecosystem metabolism to evaluate flow management outcomes Flow regimes of river ecosystems worldwide have been modified by humans. Environmental flows aim to sustain the ecological functioning of rivers whilst minimising societal and economic impacts. Evaluating the use of this environmental water is critical to adaptive management and requires specific and quantifiable ecological outcomes. However, we often lack benchmarks for functions such as ecosystem metabolism, which is an integrative measure of river condition and increasingly forms part of monitoring programs. Here, we used a multi-year dataset from a regulated floodplain river in Australia’s Murray-Darling Basin to characterise drivers of the annual metabolic regime and consider approaches to benchmarking gross primary productivity (GPP). Mean annual rates were high compared to global estimates, with daily rates peaking in summer. Natural in-channel flows reduced GPP while overbank flows were associated with high floodplain productivity. In the absence of local reference sites, we benchmarked GPP to literature derived values and identified periods when rates we abnormal relative to site-specific records. Compared to literature benchmarks, the sites were often classified as having intermediate condition. Abnormally high GPP rates for a site tended to occur when high temperatures coincided with low flows, particularly following flooding. We show that environmental flows can effectively reduce GPP at these times, potentially avoiding high algal biomass. This demonstrates that lowland rivers can be managed for ecosystem processes. Linking management outcomes based on ecosystem processes to water quality and consumer responses will provide a more holistic picture of ecosystem health, ensuring optimal use of environmental water.

Darren Giling (Primary Presenter/Author), Centre for Applied Water Science, University of Canberra, darren.giling@canberra.edu.au;

Fiona Dyer (Co-Presenter/Co-Author), Centre for Applied Water Science, University of Canberra, fiona.dyer@canberra.edu.au;

Paul McInerney (Co-Presenter/Co-Author), CSIRO, paul.mcinerney@csiro.au;

Alica Tschierschke (Co-Presenter/Co-Author), Centre for Applied Water Science, University of Canberra, alica.tschierschke@canberra.edu.au;

Ross M. Thompson (Co-Presenter/Co-Author), Centre for Applied Water Science, University of Canberra, ross.thompson@canberra.edu.au;

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6/06/2024  |   10:45 - 11:00   |  Freedom Ballroom H/G

EFFECTS OF HYDROELECTRIC RESERVOIR OPERATIONS ON INVERTEBRATE COMMUNITIES AND BIOMASS IN COASTAL BRITISH COLUMBIA, CANADA Hydroelectric power is a key renewable energy source but there are uncertainties associated with the effects of operations on aquatic production. For instance, drawdown causes the wetted edge of a reservoir to retreat from the zone of established riparian vegetation. It is hypothesized that this physical gap reduces inputs of aerial invertebrates to the littoral zone, which are an important component of certain fish diets. Drawdown may also reduce littoral primary production, as well as the inputs and rate of processing of organic material in the littoral zone, thereby reducing production of invertebrates that consume this material and contribute to fish production. We designed and conducted a three-year study to assess the impacts of hydroelectric reservoir operations on productivity in three oligotrophic reservoirs on Vancouver Island (British Columbia, Canada); specifically, how fluctuating reservoir levels influence aerial and emergent invertebrate communities and biomass. The density of aerial invertebrates declined with increasing distance from the riparian zone but there were no clear spatial relationships between emergent invertebrate biomass and proximity to the riparian and drawdown zones. However, emergent invertebrate richness was typically highest in the unmanaged control lake. Our results provide insights into how hydroelectric operations can affect aquatic resources in unproductive temperate reservoirs.

Christina Suzanne (Primary Presenter/Author), Ecofish Research Ltd., csuzanne@ecofishresearch.com;

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6/06/2024  |   11:00 - 11:15   |  Freedom Ballroom H/G

Snapshots of change: investigating DON, DOC, and DIN dynamics in a watershed-scale assessment Dissolved organic nitrogen (DON) constitutes a substantial portion of the total dissolved nitrogen pool (TDN) in streams, however, the understanding of the spatial, seasonal, and temporal drivers of DON remains incomplete. Our study addresses this gap by examining how DON, coupled with dissolved organic carbon (DOC) and dissolved inorganic nitrogen (DIN), responds to changes in flow, watershed size, and land-use along Hinkson Creek in Columbia, Missouri. The Hinkson Creek runs through a mixed land-use watershed and has been listed as impaired by the EPA since 1998. Starting in 2018, we have collected 4 “snapshots” per year of the water quality at 45 sites across the entire watershed, including tributaries, at different baseflow conditions. DOC and DON concentrations are closely coupled but show different responses to space and flow. Spatially, both DOC and DON concentrations decreased from the agricultural land-use upstream to the urban land-use downstream with DON decreasing at a faster rate than DOC. The ratio of DIN:DON has a significant relationship with flow, while the ratio of DOC:DON overall does not. Further analysis to disentangle the effects of increasing watershed size upstream to downstream with changing land-use indicates a strong influence of different land-use types on DON but less on DOC and DIN. Recognizing the dominance of DON in the TDN pool, our findings provide information on the controls of DON dynamics to inform effective water resource management on stream ecosystems.

Olivia Bongiovi (Primary Presenter/Author), University of Missouri-Columbia, olbmkf@umsystem.edu;

Jessica Scholz (Co-Presenter/Co-Author), University of Missouri-Columbia, jessica.scholz@missouri.edu;

Carol Pollard (Co-Presenter/Co-Author), University of Missouri-Columbia, pollardcar@missouri.edu;

Alba Argerich (Co-Presenter/Co-Author), University of Missouri-Columbia, argericha@missouri.edu;

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6/06/2024  |   11:15 - 11:30   |  Freedom Ballroom H/G

Drivers of water quality and biogeochemistry of waterpans in Afrotropical arid and semi-arid lands Waterpans or pans, is a colloquial term used in Africa, especially sub-Saharan Africa, to refer to shallow ponds or reservoirs that occur either naturally or are artificially constructed for water harvesting in arid and semi-arid lands. These pans are predominantly utilized for various uses. Because of their many uses by people, livestock and wildlife, their water quality is influenced by a number of factors, that also influence their biogeochemistry. This study aims to provide baseline information on the use, sizes, nutrients, organic matter, and dynamics of greenhouse gases fluxes in these waterpans. A pre-visit was conducted in lower Mara Region in Kenya, and study sites were selected along three transects, based on their sizes, land use and human influences. Observations and questionnaires were employed to collect baseline data. Waterpans were classified according to different land use types in their catchments (agriculture, livestock grazing, wildlife, and mixed land uses). Of the 20 waterpans identified, 55% were communal (shared among communities), and 45% were on private lands and 69% of them were permanent. Most of the waterpans had high organic matter and nutrient inputs from wildlife and livestock, which are likely to be major determinant of water quality and biogeochemistry through the formation of algal blooms, including the occurrence of cyanobacteria. This preliminary study has informed the study design on drivers of water quality and biogeochemistry of waterpans in arid and semi-arid lands in Kenya. The subsequent study that will be carried out for one year, from June 2024.

ELIZABETH WANDERI (Primary Presenter/Author), UNIVERSITY OF ELDORET, ewanderi428@gmail.com;

Frank Masese (Co-Presenter/Co-Author), University of Eldoret, f.masese@uoeld.ac.ke;

Gretchen Gettel (Co-Presenter/Co-Author), IHE-Dlft Institute for Water Education, Delft, The Netherlands, g.gettel@un-ihe.org ;

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6/06/2024  |   11:30 - 11:45   |  Freedom Ballroom H/G

Stream nutrient criteria to protect downstream uses in lakes across the CONUS Nutrients are consistently ranked as one of the leading causes of water quality impairment in the US, contributing to responses that include hypoxia/anoxia, habitat loss, food web shifts, nuisance growths, aesthetic impacts, and harmful cyanobacterial blooms and cyanotoxins. Stream ecological research has shown that uptake and mineralization of nutrients in streams results in cycling between the benthos and water column in various dissolved forms, resulting in spiraling of nutrients downstream. Uptake rates scale with stream size, nutrient loading, and nutrient concentration. However, nutrient uptake is often insufficient to balance increased nutrients loads, resulting in a rise in the net export of nutrients downstream. This has led to the occurrence and persistence of eutrophication in downstream waters. Based on these observations, we hypothesize that average stream concentrations within a watershed predict lake chlorophyll concentrations within the same watershed and these relationships could be useful for informing upstream nutrient control strategies. We compiled monitoring data for stream nutrients and lake chlorophyll from the EPA National Rivers and Streams Assessment, the EPA National Lakes Assessment, and from the state of Minnesota. We fit hierarchical Bayesian models to estimate the relationship between stream total phosphorus and lake chlorophyll at both state and national scales, finding that the relationships estimated at these two spatial scales were robust and indistinguishable from one another. We discuss how these relationships could be used to develop stream nutrient criteria.

Michael Paul (Primary Presenter/Author), U.S. Environmental Protection Agency, Paul.Michael@epa.gov;

Lester Yuan (Co-Presenter/Co-Author), U.S. Environmental Protection Agency, yuan.lester@epa.gov;

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6/06/2024  |   11:45 - 12:00   |  Freedom Ballroom H/G

HYDROELECTRIC GENERATING STATIONS ALTER DISSOLVED ORGANIC MATTER (DOM) QUALITY AND BENTHIC MACROINVERTEBRATE ABUNDANCES IN A LARGE NORTHEN RIVER Hydroelectric resource development can alter limnological processes, which in-turn can affect the ecology and management of aquatic species. However, few studies have examined the effects of hydroelectric development on dissolved organic matter (DOM) composition, despite its importance various ecosystem functions and productivity. Using spectral techniques, we examined DOM composition in the Moose River watershed, an expansive riverine ecosystem that is a vital part of the traditional homeland of Moose Cree First Nation (MCFN). In partnership with MCFN, we concurrently sampled DOM and benthic macroinvertebrate (BMI) community structure above, between, and below a series of four hydroelectric generating stations. Preliminary results show lower percentages of sensitive invertebrate orders (i.e., Ephemeroptera, Plecoptera, Trichoptera, or %EPT) and higher percentages of more tolerant oligochaetes moving downstream through the generating stations. We also observed significantly lower total abundance of BMIs below the most downstream station, where hydropeaking is often used. DOM concentrations (measured as total organic carbon < 0.45µm) also increased moving downstream, and the DOM became less degraded and more UV absorbent. We are currently investigating correlations among these BMI and DOM data. This work is part of the Learning from Lake Sturgeon program (https://learningfromlakesturgeon.ca/) and will be used more broadly to better understand drivers of the health of fish in the rivers of the Moose Cree Homeland. This study represents only the views and understanding of the individual co-authors; it should not be referenced as a representation of the Ililiwak Indigenous Knowledge System nor a Moose Cree First Nation position.

Gretchen Lescord (Primary Presenter/Author), University of Florida, lescord.g@ufl.edu;

Jennifer Simard (Co-Presenter/Co-Author), Moose Cree First Nation, jennifer.simard@moosecree.com;

Jacob Seguin (Co-Presenter/Co-Author), McGill University, jacob.seguin@mail.mcgill.ca;

Claire Ferrell (Co-Presenter/Co-Author), Wildlife Conservation Society Canada, cfarrell@wcs.org;

Alex Litvinov (Co-Presenter/Co-Author), Moose Cree First Nation, alex.litvinov@moosecree.com;

Haley MacLeod (Co-Presenter/Co-Author), Wildlife Conservation Society Canada, hmacleo1@lakeheadu.ca;

Erik Emilson (Co-Presenter/Co-Author), Great Lakes Forestry Centre, Canadian Forest Service, erik.emilson@canada.ca;

Connie O'Connor (Co-Presenter/Co-Author), Wildlife Conservation Society Canada, coconnor@wcs.org;

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