SFS Annual Meeting

5/21/2018  |   11:00 - 11:15   |  420 B

TRENDS IN TRIBUTARY LOADING TO LAKE ERIE: THE IMPORTANCE OF DISSOLVED PHOSPHORUS Lake Erie has been experiencing a recurrence of harmful algal blooms (HABs) in the western basin and an increase in hypoxia in the central basin. Data from the Maumee, Sandusky, and Raisin rivers collected by the National Center for Water Quality Research at Heidelberg University indicate this reeutrophication corresponds to a 2-fold increase in dissolved reactive phosphorus (DRP) loading from the mid-1990s to today. Yet, loads of total P (TP) have decreased slightly and nitrate-N have decreased more drastically over the same time period. Traditionally, TP is the most common form of P analyzed in water in part because of its stability, but also because historically much of the P entering the lake was from wastewater effluent where TP is primarily dissolved and bioavailable. Agricultural sources of TP tend to be composed primarily of particulate P (PP), which has low bioavailability. Measuring only TP in watersheds dominated by nonpoint sources of P can mask changes in the highly bioavailable dissolved portion of TP. Strategies to reduce P from western Lake Erie basin tributaries need to prioritize reductions of dissolved P in order to reduce the frequency of HABs.

David Baker (Co-Presenter/Co-Author), Heidelberg University, dbaker@heidelberg.edu;


Remegio Confesor (Co-Presenter/Co-Author), Heidelberg University, rconfeso@heidelberg.edu;


Ellen Ewing (Co-Presenter/Co-Author), Heidelberg University, eewing@heidelberg.edu;


Jack Kramer (Co-Presenter/Co-Author), Heidelberg University, jkramer@heidelberg.edu;


Laura Johnson (Primary Presenter/Author), Heidelberg University, ljohnson@heidelberg.edu;


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5/21/2018  |   11:15 - 11:30   |  420 B

REDUCED FORMS OF NITROGEN ARE A DIVER OF NON-NITROGEN-FIXING cyanHABs AND TOXICITY IN LAKE ERIE Western Lake Erie (WLE) experiences anthropogenic eutrophication and annual, toxic cyanobacterial blooms of non-nitrogen (N) fixing Microcystis. These blooms have been correlated with an increased proportion of soluble reactive phosphorus loading from the Maumee River. Here, we show that the proportion of the annual Maumee River N load of non-nitrate N, or total Kjeldahl nitrogen (TKN), has also increased significantly (p = 0.001) over the last few decades and is also significantly correlated to cyanobacterial bloom biomass (p = 0.003). We also compared the ratio of chemically reduced N to oxidized N (TKN:NO3) concentrations to extracted chlorophyll and phycocyanin concentrations from all stations within the NOAA GLERL weekly monitoring in WLE from 2009-2015. Both chlorophyll (p < 0.0001) and phycocyanin (p < 0.0001) were significantly correlated with TKN:NO3. This correlation between the increasing fraction of chemically reduced N from the Maumee River and increasing bloom biomass demonstrates the urgent need to control N loading, in addition to current P load reductions, to WLE and similar systems impacted by non-N-fixing, toxin-producing cyanobacteria.

Timothy W. Davis (Co-Presenter/Co-Author), Bowling Green State University, timdavi@bgsu.edu;


Tom Johengen (Co-Presenter/Co-Author), Cooperative Institute for Great Lakes Research, tom.johengen@noaa.gov;


Duane Gossiaux (Co-Presenter/Co-Author), NOAA Great Lakes Environmental Research Laboratory, duane.gossiaux@noaa.gov;


Ashley Burtner (Co-Presenter/Co-Author), Cooperative Institute for Great Lakes Research, aburtner@umich.edu;


Danna Palladino (Co-Presenter/Co-Author), Cooperative Institute for Great Lakes Research, danna.palladino@noaa.gov;


Mark McCarthy (Co-Presenter/Co-Author), Wright State University, mjm.kingston@gmail.com;


Silvia E. Newell (Primary Presenter/Author), Wright State University, silvia.newell@wright.edu;


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5/21/2018  |   11:30 - 11:45   |  420 B

STOICHIOMETRY OF N, P, AND SILICA LOADING TO THE WESTERN BASIN OF LAKE ERIE: HYDROLOGICAL CONTROLS AND LIMNOLOGICAL IMPLICATIONS The indicator of coastal eutrophication potential (ICEP) estimates the amount of non-siliceous algal production that could be supported by nitrogen (N) or phosphorus (P) available in excess of the stoichiometric requirement of diatoms. It often is viewed as a predictor of the occurrence and intensity of cyanobacterial blooms. We calculated ICEP using long-term (1975-2015) records of N, P, and silica (as Si) loads from the Maumee River, the major source of nutrients to the western basin of Lake Erie. Throughout the 40-year period of record, N inputs were far in excess of the N:Si ratio of 16:20 required by diatoms; lowest N:Si ratios occurred in drought years (e.g., 1988, 2012). The P:Si ratio also exceeded diatom requirements, but to a lesser degree than N:Si. The relationship between ICEP and average annual discharge indicated that flow conditions affected N and P loads far more than Si loads. Using the cyanobacterial index for the western basin of Lake Erie, we tested the ability of the ICEP to explain inter-annual variation in the abundance of cyanobacteria. Unexpectedly, ICEP was not correlated to the cyanobacterial index on an annual time scale.

Todd V. Royer (Primary Presenter/Author), Indiana University Bloomington, troyer@iu.edu;


Lienne Sethna (Co-Presenter/Co-Author), St. Croix Watershed Research Station, lsethna@smm.org;


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


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5/21/2018  |   11:45 - 12:00   |  420 B

THE INFLUENCE OF ELEVATED FLOWS ON NITRATE AND PHOSPHORUS EXPORT FROM TWO AGRICULTURAL WATERSHEDS Excess fertilizer applied to agricultural lands is exported downstream particularly during snowmelt and spring storms. Quantifying the impact of conservation on export during high flows is challenging because storms are spatially and temporally variable. In this study, we collected bi-weekly grab samples and deployed real-time nitrate sensors at the outlets of the Shatto and Kirkpatrick Ditch Watersheds (Indiana) to compare the role of storms on nitrate and soluble reactive phosphorus (SRP) export. Water yield at Shatto was ~2x higher due to groundwater, while nitrate yield was 50% lower, and SRP yields were similar. In both watersheds, >80% of nitrate and SRP export occurred during elevated flows (>60th percentile). During peak flows (>90th percentile), nitrate export was proportionally similar to water runoff in both watersheds, while SRP export was higher than runoff in Shatto, and the two were variably related in Kirkpatrick. Real-time nitrate data revealed non-linear C-Q relationships during storms, while modeling export from grab samples overestimated annual export ~5-10%. Conservation practices that reduce nutrient loss during storms potentially improves water quality, yet watershed-specific results suggest that finding the optimal conservation recipe is difficult given the variable influence of storms.

Jennifer L. Tank (Primary Presenter/Author), University of Notre Dame, tank.1@nd.edu;


Brittany Hanrahan (Co-Presenter/Co-Author), USDA Agricultural Research Service, br.hanrahan@gmail.com;


Ursula H. Mahl (Co-Presenter/Co-Author), University of Notre Dame, umahl@nd.edu;


Shannon Speir (Co-Presenter/Co-Author), University of Arkansas, slspeir@uark.edu;


Matt Trentman (Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana, matt.trentman@flbs.umt.edu;


Lienne Sethna (Co-Presenter/Co-Author), St. Croix Watershed Research Station, lsethna@smm.org;


Todd V. Royer (Co-Presenter/Co-Author), Indiana University Bloomington, troyer@iu.edu;


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5/21/2018  |   12:00 - 12:15   |  420 B

USING OXYGEN ISOTOPES TO TRACE THE FLOW OF DRP ENTERING THE WESTERN BASIN OF LAKE ERIE Algal blooms in the Western Basin of Lake Erie are dependent upon nutrients provided by major rivers within Northwest Ohio. To develop more accurate methods of defining major contributors of DRP, this study uses ?18O of phosphate molecules as a kind of tracer. 10-30L water samples were collected at several locations within the major rivers emptying into the Western Basin of Lake Erie as well as from the Lake itself. Through a series of precipitations, these water samples were transformed with an end product of silver phosphate for ?18O analysis. Initial results, from water samples collected during low flow conditions, suggest that equilibration due to biological processing within the water column may be producing deviation from expected ?18O patterns. However, more recent samples collected at high flow will depict a more accurate representation of the use of ?18O to determine paths of DRP flow into the Western Basin. Finally, these ?18O values will be compared to those of possible sources of DRP to further knowledge on the origins of nutrients contributing to the eutrophication of Lake Erie.

Melanie Marshall (Primary Presenter/Author), Bowling Green State University, melaniemarshall14@gmail.com;


Kevin McCluney (Co-Presenter/Co-Author), Bowling Green State University, kmcclun@bgsu.edu;


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5/21/2018  |   12:15 - 12:30   |  420 B

TESTING OPTIONS FOR REACHING LAKE ERIE’S PHOSPHORUS REDUCTION TARGETS USING MULTIPLE WATERSHED MODELS In 2016 the United States and Canada formally agreed to target reductions of phosphorus inputs to Lake Erie with the intention of alleviating the lake’s eutrophication. This included a 40% reduction from 2008 levels of March-July total phosphorus and dissolved reactive phosphorus loading from the Maumee River watershed. A key question remains: what land management options and rates of implementation will be needed to reach this 40% reduction? Here we will highlight results from two interdisciplinary research collaborations. A stakeholder advisory group assisted in identifying feasible and desirable conservation options for the watershed, which were in turn tested in multiple models of the Maumee watershed. In the first project the collective modeling suggested that it may be possible to meet these targets through widespread implementation and increased adoption of conservation practices, and the second project takes these findings and reworks the approach to simultaneously improve feasibility of conservation adoption and associated water quality benefits. In both projects we find dissolved phosphorus targets to be more difficult to meet than total phosphorus targets.

Margaret Kalcic (Primary Presenter/Author), The Ohio State University, kalcic.4@osu.edu;


Jay Martin (Co-Presenter/Co-Author), The Ohio State University, martin.1130@osu.edu;


Noel Aloysius (Co-Presenter/Co-Author), University of Missouri, aloysiusn@missouri.edu;


Anna Apostel (Co-Presenter/Co-Author), The Ohio State University, apostel.4@osu.edu;


Jeffrey Kast (Co-Presenter/Co-Author), The Ohio State University, kast.14@osu.edu;


Haley Kujawa (Co-Presenter/Co-Author), The Ohio State University, kujawa.21@osu.edu;


Rebecca Muenich (Co-Presenter/Co-Author), Arizona State University, rebecca.muenich@asu.edu;


Donald Scavia (Co-Presenter/Co-Author), University of Michigan, scavia@umich.edu;


Awoke Teshager (Co-Presenter/Co-Author), University of Michigan, awoke@umich.edu;


Yu-Chen Wang (Co-Presenter/Co-Author), University of Michigan, yuchenw@umich.edu;


Colleen Long (Co-Presenter/Co-Author), University of Michigan, longcm@umich.edu;


Chelsie Boles (Co-Presenter/Co-Author), LimnoTech, cboles@limno.com;


Todd Redder (Co-Presenter/Co-Author), Limnotech, tredder@limno.com;


Remegio Confesor (Co-Presenter/Co-Author), Heidelberg University, rconfeso@heidelberg.edu;


Tian Guo (Co-Presenter/Co-Author), Heidelberg University, tguo@heidelberg.edu;


Dale Robertson (Co-Presenter/Co-Author), USGS, dzrobert@usgs.gov;


Richard Becker (Co-Presenter/Co-Author), University of Toledo, richard.becker@utoledo.edu;


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