The Development of a Stressor- Response Model for the Red River of the North
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THE DEVELOPMENT OF A STRESSOR- RESPONSE MODEL FOR THE RED RIVER OF THE NORTH Topical Report RSI-2611 prepared for International Red River Board US Section 2000 L Street, NW Suite #615 Washington, DC 20440 June 2016 THE DEVELOPMENT OF A STRESSOR- RESPONSE MODEL FOR THE RED RIVER OF THE NORTH Topical Report RSI-2611 by Tony Miller Bruce Wilson Julie Blackburn Erich Weber RESPEC 1935 County Road B2, Suite 230 Roseville, Minnesota 55113 prepared for International Red River Board US Section 2000 L Street, NW Suite #615 Washington, DC 20440 June 2016 CREDITS AND ACKNOWLEDGMENTS GOVERNMENTAL AGENCIES Environment and Climate Change Canada International Joint Commission International Red River Board International Red River Board Water Quality Committee Minnesota Pollution Control Agency North Dakota Department of Health Province of Manitoba, Conservation and Water Stewardship INDIVIDUAL CONTRIBUTORS Pam Anderson, Minnesota Pollution Control Agency Nicole Armstrong, Manitoba Sustainable Development Glenn Benoy, International Joint Commission Stephen Brown, North Dakota Department of Health Joel Chirhart, Minnesota Pollution Control Agency Mike Ell, North Dakota Department of Health Kristina Farmer, Environment and Climate Change Canada Diana Fred, Environment and Climate Change Canada Mark Gabriel, International Joint Commission Iris Griffin, Environment and Climate Change Canada David Hay, Manitoba Conservation and Water Stewardship Steve Heiskary, Minnesota Pollution Control Agency Daniel Helwig, Minnesota Pollution Control Agency Joy Kennedy, Manitoba Conservation and Water Stewardship Aaron Larsen, North Dakota Department of Health Jeff Lewis, Red River Basin Commission Ben Lundeen, Minnesota Pollution Control Agency Joe Nett, North Dakota Department of Health Scott Niemela, Minnesota Pollution Control Agency James Noren, United States Army Corps of Engineers Rochelle Nustad, United States Geologic Survey Paul Olson, North Dakota Department of Health Elaine Page, Manitoba Conservation and Water Stewardship Sharon Reedyk, Agriculture and Agri-Food Canada Victor Serveiss, International Joint Commission Rob Sip, Minnesota Department of Agriculture Eric Steinhaus, United States Environmental Protection Agency Jason Vanrobaeys, Agriculture and Agri-Food Canada Mike Vavricka, Minnesota Pollution Control Agency Keith Weston, Red River Retention Authority Jim Ziegler, Minnesota Pollution Control Agency i RSI-2611 EXECUTIVE SUMMARY The International Red River Board (IRRB), a board of the International Joint Commission (IJC), identified excess nutrients as one of the greatest issues in the Red River of the North because of its impact on the ecological conditions in the Red River itself and its significant contribution to hyper-eutrophic conditions in downstream Lake Winnipeg. Excessive nutrient contributions to the lake have led to excessive algal blooms that impact drinking water, recreation, and commercial fisheries through significant accumulations of algal biomass—the Red River has been identified as the most significant contribution of the nutrients. This excessive algal buildup disrupts recreation and fisheries through its physical presence but also by indirectly attributing to dissolved oxygen depletion at night when photosynthesis shuts down and bacterial decomposition of the dead algae utilize large amounts of oxygen. To initiate determining solutions to these issues, the IRRB developed a proposed approach for a basin-wide, nutrient- management strategy for the international Red River Watershed. One component of this approach involves developing nitrogen and phosphorus concentration targets within the mainstem Red River as a first step in restoring the ecology of the Red River and reducing nutrient contributions to Lake Winnipeg. To determine an approach for establishing nutrient targets, the IRRB contracted with RESPEC to conduct a literature review and provide recommendations on the most appropriate method for developing nitrogen and phosphorus targets in the Red River [Plevan and Blackburn, 2013]1. Based on these findings, the IRRB determined that a collaborative project to determine a biological stressor response in the Red River to nutrients was necessary. The subsequent project was developed by a team that consisted of agency professionals from Manitoba, Minnesota, North Dakota, and RESPEC. The project results are described in this report and demonstrates the development of a stressor-response model that includes the identification of biologically based nutrient targets in the Red River. Initially, to consider all possible interactions of environmental conditions, a conceptual stressor-response model that characterized potential pathways for nutrient effects was developed with input and recommendations from experts. Because of their direct and documented responses to nutrient increases, algae were determined to be the ideal biological group to measure a stressor response in the Red River. However, data gaps that prevented developing a stressor-response model were identified that led to supplemental periphyton (attached algae), phytoplankton (sestonic algae), and water quality data- collection effort during the summer of 2015. This data resulted in developing an effective nutrient- stressor-response model for the Red River by using a combination of algae, water quality, and land-use information. Because of consistently elevated suspended sediment in the river, the initial goal of this project was to determine if a stressor response to elevated nutrients was discernable on the chosen biological community (because of the light limiting control on algal growth). This project was not concerned with seasonal variation of algal growth/nutrient loading or specific aspects of the downstream Lake Winnipeg. The function of the study was to determine a measurable response of the algal community to elevated nutrients and subsequently whether or not a discernable nutrient gradient could be aligned with either algal community quality or quantity. If successful, this project would therefore allow nutrient targets to be established for the Red River based on growing-season conditions and initiate local interest 1 Plevan, A. B. and J. A. Blackburn, 2013. Approaches to Setting Nutrient Targets in the Red River of the North, RSI-2328, prepared by RESPEC, Roseville, MN, for the International Joint Commission, US Section, Washington, DC. ii RSI-2611 in reducing nutrient inputs. This approach is based on the Minnesota Pollution Control Agency’s (MPCA’s) methods for using biological criteria for establishing nutrient limits. To accomplish the goals outlined above, the project team focused on ideal growth conditions for the algae (i.e., summer growing season during normal flow) and collected periphyton (using floating colonization samplers) and phytoplankton (collected from filtered surface water). Using this biological data combined with water chemistry, several analytical steps were performed to establish a statistically and ecologically valid relationship between the algae community variance between sites and the measured environmental variables, which in part included total and constituents of nitrogen and phosphorus, water temperature, total suspended solids (TSS), conductivity, pH, and various land-use measures. Overall, taxonomic response (i.e., community diversity) to nutrient stressors was not suppressed by TSS concentrations (i.e., available light); however, the effect of light limitation was seen through reduced algal biomass. Varying concentrations of nutrients was pivotal to observing a stressor effect. The first goal of this project was to determine a nutrient gradient between the river sampling sites. Using water quality data provided by the MPCA and Manitoba Conservation and Water Stewardship, a nutrient gradient was observed that appeared to be associated with both municipal and agricultural inputs. This gradient analysis, in conjunction with the algal quantity and quality results, was subsequently used to establish the nutrient target recommendations. Determining a response in the algal community to the observed nutrient gradient was documented in the measured quantity and the quality of the community. A response in quantity was apparent in both the phytoplankton and periphyton abundance, although the growth of the latter was significantly repressed by TSS concentrations. However, the response of periphyton quality, as determined by pertinent diatom metrics, was not suppressed by TSS concentrations because a significant negative quality response was seen with increasing nutrients starting at the first peak in nutrients adjacent to the Fargo/Moorhead urban area. Overall, the periphyton was found to reach nuisance levels toward the mouth of the river that coincided with the highest concentration of nutrients. Phytoplankton was found to reach nuisance concentrations in close proximity to highly developed urban areas with an occasional abundance of blue- green algae. Multivariate analyses were used to determine that both periphyton and phytoplankton responded significantly to varying nutrient concentrations. Using the information from these analyses, nutrient targets were determined by using the results from sites least influenced by high total phosphorus (TP) and total nitrogen (TN) effects. Substantial consideration was also given to results from sites meeting regional regulatory limits on primary productivity measures and higher quality diatom-based metric results. This process resulted in delineating nutrient targets of 0.15