Development and spatial application of a submerged aquatic vegetation model for Cootes Paradise Marsh, Ontario, Canada
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Aquatic Sciences
RESEARCH ARTICLE
Development and spatial application of a submerged aquatic vegetation model for Cootes Paradise Marsh, Ontario, Canada Rex W. K. Tang1 · Susan E. Doka1 · Jonathan D. Midwood1 · Jesse M. Gardner Costa1 Received: 19 February 2020 / Accepted: 29 September 2020 © Crown 2020
Abstract Cootes Paradise Marsh (CP) is an urban wetland and is part of the Hamilton Harbour Area of Concern (AOC). Anthropogenic stressors have degraded the system’s water quality. Submerged aquatic vegetation (SAV) provides critical fish habitat, and its recovery is crucial to this AOC’s delisting efforts. We developed predictive models to recommend water clarity (Secchi depth) targets that can potentially achieve a minimum SAV presence of 230 ha in CP, using macrophyte monitoring data that have been collected since 1996 by the Royal Botanical Gardens (RBG). A random forest approach was used for modelling SAV presence and SAV % cover. The final model for predicting presence of SAV consisted of Secchi depth, west wind fetch, and water level; the model had high accuracy (accuracy = 0.88, kappa = 0.77). For predicting SAV cover, the final model consisted of water depth, Secchi depth, percent slope, average fetch, water level, and substrate type; it had moderate accuracy (σ2explained = 0.66, root mean square error = 26.09, and weighted absolute percentage error = 58.96). Both models were then applied spatially using a digital elevation model to predict areas of CP where SAV would likely occur under different water level and water clarity scenarios. We recommend a delisting Secchi depth target of greater than 0.75 m to achieve the maximum potential of SAV areal extent under different water level scenarios. Keywords Macrophytes · Random forest · Area of Concern · Water clarity · Delisting targets
Introduction Submerged aquatic vegetation (SAV) is an important component of fish habitat in aquatic ecosystems. The presence of SAV affects physical and chemical factors in an ecosystem, including: anchoring substrates and reducing sediment transport (Anderson and Kalff 1988; Duarte and Kalff 1990; Barko et al. 1991; Lacoul and Freedman 2006); reducing turbidity by limiting resuspension of sediments driven by wind action; and altering nutrient and oxygen cycling (Carpenter and Lodge 1986). Also, the presence of SAV affects biological factors such as refuge, foraging areas, and the provision of habitat for fish in different life stages. SAV has been Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00027-020-00760-w) contains supplementary material, which is available to authorized users. * Rex W. K. Tang rex.tang@dfo‑mpo.gc.ca 1
Great Lakes Laboratory for Fisheries and Aquatic Sciences, Central and Arctic Region, Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, ON L7S 1A1, Canada
shown to increase fish abundance (Chick and Mclvor 1994), regulate growth rates (Werner et al. 1983), and increase fish diversity by providing structural complexity (Weaver et al.
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