Understanding and managing the re-eutrophication of Lake Erie: Knowledge gaps and research priorities

Mohamed, Mohamed N.; Wellen, Christopher; Parsons, Christopher T.; Taylor, William D.; Arhonditsis, George B.; Chomicki, Krista M.; Boyd, Duncan; Weidman, Paul; Mundle, Scott O. C.; Cappellen, Philippe Van; Sharpley, Andrew N.; Haffner, Douglas

doi:10.1086/705915

Cited by 61 publications

(33 citation statements)

References 151 publications

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“…Freshwater ecosystems are critical for sustaining life and supporting civilizations throughout history [ 1 ]. As the global human population grows, increased urbanization, agricultural and industrial productions, combined with insufficient wastewater treatment practices, have led to a widespread increase in nutrient pollution of these ecosystems, threatening clean and safe water supplies [ 2 ]. Excessive inputs of nitrogen (N) and phosphorus (P) have accelerated eutrophication, the process of increasing organic enrichment, which is largely attributable to increased microalgal and aquatic macrophyte growth [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Roles of Nutrient Limitation on Western Lake Erie CyanoHAB Toxin Production

Barnard

Chaffin

Plaas

et al. 2021

Toxins

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Cyanobacterial harmful algal bloom (CyanoHAB) proliferation is a global problem impacting ecosystem and human health. Western Lake Erie (WLE) typically endures two highly toxic CyanoHABs during summer: a Microcystis spp. bloom in Maumee Bay that extends throughout the western basin, and a Planktothrix spp. bloom in Sandusky Bay. Recently, the USA and Canada agreed to a 40% phosphorus (P) load reduction to lessen the severity of the WLE blooms. To investigate phosphorus and nitrogen (N) limitation of biomass and toxin production in WLE CyanoHABs, we conducted in situ nutrient addition and 40% dilution microcosm bioassays in June and August 2019. During the June Sandusky Bay bloom, biomass production as well as hepatotoxic microcystin and neurotoxic anatoxin production were N and P co-limited with microcystin production becoming nutrient deplete under 40% dilution. During August, the Maumee Bay bloom produced microcystin under nutrient repletion with slight induced P limitation under 40% dilution, and the Sandusky Bay bloom produced anatoxin under N limitation in both dilution treatments. The results demonstrate the importance of nutrient limitation effects on microcystin and anatoxin production. To properly combat cyanotoxin and cyanobacterial biomass production in WLE, both N and P reduction efforts should be implemented in its watershed.

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Section: Introductionmentioning

confidence: 99%

Roles of Nutrient Limitation on Western Lake Erie CyanoHAB Toxin Production

Barnard

Chaffin

Plaas

et al. 2021

Toxins

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“…Further, concentrations of glyphosate did not approach thresholds of toxicological concern and dissipated within 30 days to 1 year from water and sediment, respectively (Robichaud and Rooney, in review). However, legacy effects created by established P. australis, such as alterations to soil nutrients Rooney 2019, D'Antonio andMeyerson 2002), and shifting environmental conditions in and surrounding Lake Erie, for example nutrient pollution (e.g., Mohamed et al 2019) and climate change (e.g., Zhang et al 2020), may increase the likelihood of secondary invasions.…”

Section: Recovery Of Native Vegetationmentioning

confidence: 99%

Suppression of established invasivePhragmites australisleads to secondary invasion

Robichaud

Rooney

2020

Preprint

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Invasive Phragmites australis (European Common Reed) is rapidly spreading throughout North American wetlands, with negative impacts on wildlife and native plants. The removal or suppression of P. australis is desired to provide an opportunity for native vegetation and wetland fauna to recover. In Ontario, managers applied a glyphosate-based herbicide to >400 ha of P. australis in ecologically significant Great Lakes coastal marshes, representing the first time this tool was used over standing water to suppress P. australis in Canada. Using a replicated Before-After-Control-Impact monitoring design, we 1) evaluated the efficacy of glyphosate-based herbicide at suppression P. australis along a water depth gradient and 2) assessed the recovery of the vegetation community for two years after treatment in relation to local reference conditions. We found that herbicide reduced live P. australis stem densities by over 99% the first year after treatment and about 95% the second year post-treatment. Treatment was equally effective along the entire water depth gradient (10 – 48 cm). The initial ‘suppression’ focused management was successful, but sustained monitoring and ‘containment’ focused follow-up treatment will be required to prevent reinvasion. Two years after treatment, the vegetation community does not resemble reference conditions. Although some treated plots initially increased in similarity to the vegetation communities typical of reference areas, many plots where P. australis was suppressed are on a novel trajectory comprising a vegetation community dominated by non-native Hydrocharis morsus-ranae. Secondary invasions represent a major challenge to effective recovery of native vegetation after P. australis control.

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“…Eutrophication-related deterioration of the quality of freshwaters has become an environmental issue of global concern [ 1 ] and will remain to be the most important water quality problem in the future [ 2 ]. Global climate change and anthropogenic nutrient input have resulted in frequent occurrences of cyanobacterial blooms [ 3 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

Removal of cyanobacteria from a water supply reservoir by sedimentation using flocculants and suspended solids as ballast: Case of Legedadi Reservoir (Ethiopia)

et al. 2021

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The massive growth of potentially toxic cyanobacteria in water supply reservoirs, such as Legedadi Reservoir (Ethiopia), poses a huge burden to water purification units and represents a serious threat to public health. In this study, we evaluated the efficiency of the flocculants/coagulants chitosan, Moringa oleifera seed (MOS), and poly-aluminium chloride (PAC) in settling cyanobacterial species present in the Legedadi Reservoir. We also tested whether coagulant-treated reservoir water promotes cyanobacteria growth. Our data showed that suspended solids in the turbid reservoir acted as ballast, thereby enhancing settling and hence the removal of cyanobacterial species coagulated with chitosan, Moringa oleifera seed, or their combination. Compared to other coagulants, MOS of 30 mg/L concentration, with the removal efficiency of 93.6%, was the most effective in removing cyanobacterial species without causing cell lysis. Contrary to our expectation, PAC was the least effective coagulant. Moreover, reservoir water treated with MOS alone or MOS combined with chitosan did not support any growth of cyanobacteria during the first two weeks of the experiment. Our data indicate that the efficacy of a flocculant/coagulant in the removal of cyanobacteria is influenced by the uniqueness of individual lakes/reservoirs, implying that mitigation methods should consider the unique characteristic of the lake/reservoir.

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Understanding and managing the re-eutrophication of Lake Erie: Knowledge gaps and research priorities

Cited by 61 publications

References 151 publications

Roles of Nutrient Limitation on Western Lake Erie CyanoHAB Toxin Production

Roles of Nutrient Limitation on Western Lake Erie CyanoHAB Toxin Production

Suppression of established invasivePhragmites australisleads to secondary invasion

Removal of cyanobacteria from a water supply reservoir by sedimentation using flocculants and suspended solids as ballast: Case of Legedadi Reservoir (Ethiopia)

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