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Alan Steinman

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Al Steinman is the Allen and Helen Hunting Director of the Annis Water Resources Institute at Grand Valley State University. He previously was Director of the Lake Okeechobee Restoration Program at the South Florida Water Management District. His research interests include ecosystem restoration, phosphorus cycling, harmful algal blooms, periphyton ecology, and water policy.

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Papers by Alan Steinman

Risk assessment and identification of factors influencing the historical concentrations of microcystin in Lake Taihu, China

Journal of Environmental Sciences

Occurrence and risk assessment of microcystin and its relationship with environmental factors in lakes of the eastern plain ecoregion, China

Environmental Science and Pollution Research, 2020

The frequent occurrence of microcystins (MCs) in freshwater poses serious threats to the drinking... more The frequent occurrence of microcystins (MCs) in freshwater poses serious threats to the drinking water safety and health of human beings. Although MCs have been detected in individual fresh waters in China, little is known about their occurrence over a large geographic scale. An investigation of 30 subtropical lakes in eastern China was performed during summer 2018 to determine the MCs concentrations in water and their possible risk via direct water consumption to humans, and to assess the associated environmental factors. MCs were detected in 28 of 30 lakes, and the highest mean MCs concentrations occurred in Lake Chaohu (26.7 μg/L), followed by Lake Taihu (3.11 μg/L). MC-LR was the primary variant observed in our study, and MCs were mainly produced by Microcystis, Anabaena (Dolicospermum), and Oscillatoria in these lakes. Replete nitrogen and phosphorus concentrations, irradiance, and stable water column conditions were critical for dominance of MC-producing cyanobacteria and high MCs production in our study. Hazard quotients indicated that human health risk of MCs in most lakes was at moderate or low levels except Lakes Chaohu and Taihu. Nutrient control management is recommended to decrease the likelihood of high MCs production. Finally, we recommend the regional scale thresholds of total nitrogen and total phosphorus concentrations of 1.19 mg/L and 7.14 × 10 −2 mg/L, respectively, based on the drinking water guideline of MC-LR (1 μg/L) recommended by World Health Organization. These targets for nutrient control will aid water quality managers to reduce human health risks created by exposure to MCs.

Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, production and release of microcystin-LR

Journal of Hazardous Materials, 2020

Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, prod... more Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, production and release of microcystin-LR Mingchen Zhang (Methodology) (Formal analysis) (Investigation) (Writing-original draft) (Visualization) (Writing-review and editing), Alan D. Steinman (Writing-review and editing), Qingju Xue (Project administration), Yanyan Zhao (Project administration), Yan Xu (Conceptualization) (Writing-review and editing), Liqiang Xie (Conceptualization) (Writing-review and editing) (Funding acquisition)

Seasonal variation and potential risk assessment of microcystins in the sediments of Lake Taihu, China

Environmental Pollution, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Combined toxic effects of microcystin-LR and phenanthrene on growth and antioxidant system of duckweed (Lemna gibba L.)

Ecotoxicology and Environmental Safety, 2019

Microcystins and polycyclic aromatic hydrocarbons commonly co-exist in eutrophic freshwater envir... more Microcystins and polycyclic aromatic hydrocarbons commonly co-exist in eutrophic freshwater environments. However, their combined toxicity remains unknown. The aim of this study was to evaluate the combined toxic effects of microcystin-LR (MC-LR) and phenanthrene (Phe) on duckweed (Lemna gibba L.) during a short-term exposure (7 d). L. gibba was exposed to a range of environmentally relevant concentrations of MC-LR (5, 50, 250, 500 μg/L) and Phe (0.1, 1, 5, 10 μg/L), both individually and in MC-LR + Phe mixtures (5 + 0.1, 50 + 1, 250 + 5, 500 + 10 μg/L). Subsequently, biomarkers of toxicity such as growth, chlorophyll-a, and antioxidant enzyme activity (catalase, superoxide dismutase, and peroxidase) were analyzed in L. gibba. Growth and the antioxidant system of L. gibba were not significantly inhibited by Phe alone, whereas higher concentrations of individual MC-LR (≥50 μg/L) significantly inhibited growth and induced oxidative stress. Based on Abott's formula, their interaction effects were concentration dependent. Antagonistic effects were observed when exposed to combinations of lower concentrations of MC-LR and Phe (≤50 + 1 μg/L), while additive or synergistic effects were induced at higher concentrations of both compounds (≥250 + 5 μg/L). Moreover, higher concentrations of Phe (≥5 μg/L) increased the accumulation of MC-LR in L. gibba. Our results suggested that the toxic effects of MC-LR and phenanthrene were exacerbated only when they co-exist in water bodies at relatively high concentrations. Consequently, coexistence of MC-LR and Phe at low levels are unlikely to exacerbate ecological hazards to L. gibba in most aquatic environments, at least based on responses of this plant.

Evaluating the contamination of microcystins in Lake Taihu, China: The application of equivalent total MC-LR concentration

Ecological Indicators, 2018

The frequent occurrence and accumulation of microcystins (MCs) in freshwater systems pose serious... more The frequent occurrence and accumulation of microcystins (MCs) in freshwater systems pose serious threats to the drinking water safety and health of human beings. However, determining the overall toxicity and environmental risks from MC exposure is complex because of the variety of MC analogues and their respective toxicities. To address this issue, we conducted a survey of particulate (intracellular) and dissolved (extracellular) MC in Lake Taihu from 14 sampling sites in the northern part of the lake, and 32 stations throughout the entire lake, over a 16-month period. We propose a novel indicator, total MC-LR concentration (TLR), defined as the total concentration of MC-LR after transforming other MC variants (i.e., MC-RR and MC-YR) to an equivalent toxicity of MC-LR. Intracellular concentrations of TLR (iTLR) were usually observed, with the maximum values in July and October 2013 corresponding to periods of peaks in phytoplankton biomass. In contrast, extracellular concentrations of TLR (eTLR) were highest in May and June 2014. These differences in temporal patterns exhibited by LR, TLR, and TMC between intracellular and extracellular MC may be attributed to the influence of environmental variables. In addition, the distribution of iTLR and eTLR in the entire lake showed clear spatial heterogeneity. MC concentrations were greatest in the northern part of the lake during warm months, especially in Meiliang Bay. Based on the strong linear relationships between TLR and the concentration of chlorophyll-a (Chl-a), as well as TLR and the cell density of cyanobacteria, we propose not-to-exceed safety thresholds for Chl-a of 21.28 μg/L in the northern lake and 23.26 μg/L in the whole lake, which are paired with safety thresholds for cyanobacterial cell densities of 2.21 × 10 8 cells/L and 1.15 × 10 8 cells/L, respectively. The application of this newly proposed indicator, TLR, may contribute to better evaluation of overall MC toxicity and provide guidance on recommended limits for Chl-a concentration and cyanobacterial cell density in other freshwater ecosystems.

Phosphorus loading and ecological impacts from agricultural tile drains in a west Michigan watershed

Journal of Great Lakes Research, 2017

Phosphorus (P) loading from nonpoint sources is often implicated as a contributing factor to the ... more Phosphorus (P) loading from nonpoint sources is often implicated as a contributing factor to the proliferation of algal blooms in freshwater ecosystems. However, the influence of subsurface tile drains as a source of P, especially in agricultural areas, has received limited attention. We examined the importance of tile drain effluent in the Macatawa Watershed; this watershed is dominated by row crop agriculture and drains into hypereutrophic Lake Macatawa, which connects to Lake Michigan. Our objectives were twofold: 1) assess the importance of tile drain effluent as a source of P in the Macatawa Watershed by measuring tile drain P concentrations spatially and temporally over a one-year period; and 2) assess the ability of tile drain effluent to stimulate algal blooms using bioassays with natural phytoplankton communities. During March 2015-February 2016, P concentrations varied significantly among sample sites (SRP: b 0.005 to 0.447 mg/L; TP: 0.010 to 0.560 mg/L), and the highest P loads occurred during the non-growing season. Annual SRP yields from the tile drain sample sites ranged from 0.002 kg/ha to 0.248 kg/ha, and annual TP yields ranged from 0.003 kg/ha to 0.322 kg/ha. SRP, on average, accounted for 60% of TP, and the SRP:TP ratio measured at the tile drain outlets was positively correlated with area drained by the tile system. Algal bioassays failed to find a positive relationship between chlorophyll a and tile drain SRP; algal community structure was dominated by diatoms, not by cyanobacteria, as expected.

Ecosistemas de agua dulce sustentables (Sustaining healthy freshwater ecosystems)

Balancing human and ecological needs for freshwater

Human society has used freshwater from rivers, lakes, groundwater and wetlands for many different... more Human society has used freshwater from rivers, lakes, groundwater and wetlands for many different urban, agricultural, and industrial activities, but in doing so has overlooked its value in supporting ecosystems. Freshwater is vital to human life and societal well-being, and thus its utilisation for consumption, irrigation, and transport has long taken precedence over other commodities and services provided by freshwater ecosystems. However, there is growing recognition that functionally intact and biologically complex aquatic ecosystems provide many economically valuable services and long-term benefits to society. The short-term benefits include ecosystem goods and services, such as food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life, these are costly, if not impossible to replace(Wilson & Carpenter 1999; Daily 1997). Long-term benefits include the sustained provision of those goods and services, as well as the adaptive cap...

Assessment of the effectiveness of muck-digesting bacterial pellets

Lake and Reservoir Management, 2022

A study was conducted using sediment from three lakes in Newaygo County (MI) to assess the abilit... more A study was conducted using sediment from three lakes in Newaygo County (MI) to assess the ability of Mukk Buster pellets to "decrease levels of organic sediment in lakes and ponds while reducing odors and improving water clarity", as claimed on their product label. Controlled laboratory experiments were conducted using both core tubes and larger bins. Sediment from the 3 lakes were placed in enclosed, cylindrical tubes and incubated in growth chambers for 8 weeks under a 3 x 2 factorial design, with the 3 treatments being: 1) temperature (ambient or ambient plus 3ºC); 2) oxygen level (dissolved oxygen present or absent); and pellets (present or absent). Sediment from the 3 lakes were also placed in non-enclosed bins to provide a larger surface area and mass of organic matter, with or without pellets. Changes in organic matter, dissolved organic carbon, bacterial community composition, and water quality were assessed at various times throughout the experiments. Regardless of treatment factors or sediment volume, there were no statistically significant differences in changes of organic matter between treatments with pellets and those without pellets. While the absence of a pellet effect was consistent among lakes and treatments, the change in organic matter did differ among lakes, with a slight to no increase in Hess Lake, a significant increase in Brooks Lake, and a significant decline in Pickerel Lake. We have no mechanistic explanation for the increase in organic matter in Brooks Lake, but because it occurred in both the tubes and bins, we believe the increase to be real and not due to human error. The relative number of bacterial genera was consistent across lakes, but some bacteria dominated more in specific lakes. Overall, bacteria community composition had very little explanatory power for our results. The overlying water in the pellet treatments had significantly greater specific conductance and chloride concentrations, but not pH, than in the control treatments. We attribute these increases to the contents of the pellets themselves, given that they were introduced at a much greater dosage than recommended due to the small size of our containers. It is possible the high chloride concentrations could have significant negative impacts to biota in lakes. We identify several caveats in our study and recommend as a next step that pellet effectiveness be tested in natural lakes, using cylindrical tubes to isolate areas of sediment and water column, with control and treatment replicates. Based on these results, we conclude that these pellets are not an effective treatment to reduce sediment organic matter.

Great Lakes rivermouth ecosystems: Scientific synthesis and management implications

Journal of Great Lakes Research, Sep 1, 2013

ABSTRACT At the interface of the Great Lakes and their tributary rivers lies the rivermouths, a c... more ABSTRACT At the interface of the Great Lakes and their tributary rivers lies the rivermouths, a class of aquatic ecosystem where lake and lotic processes mix and distinct features emerge. Many rivermouths are the focal point of both human interaction with the Great Lakes and human impacts to the lakes; many cities, ports, and beaches are located in rivermouth ecosystems, and these human pressures often degrade key ecological functions that rivermouths provide. Despite their ecological uniqueness and apparent economic importance, there has been relatively little research on these ecosystems as a class relative to studies on upstream rivers or the open-lake waters. Here we present a synthesis of current knowledge about ecosystem structure and function in Great Lakes rivermouths based on studies in both Laurentian rivermouths, coastal wetlands, and marine estuarine systems. A conceptual model is presented that establishes a common semantic framework for discussing the characteristic spatial features of rivermouths. This model then is used to conceptually link ecosystem struc-ture and function to ecological services provided by rivermouths. This synthesis helps identify the critical gaps in understanding rivermouth ecology. Specifically, additional information is needed on how rivermouths collectively influence the Great Lakes ecosystem, how human alterations influence rivermouth functions, and how ecosystem services provided by rivermouths can be managed to benefit the surrounding socioeconomic networks. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.

Long‐term population dynamics of dreissenid mussels (Dreissena polymorpha and D. rostriformis): a cross‐system analysis

Ecosphere, 2019

Dreissenid mussels (including the zebra mussel Dreissena polymorpha and the quagga mussel D. rost... more Dreissenid mussels (including the zebra mussel Dreissena polymorpha and the quagga mussel D. rostriformis) are among the world's most notorious invasive species, with large and widespread ecological and economic effects. However, their long‐term population dynamics are poorly known, even though these dynamics are critical to determining impacts and effective management. We gathered and analyzed 67 long‐term (>10 yr) data sets on dreissenid populations from lakes and rivers across Europe and North America. We addressed five questions: (1) How do Dreissena populations change through time? (2) Specifically, do Dreissena populations decline substantially after an initial outbreak phase? (3) Do different measures of population performance (biomass or density of settled animals, veliger density, recruitment of young) follow the same patterns through time? (4) How do the numbers or biomass of zebra mussels or of both species combined change after the quagga mussel arrives? (5) How d...

Sustaining healthy freshwater ecosystems

Fresh water is vital to human life and economic well-being, and societies extract vast quantities... more Fresh water is vital to human life and economic well-being, and societies extract vast quantities of water from rivers, lakes, wetlands, and underground aquifers to supply the requirements of cities, farms, and industries. Our need for fresh water has long caused us to overlook equally vital benefits of water that remains in stream to sustain healthy aquatic ecosystems. There is growing recognition, however, that functionally intact and biologically complex freshwater ecosystems provide many economically valuable commodities and services to society. These services include flood control, transportation, recreation, purification of human and industrial wastes, habitat for plants and animals, and production of fish and other foods and marketable goods. Over the long term, intact ecosystems are more likely to retain the adaptive capacity to sustain production of these goods and services in the face of future environmental disruptions such as climate change. These ecosystem benefits are costly and often impossible to replace when aquatic systems are degraded. For this reason, deliberations about water allocation should always include provisions for maintaining the integrity of freshwater ecosystems. Scientific evidence indicates that aquatic ecosystems can be protected or restored by recognizing the following: • Rivers, lakes, wetlands, and their connecting ground waters are literally the "sinks" into which landscapes drain. Far from being isolated bodies or conduits, freshwater ecosystems are tightly linked to the watersheds or catchments of which each is a part, and they are greatly influenced by human uses or modifications of land as well as water. The stream network itself is important to the continuum of river processes. • Dynamic patterns of flow that are maintained within the natural range of variation will promote the integrity and sustainability of freshwater aquatic systems. • Aquatic ecosystems additionally require that sediments and shorelines, heat and light properties, chemical and nutrient inputs, and plant and animal populations fluctuate within natural ranges, neither experiencing excessive swings beyond their natural ranges nor being held at constant levels. Failure to provide for these natural requirements results in loss of species and ecosystem services in wetlands, rivers, and lakes. Scientifically defining requirements for protecting or restoring aquatic ecosystems, however, is only a first step. New policy and management approaches will also be required. Current piecemeal and consumption-oriented approaches to water policy cannot solve the problems confronting our increasingly degraded freshwater ecosystems. To begin to redress how water is viewed and managed in the United States, we recommend: 1) Framing national, regional, and local water management policies to explicitly incorporate freshwater ecosystem needs. 2) Defining water resources to include watersheds, so that fresh waters are viewed within a landscape or ecosystem context instead of by political jurisdiction or in geographic isolation. 3) Increasing communication and education across disciplines, especially among engineers, hydrologists, economists, and ecologists, to facilitate an integrated view of freshwater resources. 4) Increasing restoration efforts using well-grounded ecological principles as guidelines. 5) Maintaining and protecting remaining freshwater ecosystems that have high integrity. 6) And recognizing human society's dependence on naturally functioning ecosystems.

Building a research network to better understand climate governance in the Great Lakes

Journal of Great Lakes Research, 2022

Wetland restoration and hydrologic reconnection result in enhanced watershed nitrogen retention and removal

Wetlands, 2017

Restoration of freshwater wetlands presents a potential water quality benefit via removal of nutr... more Restoration of freshwater wetlands presents a potential water quality benefit via removal of nutrients, but complex and unresolved changes in nutrient cycling can occur following restoration. In this study, we evaluated N removal and release in a deltaic wetland under scenarios of hydrologic reconnection and sediment dredging, and we modeled potential downstream impacts of these restoration activities in a Bayesian framework. Denitrification, N 2 O production, and anammox were measured via the isotope pairing technique in intact sediment cores. Anammox was not detected. Denitrification rates in the control scenario (78.2-87.2 μmol N m −2 h −1) were significantly higher than those under hydrologic reconnection and dredging scenarios (14.7-56.0 μmol N m −2 h −1). N 2 O production rates were typical of wetland environments. Denitrification and N 2 O production were stimulated shortly following simulated dredging, indicating a short-term response to sediment disturbance. Under hydrologic reconnection, NH 4 + availability was decreased, inhibiting coupled nitrification-denitrification. Despite a decrease in denitrification activity, the wetland has the capacity to remove up to 10% of stream NO 3 − following hydrologic reconnection. Restoration is predicted to fully mitigate NH 4 + delivery to a downstream eutrophic lake, yet permanent N removal may be reduced due to the decoupling of nitrification and denitrification.

Grand challenges for research in the Laurentian Great Lakes

Limnology and Oceanography, 2017

The Laurentian Great Lakes (LGL) constitute one of the largest freshwater systems in the world wh... more The Laurentian Great Lakes (LGL) constitute one of the largest freshwater systems in the world while providing social and economic value to two powerful nations. The spatial scale of these inland seas falls between two endpoints: small lakes and oceans. Lacustrine in many characteristics, the LGL often require a scientific approach with attributes similar to those of oceanography. There is a strong sense that within the LGL support for scientific research has not kept pace with the need for process‐oriented research and that we lack basic information needed to forecast change, mitigate impacts and restore and preserve the LGL. Consequently, 58 researchers met in September 2014 and identified five “Grand Challenges for Research in the LGL”: (1) How has this vast inland freshwater system responded to shifting climate in the past, and how will it respond in the future? (2) What is the current status of the most important ecosystem processes, including their variability in space and tim...

Persistent organic pollutants, metals, and the bacterial community composition associated with microplastics in Muskegon Lake (MI)

Journal of Great Lakes Research, Oct 1, 2020

Three different types of microplastics (MPs): low density polyethylene; polypropylene; and polyes... more Three different types of microplastics (MPs): low density polyethylene; polypropylene; and polyester, were incubated for one and three months at two sites (Channel and Lake) in Muskegon Lake (MI). After retrieval, MPs were analyzed for polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), select metals, and genomic characterization of the attached microbial biofilm. Polyaromatic hydrocarbons accumulated at similar levels on all microplastic types, but were~one order of magnitude lower than sediment concentrations and~three orders of magnitude lower than the Probable Effect Concentration (PEC): the concentration in sediment above which adverse biological effects are likely to occur. In contrast, PCB levels were 4-6Â greater on polyethylene than on polypropylene or polyester, although all plastic-associated PCB concentrations were at least one order of magnitude less than the PEC. Organochlorine pesticide concentrations were very low (<1 ppb) on all microplastics and at all sites. Metal concentrations also were well below their respective PEC levels. The most abundant bacterial groups as part of the plastisphere were Burkholderiales, Rhodocyclaceae, Comamonadaceae, and Pseudomonadaceae. Polyester microplastics contained a higher number of bacterial families and the relative abundance of those families were more evenly distributed compared to the other plastic types. Overall, our results indicate that persistent organic pollutants are capable of accumulating on MPs but the concentrations generally were low; feeding trials are needed to determine if these environmentally realistic concentrations of pollutants attached to microplastics result in impacts to aquatic biota.

Alum efficacy 11 years following treatment: phosphorus and macroinvertebrates

Lake and reservoir management, Jan 2, 2018

Internal phosphorus loading and benthic macroinvertebrate community structure were analyzed at 4 ... more Internal phosphorus loading and benthic macroinvertebrate community structure were analyzed at 4 sites in Spring Lake, Michigan, ∼11 yr following an alum treatment. Phosphorus (P) release rates, benthic macroinvertebrate community structure, sediment chemistry, and water quality variables (total dissolved solids, pH, dissolved oxygen, water clarity) were compared to measurements taken previously (2003/2004: pre-alum application, 2006: 8 mo post-alum application, and 2010: 5 yr post-alum application) at the same sites and using comparable methods. Total phosphorus (TP) concentrations in surface water samples from 2016 (38-45 µg/L) were similar to those measured in 2006 and 2010 (20-80 µg/L) at all sites; however, 2016 TP concentrations in the near-bottom water at the 2 deeper sites were elevated (∼250 and 1,000 µg/L, respectively) compared to TP concentrations of <60 µg/L in 2006 and 2010, suggesting internal loading may be increasing, at least at these 2 sites. In contrast, maximum P release rates from the 2016 sediments were similar to or lower than 2010 rates, and an order of magnitude lower than before alum was applied. Phosphorus content in the sediment was fractionated; loosely sorbed sediment SRP concentrations were very low at all sites. Macroinvertebrate community was similar in density and composition to the 2010 results. These results are suggestive, but not conclusive, that internal P loading is increasing in parts of Spring Lake. Alum application can serve as an effective short-term solution to the longer-term problem of internal P loading, but its effectiveness is critically tied to concurrent reductions in external P loading.

Wetland Restoration through Excavation: Sediment Removal Results in Dramatic Water Quality Improvement

Land, Sep 14, 2022

Perfluoroalkylated Substances (PFAS) Associated with Microplastics in a Lake Environment

Toxics, May 11, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more

Risk assessment and identification of factors influencing the historical concentrations of microcystin in Lake Taihu, China

Journal of Environmental Sciences

Occurrence and risk assessment of microcystin and its relationship with environmental factors in lakes of the eastern plain ecoregion, China

Environmental Science and Pollution Research, 2020

The frequent occurrence of microcystins (MCs) in freshwater poses serious threats to the drinking... more The frequent occurrence of microcystins (MCs) in freshwater poses serious threats to the drinking water safety and health of human beings. Although MCs have been detected in individual fresh waters in China, little is known about their occurrence over a large geographic scale. An investigation of 30 subtropical lakes in eastern China was performed during summer 2018 to determine the MCs concentrations in water and their possible risk via direct water consumption to humans, and to assess the associated environmental factors. MCs were detected in 28 of 30 lakes, and the highest mean MCs concentrations occurred in Lake Chaohu (26.7 μg/L), followed by Lake Taihu (3.11 μg/L). MC-LR was the primary variant observed in our study, and MCs were mainly produced by Microcystis, Anabaena (Dolicospermum), and Oscillatoria in these lakes. Replete nitrogen and phosphorus concentrations, irradiance, and stable water column conditions were critical for dominance of MC-producing cyanobacteria and high MCs production in our study. Hazard quotients indicated that human health risk of MCs in most lakes was at moderate or low levels except Lakes Chaohu and Taihu. Nutrient control management is recommended to decrease the likelihood of high MCs production. Finally, we recommend the regional scale thresholds of total nitrogen and total phosphorus concentrations of 1.19 mg/L and 7.14 × 10 −2 mg/L, respectively, based on the drinking water guideline of MC-LR (1 μg/L) recommended by World Health Organization. These targets for nutrient control will aid water quality managers to reduce human health risks created by exposure to MCs.

Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, production and release of microcystin-LR

Journal of Hazardous Materials, 2020

Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, prod... more Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, production and release of microcystin-LR Mingchen Zhang (Methodology) (Formal analysis) (Investigation) (Writing-original draft) (Visualization) (Writing-review and editing), Alan D. Steinman (Writing-review and editing), Qingju Xue (Project administration), Yanyan Zhao (Project administration), Yan Xu (Conceptualization) (Writing-review and editing), Liqiang Xie (Conceptualization) (Writing-review and editing) (Funding acquisition)

Seasonal variation and potential risk assessment of microcystins in the sediments of Lake Taihu, China

Environmental Pollution, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Combined toxic effects of microcystin-LR and phenanthrene on growth and antioxidant system of duckweed (Lemna gibba L.)

Ecotoxicology and Environmental Safety, 2019

Microcystins and polycyclic aromatic hydrocarbons commonly co-exist in eutrophic freshwater envir... more Microcystins and polycyclic aromatic hydrocarbons commonly co-exist in eutrophic freshwater environments. However, their combined toxicity remains unknown. The aim of this study was to evaluate the combined toxic effects of microcystin-LR (MC-LR) and phenanthrene (Phe) on duckweed (Lemna gibba L.) during a short-term exposure (7 d). L. gibba was exposed to a range of environmentally relevant concentrations of MC-LR (5, 50, 250, 500 μg/L) and Phe (0.1, 1, 5, 10 μg/L), both individually and in MC-LR + Phe mixtures (5 + 0.1, 50 + 1, 250 + 5, 500 + 10 μg/L). Subsequently, biomarkers of toxicity such as growth, chlorophyll-a, and antioxidant enzyme activity (catalase, superoxide dismutase, and peroxidase) were analyzed in L. gibba. Growth and the antioxidant system of L. gibba were not significantly inhibited by Phe alone, whereas higher concentrations of individual MC-LR (≥50 μg/L) significantly inhibited growth and induced oxidative stress. Based on Abott's formula, their interaction effects were concentration dependent. Antagonistic effects were observed when exposed to combinations of lower concentrations of MC-LR and Phe (≤50 + 1 μg/L), while additive or synergistic effects were induced at higher concentrations of both compounds (≥250 + 5 μg/L). Moreover, higher concentrations of Phe (≥5 μg/L) increased the accumulation of MC-LR in L. gibba. Our results suggested that the toxic effects of MC-LR and phenanthrene were exacerbated only when they co-exist in water bodies at relatively high concentrations. Consequently, coexistence of MC-LR and Phe at low levels are unlikely to exacerbate ecological hazards to L. gibba in most aquatic environments, at least based on responses of this plant.

Evaluating the contamination of microcystins in Lake Taihu, China: The application of equivalent total MC-LR concentration

Ecological Indicators, 2018

The frequent occurrence and accumulation of microcystins (MCs) in freshwater systems pose serious... more The frequent occurrence and accumulation of microcystins (MCs) in freshwater systems pose serious threats to the drinking water safety and health of human beings. However, determining the overall toxicity and environmental risks from MC exposure is complex because of the variety of MC analogues and their respective toxicities. To address this issue, we conducted a survey of particulate (intracellular) and dissolved (extracellular) MC in Lake Taihu from 14 sampling sites in the northern part of the lake, and 32 stations throughout the entire lake, over a 16-month period. We propose a novel indicator, total MC-LR concentration (TLR), defined as the total concentration of MC-LR after transforming other MC variants (i.e., MC-RR and MC-YR) to an equivalent toxicity of MC-LR. Intracellular concentrations of TLR (iTLR) were usually observed, with the maximum values in July and October 2013 corresponding to periods of peaks in phytoplankton biomass. In contrast, extracellular concentrations of TLR (eTLR) were highest in May and June 2014. These differences in temporal patterns exhibited by LR, TLR, and TMC between intracellular and extracellular MC may be attributed to the influence of environmental variables. In addition, the distribution of iTLR and eTLR in the entire lake showed clear spatial heterogeneity. MC concentrations were greatest in the northern part of the lake during warm months, especially in Meiliang Bay. Based on the strong linear relationships between TLR and the concentration of chlorophyll-a (Chl-a), as well as TLR and the cell density of cyanobacteria, we propose not-to-exceed safety thresholds for Chl-a of 21.28 μg/L in the northern lake and 23.26 μg/L in the whole lake, which are paired with safety thresholds for cyanobacterial cell densities of 2.21 × 10 8 cells/L and 1.15 × 10 8 cells/L, respectively. The application of this newly proposed indicator, TLR, may contribute to better evaluation of overall MC toxicity and provide guidance on recommended limits for Chl-a concentration and cyanobacterial cell density in other freshwater ecosystems.

Phosphorus loading and ecological impacts from agricultural tile drains in a west Michigan watershed

Journal of Great Lakes Research, 2017

Phosphorus (P) loading from nonpoint sources is often implicated as a contributing factor to the ... more Phosphorus (P) loading from nonpoint sources is often implicated as a contributing factor to the proliferation of algal blooms in freshwater ecosystems. However, the influence of subsurface tile drains as a source of P, especially in agricultural areas, has received limited attention. We examined the importance of tile drain effluent in the Macatawa Watershed; this watershed is dominated by row crop agriculture and drains into hypereutrophic Lake Macatawa, which connects to Lake Michigan. Our objectives were twofold: 1) assess the importance of tile drain effluent as a source of P in the Macatawa Watershed by measuring tile drain P concentrations spatially and temporally over a one-year period; and 2) assess the ability of tile drain effluent to stimulate algal blooms using bioassays with natural phytoplankton communities. During March 2015-February 2016, P concentrations varied significantly among sample sites (SRP: b 0.005 to 0.447 mg/L; TP: 0.010 to 0.560 mg/L), and the highest P loads occurred during the non-growing season. Annual SRP yields from the tile drain sample sites ranged from 0.002 kg/ha to 0.248 kg/ha, and annual TP yields ranged from 0.003 kg/ha to 0.322 kg/ha. SRP, on average, accounted for 60% of TP, and the SRP:TP ratio measured at the tile drain outlets was positively correlated with area drained by the tile system. Algal bioassays failed to find a positive relationship between chlorophyll a and tile drain SRP; algal community structure was dominated by diatoms, not by cyanobacteria, as expected.

Ecosistemas de agua dulce sustentables (Sustaining healthy freshwater ecosystems)

Balancing human and ecological needs for freshwater

Human society has used freshwater from rivers, lakes, groundwater and wetlands for many different... more Human society has used freshwater from rivers, lakes, groundwater and wetlands for many different urban, agricultural, and industrial activities, but in doing so has overlooked its value in supporting ecosystems. Freshwater is vital to human life and societal well-being, and thus its utilisation for consumption, irrigation, and transport has long taken precedence over other commodities and services provided by freshwater ecosystems. However, there is growing recognition that functionally intact and biologically complex aquatic ecosystems provide many economically valuable services and long-term benefits to society. The short-term benefits include ecosystem goods and services, such as food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life, these are costly, if not impossible to replace(Wilson & Carpenter 1999; Daily 1997). Long-term benefits include the sustained provision of those goods and services, as well as the adaptive cap...

Assessment of the effectiveness of muck-digesting bacterial pellets

Lake and Reservoir Management, 2022

A study was conducted using sediment from three lakes in Newaygo County (MI) to assess the abilit... more A study was conducted using sediment from three lakes in Newaygo County (MI) to assess the ability of Mukk Buster pellets to "decrease levels of organic sediment in lakes and ponds while reducing odors and improving water clarity", as claimed on their product label. Controlled laboratory experiments were conducted using both core tubes and larger bins. Sediment from the 3 lakes were placed in enclosed, cylindrical tubes and incubated in growth chambers for 8 weeks under a 3 x 2 factorial design, with the 3 treatments being: 1) temperature (ambient or ambient plus 3ºC); 2) oxygen level (dissolved oxygen present or absent); and pellets (present or absent). Sediment from the 3 lakes were also placed in non-enclosed bins to provide a larger surface area and mass of organic matter, with or without pellets. Changes in organic matter, dissolved organic carbon, bacterial community composition, and water quality were assessed at various times throughout the experiments. Regardless of treatment factors or sediment volume, there were no statistically significant differences in changes of organic matter between treatments with pellets and those without pellets. While the absence of a pellet effect was consistent among lakes and treatments, the change in organic matter did differ among lakes, with a slight to no increase in Hess Lake, a significant increase in Brooks Lake, and a significant decline in Pickerel Lake. We have no mechanistic explanation for the increase in organic matter in Brooks Lake, but because it occurred in both the tubes and bins, we believe the increase to be real and not due to human error. The relative number of bacterial genera was consistent across lakes, but some bacteria dominated more in specific lakes. Overall, bacteria community composition had very little explanatory power for our results. The overlying water in the pellet treatments had significantly greater specific conductance and chloride concentrations, but not pH, than in the control treatments. We attribute these increases to the contents of the pellets themselves, given that they were introduced at a much greater dosage than recommended due to the small size of our containers. It is possible the high chloride concentrations could have significant negative impacts to biota in lakes. We identify several caveats in our study and recommend as a next step that pellet effectiveness be tested in natural lakes, using cylindrical tubes to isolate areas of sediment and water column, with control and treatment replicates. Based on these results, we conclude that these pellets are not an effective treatment to reduce sediment organic matter.

Great Lakes rivermouth ecosystems: Scientific synthesis and management implications

Journal of Great Lakes Research, Sep 1, 2013

ABSTRACT At the interface of the Great Lakes and their tributary rivers lies the rivermouths, a c... more ABSTRACT At the interface of the Great Lakes and their tributary rivers lies the rivermouths, a class of aquatic ecosystem where lake and lotic processes mix and distinct features emerge. Many rivermouths are the focal point of both human interaction with the Great Lakes and human impacts to the lakes; many cities, ports, and beaches are located in rivermouth ecosystems, and these human pressures often degrade key ecological functions that rivermouths provide. Despite their ecological uniqueness and apparent economic importance, there has been relatively little research on these ecosystems as a class relative to studies on upstream rivers or the open-lake waters. Here we present a synthesis of current knowledge about ecosystem structure and function in Great Lakes rivermouths based on studies in both Laurentian rivermouths, coastal wetlands, and marine estuarine systems. A conceptual model is presented that establishes a common semantic framework for discussing the characteristic spatial features of rivermouths. This model then is used to conceptually link ecosystem struc-ture and function to ecological services provided by rivermouths. This synthesis helps identify the critical gaps in understanding rivermouth ecology. Specifically, additional information is needed on how rivermouths collectively influence the Great Lakes ecosystem, how human alterations influence rivermouth functions, and how ecosystem services provided by rivermouths can be managed to benefit the surrounding socioeconomic networks. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.

Long‐term population dynamics of dreissenid mussels (Dreissena polymorpha and D. rostriformis): a cross‐system analysis

Ecosphere, 2019

Dreissenid mussels (including the zebra mussel Dreissena polymorpha and the quagga mussel D. rost... more Dreissenid mussels (including the zebra mussel Dreissena polymorpha and the quagga mussel D. rostriformis) are among the world's most notorious invasive species, with large and widespread ecological and economic effects. However, their long‐term population dynamics are poorly known, even though these dynamics are critical to determining impacts and effective management. We gathered and analyzed 67 long‐term (>10 yr) data sets on dreissenid populations from lakes and rivers across Europe and North America. We addressed five questions: (1) How do Dreissena populations change through time? (2) Specifically, do Dreissena populations decline substantially after an initial outbreak phase? (3) Do different measures of population performance (biomass or density of settled animals, veliger density, recruitment of young) follow the same patterns through time? (4) How do the numbers or biomass of zebra mussels or of both species combined change after the quagga mussel arrives? (5) How d...

Sustaining healthy freshwater ecosystems

Fresh water is vital to human life and economic well-being, and societies extract vast quantities... more Fresh water is vital to human life and economic well-being, and societies extract vast quantities of water from rivers, lakes, wetlands, and underground aquifers to supply the requirements of cities, farms, and industries. Our need for fresh water has long caused us to overlook equally vital benefits of water that remains in stream to sustain healthy aquatic ecosystems. There is growing recognition, however, that functionally intact and biologically complex freshwater ecosystems provide many economically valuable commodities and services to society. These services include flood control, transportation, recreation, purification of human and industrial wastes, habitat for plants and animals, and production of fish and other foods and marketable goods. Over the long term, intact ecosystems are more likely to retain the adaptive capacity to sustain production of these goods and services in the face of future environmental disruptions such as climate change. These ecosystem benefits are costly and often impossible to replace when aquatic systems are degraded. For this reason, deliberations about water allocation should always include provisions for maintaining the integrity of freshwater ecosystems. Scientific evidence indicates that aquatic ecosystems can be protected or restored by recognizing the following: • Rivers, lakes, wetlands, and their connecting ground waters are literally the "sinks" into which landscapes drain. Far from being isolated bodies or conduits, freshwater ecosystems are tightly linked to the watersheds or catchments of which each is a part, and they are greatly influenced by human uses or modifications of land as well as water. The stream network itself is important to the continuum of river processes. • Dynamic patterns of flow that are maintained within the natural range of variation will promote the integrity and sustainability of freshwater aquatic systems. • Aquatic ecosystems additionally require that sediments and shorelines, heat and light properties, chemical and nutrient inputs, and plant and animal populations fluctuate within natural ranges, neither experiencing excessive swings beyond their natural ranges nor being held at constant levels. Failure to provide for these natural requirements results in loss of species and ecosystem services in wetlands, rivers, and lakes. Scientifically defining requirements for protecting or restoring aquatic ecosystems, however, is only a first step. New policy and management approaches will also be required. Current piecemeal and consumption-oriented approaches to water policy cannot solve the problems confronting our increasingly degraded freshwater ecosystems. To begin to redress how water is viewed and managed in the United States, we recommend: 1) Framing national, regional, and local water management policies to explicitly incorporate freshwater ecosystem needs. 2) Defining water resources to include watersheds, so that fresh waters are viewed within a landscape or ecosystem context instead of by political jurisdiction or in geographic isolation. 3) Increasing communication and education across disciplines, especially among engineers, hydrologists, economists, and ecologists, to facilitate an integrated view of freshwater resources. 4) Increasing restoration efforts using well-grounded ecological principles as guidelines. 5) Maintaining and protecting remaining freshwater ecosystems that have high integrity. 6) And recognizing human society's dependence on naturally functioning ecosystems.

Building a research network to better understand climate governance in the Great Lakes

Journal of Great Lakes Research, 2022

Wetland restoration and hydrologic reconnection result in enhanced watershed nitrogen retention and removal

Wetlands, 2017

Restoration of freshwater wetlands presents a potential water quality benefit via removal of nutr... more Restoration of freshwater wetlands presents a potential water quality benefit via removal of nutrients, but complex and unresolved changes in nutrient cycling can occur following restoration. In this study, we evaluated N removal and release in a deltaic wetland under scenarios of hydrologic reconnection and sediment dredging, and we modeled potential downstream impacts of these restoration activities in a Bayesian framework. Denitrification, N 2 O production, and anammox were measured via the isotope pairing technique in intact sediment cores. Anammox was not detected. Denitrification rates in the control scenario (78.2-87.2 μmol N m −2 h −1) were significantly higher than those under hydrologic reconnection and dredging scenarios (14.7-56.0 μmol N m −2 h −1). N 2 O production rates were typical of wetland environments. Denitrification and N 2 O production were stimulated shortly following simulated dredging, indicating a short-term response to sediment disturbance. Under hydrologic reconnection, NH 4 + availability was decreased, inhibiting coupled nitrification-denitrification. Despite a decrease in denitrification activity, the wetland has the capacity to remove up to 10% of stream NO 3 − following hydrologic reconnection. Restoration is predicted to fully mitigate NH 4 + delivery to a downstream eutrophic lake, yet permanent N removal may be reduced due to the decoupling of nitrification and denitrification.

Grand challenges for research in the Laurentian Great Lakes

Limnology and Oceanography, 2017

The Laurentian Great Lakes (LGL) constitute one of the largest freshwater systems in the world wh... more The Laurentian Great Lakes (LGL) constitute one of the largest freshwater systems in the world while providing social and economic value to two powerful nations. The spatial scale of these inland seas falls between two endpoints: small lakes and oceans. Lacustrine in many characteristics, the LGL often require a scientific approach with attributes similar to those of oceanography. There is a strong sense that within the LGL support for scientific research has not kept pace with the need for process‐oriented research and that we lack basic information needed to forecast change, mitigate impacts and restore and preserve the LGL. Consequently, 58 researchers met in September 2014 and identified five “Grand Challenges for Research in the LGL”: (1) How has this vast inland freshwater system responded to shifting climate in the past, and how will it respond in the future? (2) What is the current status of the most important ecosystem processes, including their variability in space and tim...

Persistent organic pollutants, metals, and the bacterial community composition associated with microplastics in Muskegon Lake (MI)

Journal of Great Lakes Research, Oct 1, 2020

Three different types of microplastics (MPs): low density polyethylene; polypropylene; and polyes... more Three different types of microplastics (MPs): low density polyethylene; polypropylene; and polyester, were incubated for one and three months at two sites (Channel and Lake) in Muskegon Lake (MI). After retrieval, MPs were analyzed for polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), select metals, and genomic characterization of the attached microbial biofilm. Polyaromatic hydrocarbons accumulated at similar levels on all microplastic types, but were~one order of magnitude lower than sediment concentrations and~three orders of magnitude lower than the Probable Effect Concentration (PEC): the concentration in sediment above which adverse biological effects are likely to occur. In contrast, PCB levels were 4-6Â greater on polyethylene than on polypropylene or polyester, although all plastic-associated PCB concentrations were at least one order of magnitude less than the PEC. Organochlorine pesticide concentrations were very low (<1 ppb) on all microplastics and at all sites. Metal concentrations also were well below their respective PEC levels. The most abundant bacterial groups as part of the plastisphere were Burkholderiales, Rhodocyclaceae, Comamonadaceae, and Pseudomonadaceae. Polyester microplastics contained a higher number of bacterial families and the relative abundance of those families were more evenly distributed compared to the other plastic types. Overall, our results indicate that persistent organic pollutants are capable of accumulating on MPs but the concentrations generally were low; feeding trials are needed to determine if these environmentally realistic concentrations of pollutants attached to microplastics result in impacts to aquatic biota.

Alum efficacy 11 years following treatment: phosphorus and macroinvertebrates

Lake and reservoir management, Jan 2, 2018

Internal phosphorus loading and benthic macroinvertebrate community structure were analyzed at 4 ... more Internal phosphorus loading and benthic macroinvertebrate community structure were analyzed at 4 sites in Spring Lake, Michigan, ∼11 yr following an alum treatment. Phosphorus (P) release rates, benthic macroinvertebrate community structure, sediment chemistry, and water quality variables (total dissolved solids, pH, dissolved oxygen, water clarity) were compared to measurements taken previously (2003/2004: pre-alum application, 2006: 8 mo post-alum application, and 2010: 5 yr post-alum application) at the same sites and using comparable methods. Total phosphorus (TP) concentrations in surface water samples from 2016 (38-45 µg/L) were similar to those measured in 2006 and 2010 (20-80 µg/L) at all sites; however, 2016 TP concentrations in the near-bottom water at the 2 deeper sites were elevated (∼250 and 1,000 µg/L, respectively) compared to TP concentrations of <60 µg/L in 2006 and 2010, suggesting internal loading may be increasing, at least at these 2 sites. In contrast, maximum P release rates from the 2016 sediments were similar to or lower than 2010 rates, and an order of magnitude lower than before alum was applied. Phosphorus content in the sediment was fractionated; loosely sorbed sediment SRP concentrations were very low at all sites. Macroinvertebrate community was similar in density and composition to the 2010 results. These results are suggestive, but not conclusive, that internal P loading is increasing in parts of Spring Lake. Alum application can serve as an effective short-term solution to the longer-term problem of internal P loading, but its effectiveness is critically tied to concurrent reductions in external P loading.

Wetland Restoration through Excavation: Sediment Removal Results in Dramatic Water Quality Improvement

Land, Sep 14, 2022

Perfluoroalkylated Substances (PFAS) Associated with Microplastics in a Lake Environment

Toxics, May 11, 2021

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