Aquatic Ecosystem Health & Management

Applauding Dr. Mirza Umair Beg's contributions to the Aquatic Ecosystem Health & Management Society, Canada, and GULF conventions

M. Munawar — Mon, 16 Jun 2025 00:00:00 +0300

Up-close and personal with Dr. M. U. Beg for 24 years

Talat Saeed — Mon, 16 Jun 2025 00:00:00 +0300

Dr. Mirza Umair Beg: A complete man

Naheed Umair — Mon, 16 Jun 2025 00:00:00 +0300

A tribute to my father, Dr. Mirza Umair Beg

Uzma Khan — Mon, 16 Jun 2025 00:00:00 +0300

Papa's chit-chat

Hina Beg — Mon, 16 Jun 2025 00:00:00 +0300

In loving memory of Dr. Beg

Sherain Al-Subiai — Mon, 16 Jun 2025 00:00:00 +0300

Dr. Beg, a beacon for future scientists: An homage to an outstanding human being

Qusaie Karam — Mon, 16 Jun 2025 00:00:00 +0300

Memories of Dr. M.U. Beg

Faiza Al-Yamani — Mon, 16 Jun 2025 00:00:00 +0300

In memory of Dr. Mirza U. Beg: Remembering Dr. Beg as a dear friend, colleague, and dedicated research partner

Saleh Mohammed Al-Muzaini — Mon, 16 Jun 2025 00:00:00 +0300

Ecology of Lake Erie: Causes, consequences and management of eutrophication

Mohiuddin Munawar, Stuart A. Ludsin — Mon, 16 Jun 2025 00:00:00 +0300

Harmful algal bloom impacts on foodweb structure in western Lake Erie

Mon, 16 Jun 2025 00:00:00 +0300

Human-driven environmental change has caused harmful algal blooms to increase in aquatic ecosystems worldwide, yet our understanding of their impacts on foodwebs and the fisheries that they support remains incomplete. This information gap is especially conspicuous in Lake Erie (USA-Canada), where harmful algal blooms have been increasing owing to nonpoint source nutrient runoff and climate change. From a summer 2019 field investigation designed to test hypotheses concerning the effects of harmful algal blooms on western Lake Erie's foodweb, we confirmed that nanoplankton and netplankton primary production rates, cyanobacteria biomass, and microcystin, chlorophyll a and turbidity concentrations were higher inside of the blooms than outside, with Secchi disk transparency being ∼3-fold lower inside of these blooms. Harmful algal bloom sites also had higher levels of total and soluble reactive phosphorus, dissolved organic carbon, and silica than non-harmful algal bloom sites, with nitrate and nitrate showing the opposite pattern. Counter to expectations, crustacean zooplankton biomass was higher inside than outside the blooms due to more calanoid copepod and non-daphnid cladoceran biomass inside the harmful algal blooms; Daphnia spp., bosminid, cyclopoid copepod, and predatory cladoceran biomass did not differ between areas. Dreissenid mussel veligers were almost 10-fold lower inside than outside the blooms. Finally, fish community structure was near-identical between harmful algal bloom and non-bloom areas, except for Shiner (Notropis) species, which were more abundant inside. Collectively, our findings indicate that, despite their negative effects on water quality (e.g. toxin production, reduced water clarity), western Lake Erie harmful algal blooms are biologically productive and may not be a trophic dead end as is commonly believed. In discussing these findings, we identify knowledge gaps that can help fishery management agencies better understand how these blooms affect foodwebs and the fisheries that they support.

Harmful algal bloom effects on fish habitat use and community structure in western Lake Erie

Sun, 15 Jun 2025 00:00:00 +0300

Harmful algal blooms dominated by cyanobacteria have been increasing in frequency, duration, extent, and intensity in freshwater ecosystems worldwide, yet our understanding of their impact on aquatic foodwebs remains limited. This study aims to generate ecological insights that could benefit fisheries management in freshwater ecosystems experiencing harmful algal blooms, we conducted daytime and nighttime trawling (bottom and midwater) and hydroacoustic surveys inside and outside of blooms in western Lake Erie during July-August 2019. We evaluated if prey fishes use harmful algal blooms during the day as a refuge from predation and avoid them at night due to darkness and potential cyanotoxins. We also examined if visually feeding piscivorous fishes avoid these blooms due to low water clarity and high cyanobacteria concentration that could impair foraging. We did not find differences in total fish catch (in both types of trawls) or total fish density (estimated by down-looking acoustics) between harmful algal blooms and non-harmful algal blooms sites. Similarly, we found few differences in the use of harmful algal blooms among feeding/habitat guilds. Walleye, Sander vitreus, an important piscivore, and abundant benthivores (Yellow Perch Perca flavescens, White Perch Morone americana, and Trout-perch Percopsis omiscomaycus) did not vary between harmful- and non-harmful algal bloom sites, regardless of when sampling occurred or trawl type (bottom or midwater). While the catch of pelagic fishes preferred as prey by Walleye (i.e. Rainbow Smelt Osmerus mordax, Gizzard Shad Dorosoma cepedianum, and Notropis spp.) was higher inside of HABs relative to outside, this difference was only observed in bottom trawls (not midwater trawls). Our acoustics data did show, however, that harmful algal blooms modified the vertical distribution of fish. Specifically, fish were located deeper in the water column in non-harmful algal bloom sites during the day relative to night, with this difference disappearing inside of harmful algal blooms. In addition to explaining the likely mechanisms responsible for the extensive use of harmful algal blooms by Lake Erie fishes, we discuss implications for fisheries management during the harmful algal blooms season.

Stable isotopes reveal an imprint of harmful algal blooms on Lake Erie

Mon, 16 Jun 2025 00:00:00 +0300

In Lake Erie, harmful algal blooms have become a recurrent problem during the summer-through-fall growing season. We investigated if the annual disturbance of harmful algal blooms in Lake Erie relates to distinct differences in carbon and nitrogen stable isotope composition (δ¹³C and δ¹⁵N values). Guided by near real-time satellite imagery, we tracked the blooms in western and central Lake Erie during July and August 2019 for the collection of in-bloom and out-of-bloom suspended particulate organic matter. The δ¹⁵Npom values did not differ between in-bloom and out-of-bloom samples; however, δ¹³Cpom values were significantly higher in the in-bloom compared to out-of-bloom samples. We used principal component analysis to investigate how water quality relates to biogeochemical indicators in in-bloom and out-of-bloom samples. In-bloom samples were only found in the western basin. They contained lower concentrations of ions (Na⁺, Cl^-, SO4^2-) and inorganic nitrogen (NO₂^-, NO₃^-, NH₄⁺), and higher concentrations of total nitrogen, total phosphorus, and organic particles (TSS, VSS, DOC). After uncovering patterns in in-bloom and out-of-bloom samples in the western portion of Lake Erie, we created isoscapes to compare particulate organic matter samples collected throughout the lake during July-September. The δ¹⁵Npom values varied spatially across the three basins, and in the central and eastern basins, δ¹⁵Npom values were higher in September relative to July. We found δ¹³Cpom values displayed a longitudinal spatial gradient with higher values in the western basin and lower values towards the eastern basin with no temporal separation based on sampling month. δ¹⁵Npom and δ¹³Cpom values provide a baseline for future isotope studies in Lake Erie, and observed variation in δ¹³Cpom reveals a harmful algal bloom-produced change in the carbon biogeochemistry of Lake Erie.

Modeling and assessment of agricultural best management practices on sediment and nutrient load reductions in the Upper Medway watershed of the Lake Erie Basin

Yongbo Liu, Wanhong Yang, Hui Shao, Kevin McKague — Mon, 16 Jun 2025 00:00:00 +0300

The Upper Medway watershed is a representative rural upland watershed of the Lake Erie Basin with an undulating landscape dominated by agricultural land use activities. Various agricultural best management practices have been implemented in the study area over time to reduce sediment and nutrient loadings from the watershed. The purpose of this study was to assess the effectiveness of these practices at field and watershed scales by using a process-based hydrologic model. Higher effectiveness was found for vegetative buffer strips and wetland restoration in reducing sediment and phosphorus loadings. Controlled tile drainage was found more effective in reducing nitrogen loadings compared to other best management practices. Grassed waterways and water and sediment control basins were more effective in reducing sediment loading but less effective in reducing nutrient loadings. Fertilizer incorporation was more effective compared to conservation tillage and cover cropping in reducing nutrient loadings from the tile-drained fields. It was estimated that all existing best management practices present in the watershed, reduced sediment, total phosphorus, and total nitrogen by 21.6%, 12.9%, and 20.0% respectively at the watershed outlet. The study showed that watershed modeling, in combination with field monitoring, can be a useful technique for evaluating the effectiveness of various land management practices in improving rural water quality. Findings of these practices' effectiveness in the Upper Medway watershed modeling study can be a valuable reference for similar studies in the Lake Erie Basin. However, more field monitoring data is required to improve the model's performance and to reduce the uncertainty of best management practices assessment.

Land-use management and parameterization as sources of uncertainty in hydrologic models: A Maumee River Watershed case study

Anna Apostel, Grey Evenson, Jay Martin, Gil Bohrer, Margaret Kalci — Mon, 16 Jun 2025 00:00:00 +0300

The use of hydrological models in water management and policy has grown with increasing demand for scientifically credible solutions to rising environmental concerns. However, difficulty in quantifying uncertainty is a key limitation for interpreting model results. Uncertainties associated with parameters and data inputs are commonly reported. While some studies reported the relative effects of specific farm management implementation, the type and timing of farm field management operations remain some of the most uncertain data inputs and have been poorly studied in the context of model uncertainty. This study aims to assess the relative role of two potential drivers of uncertainty: 1) assumptions made for farm management; and 2) model parameterization through analysis of a Soil and Water Assessment Tool (SWAT) model of the Maumee River Watershed. We identified a suite of model simulations representing management practices of known importance to the region, and we identified a set of commonly calibrated model parameters and a set of prescribed value combinations representing the range of plausible values for these parameters. SWAT was run over each unique combination of parameter sets, and management realizations. Model outputs were compared with observations to quantify and attribute uncertainty to management inputs and parameterization. We examined the sensitivity of modeled outlet-level discharge and nutrient loading and found that parameterization and management were large contributors to uncertainty across all water quality outputs examined. Furthermore, model uncertainty in discharge was dominated by parameterization, while uncertainty in nutrient loading was dominated by management inputs. Based on the results, we suggest that when developing models for informing decision making, management practices that are implemented using the best available spatial and temporal data likewise undergo a management implementation sensitivity analysis and that these results are reported in the context of uncertainty, similar parameter uncertainty standards.

A retrospective analysis of climate and land management drivers of nutrient export from the western Lake Erie watershed: 1980-2019

Mon, 16 Jun 2025 00:00:00 +0300

The return of harmful algal blooms to western Lake Erie has heightened the focus on managing nutrient loading from its watershed, and particularly the large, agricultural Maumee River Watershed (MRW). Increased dissolved reactive phosphorus (DRP) loads over the last twenty years are suspected to be a primary cause of the recurrence and severity of these blooms. The primary cause of increasing DRP is still unclear, and therefore management efforts to reverse this trend are difficult to develop. We used a refined model of the MRW to investigate changes in climate and land management between 1980 and 2019 to identify key factors driving trends in DRP as well as discharge and other nutrient forms that impact algal biomass and toxicity. We found that the dominant drivers of discharge and nutrients varied: historical climate trends drove discharge and nitrogen concentrations, while historical management changes were more responsible for changing phosphorus concentrations. Among the land management changes examined, the rising adoption of minimal- and no-tillage strategies had the greatest impact on nutrient trends, leading to reductions in total phosphorus (TP), total nitrogen (TN), and nitrate (NO3), yet increases in DRP. We posit that a better understanding of the water quality impacts of past land management enables modelers and managers to more accurately predict the impacts of potential future management changes.

Addressing Lake Erie eutrophication: An assessment of recent progress and recommendations

Murray M.W, Livernois J, Bratton J.F., Burrows M. — Mon, 16 Jun 2025 00:00:00 +0300

Addressing eutrophication problems in the Great Lakes was a key motivating factor in the signing of the Great Lakes Water Quality Agreement by the U.S. and Canadian governments (the “Parties”) in 1972. In spite of progress in the intervening five decades, persistent eutrophication problems – including harmful algal blooms – continue to occur in western Lake Erie and in some embayments of most of the other Great Lakes. In 2020-2022 a work group of the International Joint Commission assessed progress in addressing nutrient loads in Lakes Erie (with a secondary emphasis on Lake Ontario). The project reviewed recent research relevant to addressing ongoing nutrient impacts in Lake Erie, reviewed and assessed progress under domestic action plans developed for Lake Erie, and the status of implementation of recommendations from previous International Joint Commission reports. The research review indicated significant progress in some areas, in particular concerning modeling, but ongoing needs in others, including on approaches to optimize appropriate best management practices at sufficient scales to reduce nutrient export from the land. The Parties' implementation of the Commission's recommendations has been mixed, with setting of targets and multiple modeling efforts on the one hand, but more limited work in other areas, including related to the economics of harmful algal blooms and on manure management. Our assessment of domestic action plans themselves, found both strengths (including in research, monitoring, adaptive management, and watershed-level planning), and limitations (including details on best management practices implementation, approaches to manure management, and funding needs for implementation). We identify multiple recommendations for strengthening programs in both countries, including through increased research addressing multiple aspects of best management practices effectiveness and implementation, consideration of an innovative approach such as group-level incentives to increase best management practices implementation in the agricultural community, and utilization of an accountability framework to advance progress towards meeting Lake Erie nutrient targ

Ecology of Lake Erie: Causes, consequences and management of eutrophication: A synthesis

Mon, 16 Jun 2025 00:00:00 +0300