Scherbaum S, Mirbach S, H & uuml;bl F, Fuchs Y, Haun S, Schneider J. 2026. Separating and analyzing wind- and boat-induced waves: a filtering framework for hydraulic lake monitoring. Lake Reserv Manag. XXX-XXX.Separating artificially induced waves by motorboats from natural wind waves on lakes is essential to assess their damage potential for lake ecosystems and to implement effective protective measures. A novel filtering framework, combining a classification of wave packet by peak period with high- and low-pass filter and wavelet denoising methods, enabled a reliable classification of small motorboat-induced and wind-induced waves. Wind waves were determined using a calibrated numerical SWAN model, while waves induced by motorboats were identified using synchronized drone footage in a field campaign at an Austrian lake. Thereby, motorboat-induced waves accounted for 83% of the total wave energy, and wind-generated waves accounted for 3%. The remaining 14% could not be classified, likely due to low signal strength or disturbances caused by other vehicles and reflections that were not identifiable as boat-induced. The framework was subsequently applied to 7 wave recordings obtained along shorelines characterized by contrasting hydraulic conditions. Results consistently indicated that motorboat-induced waves dominated the wave energy budget, and increased wind exposure resulted in a higher contribution of wind-generated waves. Pronounced buffering effects of wave-protection fences and sheltered bays were observed, whereas wave energy increased substantially near reflective shore structures compared to dissipative shorelines. Filtered boat-induced waves were characterized by higher wave heights, longer periods, and greater energy flux, with clear distinctions between planing and semi-planing modes visible in the wavelet spectrograms. The developed framework enhances the evaluation of wave recordings, enabling robust monitoring and assessment of anthropogenic wave exposure, which supports evidence-based management of lake ecosystems.
Aoki N, Fujibayashic M, Sakamaki T, Kuba T. 2026. On-site observation of reservoir EPA/DHA spatiotemporal distribution using a multi-wavelength excitation fluorometer and machine learning. Lake Reserv Manag. XXX-XXX.The quality of food resources strongly influences the health of aquatic animals in lacustrine environments. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fatty acids that are indicators of food quality. The content (absolute mass per unit lake water volume) of these fatty acids can be used to assess the adequacy of essential biochemicals in lacustrine food webs. Their levels (mass percentage of total fatty acids in suspended solids) reflect the nutritional balance and trophic transfer efficiency to higher trophic levels. Their distributions vary spatially and temporally, and detailed dynamics have rarely been captured because conventional analyses of EPA and DHA are time-consuming and labor-intensive. In this study, we applied a recently developed, simple observation method that combines a multi-wavelength excitation fluorometer with machine learning to monitor EPA and DHA contents and EPA and DHA levels. This method was used to measure these acids monthly in Hokuzan Reservoir, Saga Prefecture, Japan, from July 2021 to December 2023. Distinct vertical distribution patterns and seasonal periodicity were observed. During the summer, EPA and DHA were concentrated in the epilimnion attributed to thermal stratification, whereas winter turnover resulted in uniform and elevated concentrations throughout the water column. Seasonal variations in EPA and DHA levels indicated compositional shifts dominated by EPA- and DHA-rich phytoplankton species. The approach demonstrated here offers a practical framework for monitoring the nutritional quality of aquatic food webs and for managing lake ecosystems.
Aluminum sulfate (alum) treatments are commonly used to reduce internal phosphorus loading in lakes, which improves water clarity and potentially enhances macrophyte growth. Despite increasing use of alum to improve lake water quality, few studies have examined subsequent macrophyte responses to alum treatments. We investigated the effects of alum treatments on water quality and aquatic macrophytes in 7 lakes in the upper midwestern United States. These lakes each had several years of pre- and post-alum treatment data for water quality and macrophytes, spanning 2011 to 2023, and received 2 or more split-dose alum treatments (total dose divided across 2 or more treatment years). Six lakes were also actively managed to control invasive aquatic plants. We assessed for pre-, during-, and post-alum-treatment differences in epilimnetic total phosphorus (TP), Secchi depth, and total, native, and invasive plant frequency of occurrence. Generalized regression models indicated that epilimnetic TP decreased and Secchi depth increased significantly after alum treatments (P < 0.001). Frequency of occurrence of both total and native macrophytes increased significantly (P < 0.001) following alum treatment, coincident with the subsequent increase in water clarity. Invasive macrophyte responses were variable, with curly-leaf pondweed showing no significant response and Eurasian watermilfoil exhibiting mixed outcomes after alum treatment. Management with herbicides likely influenced invasive plant responses. Planning for aquatic plant responses should be a key component of the alum treatment strategy. Integrated management approaches that combine nutrient reduction with targeted invasive species control are essential for achieving long-term improvements in water quality and macrophyte communities.
The PhytoPAM II quantifies and attributes chlorophyll a (Chl-a) to 4 phytoplankton groups based on their unique fluorescence excitation spectra (FES): (1) "blue" group for cyanobacteria; (2) "green" group for euglenophytes and chlorophytes; (3) "brown group" for ochrophytes (e.g., diatoms), dinophytes, haptophytes; and (4) "red" group for phycoerythrin-rich phytoplankton. This rapid assessment is potentially advantageous over microscopy for monitoring algal blooms. However, calibrating the FES for more than one lake or as the community composition changes can pose a challenge for lake monitoring programs. This study assessed using the PhytoPAM II and its factory reference FES to estimate phytoplankton biomass (as Chl-a) and characterize phytoplankton community changes in a suite of freshwater lakes located in the midwestern United States. Subsurface water samples (n = 450) were collected during 3 summers (2018-2020; 15 weeks per summer). PhytoPAM II-derived Chl-a were compared with Chl-a extractions. Phytoplankton community composition was compared with 16S or 18S rRNA sequencing and optical microscopy. There was a significant correlation between spectrophotometric and PhytoPAM II-derived Chl-a (R-2 = 0.92; p < 0.001) across lakes in 2 study years. The factory reference FES correctly discriminated major taxa belonging to the "blue" group (95% occurrences detected) and "brown" group (94% occurrences detected); however, taxa belonging to the less abundant "green" and "red" groups may go undetected (67% and 61% occurrences detected, respectively). The adaptation of PhytoPAM II and its factory reference FES for near real-time phytoplankton community assessment can serve as a first line of monitoring of cyanobacterial-dominated lakes.
Wilkins CAT, R & uuml;hland KM, Meyer-Jacob C, Paterson AM, Smol JP. 2026. Have watershed disturbances over the past similar to 200 years affected lakes in Algonquin Provincial Park (Ontario, Canada)? Lake Reserv Manag. XXX-XXX.Algonquin Provincial Park (APP or the Park), located in south-central Ontario, spans an area of 7,635 km2 and is a destination for over 800,000 visitors annually. Although APP was established as a protected area in 1893, some of its lakes and catchments have experienced varying degrees of anthropogenic stress, including logging, private cottages, railways, roadways, and experimental manipulation. The effects of these stressors on lake ecosystems are not yet well understood. To address this knowledge gap, paleolimnological methods were used to assess whether anthropogenic stressors have affected APP lakes over the past similar to 200 yr. Using diatom assemblage composition, alongside spectrally inferred chlorophyll a and lake-water dissolved organic carbon (DOC) concentrations from 210Pb-dated sediment cores collected from 5 lakes, we determined preindustrial (baseline) conditions and examined whether historical catchment disturbances, as well as regional climate change, have registered a response in the sedimentary records. To help distinguish the effect of local catchment disturbances from natural and climatic variability, comparisons were made between 3 lakes (Cache, Canoe, Smoke) that support cottages and commercial establishments, as well as 2 remote reference lakes (McIntosh, Welcome). In general, diatom assemblage changes were modest in all lakes, except for a clear response to a nutrient manipulation experiment in Cache Lake in the 1940s. In all lakes, mid-19th-century diatom compositional changes, together with trends in chlorophyll a and DOC, appear to be a response to logging in the region. Importantly, we found little evidence that cottages have had a discernible effect on these lakes.
Stanislawczyk K, Braig IV EC, Laughinghouse IV HD, Raymond HA, Syed HE, Fuchs JD, Weavers LK, Chaffin JD. 2026. The relative effects of algaecides and nanobubble ozone treatment (NBOT) on nontarget zooplankton in a mesocosm study. Lake Reserv Manag. XXX-XXX. Cyanobacterial harmful algal blooms (cyanoHABs) threaten recreational and drinking water sources, and lake managers need tools that suppress or control them with minimal negative effects on nontarget organisms. Nanobubble ozone technology (NBOT) is an emerging cyanoHAB control strategy, but documentation of effects on nontarget zooplankton is limited. Using a zooplankton community sourced from Lake Erie, this study compared replicated mesocosm trials of 2 NBOT treatments (0.9 and 4.6 mg O-3/L) to 2 algaecides: registered copper (1 mg Cu/L) and hydrogen peroxide-based (10 mg H2O2/L) applied at label-approved amounts. Both algaecides had significantly (P < 0.01) greater negative effects on nontarget zooplankton than the 2 NBOT doses. Response to treatment was variable among the 7 evaluated taxa. Bosmina sp., Daphnia sp., Sididae, and Chydoridae increased in both controls and lower NBOT treatments but significantly (P < 0.01) declined in the algaecide treatments. The higher NBOT dose treatment reduced Bosmina sp. but to a lesser extent than algaecide treatments. Additional studies are needed to determine the effect of increased ozone doses on zooplankton communities. Overall, NBOT is a viable cyanoHAB treatment alternative with the potential to reduce negative effects on nontarget zooplankton compared to traditional algaecides.
Duka MA, Tamayo LVQ, Casim NCI, De Los Reyes RB, Buela LCM, Yokoyama K. 2026. Water quality response to monsoon dynamics and management interventions in a Philippine tropical lake. Reserv. Manag. XXX-XXX.Sampaloc Lake, a small tropical crater lake in the Philippines, has long faced water quality degradation linked to unregulated aquaculture and rapid urban growth. This study assessed lake stratification and water quality dynamics from 2022 to 2024 using vertical profiles and practical indices such as the Schmidt stability index (SSI), trophic state index (TSI), and euphotic zone depth (Zeu). Seasonal patterns showed that mixing during the northeast monsoon (NEM) was associated with higher productivity and reduced water clarity, while stronger stratification during the southwest monsoon (SWM) limited nutrient exchange and improved transparency. To evaluate the longer term effects of policy interventions that followed the lake's 2014 designation as a "threatened lake," surface water quality data from 2006 to 2021 were also examined. Post-2014 records showed reduced phosphate and chlorophyll-a concentrations, along with declining water quality index (WQI) values, indicating some improvements in trophic status. However, low dissolved oxygen levels persisted in recent years, suggesting that internal loading and hypoxia risks remain. These results highlight the value of sustained monitoring using integrative indicators to track lake responses over time. The findings may help guide rehabilitation planning in similar tropical lake systems where seasonal mixing and legacy nutrient sources continue to affect water quality outcomes.
Wellard Kelly H, Brady V, Pierce K, Hell B, Jeffrey P, Pederson B, Ulseth A. 2026. Removing invasive species from boat interiors: what works best? Lake Reserv Manag XXX-XXX.Cleaning boats after use is key to preventing the spread of aquatic invasive species (AIS) between waterbodies. The most effective methods to prevent AIS spread, drying and hot water decontamination, are not always possible before launching into a different waterbody. Self-service tools may be provided at launches to encourage boat cleaning. The tools vary and may include waterless tools (e.g., vacuum, cloth wipe, compressed air), as well as low-pressure water for rinses. The effectiveness of the cleaning methods at removing AIS from the interior of boats is uncertain, as most studies have focused on boat exteriors and trailers. We tested the effectiveness of 4 different cleaning methods on the interior of a boat fouled to simulate a) typical angling boat use and b) waterfowler use (usually more soiled), along with associated gear (duck decoys and waders). For each simulation, we repeatedly fouled the same boat with an exact count of dead and surrogate AIS to test 1) hand removal, 2) waterless tools, 3) low-pressure water rinse, and 4) combination of all methods. We conducted 10 replicates for each cleaning test for each simulation. All methods in combination or the vacuum alone removed the highest proportion of surrogate AIS. The effectiveness of the methods depended on the type of surrogate AIS (e.g., spiny water fleas versus plant matter) and on the type of boat fouling. These results provide guidance to state agencies, managers, and cleaning station manufacturers on the best cleaning tools to provide at boat launches to more thoroughly clean boats and gear.
Gamble A, Anderson J, Engel L. 2026. Patterns in Minnesota's lake user perception, trophic state, and lake assessment datasets: a 35-year retrospective. Lake Reserv Manag. XXX-XXX.Formal lake user perception metrics were first developed in the United States (Vermont) in the 1980s and have been used by the Minnesota Pollution Control Agency (MPCA) professional and volunteer lake monitoring programs since 1987. We present the first comprehensive, state-wide analysis of this lake user perception data. Specifically, we analyzed patterns in paired lake user perception survey data and trophic state water quality datasets from 1987-2022. Both at the statewide and US Environmental Protection Agency Level III ecoregion scale, lake user perception metrics consistently agreed with the MPCA's formal, science-based assessments of lake water quality and recreational use, despite numerous variations in field conditions, lake trophic status, and thousands of people (primarily volunteers) collecting the data. We found statistically significant differences in lake physical appearance and recreational suitability scores across gradients of total phosphorus and chlorophyll a concentrations and Secchi disk transparency. Scores were also significantly different between lakes formally assessed as impaired versus fully supporting aquatic recreation based on MPCA's standards. Impaired waters had lower mean user perception scores than full support waters. Additionally, lake surveyors in regions with very low concentrations of chlorophyll a had a lower tolerance for lake algae than lake users in regions with higher concentrations of chlorophyll a. Similar patterns were true for Secchi disk transparency. We found that lake users were consistently successful at visually matching their judgments of lake water quality to the MPCA's formal, science-based assessments of lake water quality, irrespective of geography.
Schoenebeck CW, Martin TJ, French WE. 2026. Year-round water temperature patterns of warming and cooling in Minnesota lakes. Lake Reserv Manag. XXX-XXX.Understanding annual water temperature patterns and when and where changes are occurring is essential to understanding the effects on aquatic ecology and identifying workable management strategies. We analyzed continuous epilimnetic water temperature data to identify trends in both annual and weekly water temperature metrics to evaluate if changes were uniform throughout the annual water temperature cycle (when are changes occurring) and if trends were similar across geographic regions (where are changes occurring). Beginning in 2008, the Sentinel Lakes Long Term Monitoring Program has collected year-round water temperature using continuous water temperature loggers in 25 Minnesota lakes. Using the Sentinel Lakes data, we found mean weekly water temperature and growing degree days have changed over time in Minnesota and differed among weeks of the year, geographic regions, and lake mixing type. Most of these trends consisted of warming temperatures during weeks in June and July; however, significant cooling trends in April were also identified. Maximum epilimnetic water temperature increased over time and varied by geographic region, warming the most rapidly within the Northern Lakes and Forest region. Geographically, more significant warming trends occurred in the Northern Lakes and Forests region, while the Canadian Shield region had the lowest amount of warming. Understanding where the slowest rate of change is occurring is important when working to conserve coldwater oxythermal habitat. We encourage managers to consider sampling protocols based on temperature guidelines instead of calendar dates, as changing water temperatures will affect metrics collected during established sampling dates.
Hayes D, Hartsock JA, Latimore J, Elgin E. 2026. Application of occupancy models to aquatic macrophyte data collected via rake-based point-intercept sampling. Lake Reserv Manag. XXX-XXX.Aquatic macrophytes are often surveyed with a double-sided rake using a point-intercept design. Rakes are not completely efficient at capturing aquatic macrophytes, and do not capture all taxa with equal efficiency. As such, estimates of frequency of occurrence are biased low due to incomplete detectability. We evaluated a protocol using 2 rake tosses per sampling point and applied a suite of occupancy models to data on the capture of common taxa in 78 lakes in northern Michigan, USA. A model allowing occupancy and detectability to vary freely among lakes fit best for most taxa but led to untenable estimates in lakes where macrophyte occurrence was low. A model allowing occupancy to vary freely but assuming a constant detectability among lakes fit well for many species and provided more reasonable estimates. For species that occurred in 20 or more lakes, detectability based on 2 rake tosses averaged 0.47 and ranged from 0.20 to 0.77. Depth was an important covariate for the occurrence of aquatic macrophytes. For example, applying a logistic regression to slender naiad (Najas flexilis) using depth and depth2 produced high fit scores for data pooled from all lakes. However, a model allowing for lake-specific depth distributions (i.e., including a lake x depth interaction term) was substantially better and showed that the depth distribution of this species varied widely among lakes. In summary, 2 or more rake tosses per sample point allow investigators to draw stronger conclusions about the prevalence of macrophytes than taking a single toss per sample point.
Ortiz DA, Blackburn SR, Daulton T, Kovar B, Meyer MW, Pralle CE, Stanley EH. 2026. Wake boats and lakes: physical, ecological, and policy implications. Lake Reserv Manage. XXX-XXX.The increasing use and popularity of wake boats have led to controversies about their effects on aquatic ecosystems. Where and how wake boat use is appropriate remains contentious because their physical effects on lakes have yet to be well quantified relative to other motorized nonwake boats. We conducted a systematic literature search to review current understanding of how wake boats may influence physical and ecological conditions in lakes. Despite their unique characteristics, wake boats appear to have effects similar to those of recreational motorboat use, although the magnitude of these effects is greatly amplified. These include increased risk of invasive species spread associated with large ballast tanks, littoral and shoreline erosion, sediment resuspension, and water quality modification due to the generation of large, high-energy wakes and deep turbulent mixing. Expected and demonstrated ecological and safety issues have led to widespread changes in boating regulations, and we reviewed examples of some of these adjustments. Because stricter limits may reduce the availability of lakes for wake boat recreation, we used Wisconsin (USA) lakes to consider how different regulatory scenarios might affect wake boat access to lakes. The number of available lakes was reduced for all scenarios, by up to 95% for the most extreme case, but even modest changes reduced eligible lakes by 25-43%. Key gaps remain in understanding the effects of wake boat recreation on lakes, and collaboration among researchers, agencies, and communities is needed to fill these gaps and develop regulations that safeguard lake health while accommodating recreation.
Cyanobacterial harmful algal blooms (cHABs) in lakes and reservoirs often contain cyanotoxins such as microcystins (MC), which can lead to various acute and long-term health complications in humans. During cHABs, MC concentrations can exceed local safety thresholds for recreation, forcing management groups to close public swimming areas. Private beaches and public boat launches may remain open, providing a pathway that could expose recreators to cyanobacteria and cyanotoxins. We hypothesized that persons engaged in motorized recreational activities during cHABs could be exposed to measurable quantities of cyanotoxins through repetitive water splashing without full-body immersion, and that weather conditions, innertube pressure, and tow cleat height could affect the MC exposure. A sampling method simulating a person being towed behind a motorboat on an innertube collecting water splashing was developed. Splash collected contained MC ranging from 0.02 to 4.10 mu g/L by liquid chromatography with tandem mass spectrometry and was highly correlated to the lake surface MC concentration (R-2 = 0.95, P < 0.05). Collected splash volumes correlated to wind speed, wave heights, towing cleat height, and degree of tube deflation. Five minutes of tubing from a low cleat with a deflated tube could expose a person to 7.22 g MC, while using a higher tow cleat and a properly inflated tube decreased the potential MC exposure to 0.04 mu g. Recreators on cHAB-prone waters must be informed about safer recreational practices to reduce potential cyanotoxin exposure.
Bennett JF, Campbell J, Rippey B, Douglas R. 2026. Determination of aluminum in fish tissue to assess the safety of phosphorus fixing chemicals: the case of two Irish lakes. Lake Reserv Manage. XXX-XXX.Phosphorus (P) fixing chemicals have been used for over 4 decades to counteract lake eutrophication by reducing internal P loading. In this study, an aluminum sulfate application was implemented in 2 shallow lakes in Ireland. A treatment targeting the water column added about 1 mg/L or 4 g/m2 of aluminum. Comparison of liver, gill, and muscle tissue from fish captured before and after treatment indicated no increase in aluminum concentrations up to 2 months after treatment. Muscle tissue contained less aluminum than gills or liver. Aluminum concentrations reported in edible fish tissue in these 2 lakes were lower than in multiple other studies and safety thresholds suggested by international health organizations. Despite some limitations of the research, such as the short sampling duration and low treatment dose, no results suggested any potential health hazard from consumption of fish in these treated lakes.
Singh A, Maury C, Shiwani K, Sharma VN, Rana NK. 2026. Siltation-induced lake deterioration and obligation of lake stewardship: bathymetric survey of Ramgarh Lake in Tarai region, India. Lake Reserv Manag. XXX-XXX.Lakes fed by surface runoff and altered by human-induced effluents such as sewage from direct or indirect sources can result in substantial deposition of silt into the underlying sediments. This study investigates siltation problems in Ramgarh Lake, which is nurtured by many rivers (Rapti, Ami, Rohini, Ghaghara) and small channels of the Himalayan foothills. The research aims to analyze the problem of siltation in Ramgarh Lake based on the measurements of silt thickness determined from the bathymetric survey. Ramgarh Lake is situated in an urban area with a tray-like bottom for water storage. In 1998, the maximum depth of the lake was 4.5 m. In 2019 the depth was only 2.56 m, a reduction of 2 m recorded across 21 yr. As of 2019, 342 m3 of silt is deposited on the floor of the lake bed with 1-1.5 m thickness. The lake's total area in 1922 was 1098 ha, which decreased by 390 ha across 97 yr (1922-2019). In total, 12 sewage outfalls have been identified. Concentrations of phosphorus and nitrate in the water column increased by 3 and 2 orders of magnitude across 50 yr (1969-2019), respectively. Both dredging and reduced sewage discharge are required to rejuvenate the health of Ramgarh Lake's ecosystem.
Smith JW. 2026. Public awareness and visual water quality thresholds at a bloom-prone urban lake (Utah Lake, Utah, USA). Lake Reserv Manage. XXX-XXX.Most recreationists at Utah Lake do not make decisions about when and how to recreate based on chlorophyll a (chl-a) concentrations, highlighting the need for more visible and targeted public communication about water quality. This study evaluated the extent to which recreationists and nearby residents were aware of water quality issues at Utah Lake and whether specific aesthetic thresholds-particularly related to chl-a and turbidity-influenced perceptions of recreational suitability. Two surveys were conducted in 2022. An intercept survey of 290 active recreationists was administered at various access points around the lake, and a mail survey was distributed to a stratified random sample of 541 households in Utah and Salt Lake Counties. Respondents evaluated images representing different levels of chl-a and turbidity and rated the water's suitability for swimming, boating, fishing, fish consumption, and near-water activities. The analysis suggests turbidity, not chl-a, may be a more noticeable visual cue shaping perceptions of recreation suitability; however, neither appears to provide a consistent optical proxy for water quality. Additionally, despite recent harmful algal blooms, 35.2% of those in the on-site sample and 48.8% of those in the resident sample reported no awareness of water quality issues at the lake. Together, these findings suggest resource managers should not assume the public understands or recognizes water quality hazards without direct or more targeted communication. Resource managers should consider deploying a broader array of communication tools, including digital alerts, more signage at trailheads and parking areas, and public outreach to support safe, informed recreation and enhance water quality management.
Jaiswal A. 2026. Equilibrium scour depth evaluation using well-established regression models in non-cohesive sediment desilting through hydro-suction. Lake Reserv Manage. XXX-XXX.Sediment inflow into reservoirs gradually reduces storage capacity over time. Hydro-suction is an innovative and cost-effective technique for sediment removal that employs siphonic action to desilt reservoirs. Equilibrium scour depth during hydro-suction is directly related to the desilted volume, and its accurate estimation is essential to optimize hydro-suction performance. This study evaluates the predictive capability of 5 machine-learning regression models, artificial neural network (ANN), k-nearest neighbors (KNN), decision tree (DT), random forest (RF), and Gaussian process (GP), for computing equilibrium scour depth during hydro-suction desilting of non-cohesive sediment. A scour depth dataset of 252 laboratory experiments, covering suction pipe diameter (D), suction inlet height (C), sediment median size (d50), and suction velocity (V) as key hydraulic parameters, was used to train and validate the models. Performance was evaluated based on various evaluation parameter metrics, supported by percentage error plots and a Taylor diagram. Results show that GP and RF outperform the other models, with GP providing the most stable predictions, achieving correlation coefficient (CC) values of 0.965 and 0.984 across training and testing datasets (MAE = 0.004 m, NSE = 0.965). Sensitivity analysis identified D as dominant parameter influencing the scour depth prediction, followed by V, C, and d50, exerting secondary but relevant effects. The findings highlight the potential of data-driven approaches to accurately predict scour depth under suction flow, reducing dependence on expensive physical modeling and facilitating efficient hydro-suction design and operation.
Freshwater quality is increasingly threatened by nutrient pollution, especially in closed-basin lakes like Lake Hashenge (LH), Ethiopia. This study explored how nutrient levels change across space and time between 2022 and 2025 and how they affect water quality, using the Drivers-Pressures-State-Impact-Response (DPSIR) framework. We collected 180 water samples from 15 sites during both wet and dry seasons and analyzed key physico-chemical and nutrient parameters using standard methods. Statistical tools—Principal Component Analysis (PCA) and Cluster Analysis (CA)—helped identify pollution sources and group sites by pollution status, while the Water Quality Index (WQI) and Comprehensive Pollution Index (CPI) provided an overall picture of ecological health. Results showed clear seasonal differences: nutrients tended to accumulate more during the dry season when dilution was limited. PCA pointed to nutrient-driven eutrophication, particularly at Debir, Endedo, and Abakiros, linked to human activities. Chlorophyll-a levels confirmed hypertrophic conditions throughout the year. CA revealed three pollution categories, highlighting spatial variability. While overall pollution was moderate, local hotspots stress the need for targeted watershed management, including land-use planning, buffer zones, and community awareness programs.
Cameron C. 2026. Waterbird species-area relationships at Florida lakes: evaluating a lake area management threshold using citizen science data. Lake Reserv Manag. XXX-XXX.Bird species richness and lake area are highly correlated all around the world. In Florida, this relationship informs establishment of lake regulatory levels using a lake area threshold reduction of 15%, corresponding to loss of one waterbird species. This study demonstrated the efficacy of using citizen science (eBird) data to estimate waterbird species richness through comparison to professional data for 25 Florida lakes. Using eBird data for up to 721 lakes, several statistical approaches produced threshold estimates of lake surface area reduction of 10-16%. While the existing 15% threshold remains supported, a 12% threshold may be warranted for lakes with characteristics different from previous studies or for more conservative management. Methods for the use of eBird data to assess relative species richness differences, account for sampling effort, and establish regulatory thresholds may translate to other regions. While this approach considers one narrow aspect of lake ecology and should only be used as part of a suite of ecologic and hydrologic metrics, it can serve as a practical and critical backstop for lake protection.
Olagunju TE, Ibini OD, Mustapha MK. 2026. Socioenvironmental dynamics and determinants of riverscape pollution in Nigeria: insights from the Oyun River-Reservoir system, Offa. Lake Reserv Manag. XX-XX. Riverscape pollution poses significant threats to both ecological integrity and socioeconomic well-being worldwide. This study examines the socioenvironmental dynamics and determinants of riverscape pollution in the Oyun River-Reservoir system, Offa, in Nigeria. Using a cross-sectional descriptive design, data were collected from randomly selected 35 cohorts and 387 respondents (5% margin of error) through pretested semistructured interviews and questionnaires, respectively. Statistical analyses, including chi-squared tests and Kendall's coefficient of concordance, were employed to identify associations and to rank pollution risk factors. Key findings indicate that low education, low income, and employment significantly (P < 0.05) influenced knowledge of riverscape pollution. The predominant drivers of pollution include open defecation, waste dumping, and nonsustainable fishing and agricultural practices, all compounded by poverty, weak governance, cultural beliefs, and inadequate infrastructure. Despite awareness of the risk factors associated with riverscape pollution, pro-environmental behaviors remain low due to structural barriers. The study underscores the importance of community-driven conservation, policy enforcement, and infrastructural improvements to mitigate riverscape pollution. The findings also provide critical insights for policymakers and environmental stakeholders, advocating for targeted interventions to ensure sustainable management of freshwater ecosystems, especially in developing countries. Future research should adopt longitudinal approaches to assess evolving perceptions and behavior.
