Limnological Review

16 pages, 2440 KiB

Open AccessArticle

Maximum Potential Age of Pondcypress Hydrologic Indicators Using Diameter at Breast Height

by Cortney R. Cameron and Thomas J. Venning

Limnol. Rev. 2025, 25(1), 9; https://doi.org/10.3390/limnolrev25010009 - 20 Mar 2025

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In the absence of long-term hydrologic records, field-measured hydrologic indicators are useful for inferring past wetland hydrologic conditions, which can support research, regulation, and restoration. Inflection points on the buttresses of pondcypress trees (Taxodium ascendens) are frequently used in west-central Florida [...] Read more.

In the absence of long-term hydrologic records, field-measured hydrologic indicators are useful for inferring past wetland hydrologic conditions, which can support research, regulation, and restoration. Inflection points on the buttresses of pondcypress trees (Taxodium ascendens) are frequently used in west-central Florida to estimate cypress wetland high water levels, known as normal pool. However, little is known about how this indicator develops. A method to estimate tree age using diameter at breast height was developed for Florida pondcypress, which can be used by forested wetland managers to constrain the maximum potential age of hydrologic indicators in groups of cypress trees. This model was applied to a waterbody with a complex history of hydrologic alterations. The waterbody had two distinct populations of buttress inflection elevations, corresponding to historic versus current water level regimes. This represents one of the first documented instances in the literature where a waterbody showed multiple buttress inflection populations in the absence of soil subsidence. This work underscores the need to consider the development timelines when interpreting the hydrologic meaning of indicator elevations. Full article

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16 pages, 1489 KiB

Open AccessArticle

Longitudinal Distribution of Benthic Macroinvertebrates Related to River Ecological Quality

by Māra Kostanda, Gunta Spriņģe, Dāvis Ozoliņš, Agnija Skuja and Oskars Purmalis

Limnol. Rev. 2025, 25(1), 8; https://doi.org/10.3390/limnolrev25010008 - 14 Mar 2025

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Abstract

Macroinvertebrates of the Venta River have been studied since the beginning of the 20th century. However, complex studies along the Venta River from the Latvian–Lithuanian border to its mouth into the Baltic Sea have been irregular and fragmentary. The aim of this study [...] Read more.

Macroinvertebrates of the Venta River have been studied since the beginning of the 20th century. However, complex studies along the Venta River from the Latvian–Lithuanian border to its mouth into the Baltic Sea have been irregular and fragmentary. The aim of this study was to assess the ecological status of the Venta River and to analyze the abundance and fauna composition of macroinvertebrates along the entire length of the river in the territory of Latvia. This is the first study of its kind for the Venta River examining the specialization of macroinvertebrates in sediment substrates and their functional feeding groups. Within the framework of the study, the composition and functional importance of macroinvertebrates was assessed in 10 sampling sites together with the ecological quality of the river using several indices. The results show that the Venta River is dominated by benthic invertebrate collectors/gatherers, active filterers, grazers, and scrapers that have adapted to the particular type of sediments formed by silt, macrophytes, rocks, and pebbles. Different indices were calculated in order to assess the ecological quality of the Venta River. According to the saprobity index, the water quality corresponds to β-mesosaprobity, while ecological quality is mostly average; however, according to the multimetric indices, the quality of the Venta River varies from poor to high depending on the sampling station. Full article

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15 pages, 5073 KiB

Open AccessArticle

Influence of Optically Active Substances on Light Attenuation in a Tropical Eutrophic Urban Reservoir

by Renata C. H. Amancio, Stella P. Pacheco, Karen A. F. Moura, Bianca L. Valle, Julia T. C. Alves, Fernanda F. Melo, Vitor J. G. Silva, Lívia S. Botelho, Raquel T. Rocha, Daiana R. Pelegrine, Thiago M. Salgueiro, Carlos M. O. Tadeu, Vitor G. Elian, Giulia A. Ducca, Arielli G. Zavaski, Renata L. Moreira, Winnícius M. S. Sá, Estevão E. O. Eller, Renato B. de Oliveira-Junior, Ivan M. Monteiro, Lorena T. Oporto, Diego G. F. Pujoni and José F. Bezerra-Neto Show full author list Hide full author list

Limnol. Rev. 2025, 25(1), 7; https://doi.org/10.3390/limnolrev25010007 - 12 Mar 2025

Cited by 1 | Viewed by 460

Abstract

This study investigated the impact of optically active substances on light attenuation in a tropical eutrophic urban reservoir under different seasonal conditions. Diffuse attenuation coefficients for photosynthetically active radiation (Kd_PAR) and ultraviolet radiation (Kd_UVA and Kd_UVB) [...] Read more.

This study investigated the impact of optically active substances on light attenuation in a tropical eutrophic urban reservoir under different seasonal conditions. Diffuse attenuation coefficients for photosynthetically active radiation (Kd_PAR) and ultraviolet radiation (Kd_UVA and Kd_UVB) were measured at three representative sites and correlated with water quality parameters (chlorophyll-a, total suspended solids [TSS], dissolved organic carbon, and colored dissolved organic matter [CDOM]). The results revealed significant spatial and seasonal differences, with the highest attenuation observed during the rainy season. The Ilha site exhibited the greatest coefficients (Kd_PAR = 6.0 m⁻¹, Kd_UVA = 17.9 m⁻¹, Kd_UVB = 19.0 m⁻¹), while lower values were recorded at Barragem (Kd_PAR = 2.4 m⁻¹, Kd_UVA = 9.1 m⁻¹, Kd_UVB = 12.0 m⁻¹) and Igrejinha (Kd_PAR = 3.1 m⁻¹, Kd_UVA = 10.8 m⁻¹, Kd_UVB = 11.9 m⁻¹). Statistical analyses showed strong correlations between TSS and Kd_PAR (r = 0.66) and between CDOM and both Kd_UVA (r = 0.66) and Kd_UVB (r = 0.59), with regression models confirming TSS and CDOM as key predictors of light attenuation. These findings underscore the pivotal role of particulate and dissolved organic matter in underwater light dynamics, emphasizing the need to reduce their input during periods of heavy rainfall. Full article

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19 pages, 5256 KiB

Open AccessArticle

Comparison of Machine Learning Models for Real-Time Flow Forecasting in the Semi-Arid Bouregreg Basin

by Fatima Zehrae Elhallaoui Oueldkaddour, Fatima Wariaghli, Hassane Brirhet, Ahmed Yahyaoui and Hassane Jaziri

Limnol. Rev. 2025, 25(1), 6; https://doi.org/10.3390/limnolrev25010006 - 5 Mar 2025

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Abstract

Morocco is geographically located between two distinct climatic zones: temperate in the north and tropical in the south. This situation is the reason for the temporal and spatial variability of the Moroccan climate. In recent years, the increasing scarcity of water resources, exacerbated [...] Read more.

Morocco is geographically located between two distinct climatic zones: temperate in the north and tropical in the south. This situation is the reason for the temporal and spatial variability of the Moroccan climate. In recent years, the increasing scarcity of water resources, exacerbated by climate change, has underscored the critical role of dams as essential water reservoirs. These dams serve multiple purposes, including flood management, hydropower generation, irrigation, and drinking water supply. Accurate estimation of reservoir flow rates is vital for effective water resource management, particularly in the context of climate variability. The prediction of monthly runoff time series is a key component of water resources planning and development projects. In this study, we employ Machine Learning (ML) techniques—specifically, Random Forest (RF), Support Vector Regression (SVR), and XGBoost—to predict monthly river flows in the Bouregreg basin, using data collected from the Sidi Mohamed Ben Abdellah (SMBA) Dam between 2010 and 2020. The primary objective of this paper is to comparatively evaluate the applicability of these three ML models for flow forecasting in the Bouregreg River. The models’ performance was assessed using three key criteria: the correlation coefficient (R²), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC). The results demonstrate that the SVR model outperformed the RF and XGBoost models, achieving high accuracy in flow prediction. These findings are highly encouraging and highlight the potential of machine learning approaches for hydrological forecasting in semi-arid regions. Notably, the models used in this study are less data-intensive compared to traditional methods, addressing a significant challenge in hydrological modeling. This research opens new avenues for the application of ML techniques in water resource management and suggests that these methods could be generalized to other basins in Morocco, promoting efficient, effective, and integrated water resource management strategies. Full article

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24 pages, 2186 KiB

Open AccessArticle

Characteristics of the Zooplankton Community Structure in Shengjin Lake and Its Response to the Restored Aquatic Vegetation

by Dagne Tafa Dibar, Kun Zhang and Zhongze Zhou

Limnol. Rev. 2025, 25(1), 5; https://doi.org/10.3390/limnolrev25010005 - 25 Feb 2025

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Abstract

Macrophytes taxa composition determines microinvertebrates utilized as environmental indicators in freshwater ecosystems. This study was conducted in Shengjin Lake. In this lake, local communities have been practicing using sine fishing nets for fishing and this has a disrupting effect on macrophyte vegetation, even [...] Read more.

Macrophytes taxa composition determines microinvertebrates utilized as environmental indicators in freshwater ecosystems. This study was conducted in Shengjin Lake. In this lake, local communities have been practicing using sine fishing nets for fishing and this has a disrupting effect on macrophyte vegetation, even though it was the major for the disappearance of submerged vegetation before it was banned. As a result of this sine fishing net ban by the local authorities, the vegetation that had disappeared began to recover. Thus, this study investigated the role of architecturally differentiated macrophytes restoration effect on zooplankton communities’ diversity, abundance, and species composition; open water was used as a control. For this, the data were collected from different habitats via site 1 (open water) site 2, (free-floating), site 3 (emergent and submerged), site 4 (submerged), and site 5 (emergent) macrophytes. In the present study, the results demonstrated that the relative mean density of Rotifer was measured high which ranged from (219 ± 141–678 ± 401 ind L⁻¹), mainly dominated by Keratella cochlearis and Lecane cornuta species. Following Rotifera, Cladocera population density was reported high and ranged within (36 ± 6.2–262.5 ± 49.4 ind L⁻¹). The Cladocera group was dominated by Daphnia spp., Moina micura, Ceriodaphnia reticulata, and Chydorus latus species. Compared to Rotifer and Cladocera, Copepod community were recoded least with relative mean density ranged within (11.52 ± 2.22–85.5 ± 27 ind L⁻¹) and dominated by Microcyclops javanus, Thermodiaptomus galebi, and Sinocalanus doerrii species. From environmental variables and the zooplankton density relationship analyzed, the redundancy analysis (RDA) results indicated that Water Temperature, Chlorophyll a, Dissolved Oxygen, Total Phosphorus, and Ammonium Nitrogen were found the most influential variables on zooplankton communities. Stepwise regression correlation showed that Copepod and Cladocera were found more dependent on environmental factors. For instance, Nitrate Nitrogen was negatively correlated with Cladocera, Copepod, and total zooplankton biomass but positively with Cladocera diversity. Water Temperature showed a positive relationship with Rotifer diversity; however, both Chlorophyll a and Electrical Conductivity were correlated positively with Cladocera biomass. Species diversity by the Shannon–Wiener index (H) illustrated a dynamic trend among the monitored sites which ranged between (0.65–4.25). From the three groups of zooplankton communities in contrast to Cladocera and Copepod, Rotifer species obtained more diversity across the studied sites. The Cladocera diversity (H′) index indicated a similar tendency in all sites. However, more Copepod diversity (H′) was observed in site 4. In conclusion, this study results can provide valuable insights into the health and dynamics of the aquatic ecosystem to understand factors deriving ecological imbalance and develop an integrated approach for effective strategies for management and conservation. Full article

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20 pages, 2950 KiB

Open AccessArticle

Nutrient Load Fluctuations in the Bottom Water of Estuarine Lakes Under the El Niño Phenomenon: Possible Connections and Coping Strategies—Based on the Preliminary Studies of Lake Nakaumi

by Xizhe Wang and Kengo Kurata

Limnol. Rev. 2025, 25(1), 4; https://doi.org/10.3390/limnolrev25010004 - 21 Feb 2025

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Abstract

Estuarine lakes possess significant ecological value. Their complex hydrological environments give rise to diverse habitats, providing a home to numerous life forms. However, with the intensification of the impacts of global climate change, the estuarine lake ecosystem is facing severe challenges. Through trend [...] Read more.

Estuarine lakes possess significant ecological value. Their complex hydrological environments give rise to diverse habitats, providing a home to numerous life forms. However, with the intensification of the impacts of global climate change, the estuarine lake ecosystem is facing severe challenges. Through trend analysis and differential analysis, this paper elaborates on the changes in nitrogen and phosphorus nutrients in the bottom water of Lake Nakaumi from 2013 to 2017. It analyzes the differences between the El Niño period and the non-El Niño period, speculates on the possible connections between the changes in nutrient load and the El Niño phenomenon, and uses the traditional water quality assessment method of the WQI to more intuitively demonstrate the fluctuations in nutrient load. Based on the analysis of the case of Lake Nakaumi, possible environmental management suggestions are put forward. Additionally, the paper compares and discusses the differences in the changes of lakes at adjacent latitudes during similar periods. As for the bottom water of Lake Nakaumi, there may be the following connections between the changes in its nutrient load and the El Niño phenomenon: (1) DPO₄-P was most sensitive to the peak intensity of the El Niño phenomenon. (2) Compared with NO₃-N, the changes in NO₂-N and DPO₄-P were more sensitive to the start of the El Niño cycle. (3) The El Niño phenomenon had differential impacts on various forms of nitrogen and phosphorus in Lake Nakaumi. The focus of this paper is to explore the connection between the El Niño phenomenon and the changes in the nutrient load of the bottom water of estuarine lakes and to find a method beneficial to environmental management. However, due to the limitations of the currently available data, there are still many deficiencies that need to be further addressed. It is hoped that this paper can attract the attention of relevant researchers to this issue. Full article

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15 pages, 1262 KiB

Open AccessArticle

A Study on the Optimal Planning of Forest Ecosystems on Hainan Island in the Context of the Integrated Development of Lakes, Wetlands and Forests

by Ying Zhang, Keren Zhang and Zixuan Zhang

Limnol. Rev. 2025, 25(1), 3; https://doi.org/10.3390/limnolrev25010003 - 10 Feb 2025

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Abstract

Hainan Island has rich water resources and unique lake ecosystems. Organically connecting lakes and wetlands with forest ecosystems should be considered in order to strengthen biodiversity protection, form a continuous green corridor to promote species migration and gene exchange, and enhance the stability [...] Read more.

Hainan Island has rich water resources and unique lake ecosystems. Organically connecting lakes and wetlands with forest ecosystems should be considered in order to strengthen biodiversity protection, form a continuous green corridor to promote species migration and gene exchange, and enhance the stability and resilience of the overall ecological system and maximize its benefits. The method of linear programming was used in this study to analyze the forest ecosystem on Hainan Island in China in order to provide a scientific basis for the integration, protection and management of lakes, wetlands and forests. This study points out that the ratio of the area of timber forest, protection forest, special-purpose forest and bamboo forest should be adjusted from the current 68:22.9:7.1:1.8 to 24:72.8:2.5:0.6. The average shadow price of the reasonable use of different forest lands on Hainan Island is 2512.46 CNY/ha and the optimal value of special-purpose forest is 4376.04 CNY/ha, rather than the current 6888.50 CNY/ha. This study also shows that the timber forest, special-purpose forest and bamboo forest on Hainan Island are short-term products, while protection forest, wood-fuel forest, economic forest, open forest land, shrub land, young afforested land and non-forest land are long-term products, for which it is not easy to obtain benefits in the short-term. A combination of long- and short-term forest ecological planning should be considered to maintain the various long-term benefits. This study finally proposes that Hainan Island should reduce its proportion of timber forest area; increase its proportion of protection forest area; focus on the integrated development of lakes, wetlands and forests and biodiversity conservation goals; and pay close attention to the adjustment of forest type structure in order to meet the needs of ecological province construction and sustainable development. Full article

(This article belongs to the Special Issue Trends in the Trophic State of Freshwater Ecosystems)

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13 pages, 6041 KiB

Open AccessReview

Recent Progress in Diatom Research in the Yangtze River Basin

by Hui Liu, Xiangqun Wu and Xu Chen

Limnol. Rev. 2025, 25(1), 2; https://doi.org/10.3390/limnolrev25010002 - 10 Feb 2025

Viewed by 585

Abstract

Diatoms have been widely used for aquatic environment assessment. However, the progress of diatom research is uneven in different regions of the world. This study gathered both Chinese and English articles on diatom research in the Yangtze River Basin in order to explore [...] Read more.

Diatoms have been widely used for aquatic environment assessment. However, the progress of diatom research is uneven in different regions of the world. This study gathered both Chinese and English articles on diatom research in the Yangtze River Basin in order to explore recent progress in this field. Using the Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases, we gathered 419 articles (1995–2024) on diatom research in the Yangtze River Basin. There is a substantial increase in the number of articles since 2000. Since the mid-1990s, a total of 63 new diatom species have been identified in this region. Based on limnological investigations of lakes in the Yangtze River Basin, diatom-based conductivity and total phosphorus (TP) transfer functions have been developed for quantitative reconstruction of past conductivity and TP in the water column. The results revealed a recent shift in thematic focus from eutrophication to biodiversity dynamics, the ecosystem regime shift, and ecohydrological change. Although diatom research in the Yangtze River Basin has achieved fruitful outputs, further studies are urgently needed to explore diatom biodiversity and the ecological status of aquatic ecosystems in this rapidly-developing region. The results can improve our understanding of diatom research progress and hence provide important clues for further studies. Full article

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11 pages, 1123 KiB

Open AccessArticle

Risk of Chemical Pollution in Olifants River Basin, South Africa: Human Health Implications

by Abraham Addo-Bediako

Limnol. Rev. 2025, 25(1), 1; https://doi.org/10.3390/limnolrev25010001 - 7 Jan 2025

Cited by 1 | Viewed by 2446

Abstract

Chemical pollution in freshwater ecosystems poses a significant environmental threat, often hindering access to safe drinking water for human populations. The Olifants River Basin in South Africa is particularly vulnerable due to escalating mining and agricultural activities, and domestic waste discharged into the [...] Read more.

Chemical pollution in freshwater ecosystems poses a significant environmental threat, often hindering access to safe drinking water for human populations. The Olifants River Basin in South Africa is particularly vulnerable due to escalating mining and agricultural activities, and domestic waste discharged into the rivers. In this study, the risk posed to humans by exposure to potentially toxic elements (PTEs) in water from two rivers, the Blyde and Steelpoort, was assessed. Water samples were collected from upstream, midstream, and downstream locations of these rivers, and the concentrations of eight PTEs (Arsenic, Cadmium, Chromium, Iron, Manganese, Nickel, Lead, and Zinc) were determined using inductively coupled plasma-optical emission spectrophotometry. Furthermore, two pathways of exposure, direct ingestion and dermal absorption, were used to evaluate their potential impacts on human health. The findings indicate that direct ingestion poses a greater risk to human health compared to dermal absorption. While PTEs may pose little non-carcinogenic risk for adults, higher risk was observed in children. This is an indication that children are at higher risk using water from the rivers, sometimes without any form of treatment. When carcinogenic risks (CRs) were computed for both adults and children for As, Cr, Ni, and Pb levels, the CR values were above the threshold limit, except for Pb, indicating a potential carcinogenic risk. This study underscores the need for regular monitoring of chemical pollution, and the implementation of effective mitigation strategies to safeguard both river ecosystems and human health, including proper treatment of water for domestic and agricultural purposes. Full article

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Limnol. Rev., Volume 25, Issue 1 (March 2025) – 9 articles

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