Lakes & Reservoirs: Science, Policy and Management for Sustainable Use

doi: 10.1111/lre.12455pmid: N/A

Khatun, Dalia; Tanaka, Tomomi; Horinouchi, Masahiro; Yoshioka, Hidekazu; Aranishi, Futoshi

doi: 10.1111/lre.70011pmid: N/A

Ayu Plecoglossus altivelis altivelis is a commercially and recreationally important freshwater fish in Japan. This species is categorised into two ecological forms: amphidromous migrating between rivers and sea and landlocked migrating between rivers and lakes or dam reservoirs. Despite its ecological and economical values, growth analysis has been developed limitedly in the early life history of particularly the amphidromous form, and the growth potential of the landlocked form throughout an annual life history remains almost unknown. This study investigated the allometric growth and condition factors along with their variation among months and life stages of artificial landlocked ayu in Haidzuka Dam reservoir and its connected Tabusa River. A total of 281 individuals were collected monthly from October 2017 to September 2018, and their total length (TL) and body weight (BW) ranged from 1.11 to 14.98 cm and 0.001 to 32.148 g, respectively. Although the allometric coefficient (b) of the length–weight relationship varied from 2.71 to 3.44 among months, it indicated overall positive allometric growth (b = 3.83) calculated from the equation BW = 0.0013TL3.83. The growth pattern altered significantly among life stages from positive allometric for larvae, juveniles, and youngs to negative allometric for adults. The calculated asymptotic length and growth coefficient of the logistic growth model were 17.71 cm and 3.91 year−1, respectively. Significant differences were found in allometric (KA) and Fulton's (KF) condition factors among months, while there was no difference in relative condition factor and relative weight (WR). Life stage‐specific analysis also revealed that the adult stage was nutritionally healthier compared to other life stages based on KA and KF. Only KF showed significant correlations with both TL and BW, making it an ideal condition factor to predict the wellbeing of ayu in this reservoir. Moreover, the Wilcoxon signed‐rank test for WR showed no significant divergence from 100, suggesting a balanced habitat in this reservoir for ayu. These findings will be crucial for further studies and to develop appropriate strategies for the sustainable management of artificial landlocked ayu in dam reservoirs.

Pamela, Tendaupenyu; Timothy, Dube; Magadza, Christopher Hilary Dennis

doi: 10.1111/lre.70015pmid: N/A

Major dams in Zimbabwe are losing more than half of their design capacity in the first 11 to 12 years of operation. Despite these obvious impacts of sedimentation in the country's reservoirs, sedimentation studies have only been conducted once for 90% of the reservoirs. Thus, a sedimentation estimation study was conducted in November 2014 in Lake Chivero to quantity storage loss due to sedimentation, determine the spatial distribution of sediment deposition in the reservoir, update its elevation‐capacity curves and estimate its useful life. The study used a dual beam echo sounder for determining depth measurements. Depth measurements were converted to digital elevation models in a Geographic Information System environment. A comparison of the 1953 and 2014 digital elevation models indicated that the lake was losing depth uniformly. The highest deposition depths were observed towards the dam wall and the deep central parts of the lake along the old river channel. Minimal sediment deposition was generally observed at the shallower parts of the lake, on the north‐east and south‐western locations. A total of 49126170.34 m3 (18%) of the lake's storage capacity has been lost to sedimentation, which translates to an average annual capacity loss of 792,357 m3 year−1 (0.295% per year) since construction in 1953. The lake's specific sediment yield and remaining useful life were calculated at 352.31 m3 year−1 km−2 and 106.63 years; respectively. This loss of storage in the lake will impact the operational and economic benefits for which it was built. It will also affect the habitats of its varied flora and fauna. In the absence of original topographic maps produced at the inundation, the dual frequency echo sounder can be used to generate data to estimate sediment loads into the reservoir as well as update elevation‐capacity curves.

Quarcoopome, Theodore; Hotor, Divine Worlanyo; Addo, Acheampong; Asmah, Ruby

doi: 10.1111/lre.70013pmid: N/A

After five years of impoundment, Bui Reservoir fisheries has evolved with silver catfish, Chrysichthys nigrodigitatus among the most important commercial species. Based on standard length analyses of 162 individuals (62 males, 39 females) from post‐impoundment seasonal sampling at three (3) stations, the population structure, well‐being, growth type, sex ratio, length at first capture and rates of growth, mortality, exploitation, and other derived parameters of C. nigrodigitatus were estimated to provide requisite information for sustainable management. The population is composed of fewer juveniles and more males than females, with females relatively larger than males (modal size 7.0–7.9 for males and 9.0–9.9 for females). Females were physiologically better than males (79.49% of females had condition factor above 2.0 compared to 53.23% males) notwithstanding seasonal fluctuations. Unimodal length structure was observed for all seasons except for the post‐rainy season with 2 modes, all of which, however, indicated a single year class and single spawning. Estimated hypoallometric and hyperallometric growth values among seasons and sexes were not significantly different from the isometric pattern. Estimated von Bertalanffy growth parameters were asymptotic size (L∞) = 13.07 cm SL, growth constant (K) = 1.01 year,−1 and length at time 0 (to) = 0.18. Growth performance index (ϕ') was 2.27, indicating slow growth while the lifespan was 2.73 years. Total mortality, natural mortality, and fishing mortality estimates were high (3.56, 2.44 and 1.12 respectively) while exploitation was below optimum (E = 0.32). Regular assessment of fish population, growth, and other characteristics is recommended to provide requisite information for strategic interventions for sustainable management and development of reservoir fisheries.

Hamdhani, Hamdhani; Maleni, Rima; Eppehimer, Drew E.; Abdunnur, Abdunnur; Rizal, Samsul; Ardianor, Ardianor

doi: 10.1111/lre.70008pmid: N/A

The widespread use of plastic materials globally has sparked concerns regarding microplastic (MP) pollution, which is prevalent in water bodies worldwide and poses threats to aquatic life. Despite this, there remain uncertainties regarding the quantity, types and chemical makeup of MP, particularly in tropical urban lakes. This study aimed to examine the presence, distribution, types and chemical composition of MP in both the surface water and sediment of Air Hitam Lake, located in Samarinda City, East Kalimantan, Indonesia. Field sampling was conducted in February 2023 at 10 sites within the lake. The average concentration of MP in water was measured at 0.91 particles per litre, while sediment concentrations reached 375 particles per kilogram of dried sediment. Higher concentrations were observed near the lake inlet. Fibres were the most commonly observed type of MP in both surface water (79%) and sediment (76%) samples, followed by fragments and films. There was no significant correlation between MP concentrations in water and sediment. Fourier Transform Infrared (FTIR) analysis revealed the presence of polyester, polypropylene, nylon fibres, polyethylene, polystyrene polyvinylchloride in the samples, with polyethylene being the predominant compound, accounting for 46% of all surface water and sediment samples. The presence of MP derived from the degradation of larger plastic debris originating from visitors and the local community who dispose of plastic trash improperly highlights the importance of implementing effective plastic waste management strategies in communities surrounding the lake. This is crucial for preserving the ecosystem benefits provided by the lake. This study contributes to addressing knowledge gaps regarding MP pollution in tropical urban lakes and lays the groundwork for further research into inland freshwater environments.

Maheshwari, Shobhit

doi: 10.1111/lre.70019pmid: N/A

This study examines the current state and projected future of India's dams, focusing on the challenges posed by ageing infrastructure, sedimentation, increasing water demands and climate change. With over half of India's major dams now surpassing 50 years of age, the risk of structural deterioration and reduced functionality is escalating. Sedimentation, a critical issue, has led to a substantial decrease in reservoir storage capacity, impacting water availability for agriculture, drinking water and hydropower generation. Additionally, climate change is anticipated to intensify these challenges, with more frequent and severe weather events stressing dams that were not originally designed for such variability. To ensure the longevity and resilience of these structures, comprehensive adaptation measures are essential. Key recommendations include modernising dam infrastructure, implementing advanced sediment management strategies, integrating climate‐responsive design features and enhancing real‐time monitoring systems. Future research should prioritise climate modelling, innovative sediment control and seismic resilience improvements. Proactive policy, combined with sustained funding and community engagement, is vital to safeguarding India's water resources and addressing the complexities of an evolving environmental landscape.

Hussain, Jafrin Farha; Bordoloi, Sabitry

doi: 10.1111/lre.70000pmid: N/A

A badid, Badis assamensis Ahl, 1937, was recorded for the first time from the intermediate zone of a semi‐torrential stream called Basistha in Assam, which is a small tributary of the river Brahmaputra. The fish species Badis assamensis is currently listed in the data deficient (DD) category of IUCN. The species has previously been reported in swampy wetlands in the upper reaches of the Brahmaputra valley in Assam; with no detail description on its biology however. The current work redescribes morphology and presents detail reproductive biology of this species based on fresh collection of 377 individuals from the Basistha. length‐weight relationships (LWR) analysed in this species indicated an isometric growth; and condition factor (K) indicated a suitable habitat for this species. Badis assamensis exhibits a non‐seasonal breeding behaviour twice a year, as analysed from the Gonado‐somatic and ovarian indices. During certain period of the year, local people use unscientific ways of fish collection thereby resulting in a steep decline in fish population. The study is believed to lay an insight into this species' geographical range from a swampy wetland habitat in upper reaches of the Brahmaputra basin; to a semi‐torrential hill stream habitat in the lower Brahmaputra sub‐basin; thereby providing baseline information on this DD species. Analysis of morphometric and reproductive parameters of this species not reported earlier is the major highlight of the present study.

Laishram, Ranu Jajo; Yumnam, Gyanendra; Singh, Tensubam Basanta; Alam, Wazir

doi: 10.1111/lre.70010pmid: N/A

The assessment of nutrient and heavy metal accumulation in lake sediments is essential for understanding their role in the ecohydrological dynamics of lake ecosystems, as sediments can function both as a sink and source of nutrients, metals and various contaminants aquatic ecosystem. The main objective of this study was to evaluate the concentrations of nutrients and heavy metals and their accumulation in the sediments across different sampling locations of Loktak Lake and to compare them against geochemical background values and sediment quality guidelines. The key findings of the study revealed substantial nutrient accumulation in sediments from the Keibul Lamjao National Park site, which can be attributed to the decomposition of organic matter from dense floating vegetative masses called ‘Phumdis’. Iron concentrations in sediments were significantly high, ranging from 909.83 to 1004 mg/kg and its enrichment is likely due to diffused surface runoff from the iron‐rich soils from the surrounding catchment entering the lake through feeder rivers and other anthropogenic influences. The average metal concentrations were in the order of Fe > Mn > Zn > Cu, and all values were below the average shale concentrations and the Interim freshwater Sediment Quality Guidelines (ISQG) set by the Canadian Council of Ministers of the Environment (CCME). The evaluation of the heavy metal pollution status of the lake sediments based on various pollution indices such as the contamination factor, degree of contamination, modified degree of contamination, geoaccumulation index, pollution load index and potential ecological risk index, suggested an overall low level of metal pollution in the sediments of Loktak Lake. The findings of this study provide a crucial baseline for understanding on the sediment‐associated nutrient and metals dynamics in Loktak Lake which can aid in the formulation of long‐term lake management strategies for preserving the ecological integrity and health of this precious lake ecosystem of the region.

Rose, Lucy A.; Serediak, Nancy; Kolka, Randall K.; Wickman, Trent R.

doi: 10.1111/lre.70003pmid: N/A

In some seepage lakes, acid neutralising capacity (ANC) is regulated by precipitation chemistry and in‐lake biogeochemical processes with little influence from groundwater and catchment runoff. However, additional environmental contexts, for example, landscape position and changing precipitation dynamics, may also contribute to variability in ANC across lakes over time. We used a mixed effects model to assess the influence of changing precipitation patterns and the chemistry of hydrologic inputs on ANC in seven northern Wisconsin, USA seepage lakes from 1984 to 2018. We observed differential ANC responses across lakes to the concomitant changes in precipitation acidity and post‐drought oxidative acidity pulses from adjacent wetland soils. Although all study lakes lie within a 4 km2 area, mean lake ANC values ranged from 32.8 ± 25.2 μeq L−1 to 71.9 ± 26.8 μeq L−1 and were inversely related to lake landscape position. Lakes with higher mean ANC also showed lower relative variability over time, suggesting that these lakes were better buffered than those with lower ANC. Mixed effects modelling explained 50% of the ANC variability across all lakes, while model explanatory power ranged from 39% to 71% when ANC was assessed within individual lakes. The range of modelled ANC accuracy highlights the complex nature of biogeochemical regulation in individual seepage lakes, despite their shared geographic setting. Our study demonstrates the utility of mixed effects modelling for repeated measures analysis, emphasising the necessity of long‐term studies to evaluate seepage lake ANC responses to changing hydrologic and biogeochemical inputs.

Jayaswal, Rajesh; Verma, Durgesh Kumar; Paul, Sanatan; Alam, Absar; Jha, Dharm Nath; Das, Basanta Kumar; Johnson, Canciyal

doi: 10.1111/lre.70018pmid: N/A

In this study, length‐weight relationships of seven catfish species collected from the middle stretch of the Ganga River in India were determined. The specimens were gathered from the Sadiyapur and Daraganj fish landing centers in this region of the Ganga River between November 2022 and October 2023. Digital callipers and digital balances were utilised to measure the total length (TL) and body weight (BW) of all fish specimens. The growth coefficient b ranged from 1.98 for Sperata aor to 3.31 for Sperata seenghala. Also, Rita rita, Sperata aor, Eutropiichthys vacha, Wallago attu and Bagarius bagarius exhibited negative allometric growth (b < 3) while Sperata seengala and Clupisoma garua showed positive allometric growth (b > 3). The coefficient of determination (R2) values ranged from 0.66 to 0.93 across the seven catfish species. Additionally, the relative condition factor (Kn) value is greater than 1 for all the catfish species, indicating that all the catfish species are in good health.