Lakes and Reservoirs: Research and Management最新文献

Despite the growing importance of digital technology in modern society, its adoption in some sectors and regions has been slow. One such sector is fishing in developing countries, where the potential benefits of technology have yet to be fully realized. This study examines the adoption of communication technology among Nile perch fishers on Lake Victoria in Mwanza, Tanzania. Using a Probit model and Ordinary Least Square (OLS) estimations with Robust Standard Errors (OLSR), the study analyzes the impact of technology adoption on fishers' welfare, with a focus on income. The results suggest that the type of mobile phone, fishing experience, and the desire to exploit digital marketing are key factors in technology adoption among fishers. Furthermore, the study finds that technology adoption has a significant positive impact on fishers' welfare, indicating that digitalization can increase market competitiveness, openness, and improve livelihoods. To capitalize on these benefits, the study recommends that the government should support the digitalization of the fishing market and make accurate and timely market information readily available to fishers.

The Local Government and the Government Agency shape the Seven Crater Lakes. The present study focused on understanding the predominant Governments and Lake Governance's concept vis-a-vis the small lakes and their basin communities. These foremost authorities are intertwined, and Lake Governance's essential criteria interplayed and continuous to the responsibility. Although the City Government of San Pablo City and the Laguna Lake Development Authority (LLDA) have improved the small lake's situations and they are satisfactorily functioning, serious issues still remain at present and into the future. Focusing on the criteria's lessons, Pandin Lake, Yambo Lake, Mohicap Lake and Sampaloc Lake have been ameliorated to varying degrees. In contrast, Bunot Lake, Palakpakin Lake and Calibato Lake continue to struggle with deficiencies. Thus, over the dual governments need to exhibit greater commitment, decisiveness and effectiveness if the Seven Crater Lakes are to flourish in development and conservation. Furthermore, while the Structuring Government and Administering Water criteria are adequate, completing the Developing Tourism, accomplishing the Regulating Fishery and substantially subsidizing the Supporting Finance in the City Government and the LLDA remain deficient. Accordingly, the main target of the paired Governments' over time is to address the remaining challenges facing the Seven Crater Lakes.

Water quality is a critical component regulating ecosystem functioning in aquatic habitats, requiring regular monitoring for sustainable ecosystem services. Cage fish farming has the potential to affect water quality because of its rapid increase in many African waterbodies in response to dwindling wild fish stocks. Thus, there is a need for more studies to guide sustainable cage aquaculture in African lakes and reservoirs. This study evaluated the possible effects of cage farming of Nile tilapia (Oreochromis niloticus) on water quality parameters and the trophic state of Kadimu Bay, Lake Victoria, Kenya. Sampling for physicochemical and biological variables, including nutrient load, was conducted from January to October 2021, at five fish cage sites and a control site within the bay. In situ measurements of physical variables were undertaken in the field, while analysis of water samples for nutrient loads, biological and chemical variables was undertaken in the laboratory, following the methods described in APHA (American public health association standard methods for the examination of water and waste water. APHA-AWWA-WEF, 2005). The Carlson's Trophic State Index (CTSI) was used to classify the trophic state of the cage sites, while the total nitrogen:total phosphorus (TN:TP) ratio was used to determine the primary productivity limiting nutrient in the bay. The study results indicated electrical conductivity was significantly lower at the control (97.53 ± 4.17 μS/cm), compared to cage sites (105.42 ± 5.32 μS/cm at the Utonga cage site to 112.84 ± 1.94 μS/cm at the Oele cage site), indicating water of relatively lower quality at the cage sites. Similarly, the nitrite concentrations were higher at cage sites (6.35 ± .96 μg/L at the Uwaria cage site to 3.16 ± 2.25 μg/L at the Utonga cage site), and lower at the control site (2.68 ± 1.39 μg/L). In all, 14 physicochemical variables did not vary significantly between the cage and control sites, with nine variables (temperature, turbidity, electrical conductivity, total suspended solids, particulate organic matter, chlorophyll-a, TP, nitrate and TN) being within the recommended thresholds for aquatic life processes. The bay was evaluated as being in a light eutrophic state, indicating moderate influence of the fish cages on the trophic state of the sites. There was a moderate relationship between chlorophyll-a and TP concentration at the sampling sites (R² = .50), compared to a stronger relationship with $��{\mathrm{NO}}_3^{-}�$ (R² = .78). The TN:TP ratios were <10 at the sampling sites, indicating nitrogen was the limiting factor for primary produc

Wild fish populations are unceasingly diminishing in the rivers, ox-bow lakes and floodplains in the Southwestern region of Bangladesh. Investigating the population status of vulnerable wild fish species are vital for the management and conservation of that species. This study aimed to identify the intra-specific morphological variation and determine the population status of Lepidocephalichthys annandalei, in two rivers, the Nabaganga River in Jhenaidah (NRJ) and the Bhairab River in Jashore (BRJ) as well as a flood plain, the Dhakuria Beel in Jashore (DBJ) from Southwestern Bangladesh. Significant differences were observed in seven conventional and five truss-based characters in univariate statistics. Conventional and truss-network results from principal component analysis and CVA exhibited that populations were entirely intermixed, creating a compact cluster within intra-population stages. Four principal components explained 51.93% of the variation in conventional morphometric characters and truss-based characters. A UPGMA dendrogram was independently developed based on conventional and truss-based morphometric characters. Among the individuals of NRJ and BRJ populations confirmed the presence of out-group rather than the DBJ based on morphometric (conventional and truss) features. These notable isolations of populations of this species were supposed to be geographic disconnection and abiotic parameters. The evidence ensuing from the present study would be valuable for genetic studies as well as for in situ management.

Tilapia invasion has become a significant concern to ecologists and conservationists, posing severe threat to freshwater biodiversity. Many tilapia species have been introduced to China since 1957, with some having invaded freshwater ecosystems in South China. Accordingly, the present review examined the driving factors for successful tilapia invasion and their ecological impacts, information essential for practical management purposes. This review identified aquaculture as the main pathway spreading tilapias into the wild freshwater systems through their escape and release. Their biological and life history traits, including flexible habitat requirements, environmental tolerance, and generalist feeding are essential factors facilitating their ability to inhabit varying habitats. Biodiversity loss and habitat degradation further promote tilapia invasions by creating exploitable habitats for them, noting their considerable tolerance to degraded ecosystems. Regarding ecological effects, tilapias stimulate phytoplankton growth by increasing nutrient concentrations in the water column through excretion and bioturbation. Tilapias also depress benthic algal growth by promoting sediment resuspension, deteriorating water quality, and enhancing eutrophication. Moreover, tilapias cause the decline of native fish species biomass through competition and may threaten fish biodiversity. The findings in the present review suggest direct removal of tilapias can be a useful practice for controlling them. Furthermore, imposing regulations on tilapias introductions, efficient aquaculture management, and biodiversity conservation should also be considered in controlling and preventing the invasion and spread of tilapias.

The present study focused on evaluating the quality of the Oued Guigou River located in Middle Atlas (Morocco) by studying relevant physicochemical and metallic parameters. Samples for determining the organic matter and trace metal elements trapped in water samples were collected at upstream of Oued Guigou between December 2020 and April 2021. The samples were analysed for physicochemical quality, while the trace metal elements (lead, zinc, copper, chromium, iron, nickel, calcium and magnesium) were determined using ICP-AES analysis. The results indicated significant organic pollution, as well as standard deviation and average changes in the values of the studied metals, most likely attributable to domestic effluents. The metal content in particular exhibited high values exceeding the recommended Moroccan standard limits, suggesting domestic and agricultural pollution is a potential threat to both the receiving rivers and their associated lakes and reservoirs.

Water resources around the world are facing serious threats attributable to various natural and anthropogenic activities. Civil societies around the world, including India, are facing increasing difficulty in the allocation and sustainable use of their available water resources. Many lakes and rivers, the major surface water sources in India, are highly polluted and on the verge of depletion. Accordingly, there is a growing interest in protecting the ecosystem services provided by the lakes and rivers using several management approaches for lake rejuvenation and conservation. A similar study focusing on water supply situation and its restoration was performed in Nainital, a major hill town located in the state of Uttarakhand. The lake water level has been declining in recent years, raising serious concerns. To address this issue, a plan has been developed to address the decreasing lake level and conserving this vital water supply source for the town. The present study provides an integrated framework enabling conservation practitioners to strategically implement water conservation actions to balance both the ecosystem and societal water needs.

Phewa Lake, Nepal's second largest lake, has been the subject of many short-term water quality studies in the past, although the results of such studies have not been consistent. Long-term monitoring data can distinguish typical seasonal dynamics from atypical occurrences. Accordingly, the objective of the present study was to describe typical seasonal patterns and quantify variability, detect long-term trends and provide reliable baseline data for future trend detection. The present study provides 17 years of monthly water quality data (1993–2010) and occasional data to 2018 from the 0.5 to 10 m depth at one sampling site. Phewa Lake experiences a subtropical monsoonal climate, typically being stratified from March to September, although heavy rainfalls disrupted stratification. Bottom-water anoxia, occurring typically between April and June, was associated with increased ammonium concentrations, but not with increased dissolved reactive phosphorus concentrations. The observed nutrient and chlorophyll-a concentrations were generally typical of an oligo- to mesotrophic lake. The water clarity was lowest in the autumn and winter, being associated with high phytoplankton biomass, as well as during the summer, the latter likely attributable to suspended silt in the water. Lake surface waters warmed by 1.1–1.8°C during 1993–2018. Water clarity data suggested slight eutrophication from 1993 to 2018, although no increased nutrient or chlorophyll-a concentrations was detected up to 2010. The water clarity data gave no evidence of a long-term increase in the suspended sediment concentrations. All studied water quality variables exhibited high variability within and between years. The results of the present study provide a baseline for the detection of future water quality trends. The data confirm some previous research findings, while at the same time indicating long-term regular monitoring is needed to accurately characterize Phewa Lake's limnology and to detect long-term trends. Correct trend detection and proper understanding of the lake limnology are essential for proper management of Phewa Lake and other subtropical lakes. The present study represents one of only a few studies that examine water quality and other seasonality variables in subtropical lakes over multiple years.

Gilbert Bay, the largest embayment of the expansive Great Salt Lake (GSL) in the United States, is a productive aquatic system providing a suite of ecosystem services, both locally and across hemispheric flyways and global aquaculture networks. Gilbert Bay is currently at a record low stand and elevated salinity attributable to the coupled effects of drought and human water use in the basin. However, a recent management berm at the breach in the mid-lake causeway provides a unique adaptive management tool to mitigate harmful salinity changes. The present study measured the fluctuating Gilbert Bay salinities and salt loads across a multi-year period of changing causeway breach management. Opening of the breach in 2016 and a high spring runoff in 2017 exported a substantial portion of Gilbert Bay salt load into adjacent Gunnison Bay, lowering the salinity–elevation relationship in Gilbert. The salt load in the bay has since returned to nearly pre-breach levels with salinities at the current low stand now exceeding the ecologically optimal range. The chronicled salt movement and salinity relationships were used to recommend short- and long-term adaptive management strategies for the causeway berm in order to sustain the crucial Gilbert Bay aquatic ecosystem in the face of drought and future variability, as well as highlighting the structural advantages GSL has over other saline lakes experiencing anthropogenic water loss.

The present study was conducted to assess the levels of selected organochlorine pesticide (OCP) residues in water, sediments and Nile tilapia, as well as the potential health risks to humans who consume the fish of Lake Nakuru. Nine composite water and nine sediment samples, as well as 30 fish specimens, were collected from five representative sampling sites within Lake Nakuru. The OCPs targeted in the present study included p,p′-Dichlorodiphenyl dichloroethane (p,p′-DDD), p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE), p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT), heptachlor, heptachlor epoxide, α endosulfan (1), β endosulfan (2), endosulfan sulphate, endrin, lindane, aldrin, dieldrin, methoxychlor and hexachlorocyclohexanes (alpha; beta; gamma; delta). Except for aldrin, all 16 OCPs targeted in the present study were detected. The OCP residue levels ranged from below detection limit (BDL) to 7.44 ± 0.66 μg/L, BDL to 6.39 ± 1.10 μg/kg ww and BDL to 319.74 ± 66.94 μg/kg ww in water, sediment and fish samples respectively. Some OCP concentrations exhibited significant differences across the sampling sites (p < .05). The residue level of endosulfan was above the European Union standard, whereas the target hazard quotient of heptachlor epoxide was above 1, therefore being unsafe for human consumption. The present study results indicate that most of organochlorine pesticides though banned in Kenya are still detected in the environment, posing potential long-term health hazards to humans. Accordingly, environmental monitoring programme and mitigation strategies of reducing pollutant inputs into the lake is recommended, as well as an immediate ban on harvesting and consumption of fish from Lake Nakuru.