Freshwater Areas Research Articles

Variable habitat use supports fine-scale population differentiation of a freshwater piscivore (northern pike, Esox lucius) along salinity gradients in brackish lagoons.

In mobile animals, selection pressures resulting from spatio-temporally varying ecological factors often drive adaptations in migration behavior and associated physiological phenotypes. These adaptations may manifest in ecologically and genetically distinct ecotypes within populations. We studied a meta-population of northern pike (Esox lucius) in brackish environments and examined intrapopulation divergence along environmental gradients. Behavioral phenotypes in habitat use were characterized via otolith microchemistry in 120 individuals sampled from brackish lagoons and adjacent freshwater tributaries. We genotyped 1514 individual pike at 33highly informative genetic markers. The relationship between behavioral phenotype and genotype was examined in a subset of 101 pikes for which both phenotypic and genomic data were available. Thermosaline differences between juvenile and adult life stages indicated ontogenetic shifts from warm, low-saline early habitats towards colder, higher-saline adult habitats. Four behavioral phenotypes were found: Freshwater residents, anadromous, brackish residents, and cross-habitat individuals, the latter showing intermediary habitat use between brackish and freshwater areas. Underlying the behavioral phenotypes were four genotypes,putative freshwater, putativeanadromous, and two putativelybrackish genotypes. Through phenotype-genotype matching, three ecotypes were identified: (i) a brackish resident ecotype, (ii) a freshwater ecotype expressing freshwater residency or anadromy, and (iii) a previously undescribed intermediary cross-habitat ecotype adapted to intermediate salinities, showing limited reliance on freshwater. Life-time growth of all ecotypes was similar, suggesting comparable fitness. Bycombining genetic data with lifelong habitat use and growth as a fitness surrogate, our study revealed strong differentiation in response to abiotic environmental gradients, primarily salinity, indicating ecotype diversity in coastal northern pike is higher than previously believed.

Picophytoplankton prevail year-round in the Elbe estuary.

Picophytoplankton are important primary producers, but not always adequately recognized, for example, due to methodological limitations. In this study, we combined flow cytometry and metabarcoding to investigate seasonal and spatial patterns of picophytoplankton abundance and community composition in the Elbe estuary. Due to the mixing of freshwater and seawater and the tidal currents this ecosystem is characterized by typical estuarine features such as salinity gradients and high turbidity. Picophytoplankton (mostly picoeukaryotes such as Mychonastes and Minidiscus) contributed on average 70% (SD = 14%) to the total phytoplankton counts. In summer picocyanobacteria (e.g., Synechococcus) played a more significant role. The contributions of picophytoplankton to the total phytoplankton were particularly high from summer to winter as well as in the mid estuary. However, at salinities of around 10 PSU in the mixing area of freshwater and seawater, the proportion of picophytoplankton was comparably low (average 49%, SD = 13%). Our results indicate that picophytoplankton prevail in the Elbe estuary year-round with respect to cell counts. Picophytoplankton could occupy important niche positions to maintain primary production under extreme conditions where larger phytoplankton might struggle (e.g., at high or low temperature, high turbidity, and in areas with high grazing pressure) and also benefit from high nutrient availability here. However, we did not find evidence that they played a particularly significant role at the salinity interface. Our study highlights the importance of including picophytoplankton when assessing estuarine phytoplankton as has been suggested for other ecosystems such as oceans.

Fish diversity, assemblage pattern along with the environmental variables in tidal fresh water stretch in the Hooghly estuary of Gangetic delta, West Bengal, India

The greatest estuary created by the Gangetic delta in India is the Hooghly estuary. Despite their importance to the estuarine biodiversity, the tidal freshwater areas of this estuary have gained little interest from ecologists. Present study aims to explore the fish diversity with its assemblage pattern and their relationship with physico-chemical parameters from June 2020 to May 2021. There have been identified 118 fish species in total, from 14 orders and 47 families, with seven (7) being near threatened, fifteen (15) vulnerable, four (4) endangered, and eight (8) not evaluated. Perciformes (29.66 %), Cypriniformes (22.88 %), and Siluriformes (21.18 %) accounted for 73.72 % of the overall species count. Station-1 has significantly higher species richness, rarefied richness, and abundance. Station-3 and station-2 followed station-1 respectively. The composition of fish species changed significantly among the stations, as shown by cluster analysis, nMDS (nonmetric multidimensional scaling), ANOSIM (analysis of similarities), and SIMPER (similarity percentage analysis) (p <0.05). The canonical correspondence analysis revealed that alkalinity, conductivity, phosphate, and total carbon dioxide of the water were the key environmental parameters. In addition to defining a sustainable management method for the fish resources in the Hooghly estuary, this effort will act as a baseline study for further investigation.

The Impact of Artificial Barriers on the Varuna litterata Migration Route in the Lower Serayu River, Central Java and Its Molecular Identification

The Serayu River is one of the longest rivers in Central Java. Dams built in the lower reaches of the Serayu River are thought to block the migration paths of fish and aquatic macrocrustaceans. This study aimed to determine the effect of dam on Varuna litterata migration and its molecular identification. This research was conducted using the observation method. Migration observations were made on vertical paths while molecular identification of V. litterata in the lower reaches of the Serayu River was compared with existing data in GenBank. The study covered the freshwater area above the Serayu Dam, the open area with freshwater below the Serayu Dam, and the open area with brackish water at the estuary of the Serayu River, with a study length of 33.37 km. The results showed that the presence of dams in the lower reaches of the Serayu River inhibited the migration pattern of V. litterata. The vertical shape of the dam causes only a few V. litterata to migrate to the top of the dam. The dam in the lower reaches of the Serayu River resulted in not many V. litterata being able to migrate to the top of the dam, so there were very few V. litterata found in the population upstream of the dam (115 ind). The results of molecular identification of V. litratata using the cytochrome C oxidase subunit I (COI) gene show that this crab is 100% the same as the data in GenBank and is closely related to Varuna yui and other Varunidae crab species.Keywords: Dams, Molecular, Migration, Serayu River, Varuna litterata

Ecotoxicological Assessment of Ibayo River in Balanga City, Bataan using Water Fleas (Daphnia Magna): A Basis for Intervention

The water quality of surface waters is degrading tremendously due to human interventions and development. Especially in the Philippines, water pollution has become a prominent problem in urbanized areas. Thus, this study aims to investigate the ecotoxicological effects of the Ibayo River in Balanga City, Bataan using water fleas (daphnia magna), a type of zooplankton living in freshwater areas. Daphnids are used as indicators in toxicity testing, and in assessing water quality. The survival rate of water fleas is utilized to examine the properties of the examined. As the water fleas were subjected to the river water samples and their dilutions for a week, results showed a high survival rate in all samples. It also exhibited no significant difference in the sample places Meanwhile, laboratory analysis revealed that there is an organic pollution as an excessive amount of biological oxygen demand (BOD) and lesser dissolved oxygen from the sample places were found. Analysis for chlorine and pH level indicates a n ormal quantity. Overall, there are chemicals in the Ibayo river that may kill aquatic organisms residing in it, but the long-term survival of these species is still questionable.

Postmortem characteristics of drowning death in freshwater: a systematic review

BACKGROUND: Drowning is the third leading cause of death by unintentional injury, accounting for 7% of all injury-related deaths worldwide. According to the latest World Health Organization Global Health Estimates, 236,000 people died from drowning in 2019. AIM: This systematic review aimed to examine the clinical, laboratory, and other postmortem characteristics associated with death from drowning in freshwater areas. MATERIALS AND METHODS: A systematic search of PubMed, Epistemonikos, and Cochrane Library databases was performed with no restrictions to find relevant articles. After the removal of duplicates, articles were reviewed, and information on the clinical, laboratory, and other postmortem characteristics of freshwater drowning deaths was extracted. RESULTS: Of the 493 articles, 73 papers were considered relevant for full-text review. Of these, 22 articles met the inclusion criteria for the review. Most drowning deaths occurred in freshwater. Victims were males, with a male-to-female ratio of 8:3. External and internal clinical characteristics that are widely reported included signs of asphyxia such as cyanosis of the lips and bilateral fingernails, immersion signs such as washerwoman’s hand, pink teeth, Neil’s sign, Svechnikov’s sign, Wydler’s sign, and debris in the airways, and typical drowning signs such as froth in the airway, emphysema aquosum, and Paltauf spot. CONCLUSION: The results of this study suggest that the presence of signs of asphyxia, immersion signs, and typical drowning signs such as froth in the airway, emphysema aquosum, and Paltauf spots were associated with drowning deaths in freshwater.

Distribution of Aquatic Insects in Freshwater Areas in Antalya and Mersin Provinces (Türkiye)

Distribution of Aquatic Insects in Freshwater Areas in Antalya and Mersin Provinces (Türkiye)

Comprehensive Assessment of Environmental Emissions, Fate, and Risks of Veterinary Antibiotics in China: An Environmental Fate Modeling Approach.

China is one of the major global consumers of veterinary antibiotics. Insufficient recognition of emissions and environmental contamination hamper global efforts to prevent antibiotic resistance development. This pioneering study combined empirical data and modeling approaches to predict total 2010-2020 emissions of 80 veterinary antibiotics ranging from 23,110 to 40,850 tonnes/year, after 36-50% antibiotic removal by manure treatment. Following an initial increase of 10% from 2010 to 2015, emissions declined thereafter by 43%. While 85% of emissions discharged into soils, approximately 56%, 23%, and 18% of environmental residue were ultimately distributed in soils, freshwaters, and seawaters under steady-state conditions. In 2020, 657 (319-1470) tonnes entered the ocean from inland freshwaters. Median ∑antibiotics concentrations were estimated at 4.7 × 103 ng/L in freshwaters and 2.9 ng/g in soils, with tetracyclines and sulfonamides as the predominant components. We identified 44 veterinary antibiotics potentially posing high risks of resistance development in freshwaters, with seven exhibiting high risks in >10% of Chinese freshwater areas. Tetracyclines were the category with the most antibiotics exhibiting elevated risks; however, sulfamethylthiazole demonstrated the highest individual compound risk. The Haihe River Basin displayed the highest susceptibility overall. The findings offer valuable support for control of veterinary antibiotic contamination in China.

Discussion on the development of offshore floating photovoltaic plants, emphasizing marine environmental protection

The development of solar energy is one of the most effective means to deal with the environmental and energy crisis. The floating photovoltaic (PV) system is an attractive type because of its multiple advantages and has been well developed based on fresh water areas on land. This paper focuses on the expansion of this sector towards the ocean, offshore floating PV plants, which is the new growth point with huge potential for the future PV sector. For this new field, the technology readiness level is really low and research to understand the interaction between offshore floating PV plants and marine environment are proceeding. In this paper, we aim to discuss the technological feasibility of offshore floating PV plants as well as analyze potential impacts on the marine environment during the life cycle of PV from manufacturing until disposal.

Содержание ртути в рыбе, выловленной ниже целлюлозно-бумажного комбината в Северной Двине

Subarctic Russian rivers tend to have swampy watersheds with a high content of hydro­gen ions and humic substances. These conditions are favourable for the formation of bioavail­able mercury. Thus, even background mercury concentrations can pose a danger to aquatic organisms. The Northern Dvina River attracts particular attention regarding mercury pollu­tion due to the presence of pulp and paper mills in the area. These mills have historically uti­lised mercury in their production processes. This study aims to analyse the mercury content in commercially important fish species living in the mouth of the Northern Dvina River. The content and distribution of mercury in tissue samples of various fish species were determined to provide insight into components of the mercury cycle in the study area. Lower mercury levels in pristine areas of the Russian subarctic showed the role of aquatic organisms as indicators of the biogeochemical cycle of mercury migration in northern freshwater areas. This study provides new scientific data on the levels of mercury found in fish from the Northern Dvina, particularly those in its estuary zone affected by the pulp and paper industry. The content and distribution of mercury were characterised using the most common fish species as an example. The difference was shown between mercury accumulation in different conditions and areas, with an analysis of relevant factors carried out.

Screening of the Bacterial Consortium Related to the Microcystin-LR Degradation Isolated From the Marine Area, Isahaya-Bay, and the Freshwater Area, Isahaya-Shin-ike-Pond, Japan

Eutrophication is still a severe global problem, and cyanobacterial microcystins (MCs) have been detected in sea areas such as harbors and coastal regions in addition to freshwater areas. Therefore, it is necessary to clarify the fate of MCs in sea areas. In Japan, Isahaya-Shin-ike-Pond, a freshwater area divided by the dike from Isahaya-bay, Nagasaki-prefecture, has eutrophicated, and cyanobacterial blooms have occurred sometimes. Water in Isahaya-Shin-ike-Pond is regularly discharged to Isahaya-bay to control the water levels in Isahaya-Shin-ike-Pond. Some researchers in Japan detected MCs from the sediment sample of Isahaya-bay; thus, MCs discharged from Isahaya-Shin-ike-Pond could be threatening the environment in Isahaya-bay. In this regard, some bacterial consortiums were isolated from Isahaya-Shin-ike-Pond and Isahaya-bay, which might degrade Microcystin-LR (MC-LR), the highly toxic representative MCs. In this report, we screened and determined the MCs degradation activity in these bacterial consortiums. As a result, we found that all bacterial consortiums degrade MC-LR. Furthermore, the HPLC chromatogram had the peak of substance-like intermediate of MC-LR decomposition. Consortium collected from approximately 4,900 m offshore from the dike degraded 97% of MC-LR. Although the bacterial communities in these consortiums differed, Bacillus sp. was in both consortiums collected from Isahaya-Shin-ike-Pond and Isahaya-bay. Because some strain of Bacillus sp. has the potential for MCs degradation, it might play an essential role in these bacterial consortiums. These results indicate that the bacteria degrade MCs even though MCs are discharged from the Isahaya-Shin-ike-Pond to Isahaya-bay.

Freshwater conservation: Lost in limnology?

Abstract Although scientific research has identified the causes of undesirable ecological changes in fresh waters, translating the results of research into practical conservation and management, and raising awareness of the need for action, is often inadequate. This Viewpoint considers the present coverage of conservation‐related freshwater research, the application of science to conservation, the extent of collaboration between international organizations, and the level of awareness of freshwater ecosystems and the need for their conservation. Far greater attention has been given to conservation in marine than freshwater areas. This is illustrated by the respective number of publications in the scientific literature, an imbalance in the UN Sustainable Development goals, and, until recently, the lack of an explicit reference to freshwater ecosystems in the UN Global Biodiversity Framework. Four case studies are presented as examples of how freshwater conservation can be made more effective: involving local communities in applying nature‐based solutions; bringing scientists and stakeholders together to discuss how to improve freshwater management; collaborating at a global scale in freshwater protection and restoration; and demonstrating how scientists and government can work together to reconcile the competing needs of nature and human society. Producing and implementing effective conservation and management plans needs a recognition of the extensive diversity of freshwater habitats and species, as well as a systematic evaluation of how scientific information can be translated into action at local, regional and global scales. Data on freshwater ecosystems need to be accessible, comprehensible, unambiguous and available to all those working on practical conservation projects. Many international organizations are already active in this field, but greater collaboration would make their work more effective. Raising awareness needs education and training, carefully targeted at a wide range of audiences, and communicated using the full range of media now available.

The Synergistic Effects of Corbicula fluminea and Sarcodia montagneana on Alleviating Systemic Inflammation and Osteoarthritis Progression.

Osteoarthritis (OA) is a progressive disease that causes pain, stiffness, and inflammation in the affected joints. Currently, there are no effective treatments for preventing the worst outcomes, such as synovitis or cartilage degradation. Sarcodia montagneana and Corbicula fluminea are common species found in the ocean or in freshwater areas. Their extracts are demonstrated to possess both antioxidative and anti-inflammatory functions. This study aimed to investigate the synergistic effects of the extracts of Sarcodia montagneana (SME) and Corbicula fluminea (FCE) on reducing local and systemic inflammation, as well as their efficacy in OA symptom relief. An in vitro monocytic LPS-treated THP-1 cell model and in vivo MIA-induced mouse OA model were applied, and the results showed that the combinatory usage of SME and FCE effectively suppressed IFN-γ and TNF-α production when THP-1 cells were treated with LPS. SME and FCE also significantly decreased the systemic TNF-α level and joint swelling and prevented the loss of proteoglycan in the cartilage within the joints of OA mice. The data shown here provide a potential solution for the treatment of osteoarthritis.

Using solicited research diaries to assess the restorative potential of exposure to inland blue space across time

Inland blue spaces, or freshwater environments, have been shown to provide people with positive mental health and wellbeing outcomes. Most inland blue space research focusing on wellbeing outcomes has so far been cross-sectional, utilising questionnaires and interviews. Therefore, there is significant uncertainty regarding the potential for inland waterways to benefit human populations over longer-term time scales. Across a sixteen-month data collection period, this study recruited four distinct sample groups to complete diaries for periods of three-months, focusing on inland blue space experiences in Scotland. The aim of the study was to use solicited diary methods to establish whether restorative exposure outcomes gained from visiting blue spaces may vary across time. Results from the diary data show that visiting freshwater areas consistently led to positive restorative outcomes, with minimal variation in restorative outcomes observed across time. Participants recorded three principal categories of blue space experiences; routine visits, getting fresh air; and day trips, with each visit type providing a range of restorative benefits. The findings highlight the potential for inland blue spaces to act as versatile public health resources and the need to consider long-term strategies to ensure these environments benefit populations across time.

Strontium isotope analysis of otoliths reveals differences in the habitat salinity among three sympatric stickleback species of the genus Pungitius.

The analysis of otolith Sr isotope ratios (87Sr/86Sr) is a powerful method to study fish migration in freshwater areas. However, few studies have applied this method to study fish movement in brackish-water environments. Furthermore, despite the fact that habitat differentiation has been shown to drive genetic differentiation and reproductive isolation among stickleback fish, no studies have used the otolith 87Sr/86Sr ratios to analyze habitat differentiation between stickleback ecotypes and species. In this study, we analyzed the otolith 87Sr/86Sr ratios of three sympatric stickleback species of the genus Pungitius in the Shiomi River on Hokkaido Island, Japan: P. tymensis, the brackish-water type of the P. pungitius-P. sinensis complex, and the freshwater type of the P. pungitius-P. sinensis complex. First, we created a mixing equation to depict the relationship between habitat salinity and the 87Sr/86Sr ratios of river water. We found that the otolith 87Sr/86Sr ratios differed significantly among the three species, indicating that the three species utilize habitats with different salinities: P. tymensis and the brackish-water type inhabit freshwater and brackish-water environments, respectively, with the freshwater type using intermediate habitats. In addition, we found that some freshwater individuals moved to habitats with higher salinities as they grew. Our study demonstrates that the analysis of otolith 87Sr/86Sr ratios is a useful method for studying the habitat use of fish in brackish-water environments and habitat differentiation among closely related sympatric and parapatric species.

Spatiotemporal changes of coastal land use land cover and its drivers in Shanghai, China between 1989 and 2015

The coastal zone, an ecotone that provides vital diverse ecosystem services, is one of the most ecologically fragile and sensitive areas on the Earth. It has been strongly influenced by human activities and climate change. Thus, understanding the spatiotemporal changes of land use land cover in the coast is an essential prerequisite for the comprehensive evaluation of coastal ecosystems and the promotion of sustainable development. This study investigated the spatial and temporal changes of land use land cover in the coastal zone of mainland Shanghai by using high spatial resolution aerial images, and the associated driving factors obtained from statistical yearbooks between 1989 and 2015. Our results show that the total land area in the coastal zone exhibited an increasing trend at an annual rate of 7.6% on average. The coastal urban land use also experienced substantial increases, with the degree of urban expansion reaching 42.1% in 2015. The coastal urbanization was at the cost of natural and semi-natural lands. Nearly 64.4% of agricultural land, 24.4% of ocean area within the buffer, 84.9% of fresh water, and 92.8% of the tidal flat had been converted to urban land during 1989–2015. The gradient analysis of land use land cover change along the north-to-south coastal line revealed the spatiotemporal patterns of total land, urbanization degree, and natural and semi-natural lands. The majority of the socioeconomic factors influenced land use land cover change in the coastal zone, positively contributing to the increase of public facilities’ use of land, but negatively affecting the freshwater areas. These findings can provide insights for decision-making in the future for coastal land use land cover planning and management in Shanghai.

On Variations of the Sound Signal Propagation Time under a Stationary Ice Cover

In experiments on a stationary acoustic track under a solid ice cover, estimates of possible sound signal propagation time variations at distances of ∼4 km with a period of more than 100 s were obtained. The experiments were carried out on Lake Baikal in the spring period, when the vertical profile of the sound speed has two sections characteristic of freshwater areas: an upper layer with a near constant sound speed and a lower layer with linear growth of sound speed. Under these conditions, the variations of the propagation time did not exceed ~10–4 s. Numerical modeling showed that the variations of propagation times due to the variability of the medium are minimal for the case when the sound source and receiver are located in the upper layer. It is demonstrated that in this case it is acceptable to take the sound speed in the upper quasi-homogeneous layer as the effective value of the sound speed, which determines the propagation time. The obtained results allowed us to formulate recommendations on under-ice acoustic positioning of autonomous underwater vehicles.

Use of hydrogeochemical tools to evaluate seawater intrusion: a case study of Upper Pliocene Aquifer in the Ca Mau Peninsula, Vietnam

Groundwater resources have been withdrawn significantly to meet the demands of agricultural economic development in the Ca Mau Peninsula, Mekong River Delta. As a result, aquifers face the risk of groundwater levels decline and high salinization potential. This study uses the groundwater quality index (GQI) and hydrochemical facies evolution diagram (HFE-D) to assess the hydrochemical characteristics and salinization potential of the Upper Pliocene aquifer (n2 2), which is one of the two most exploited aquifers in the Mekong River Delta. A total of 6 monitoring wells were used to observe groundwater level and water quality from 2017 to 2020. The GQI results ranged from 33.38 to 75.61, indicating that groundwater in Hau Giang and Soc Trang areas is salinized. The spatial distribution results of HFE-D stated that the boundaries of intrusion and freshening have varied in space and time. Specifically, the Upper Pliocene aquifer has been in the process of seawater intrusion. The freshwater area in the Ca Mau has been gradually shrinking in the East Sea area faster than the West Sea area. The displacement speed of the intrusion and freshening boundary varied considerably from 0.04 to 0.67 km/year from 2017 to 2020.

Effects of chlorantraniliprole-based pesticide on transcriptional response and gut microbiota of the crucian carp, Carassius carassius

Chlorantraniliprole (CAP) is a presentative diamide pesticide utilized in agricultural area and as well as rice-fish co-culture system for pest control. However, the understanding of toxic effects of CAP on fish species is still incomplete. In the present study, we performed an integrated study of the acute toxicity and bioaccumulation of CAP on the crucian carp, Carassius carassius, a fish species widely distributed in freshwater area in China and commonly farmed in the rice-fish co-culture systems. Besides, biochemical changes, transcriptional responses and gut microbiota of fish were investigated upon sub-chronic CAP exposure. The results showed that CAP is low toxic to crucian carp with a 96 h LC50 of 74.824 mg/L, but has considerable accumulation in the fish muscles when exposed to 3 mg/L of CAP for 14 d and still detectable after 18 d recovery in fresh water. For sub-chronic test, fish were exposed to CAP at 0, 0.3, 3 and 30 mg/L respectively for 14 d. CAP induced oxidative stress and detoxification inhibition in the liver of fish by decreasing antioxidative and detoxicated enzymes activities and downregulating relevant genes expression. In addition, disrupted gut flora composition was found in all experimental groups by the 16 S rRNA sequencing data, indicating the gut microbiota dysbiosis in crucian carp and potential adverse host effect. All the results suggest that CAP at sublethal concentrations has prominent toxic effect on crucian carp and more attentions should be paid especially using directly in an integrated aquaculture system.

A Review and Analysis of Heavy Metals in Freshwater Reservoirs of Pakistan: their Bioaccumulation, Biological Magnification and Biotic Transmission

Problems associated with pollution are becoming more severe as industrialization advances rapidly. Inorganic and organic wastes, both water-soluble and insoluble, are discharged into the aquatic environment, contributing to one of the most critical problems: water pollution. The discharge of waste in water channels allows heavy metal ions, which are toxic to all kinds of life, to enter the food chain. Lead, nickel, sodium, potassium, zinc, copper, iron lithium, cadmium, and chromium (VI) are among the most hazardous metal ions. Because they don't break down, metal ions build up in the environment and move up the food chain. Therefore, higher trophic level animals are more susceptible to their toxicityHeavy metals found in freshwater and sediments have been found to bioaccumulate in fish tissues. Rawal Dam, Mangla Dam, and Zabi Dam were identified as highly contaminated areas of freshwater that had detrimental effects on fish and human health. The Rawal Dam, which received a lot of industrial and sewage drainage from Punjab's metropolitan areas and industry, was significantly contaminated compared to other Pakistani Dams. Changhoz and Ghol Dams, with their massive water flows and relatively few accompanying industrial facilities, have the healthiest ecosystems of all Pakistan's dams. Changhoz Dam's freshwater fish are considered to be safe for human consumption. Heavy metals are accumulated by migratory birds at Rawal Dam from eating fish from freshwater reservoirs. Heavy metal pollution has been linked to a variety of social, ecological, and economic issues. The detrimental effects of heavy metals on aquatic organisms and human well-being can be reduced if wastewater is purified before being released into freshwater.