Lake Fish Research Articles

Counting fish at night using artificial light: transect survey of common bream Abramis brama and northern pike Esox lucius abundance as an example.

Visual transect counting of large-bodied fish using artificial light at night in a shallow littoral zone (<1 m water depth) is introduced as a complementary survey method for fishes such as common bream Abramis brama and northern pike Esox lucius that are under-represented in standard gillnet surveys. The results suggest that transect counting at night and applying necessary corrections for environmental variables could provide a simple and repeatable method to assess the presence and abundance of large-bodied fishes in lakes with satisfactory water clarity.

Interactive Effects of Anthropogenic Stressors on the Temporal Changes in the Size Spectrum of Lake Fish Communities

ABSTRACTThe size spectrum represents a powerful approach for quantifying the effects of environmental changes from individuals to communities in aquatic ecosystems. However, our understanding of its temporal stability in freshwater ecosystems is still limited. In the present study, we used a size spectrum approach to investigate the responses of 126 lake fish communities to changes in the intensity of three common anthropogenic stressors (i.e., global warming, nutrient loading and biological invasions) in French natural lakes and reservoirs over an average 5‐year time period. Using a backward selection on a full model including all possible effects of stressors on the size spectrum slope, we demonstrated that (i) increasing summer temperature shifted fish abundance towards the largest size classes, resulting in a flatter size spectrum slope and (ii) nutrient loading and biological invasions were associated with a shift towards smaller size classes in natural lakes, while the opposite effect was observed in reservoirs. In addition, these two stressors interacted in determining changes in the size structure of fish communities, complicating what the size spectrum can reveal about changes in stressor intensity during monitoring programs. All predictors accounted for a limited part of the observed changes in size spectra, and further investigations are needed to fully apprehend the interplay between natural and human‐induced drivers of the temporal changes in size spectra in contrasting environmental conditions.

Influence of water chemistry and contaminant occurrence on the oxidative stress ecology of Cottus gobio in a high-mountain lake (Carnic Alps)

Understanding oxidative stress in high-mountain lake fish offers crucial insights into their health, resilience, and adaptation to extreme environmental changes. This study investigates the oxidative stress response of Cottus gobio in a high-mountain lake (Dimon Lake) located in the northeast Italy during the ice-free season, focusing on the relationship between oxidative stress biomarkers and physicochemical water parameters, as well as persistent and emerging contaminants. Significant seasonal variations were observed in water parameters, with lower oxygen, pH, conductivity, and phosphate levels in summer compared to autumn, while temperature, ammonium, and nitrate were higher in summer. Metal concentrations in C. gobio muscle were higher in autumn, with Zn showing the most significant increase. PAHs, NDL-PCBs, and pesticides were all below the limit of quantification in the fish muscle samples. No microplastics items were found in the gastrointestinal tracts of fish. Oxidative stress biomarkers revealed organ-specific and seasonal variations. The liver exhibited the highest activities of catalase (CAT), glutathione peroxidase (GPx), glutathione S-tranferase (GST), and glutathione reductase (GR), highlighting its central role in detoxification and metabolic processes. Superoxide dismutase (SOD) activity was notably higher in muscle tissue during summer, suggesting increased metabolic activity. A strong correlation was found between pH and the activities of SOD, CAT, GPx, GR, and metallothioneins (MTs), emphasizing the importance of water chemistry in influencing oxidative stress responses. This approach not only aids in understanding the local adaptations of these fish but also highlights the impacts of environmental stressors on high-mountain ecosystems. Continuous monitoring of water chemistry, particularly pH, is crucial for understanding and managing oxidative stress in aquatic organisms, especially in the context of global environmental changes.

Examining Bald Eagle Contaminant Exposure and Reproductive Risk Above and Below Dams on Great Lakes Tributaries.

Removing lowermost dams can reestablish fish passage on Great Lakes tributaries. This can increase the transfer of contaminants from anadromous fish to piscivorous wildlife upstream; however, concentrations of bioaccumulative contaminants in Great Lakes fish have decreased over the last several decades. We analyzed concentrations of PCBs and the toxic equivalence (TEQs) calculated from PCBs, DDTs, other organochlorine pesticides, and PBDEs in the plasma of bald eagle nestlings above and below lowermost dams on five river systems in Michigan from 1999 to 2013. We examined relationships between contaminants and metrics of reproductive success from 1997 to 2018, including the effects of year and location relative to the lowermost dam. Σ20PCB and p,p'-DDE were important in characterizing differences in contaminant mixtures above and below dams. Concentrations of contaminants were generally greater below dams than above. There were generally greater nest success and more nestlings per nest below dams, but nest location explained little variability (R2 values = 0.03-0.15). Neither Σ20PCB nor p,p'-DDE was a significant predictor of 5-year productivity means by river reach despite concentrations exceeding previously established effects thresholds for healthy bald eagle populations in the Great Lakes (≥ 1 nestling/nest). Our study indicates that dams may continue to reduce the upstream movement of contaminants to bald eagles, but at the measured concentrations, contaminants did not impair productivity and reproductive success as indicated by nestlings per nest. Additional information about population dynamics could clarify population-level effects of contaminants on bald eagles and to what degree these populations are self-sustaining throughout the Great Lakes.

Genetic Identification of Endemic Fish Nomorhamphus liemi Vogt, 1978 from Sigi, Central Sulawesi, Indonesia

Sulawesi Island is geographically included in the Wallacea region, a transitional area between the Oriental and Australian zones, which makes Sulawesi’s fresh waters have a high level of fish species diversity. Some fish species found in Sulawesi freshwater are endemic. Research on Sulawesi endemic fishes in rivers is not as much as research on endemic fishes in lakes. Nomorhamphus liemi or locally known as angculung is one of Sulawesi’s endemic fishes. This species belongs to the sub-family Zenarchopterinae. The majority of species from the Zenarchopterinae sub-family are sexually dimorphic. This study aimed to molecularly identify angculung fish species using COI markers in the region. A total of nine angculung fish were collected and preserved using 96% alcohol. In the laboratory, tissue taken from the back of the dorsal fin was isolated and extracted, then amplified by PCR before sequencing. Sequencing results were validated on BLASTn, showing that nine samples belonged to Nomorhamphus liemi with 98-99% sequence similarity. The nucleotide base sequences were then analyzed using MEGA 7.0 software. The genetic distance of mackerel in these waters showed a close relationship. Phylogeny tree results showed population mixing so that mackerel in these waters can be managed in one management unit, especially in Sulawesi.

An Updated Assessment of Fishes in Lake Çıldır: A Comprehensive Study and Conservation Recommendations

An Updated Assessment of Fishes in Lake Çıldır: A Comprehensive Study and Conservation Recommendations

Preying on cyprinid snout warts (pearl organs) as a novel and peculiar habit in the Lake Malawi cichlid Docimodus evelynae

Cichlid fishes in the African Great Lakes have undergone explosive speciation, acquiring markedly varying ecologies and diets. There are multiple lineages of scale-eating cichlids, and their natural history and evolutionary ecology is only partially understood. We examined the feeding habit of Docimodus evelynae, a known scale eater, in Lake Malawi. The stomach contents of young individuals mainly consisted of unknown 1 mm hard, white warts (> 30%). To clarify the origin of these warts, we conducted an X-ray fluorometer analysis, and found they were rich in sulphur but low in silicon and calcium, suggesting they were epidermal tissues. Histological and morphological analyses revealed they were multicellular and cup-shaped. These characteristics matched only those of the pearl organs of the coexisting cyprinid Labeo cylindricus. DNA was extracted from the warts found in the stomach of five D. evelynae individuals, followed by PCR using primers targeting the partial COI gene of L. cylindricus. The resulting sequences exhibited 98% similarity to those of L. cylindricus. Pearl organs, never reported as a primary food for fish, could offer a substantial nutritional source based on calorific calculations. Understanding how this peculiar diet is foraged is essential for full comprehension of the food-web structure in this lake.

Relationship between fish traits and the methane‐derived carbon contribution to fish in a shallow lake

Abstract Although the transfer of methane‐derived carbon (MDC) to benthic macroinvertebrates such as chironomid larvae and oligochaetes has been well documented, knowledge of the transfer of MDC to fish is limited. We investigated the MDC contribution to 28 fish species through their growth stages and examined the relationship between fish traits including body size, and MDC contribution to fish within species in Lake Kasumigaura, Japan. We used carbon stable isotope ratios and a two‐source mixing model (methane‐oxidation bacteria [MOB] and particulate organic matter) to estimate the MDC contribution to fish. The MDC contribution to individual fish ranged from 0% to 21.5%. Anguilla japonica showed the highest MDC contribution (mean 3.8%). Fish species were classified into four groups according to two criteria: (a) whether the correlation between the MDC contribution and fish size (within species) was significantly negative (negative vs. not significant; ns); and (b) whether the 90th percentile of MDC contribution was 0% or not. The mean MDC contribution was highest (2.18% ± 2.93%, 12 species) for the group with (a)ns/(b)&gt;0%, including the high contribution species such as Abbottina rivularis (mean 5.5%) and Biwia zezera (mean 9.8%). This group (12 species) included relatively high numbers of benthic habitat use (eight species) and omnivores (nine species). The mean MDC contributions were almost zero for the group with (a)ns/(b)=0% (seven species), which included only two species of benthic habitat use and one species of omnivores. The mean MDC contributions were intermediate for the other groups with (a)negative/(b)&gt;0% (1.30% ± 1.17%, seven species) and (a)negative/(b)=0% (0.10%, two species). The negative correlation between fish size within species and MDC contribution in groups with (a)negative/(b)&gt;0% and (a)negative/(b)=0% indicated that ontogenetic habitat and dietary shifts induced changes in MDC transfer. Our results suggest that 21 out of 28 fish species were involved in the MDC transfer in a shallow lake, but variation in MDC transfer could be explained by fish traits (trophic guild and habitat use). Although the mean MDC contribution to all fish species was low (0.61% ± 1.97%), the roughly estimated annual consumption rate of fish on MOB corresponded to approximately 10% of the MOB production in the sediment, suggesting that fish contribute to methane dynamics from the perspective of biogeochemical cycles.

Effects of filter-feeding fish faeces on microbial driving mechanism of lake sediment carbon transformation

Silver carp (Hypophthalmichthys molitrix) can filter the carbon in the food taken up by phytoplankton and plays an important role in carbon fixation. In this study, the faeces of silver carp, the dominant fish species in Qiandao Lake, China, were collected and subjected to a closed incubation and transformation experiment for three months. The physical and chemical indices of water and sediment mixture, carbon metabolic enzyme activity, and microbial sequences were analyzed to identify the key microbial strains that affect carbon transformation as well as the main factors influencing carbon transformation. The results showed maximum CO2 and CH4 emission fluxes on day 15 of fish faeces and sediment interaction. In the faeces addition group, the contents of soluble organic carbon, soluble inorganic carbon, SO42−, and PO43− were significantly increased, while the dissolved oxygen content was significantly decreased. Furthermore, the pH, total carbon content, volatile suspended solids content, and activities of four carbon-metabolizing enzymes were significantly increased in the faeces addition group. The 16sRNA analysis of methanogenic and methane-oxidizing bacteria showed that Euryarchaea and Pseudomonas accounted for the highest proportion respectively. The most significant differences expression were found for Methylbacterium in the methanogenic bacteria and Methylobacter in the methane oxidizing bacteria. Structural variance model showed that interaction of fish faeces and sediments mainly caused changes in sulfate content, leading to variations in methanogens and methanotrophs and promotion of CH4 emission. The results of this study can provide a theoretical reference for the mechanism of carbon reduction and emission reduction of lake filter-feeding fish.

Origin of the Laurentian Great Lakes fish fauna through upward adaptive radiation cascade prior to the Last Glacial Maximum

The evolutionary histories of adaptive radiations can be marked by dramatic demographic fluctuations. However, the demographic histories of ecologically-linked co-diversifying lineages remain understudied. The Laurentian Great Lakes provide a unique system of two such radiations that are dispersed across depth gradients with a predator-prey relationship. We show that the North American Coregonus species complex (“ciscoes”) radiated rapidly prior to the Last Glacial Maximum (80–90 kya), a globally warm period, followed by rapid expansion in population size. Similar patterns of demographic expansion were observed in the predator species, Lake Charr (Salvelinus namaycush), following a brief time lag, which we hypothesize was driven by predator-prey dynamics. Diversification of prey into deep water created ecological opportunities for the predators, facilitating their demographic expansion, which is consistent with an upward adaptive radiation cascade. This study provides a new timeline and environmental context for the origin of the Laurentian Great Lakes fish fauna, and firmly establishes this system as drivers of ecological diversification and rapid speciation through cyclical glaciation.

Growth and Condition of Largemouth Bass (Micropterus nigricans) and Bluegill (Lepomis macrochirus) in a Minnesota, USA, Lake with Separate Dredged and Non-Dredged Basins

The objective of this study was to assess the growth rates and general body condition of two common game fishes (largemouth bass Micropterus nigricans and bluegill Lepomis macrochirus) in a productive midwestern USA lake, Lake Winona, 20+ years after one of its two separate basins was partially dredged. We also used historical lake survey data spanning 19 years before and 15 years after dredging to assess the pre- and post-dredging growth of these species. Dredging was expected to improve the growth rates and conditions (relative weights) of both species due to post-dredging changes to lake habitats (more open water and reduced macrophyte beds) and the fish community structure in the dredged basin. Both species displayed significantly faster growth in the dredged basin, with the bluegill by age 3 and the bass by age 6. The mean relative weights of both species were significantly higher in the non-dredged basin (bass were in good condition: 106% versus 100%; bluegill were in fair condition: 84% versus 80%), although both bluegill and largemouth bass exhibited significant declines in relative weight with increasing lengths in the non-dredged basin. The growth rates for largemouth bass have declined from historical levels, especially in the non-dredged basin, whereas bluegill growth rates have remained stable or improved, especially in the dredged basin. Overall, largemouth bass and bluegill growth rates and relative weights are responding to differences in habitat and fish communities between dredged and non-dredged basins, indicating that the two lake basins are isolated enough from one another to allow for separate biological responses to occur in each.

Optimising species detection probability and sampling effort in lake fish eDNA surveys

Environmental DNA (eDNA) metabarcoding is transforming biodiversity monitoring in aquatic environments. Such an approach has been developed and deployed for monitoring lake fish communities in Great Britain, where the method has repeatedly shown a comparable or better performance than conventional approaches. Previous analyses indicated that 20 water samples per lake are sufficient to reliably estimate fish species richness, but it is unclear how reduced eDNA sampling effort affects richness, or other biodiversity estimates and metrics. As the number of samples strongly influences the cost of monitoring programmes, it is essential that sampling effort is optimised for a specific monitoring objective. The aim of this project was to explore the effect of reduced eDNA sampling effort on biodiversity metrics (namely species richness and community composition) using algorithmic and statistical resampling techniques of a data set from 101 lakes, covering a wide spectrum of lake types and ecological quality. The results showed that reliable estimation of lake fish species richness could, in fact, usually be achieved with a much lower number of samples. For example, in almost 90% of lakes, 95% of complete fish richness could be detected with only 10 water samples, regardless of lake area. Similarly, other measures of alpha and beta-diversity were not greatly affected by a reduction in sample size from 20 to 10 samples. We also found that there is no significant difference in detected species richness between shoreline and offshore sampling transects, allowing for simplified field logistics. This could potentially allow the effective sampling of a larger number of lakes within a given monitoring budget. However, rare species were more often missed with fewer samples, with potential implications for monitoring of invasive or endangered species. These results should inform the design of eDNA sampling strategies, so that these can be optimised to achieve specific monitoring goals.

About mathematical modeling in limnology, oceanology, ecology and economics in the works of V.V. Menchutkin

The article gives a brief review of the works of Doctor of Biological Sciences, Prof. V.V. Menshutkin for the 65-year period of scientific activity, which began in the 60s of the XX century with experimental works on the hydrophisics of Lake Baikal and the first mathematical models of the perch population of the small lake Kherya-Yarvi (Karelian Isthmus) and fish community in Lake Dalneye (Kamchatka). The latter was of great practical importance when concluding an agreement with Japan on catch quotas for sockeye salmon.V.V. Menshutkin’s range of interests was very wide and included mathematical modeling in biology, physiology, limnology, oceanology, demography, economics, ecology and rational nature management. The works on research of water objects and processes in them include modeling of dynamics of fish and aquatic invertebrate populations, Antarctic krill. He created mathematical models of ecosystems of Ladoga and Onega lakes, and during oceanic expeditions of the Academy of Sciences — of the Sea of Japan and the Peruvian upwelling area.His research in the field of physiology of blood circulation and water-salt metabolism, works related to space subjects, modeling of diagnostics and treatment of mental diseases are interesting. V.V. Menshutkin paid special attention to the issues of biological evolution. V.V. Menshutkin paid special attention to the issues of biological evolution and modeling of evolutionary process. The mathematical apparatus used by V.V. Menshutkin is very broad. The mathematical apparatus used by V.V. Menshutkin is very wide: from systems of differential equations to finite automata, neural networks, fuzzy logic and cognitive modeling (a new direction in artificial intelligence), with which the studies of ecological-socio-economic systems of water bodies catchments were connected.O.P. Savchuk and V.V. Menshutkin united research methods — mathematical modeling and objects under study: oceans, seas and lakes. However, their only joint work was the collective monograph on the results of “Nevskaya Guba” project, which conclusions became the basis for the important decision to complete the construction of the dam in St. Petersburg.

Can remotely sensed catchment to lake area ratios predict mercury levels in subarctic fishes?

Mercury concentrations ([Hg]) in fish reflect a complex array of interacting biogeochemical and ecological variables. In northern regions where fish are a critical subsistence food, understanding and predicting fish [Hg] can be particularly difficult, largely due to a paucity of comprehensive data associated with the logistical challenges of field sampling. Building on previous work where we elucidated causal relationships between fish [Hg] and a variety of catchment, water quality, and ecological variables in subarctic lakes, we investigated whether using only ratios of catchment area to lake area (CA:LA) can predict [Hg] in northern freshwater fish species. As CA:LA can be sensed remotely, they may be more feasible and practical to obtain than field data in far northern regions. Our study included thirteen remote lakes that represent a CA:LA gradient of 6.2–423.5 within an ∼66,000 km2 subarctic region of Northwest Territories, Canada. We found that size-standardized [Hg] in three widespread fish species, including Lake Whitefish (Coregonus clupeaformis), Walleye (Sander vitreus), and Northern Pike (Esox lucius), were significantly and positively related to CA:LA (p < 0.007, r2 = 67–80%), indicating higher fish [Hg] in smaller lakes surrounded by relatively larger catchments. Our findings provide compelling evidence that remotely sensed CA:LA can be used to predict [Hg] in northern fishes and aid in prioritizing understudied and subsistence fishing lakes of the Canadian subarctic for [Hg] monitoring programs.

Modification of a commercial fish feeder for use in small rearing ponds

AbstractObjectiveAutomatic feeders are commonly used in aquaculture, but the feed delivery pattern cannot be adjusted to accommodate a variety of rearing unit sizes. For those few feeders that can be adjusted, their use has been limited because of initial costs, availability, and other issues. This paper describes modification to a commercially available fish feeder (Texas Hunter Products 31.75‐kg [70‐lb] Lake and Pond Directional Fish Feeder) to effectively provide feed to different‐sized ponds.MethodsThis feeder has a 14‐m fish feed distribution pattern, making it unusable for smaller ponds. To reduce the distance of fish feed projected from the feeder, a resistor (rheostat) was installed in series with the fan motor.ResultThe rheostat reduced the power to the fan motor, thereby decreasing the feed projection distance. In addition, because the rheostat was adjustable, the resistance—and the resulting power to the fan motor—could be easily changed, making it possible for the same feeder to be used in different‐sized ponds while using approximately the same amount of power from the battery and solar panels.ConclusionThis modification was inexpensive and relatively easy to perform. The feeders reliably dispensed feed in a number of small ponds during an 8‐month evaluation period.

From lake to fisheries: Interactive effect of climate and landuse changes hit on lake fish catch?

Global warming and unpredictable nature possess a negative impact on fisheries and the daily activities of other habitats. GIS and remote sensing approach is an effective tool to determine the morphological characteristics of the lake. The present study addresses the interactive effect of climate and landuse changes hit on fish catch in lake fisheries. We used a combination of the landscape disturbance index, vulnerability index, and loss index to construct a complete ecological risk assessment framework based on the landscape structure of regional ecosystems. The results indicate an increase from around 45%–76% in the percentage of land susceptible to moderate to ecological severe risk in the landscape from 2004 to 2023. Since 1950, temperature changes have increased by 0.4%, precipitation has decreased by 6%, and water levels have decreased by 4.2%, based on the results. The results indicate that landuse, water temperature, precipitation, and water depth significantly impact the aquaculture system. The findings strongly suggest integrating possible consequences of environmental change on fish yield for governance modeling techniques to minimize their effects.

Pattern and Dynamics of Genetic Stock of Freshwater Fishes Using Various Molecular Markers for Their Conservation Management Concerns in the Indian Riverine System

India has a world's richest, most abundant and most promising inland fisheries resources with variety fishes in tributaries, streams, canals, lakes, ponds, and reservoirs. There are several significant river systems in India, including the Cauvery, Tapi, Narmada, Krishna, Indus, Brahmaputra, Ganga, Mahanadi, and Godavari which showing shrinkage of fish fauna because of environmental disturbance, human interference and human threats. In order to conserve the fish diversity, the molecular markers are helpful in determining genetic diversity, gene polymorphism and gene flows from generation to generation. The topic experienced a surge in interest due to the introduction of strong statistical analysis tools and the accessibility of DNA fingerprinting, DNA sequencing techniques and consequently population genetic studies. Some molecular markers, Microsatellite markers, RAPD, Allozymes and mitochondrial (cox1, cytob, ATPase6/8) implications have been discussed in this review which will provide an overview that have been used by scientists to studied population genetic structure and genetic variations at various levels.

Chemical properties indices for nutritional quality evaluation of Nasser Lake fish, Aswan, Egypt.

Fish is considered an important food because it includes main nutrients (proteins, fats, and ash) and micronutrients (vitamins and minerals). The assessment of fish nutritional content data may offer crucial recommendations regarding freshwater fish consumption and preserving human well-being. Evaluate the safety and quality properties of Nasser Lake fish, Aswan, Egypt. A total of 250 samples, 50 of each Nile tilapia, Nile perch, Zander, Catfish, and Elephant-snout, from Nasser Lake, Aswan, Egypt; beheaded, eviscerated, filleted, and minced for determination of proximate analysis, amino acid, fatty acids (FAs), minerals and heavy metal, histamine content, cholesterol content, and sensory assessment. The proximate analysis showed that all the samples examined were of good protein sources, with mean values ranging from 15.92% to 22.89%. Nile perch exhibits the highest levels of total FAs and amino acids. Heavy metal concentrations varied considerably among the analyzed samples, with a significant variance in the detection of metals among the examined fish. The findings show low histamine and cholesterol levels in the examined species, and were in accordance with those set by the National Food Safety Authority (NFSA) and the European Union Commission (EC). Accordingly, all samples are accepted based on their sensory properties. Nasser Lake fish are of high nutritional value and have an excellent supply of amino and FAs.

Occurrence, molecular characterization, and antimicrobial susceptibility of sorbitol non-fermenting Escherichia coli in lake water, fish and humans in central Oromia, Ethiopia

Contaminated lake water and fish can be sources of bacterial pathogens of public health concern, including pathogenic E. coli. Within Ethiopia, specifically, Central Oromia, raw fish consumption is a common practice. Although there are few reports on occurrence of E. coli O157 in fish destined for human consumption and children under five years, information on the transmission pathways of E. coli O157 and other sorbitol non-fermenting (SN-F) E. coli from water-to-fish-to-human, and their virulence factors and antimicrobial resistant determinants along the fish supply chain is lacking. The study aimed to investigate the occurrence, molecular characteristics, and antimicrobial susceptibility of E. coli O157 and other SN-F E. coli strains in fish, lake water and humans in central Oromia, Ethiopia. A total of 750 samples (450 fish samples, 150 water samples, 150 human stool samples) were collected from five lakes and three health facilities. The samples were processed following the standard protocol recommended by European Food Safety Authority and Kirby–Bauer disc diffusion method for detection of the bacteria, and antimicrobial susceptibility tests, respectively. Molecular characterization of presumptive isolates was performed using Whole-Genome Sequencing (WGS) for serotyping, determination of virulence factors, antimicrobial resistance traits, and genetic linkage of the isolates. Overall, 3.9% (29/750) of the samples had SN-F E. coli; of which 6.7% (n = 10), 1.8% (n = 8) and 7.3% (n = 11) were retrieved from water, fish, and diarrheic human patients, respectively. The WGS confirmed that all the isolates were SN-F non-O157: H7 E. coli strains. We reported two new E. coli strains with unknown O-antigen from fish and human samples. All the strains have multiple virulence factors and one or more genes encoding for them. Genetic relatedness was observed among strains from the same sources (water, fish, and humans). Most isolates were resistant to ampicillin (100%), tetracycline (100%), cefotaxime (100%), ceftazidime (100%), meropenem (100%), nalidixic acid (93.1%) and sulfamethoxazole/trimethoprim (79.3%). Majority of the strains were resistant to chloramphenicol (58.6%) and ciprofloxacin (48.3%), while small fraction showed resistance to azithromycin (3.45%). Isolates had an overall MDR profile of 87.5%. Majority, (62.1%; n = 18) of the strains had acquired MDR traits. Genes encoding for mutational resistance and Extended-spectrum beta-lactamases (ESBL) were also detected. In conclusion, our study revealed the occurrence of virulent and MDR SN-F E. coli strains in water, fish, and humans. Although no genetic relatedness was observed among strains from various sources, the genomic clustering among strains from the same sources strongly suggests the potential risk of transmission along the supply chain at the human–fish-environment interface if strict hygienic fish production is not in place. Further robust genetic study of the new strains with unknown O-antigens, and the epidemiology of SN-F E. coli is required to elucidate the molecular profile and public health implications of the pathogens.

Determinants of per- and polyfluoroalkyl substances (PFAS) exposure among Wisconsin residents

BackgroundPer- and polyfluoroalkyl substances (PFAS) include thousands of manufactured compounds with growing public health concerns due to their potential for widespread human exposure and adverse health outcomes. While PFAS contamination remains a significant concern, especially from ingestion of contaminated food and water, determinants of the variability in PFAS exposure among regional and statewide populations in the United States remains unclear. ObjectivesThe objective of this study was to leverage The Survey of the Health of Wisconsin (SHOW), the only statewide representative cohort in the US, to assess and characterize the variability of PFAS exposure in a general population. MethodsThis study sample included a sub-sample of 605 adult participants from the 2014–2016 tri-annual statewide representative sample. Geometric means for PFOS, PFOA, PFNA, PFHxS, PFPeS, PFHpA, and a summed measure of 38 analyzed serum PFAS were presented by demographic, diet, behavioral, and residential characteristics. Multivariate linear regression was used to determine significant predictors of serum PFAS after adjustment. ResultsOverall, higher serum concentrations of long-chain PFAS were observed compared with short-chain PFAS. Older adults, males, and non-Hispanic White individuals had higher serum PFAS compared to younger adults, females, and non-White individuals. Eating caught fish in the past year was associated with elevated levels of several PFAS. DiscussionThis is among the first studies to characterize serum PFAS among a representative statewide sample in Wisconsin. Both short- and long-chain serum PFAS were detectable for six prominent PFAS. Age and consumption of great lakes fish were the most significant predictors of serum PFAS. State-level PFAS biomonitoring is important for identifying high risk populations and informing state public health standards and interventions, especially among those not living near known contamination sites.