Studies in recent years have shown that aquatic pollution by microplastics(MPs)can be considered to pose additional stress to amphibian populations.However,our knowledge of how MPs affect amphibians is very rudimentar...Studies in recent years have shown that aquatic pollution by microplastics(MPs)can be considered to pose additional stress to amphibian populations.However,our knowledge of how MPs affect amphibians is very rudimentary,and even more limited is our understanding of their effects in combination with other emerging pollutants.Thus,we aimed to evaluate the possible toxicity of polyethylene MPs(PE-MPs)(alone or in combination with a mix of pollutants)on the health of Physalaemus cuvieri tadpoles.After 30 days of exposure,multiple biomarkers were measured,including morphological,biometric,and developmental indices,behavioral parameters,mutagenicity,cytotoxicity,antioxidant and cholinesterase responses,as well as the uptake and accumulation of PE-MPs in animals.Based on the results,there was no significant change in any of the parameters measured in tadpoles exposed to treatments,but induced stress was observed in tadpoles exposed to PE-MPs combined with themixture of pollutants,reflecting significant changes in physiological and biochemical responses.Through principal component analysis(PCA)and integrated biomarker response(IBR)assessment,effects induced by pollutants in each test group were distinguished,confirming that the exposure of P.cuvieri tadpoles to the PE-MPs in combination with a mix of emerging pollutants induces an enhanced stress response,although the uptake and accumulation of PE-MPs in these animalswas reduced.Thus,our study provides newinsight into the danger to amphibians of MPs coexisting with other pollutants in aquatic environments.展开更多
The study investigated the genetic variation of Parachanna obscura from five rivers(Anambra,Ibbi,Imo,Katsina-Ala and Ogun)in Nigeria using the mitochondrial cytochrome oxidase 1 gene.DNA was extracted from 19,22,16,18...The study investigated the genetic variation of Parachanna obscura from five rivers(Anambra,Ibbi,Imo,Katsina-Ala and Ogun)in Nigeria using the mitochondrial cytochrome oxidase 1 gene.DNA was extracted from 19,22,16,18 and 21 fin clips per river population,respectively and subjected to polymerase chain reaction.A total of 96 sequences,each with 671 bp were obtained with 38(5.6%)polymorphic,27(3.8%)parsimoniously informative and 659(98.2%)conserved sites.Mean nucleotide composition was C=28.07%,T=29.43%,A=22.18%,G=20.32%.A total of 40 haplotypes with 38 unique sequences as well as 24 substitutions with 22 transversions and two transitions were obtained.Nucleotide diversity among populations ranged from 0.00184 to 0.00888 representing Ibbi and Imo,respectively while haplotype diversity ranged from 0.77056 to 0.95000 also,from Ibbi and Imo,respectively.Analyses of molecular variance showed that the intra-population variation accounted for 50.05%.Topology from phylogenetic analyses revealed that P.obscura from Imo River was distinctly different from the rest.展开更多
The lower Mississippi River(LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that incl...The lower Mississippi River(LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to "notch" wing-dike structures that close secondary(side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer(rkm) 628(Louisiana-Mississippi, U.S.A.) upstream to rkm 1504(Missouri-Kentucky, U.S.A.). Four secondary channels were termed "permanent"(i.e.,with notched dikes) while three secondary channels were termed "temporary"(i.e., without notched dikes).Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad(Dorosoma cepedianum), threadfin shad(D. petenense), and white bass(Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish(Ictalurus furcatus), flathead catfish(Pylodictis olivaris), and freshwater drum(Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However展开更多
基金supporting the financing of this study(Process#307743/2018–7)the granting of research productivity grants to Dr.Malafaia G.(Proc.#307743/2018–7)and Dr.Melo e Silva D.(Process#307652/2018-1)+1 种基金for the scientific initiation scholarships to students Silva A.M.and Luz T.M.In addition,the authors thank the Federal Institute of Goiano(GO,Brazil)granting important financial assistance for the publication of this study(Proc.#23219.000139.2022-17).
文摘Studies in recent years have shown that aquatic pollution by microplastics(MPs)can be considered to pose additional stress to amphibian populations.However,our knowledge of how MPs affect amphibians is very rudimentary,and even more limited is our understanding of their effects in combination with other emerging pollutants.Thus,we aimed to evaluate the possible toxicity of polyethylene MPs(PE-MPs)(alone or in combination with a mix of pollutants)on the health of Physalaemus cuvieri tadpoles.After 30 days of exposure,multiple biomarkers were measured,including morphological,biometric,and developmental indices,behavioral parameters,mutagenicity,cytotoxicity,antioxidant and cholinesterase responses,as well as the uptake and accumulation of PE-MPs in animals.Based on the results,there was no significant change in any of the parameters measured in tadpoles exposed to treatments,but induced stress was observed in tadpoles exposed to PE-MPs combined with themixture of pollutants,reflecting significant changes in physiological and biochemical responses.Through principal component analysis(PCA)and integrated biomarker response(IBR)assessment,effects induced by pollutants in each test group were distinguished,confirming that the exposure of P.cuvieri tadpoles to the PE-MPs in combination with a mix of emerging pollutants induces an enhanced stress response,although the uptake and accumulation of PE-MPs in these animalswas reduced.Thus,our study provides newinsight into the danger to amphibians of MPs coexisting with other pollutants in aquatic environments.
基金The authors appreciate the International Foundation for Science(IFS),Stockholm,Sweden for funding this research through their Grant Number I-2-A-6090-1 provided to Friday Elijah Osho to study the phenotypic and genetic characterization of Parachanna obscura from Nigeria’s freshwater environments.
文摘The study investigated the genetic variation of Parachanna obscura from five rivers(Anambra,Ibbi,Imo,Katsina-Ala and Ogun)in Nigeria using the mitochondrial cytochrome oxidase 1 gene.DNA was extracted from 19,22,16,18 and 21 fin clips per river population,respectively and subjected to polymerase chain reaction.A total of 96 sequences,each with 671 bp were obtained with 38(5.6%)polymorphic,27(3.8%)parsimoniously informative and 659(98.2%)conserved sites.Mean nucleotide composition was C=28.07%,T=29.43%,A=22.18%,G=20.32%.A total of 40 haplotypes with 38 unique sequences as well as 24 substitutions with 22 transversions and two transitions were obtained.Nucleotide diversity among populations ranged from 0.00184 to 0.00888 representing Ibbi and Imo,respectively while haplotype diversity ranged from 0.77056 to 0.95000 also,from Ibbi and Imo,respectively.Analyses of molecular variance showed that the intra-population variation accounted for 50.05%.Topology from phylogenetic analyses revealed that P.obscura from Imo River was distinctly different from the rest.
基金Supported by the Financial from the U.S.Army Corps of Engineers-Lower Mississippi Valley Division,Vicksburg,Mississippi,U.S.A.
文摘The lower Mississippi River(LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to "notch" wing-dike structures that close secondary(side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer(rkm) 628(Louisiana-Mississippi, U.S.A.) upstream to rkm 1504(Missouri-Kentucky, U.S.A.). Four secondary channels were termed "permanent"(i.e.,with notched dikes) while three secondary channels were termed "temporary"(i.e., without notched dikes).Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad(Dorosoma cepedianum), threadfin shad(D. petenense), and white bass(Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish(Ictalurus furcatus), flathead catfish(Pylodictis olivaris), and freshwater drum(Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However
