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  Subjects -> BIOLOGY (Total: 3237 journals)
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    - BIOLOGY (1548 journals)
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BIOLOGY (1548 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 25)
Achievements in the Life Sciences     Open Access   (Followers: 5)
ACS Synthetic Biology     Hybrid Journal   (Followers: 25)
Acta Biologica Colombiana     Open Access   (Followers: 7)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Biologica Sibirica     Open Access   (Followers: 2)
Acta Biologica Turcica     Open Access  
Acta Biologica Venezuelica     Open Access  
Acta Biomaterialia     Hybrid Journal   (Followers: 28)
Acta Biotheoretica     Hybrid Journal   (Followers: 4)
Acta Chiropterologica     Full-text available via subscription   (Followers: 6)
acta ethologica     Hybrid Journal   (Followers: 4)
Acta Fytotechnica et Zootechnica     Open Access   (Followers: 1)
Acta Limnologica Brasiliensia     Open Access   (Followers: 3)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Musei Silesiae, Scientiae Naturales     Open Access  
Acta Neurobiologiae Experimentalis     Open Access  
Acta Parasitologica     Hybrid Journal   (Followers: 11)
Acta Scientiarum. Biological Sciences     Open Access   (Followers: 2)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis     Open Access   (Followers: 1)
Actualidades Biológicas     Open Access   (Followers: 1)
Advanced Health Care Technologies     Open Access   (Followers: 4)
Advanced Journal of Graduate Research     Open Access  
Advanced Nonlinear Studies     Hybrid Journal  
Advanced Studies in Biology     Open Access  
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Bioinformatics     Open Access   (Followers: 17)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4)
Advances in Biology     Open Access   (Followers: 10)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 7)
Advances in Cell Biology/ Medical Journal of Cell Biology     Open Access   (Followers: 27)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 13)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Ecological Research     Full-text available via subscription   (Followers: 43)
Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 16)
Advances in Enzyme Research     Open Access   (Followers: 11)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Genome Biology     Full-text available via subscription   (Followers: 10)
Advances in High Energy Physics     Open Access   (Followers: 19)
Advances in Human Biology     Open Access   (Followers: 4)
Advances in Life Science and Technology     Open Access   (Followers: 18)
Advances in Life Sciences     Open Access   (Followers: 6)
Advances in Marine Biology     Full-text available via subscription   (Followers: 18)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 23)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3)
Advances in Regenerative Biology     Open Access   (Followers: 1)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Tropical Biodiversity and Environmental Sciences     Open Access  
Advances in Virus Research     Full-text available via subscription   (Followers: 5)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 8)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 1)
Ageing Research Reviews     Hybrid Journal   (Followers: 11)
Aging Cell     Open Access   (Followers: 24)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
AJP Cell Physiology     Hybrid Journal   (Followers: 18)
AJP Endocrinology and Metabolism     Hybrid Journal   (Followers: 24)
AJP Lung Cellular and Molecular Physiology     Hybrid Journal   (Followers: 3)
Al-Kauniyah : Jurnal Biologi     Open Access  
Alasbimn Journal     Open Access   (Followers: 1)
Alces : A Journal Devoted to the Biology and Management of Moose     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Fern Journal     Full-text available via subscription   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 8)
American Journal of Bioethics     Hybrid Journal   (Followers: 13)
American Journal of Human Biology     Hybrid Journal   (Followers: 15)
American Journal of Medical and Biological Research     Open Access   (Followers: 8)
American Journal of Plant Sciences     Open Access   (Followers: 19)
American Journal of Primatology     Hybrid Journal   (Followers: 16)
American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 76)
Amphibia-Reptilia     Hybrid Journal   (Followers: 6)
Anadol University Journal of Science and Technology B : Theoritical Sciences     Open Access  
Anadolu University Journal of Science and Technology : C Life Sciences and Biotechnology     Open Access  
Anaerobe     Hybrid Journal   (Followers: 4)
Analytical Methods     Full-text available via subscription   (Followers: 12)
Anatomical Science International     Hybrid Journal   (Followers: 3)
Animal Cells and Systems     Hybrid Journal   (Followers: 4)
Animal Models and Experimental Medicine     Open Access  
Annales de Limnologie - International Journal of Limnology     Hybrid Journal   (Followers: 1)
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales Universitatis Mariae Curie-Sklodowska, sectio C – Biologia     Open Access   (Followers: 1)
Annals of Applied Biology     Hybrid Journal   (Followers: 7)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 17)
Annals of Human Biology     Hybrid Journal   (Followers: 5)
Annals of Science and Technology     Open Access  
Annual Review of Biomedical Engineering     Full-text available via subscription   (Followers: 13)
Annual Review of Biophysics     Full-text available via subscription   (Followers: 24)
Annual Review of Cancer Biology     Full-text available via subscription   (Followers: 1)
Annual Review of Cell and Developmental Biology     Full-text available via subscription   (Followers: 38)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 24)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 13)
Anthropological Review     Open Access   (Followers: 23)
Antibiotics     Open Access   (Followers: 9)
Antioxidants     Open Access   (Followers: 4)
Antioxidants & Redox Signaling     Hybrid Journal   (Followers: 9)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apidologie     Hybrid Journal   (Followers: 4)
Apmis     Hybrid Journal   (Followers: 1)
APOPTOSIS     Hybrid Journal   (Followers: 9)
Applied Biology     Open Access  
Applied Bionics and Biomechanics     Open Access   (Followers: 7)
Applied Vegetation Science     Full-text available via subscription   (Followers: 10)
Aquaculture Environment Interactions     Open Access   (Followers: 4)
Aquaculture International     Hybrid Journal   (Followers: 26)
Aquaculture Reports     Open Access   (Followers: 3)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 7)
Aquatic Biology     Open Access   (Followers: 6)
Aquatic Ecology     Hybrid Journal   (Followers: 37)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 15)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 23)
Archaea     Open Access   (Followers: 3)
Archiv für Molluskenkunde: International Journal of Malacology     Full-text available via subscription   (Followers: 3)
Archives of Biological Sciences     Open Access  
Archives of Microbiology     Hybrid Journal   (Followers: 9)
Archives of Natural History     Hybrid Journal   (Followers: 7)
Archives of Oral Biology     Hybrid Journal   (Followers: 3)
Archives of Virology     Hybrid Journal   (Followers: 5)
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2)
Arid Ecosystems     Hybrid Journal   (Followers: 2)
Arquivos do Instituto Biológico     Open Access   (Followers: 1)
Arquivos do Museu Dinâmico Interdisciplinar     Open Access  
Arthropod Structure & Development     Hybrid Journal   (Followers: 2)
Arthropods     Open Access   (Followers: 1)
Artificial DNA: PNA & XNA     Hybrid Journal   (Followers: 3)
Asian Bioethics Review     Full-text available via subscription   (Followers: 3)
Asian Journal of Biodiversity     Open Access   (Followers: 4)
Asian Journal of Biological Sciences     Open Access   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 5)
Asian Journal of Developmental Biology     Open Access   (Followers: 2)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 4)
Asian Journal of Nematology     Open Access   (Followers: 4)
Asian Journal of Poultry Science     Open Access   (Followers: 4)
Atti della Accademia Peloritana dei Pericolanti - Classe di Scienze Medico-Biologiche     Open Access  
Australian Life Scientist     Full-text available via subscription   (Followers: 2)
Australian Mammalogy     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 4)
Avian Biology Research     Full-text available via subscription   (Followers: 4)
Avian Conservation and Ecology     Open Access   (Followers: 10)
Bacteriology Journal     Open Access   (Followers: 1)
Bacteriophage     Full-text available via subscription   (Followers: 3)
Bangladesh Journal of Bioethics     Open Access  
Bangladesh Journal of Plant Taxonomy     Open Access  
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Batman Üniversitesi Yaşam Bilimleri Dergisi     Open Access  
Berita Biologi     Open Access   (Followers: 1)
Between the Species     Open Access   (Followers: 1)
Bio Tribune Magazine     Hybrid Journal  
BIO Web of Conferences     Open Access  
BIO-Complexity     Open Access  
Bio-Grafía. Escritos sobre la Biología y su enseñanza     Open Access  
Bio-Lectura     Open Access  
Bioanalytical Reviews     Hybrid Journal   (Followers: 2)
Biocatalysis and Biotransformation     Hybrid Journal   (Followers: 6)
BioCentury Innovations     Full-text available via subscription   (Followers: 1)
Biochemistry and Cell Biology     Hybrid Journal   (Followers: 16)
Biochimie     Hybrid Journal   (Followers: 6)
BioControl     Hybrid Journal   (Followers: 6)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 6)
Biodemography and Social Biology     Hybrid Journal  
BioDiscovery     Open Access   (Followers: 2)
Biodiversidade e Conservação Marinha : Revista CEPSUL     Open Access  
Biodiversitas : Journal of Biological Diversity     Open Access  
Biodiversity Data Journal     Open Access   (Followers: 4)
Biodiversity Informatics     Open Access   (Followers: 1)
Biodiversity Information Science and Standards     Open Access   (Followers: 1)
Biodiversity: Research and Conservation     Open Access   (Followers: 27)
Bioedukasi : Jurnal Pendidikan Biologi FKIP UM Metro     Open Access  
Bioeksperimen : Jurnal Penelitian Biologi     Open Access  
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Bioelectromagnetics     Hybrid Journal   (Followers: 1)
Bioenergy Research     Hybrid Journal   (Followers: 3)
Bioengineering and Bioscience     Open Access   (Followers: 1)
BioEssays     Hybrid Journal   (Followers: 10)
Bioethics     Hybrid Journal   (Followers: 15)
BioéthiqueOnline     Open Access  
Biofabrication     Hybrid Journal   (Followers: 5)
Biofilms     Full-text available via subscription   (Followers: 1)
Biogeosciences (BG)     Open Access   (Followers: 9)
Biogeosciences Discussions (BGD)     Open Access   (Followers: 2)
Bioinformatics     Hybrid Journal   (Followers: 345)
Bioinformatics and Biology Insights     Open Access   (Followers: 11)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 7)
Biointerphases     Open Access   (Followers: 1)
Biojournal of Science and Technology     Open Access  
BioLink : Jurnal Biologi Lingkungan, Industri, Kesehatan     Open Access   (Followers: 1)
Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 6)
Biological Control     Hybrid Journal   (Followers: 5)
Biological Invasions     Hybrid Journal   (Followers: 22)

        1 2 3 4 5 6 7 8 | Last

Similar Journals
Journal Cover
Aquatic Toxicology
Journal Prestige (SJR): 1.456
Citation Impact (citeScore): 4
Number of Followers: 23  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0166-445X - ISSN (Online) 1879-1514
Published by Elsevier Homepage  [3160 journals]
  • Effects of Corexit 9500A alone and Corexit-crude oil mixtures on
           transcriptomic pathways and developmental toxicity in early life stage
           mahi-mahi (Coryphaena hippurus)
    • Abstract: Publication date: Available online 23 May 2019Source: Aquatic ToxicologyAuthor(s): Justin B. Greer, Christina Pasparakis, John D. Stieglitz, Daniel Benetti, Martin Grosell, Daniel Schlenk Crude oil and polycyclic aromatic hydrocarbon (PAH) exposure in early life stage fish has been well-characterized to induce phenotypic malformations such as altered heart development and other morphological impacts. The effects of chemical oil dispersants on toxicity are more controversial. To better understand how chemical dispersion of oil can impact toxicity in pelagic fish, embryos of mahi-mahi (Coryphaena hippurus) were exposed to three concentrations of the chemical dispersant Corexit 9500A, or Corexit 9500A-oil mixtures (chemically enhanced water accommodated fractions: CEWAF) of Deepwater Horizon crude oil for 48 hours. RNA sequencing, gene ontology enrichment, and phenotypic measurements were conducted to assess toxicity. Exposure to Corexit 9500A altered expression of less than 50 genes at all concentrations (2.5, 5, and 10 mg/L nominal concentration) and did not induce acute mortality or phenotypic malformations, corroborating other studies showing minimal effects of Corexit 9500A on developing mahi-mahi embryos. CEWAF preparations contained environmentally relevant ∑PAH concentrations ranging from 1.4-3.1 μg/L and similarly did not alter larval morphology. Differentially expressed genes and significantly altered pathways related to cardiotoxicity, visual impairments, and Ca2+ homeostasis reinforced previous work that expression of genes associated with the heart and eye are highly sensitive molecular endpoints in oil-exposed early life stage fish. Differential expression and gene ontology pathways were similar across the three CEWAF treatments, indicating that increased chemical dispersion did not alter molecular outcomes within the range tested here. In addition, significant sublethal molecular responses occurred in the absence of observable phenotypic changes to the heart, indicating that effects of oil on early life stage fish may not be completely dependent on cardiac function.
       
  • Combined effects of toxic Microcystis aeruginosa and hypoxia on the
           digestive enzyme activities of the triangle sail mussel Hyriopsis cumingii
           
    • Abstract: Publication date: Available online 22 May 2019Source: Aquatic ToxicologyAuthor(s): Huaxin Gu, Menghong Hu, Shuaishuai Wei, Hui Kong, Xizhi Huang, Yongbo Bao, Youji Wang Nowadays, eutrophication is a very common environmental problem in numerous waters around the world. The main reason of eutrophication is the enrichment with nutrients, which results in the excessive growth of prokaryotes and algae and some of them are toxic and harmful. Fortunately, some studies have shown that some bivalves can filter the overgrown phytoplankton in water, which may alleviate water eutrophication. However, the physiological effects of toxic blue-green algae (cyanobacteria) on filter feeding animal have not been clarified very well. In this experiment, digestive enzyme activities in Hyriopsis cumingii exposed to different concentrations of the toxic Microcystis aeruginosa (0, 5 * 105 and 5 *106 cell ml-1) at two dissolved oxygen (DO) levels (6 and 2 mg l-1) for 14 days were investigated. Toxic M. aeruginosa significantly affected all digestive enzyme activities throughout the experiment. At high toxic M. aeruginosa concentration, the activities of cellulase, amylase and lipase in digestive gland and stomach were significantly increased (P 
       
  • Assessment of the cytotoxic impact of cyanotoxin
           beta-N-methylamino-L-alanine on a fish immune cell line
    • Abstract: Publication date: Available online 20 May 2019Source: Aquatic ToxicologyAuthor(s): Anna Sieroslawska, Anna Rymuszka Beta-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid produced by several cyanobacteria species. It is considered to be a potent neurotoxin. Although its neurotoxic effects are well studied, other negative effects of BMAA have not yet been completely elucidated. In the present study, we studied the cytotoxic effects of a wide range of concentrations of BMAA (0.25–2.0 mM) on a stable fish immune cell line (CLC) obtained from carp monocytes. The cells exposed to higher concentrations of BMAA exhibited an altered morphology, changed ATP levels, and reduced proliferation. On the basis of toxic effects of BMAA on lysosomes, mitochondrial dehydrogenases activity, and cell membrane integrity, we determined its cytotoxic concentrations. We also investigated effects of the toxin at non-cytotoxic concentrations on the basic functions of CLC cells. BMAA did not affect the production and release of IL-1β or phagocytic activity of the cells. However, higher non-toxic BMAA concentrations altered the levels of extracellular and intracellular total proteins compared to those in control cells.
       
  • Additive bioenergetic responses to a pesticide and predation risk in an
           aquatic insect
    • Abstract: Publication date: Available online 18 May 2019Source: Aquatic ToxicologyAuthor(s): Marie Van Dievel, Lizanne Janssens, Robby Stoks Ignoring natural stressors such as predation risk may contribute to the failure of ecological risk assessment of pesticides to protect freshwater biodiversity. To better understand combined effects of multiple stressors, bioenergetic responses are important as these inform about the balance between energy input and consumption, and provide a unifying mechanism to integrate the impact of multiple stressors with different modes of action. We studied in Enallagma cyathigerum damselfly larvae the single and combined effects of exposure to the pesticide chlorpyrifos and predation risk on life history (survival and growth rate) and bioenergetic response variables at the organismal level (assimilation and conversion efficiency) and the cellular level (cellular energy allocation CEA, energy storage Ea, and energy consumption Ec). Chlorpyrifos exposure almost halved the survival of the damselfly larvae, while predation risk had no effect on survival. Both exposure to the pesticide and to predation risk reduced larval growth rates. This was caused by a reduced conversion efficiency under chlorpyrifos exposure, and by a reduced assimilation efficiency under predation risk. Both chlorpyrifos and predation risk reduced the CEA because of a decreased Ea, and for chlorpyrifos also an increased Ec. The lower Ea was driven by reductions in the fat and glycogen contents. Effects of the pesticide and predation risk were consistently additive and for most variables the strongest response was detected when both stressors were present. The absence of any synergisms may be explained by the high mortality and hypometabolism caused by the pesticide. Our results indicate that CEA can be a sensitive biomarker to evaluate effects of not only contaminants but also natural stressors, such as predation risk, and their combined impact on organisms.
       
  • Ecotoxicological QSAR modeling of organic compounds against fish:
           Application of fragment based descriptors in feature analysis
    • Abstract: Publication date: Available online 17 May 2019Source: Aquatic ToxicologyAuthor(s): Kabiruddin Khan, Diego Baderna, Claudia Cappelli, Cosimo Toma, Anna Lombardo, Kunal Roy, Emilio Benfenati Organic compounds (OCs) constitute an enormously large class of highly persistent and toxic chemicals widely used for various purposes throughout the world. Their increased detection in water bodies, mainly sewage treatment plants via industrial discharge, has rendered them to become a cause for ecological concern. The limited availability of experimental toxicological data has necessitated development of models that can help us identify the most hazardous and potentially toxic compounds thus prioritizing the experiments on the selected chemicals. Computational tools such as quantitative structure-activity relationship (QSAR) can be used to predict the missing data and classify the chemicals based on their acute predicted responses for existing as well as not yet synthesized chemicals. In the current study, novel, externally validated, highly robust local QSAR models for different chemical classes and moderately robust global QSAR models were developed using partial least squares (PLS) regression technique using a large dataset of 1121 OCs for the fish mortality endpoint. For feature selection, genetic algorithm along with stepwise regression was used while model validation was performed using various stringent validation criteria following the strict rules of OECD guidelines of QSAR validation. The variables included in the models were obtained from simplex representation of molecular structures (SiRMS) (Version 4.1.2.270), Dragon (Version 7.0) and PaDEL-descriptor software (Version 2.20). The final developed models were robust, externally predictive and characterized by a large chemical as well as biological domain. The predictive efficiency of the developed models was then compared with the ECOSAR tool in order to justify the applicability of the developed models in ecotoxicological predictions for organic chemicals. Better predictive efficiency of the developed QSAR models compared to the ECOSAR derived predictions signifies their applicability in early risk assessment of known as well as untested chemicals in order to design safer alternatives to the environment.Graphical abstractGraphical abstract for this article
       
  • Interactive effects of 3,4-DCA and temperature on the annual killifish
           Nothobranchius furzeri
    • Abstract: Publication date: Available online 16 May 2019Source: Aquatic ToxicologyAuthor(s): Charlotte Philippe, Pauline Hautekiet, Arnout F. Grégoir, Eli S.J. Thoré, Luc Brendonck, Gudrun De Boeck, Tom Pinceel Although aquatic organisms are increasingly exposed to pollutants and abnormally high temperatures as a consequence of climate change, interactive effects between those stressors remain poorly assessed. Especially in ectotherms, such as fish, increases in ambient temperature are expected to affect fitness-related traits and physiology. We used the turquoise killifish Nothobranchius furzeri to study the effects of a range of 3,4-dichloroaniline concentrations (0, 50, 100 µg/L) in combination with two temperature conditions (control and control +4 °C) during four months of exposure. As part of an integrated multi-level approach, we quantified effects on classic life history traits (size, maturation time, body mass, fecundity), critical thermal maximum and physiology (energy reserves and stress-associated enzymatic activity). While no interactive effects of 3,4-DCA exposure and increased temperature emerged, our results do show a negative effect of 3,4-DCA on thermal tolerance. This finding is of particular relevance in light of increasing temperatures under climate change. Due to increases in pest species and faster degradation of 3,4-DCA under higher temperatures, increased use of the pesticide is expected under climate change which, in turn, could result in a decreased tolerance of aquatic organisms to high temperatures.
       
  • Impact and tissue metabolism of nitrite at two acclimation temperatures in
           striped catfish (Pangasianodon hypophthalmus)
    • Abstract: Publication date: Available online 16 May 2019Source: Aquatic ToxicologyAuthor(s): Thi Kim Ha Nguyen, Thi Thanh Huong Do, Thanh Phuong Nguyen, Bayley Mark, Bo Jensen Frank Elevated concentrations of nitrite develop occasionally in various aquatic habitats and aquaculture facilities, providing a potential danger for freshwater fish that take up nitrite via the gill chloride uptake mechanism. We studied the uptake, effects and metabolism of nitrite in blood, heart and skeletal muscle at two temperatures in striped catfish Pangasianodon hypophthalmus, a facultative air-breathing fish that is heavily cultivated in Southeast Asia. Exposure to 0.8 mM ambient nitrite increased blood [nitrite] and [methaemoglobin] (metHb) to high values at day 1, but values subsequently decreased towards controls at day 7. Blood [nitrite] and metHb content were unexpectedly higher at 27 °C (˜1.2 mM; 69% at day 1) than at 33 °C (˜0.9 mM; 55%), reflecting a lower nitrite uptake at the highest temperature, possibly via an increased reliance on air-breathing relative to water-breathing with temperature increase. A large fraction of the nitrite taken up was effectively eliminated by being detoxified to nitrate. Further, erythrocyte metHb reductase activity was increased during nitrite exposure, efficiently reducing metHb to functional haemoglobin. The uptake of nitrite into white skeletal musculature (main part of the fish) was much lower than into heart tissue. While heart [nitrite] was close to blood plasma levels, muscle [nitrite] peaked at ˜0.2 mM at day 1 and subsequently declined to ˜0.05 mM at day 7, which is below levels reported in various commercial cured meat products. Nitrite was partly metabolized to iron-nitrosyl, S-nitroso and N-nitroso compounds. The increase in nitros(yl)ated compounds was marginal in skeletal muscle and more pronounced in heart tissue.
       
  • Effects of ocean acidification on life parameters and antioxidant system
           in the marine copepod Tigriopus japonicus
    • Abstract: Publication date: Available online 15 May 2019Source: Aquatic ToxicologyAuthor(s): Young Hwan Lee, Hye-Min Kang, Min-Sub Kim, Minghua Wang, Jeong Ha Kim, Chang-Bum Jeong, Jae-Seong Lee Ocean acidification (OA) is caused by alteration of global ocean carbon chemistry due to the increased pCO2 in the atmosphere and caused deleterious impacts on the marine ecosystem. Although various detrimental effects of OA were reported in marine organisms, the potential impact of OA on aquatic invertebrates still remains largely unknown. Here, we examined changes in life parameters and antioxidant system in response to low pH (7.5 and 7) in the marine copepod Tigriopus japonicus. Exposures to lower pHs (pH 7.5 and 7.0) of copepods resulted in lengthening of the developmental time with decreased fecundity and body length. Also, they showed increased reactive oxygen species contents with enhanced glutathione S-transferase and glutathione reductase activities but decreased glutathione peroxidase and superoxide dismutase activities in pH-dependent manner, indicating that OA exposure caused disturbance of the redox system in T. japonicus. Among several oxidative stress-related genes, GSTs2b was significantly up-regulated in response to OA. These findings will be helpful for a better understanding on the potential impact of OA on life parameters and antioxidant system in the marine copepod T. japonicus.
       
  • Assessing interactions between environmental factors and aquatic toxicity:
           influences of dissolved CO2 and light on Cd toxicity in the aquatic
           macrophyte Potamogeton crispus
    • Abstract: Publication date: Available online 13 May 2019Source: Aquatic ToxicologyAuthor(s): Wenmin Huang, Shijuan Han, Qin Zhou, Wei Li, Wei Xing The objective of this study was to investigate the combined effects of varying dissolved CO2 concentration (ambient CO2, 3˜17 µmol L-1, elevated CO2, 48˜81 µmol L-1) and light intensity (high light, c. 150 µmol photon m-2 s-1, low light, c. 25 µmol photon m-2 s-1) on the bioaccumulation and phytotoxicity of cadmium (Cd) in a macrophyte Potamogeton crispus, under constant Cd exposure. The data confirmed that 100 µM Cd led to adverse changes in morphology, ultrastructure and biochemistry in P. crispus. The toxic effects depended strongly on CO2 concentration and light intensity: elevated CO2 and high light both increased Cd concentrations in P. crispus, and there was a significant interaction between the two factors. Compared to high light grown plants, the photochemical efficiency and chlorophyll content of low light grown P. crispus were much less affected and the MDA content was lower, when exposed to 100 µM Cd. In addition, an antioxidative response was observed with a significant increase in SOD, POD and GST activities, indicating that low light grown P. crispus are more protected against Cd toxicity. When compared with ambient CO2 concentrations, chlorophyll content, chlorophyll fluorescence, photosynthetic rate and starch content, as well as the activity of SOD and GST, were significantly enhanced in Cd treated P. crispus under elevated CO2. This suggests that elevated CO2 reduced Cd toxicity in P. crispus by increasing photosynthesis and enhancing the antioxidant system. Moreover, the statistical results showed that dissolved CO2 and light had additive effects on Cd toxicity in P. crispus, reflected by the physiological parameters of total chlorophyll content, SOD activity and MDA content, indicating that the combination of high CO2 and low light produced more protection against Cd toxicity than did the factors alone. Based on the results of this study, it appears clear that referring to a specific site in aquatic ecosystem, dissolved CO2 concentration and light availability should be considered when assessing and managing Cd impacts on aquatic plants.
       
  • Ocean acidification buffers the physiological responses of the king
           ragworm Alitta virens to the common pollutant copper
    • Abstract: Publication date: Available online 10 May 2019Source: Aquatic ToxicologyAuthor(s): Clara Nielson, Cameron Hird, Ceri Lewis Ocean acidification (OA) has the potential to alter the bioavailability of pH sensitive metals contaminating coastal sediments, particularly copper, by changing their speciation in seawater. Hence OA may drive increased toxicity of these metals to coastal biota. Here, we demonstrate complex interactions between OA and copper on the physiology and toxicity responses of the sediment dwelling polychaete Alitta virens. Worm coelomic fluid pCO2 was not increased by exposure to OA conditions (pHNBS 7.77, pCO2 530 μatm) for 14 days, suggesting either physiological or behavioural responses to control coelomic fluid pCO2. Exposure to 0.25 µM nominal copper caused a decrease in coelomic fluid pCO2 by 43.3% and bicarbonate ions by 44.6% but paradoxically this copper-induced effect was reduced under near-future OA conditions. Hence OA appeared to ‘buffer’ the copper-induced acid-base disturbance. DNA damage was significantly increased in worms exposed to copper under ambient pCO2 conditions, rising by 11.1% compared to the worms in the no copper control, but there was no effect of OA conditions on the level of DNA damage induced by copper when exposed in combination. These interactions differ from the increased copper toxicity under OA conditions reported for several other invertebrate species. Hence this new evidence adds to the developing paradigm that species’ physiology is key in determining the interactions of these two stressors rather than it purely being driven by the changes in metal chemistry under lower seawater pH.
       
  • Combined effects of erythromycin and enrofloxacin on antioxidant enzymes
           and photosynthesis-related gene transcription in Chlorella vulgaris
    • Abstract: Publication date: Available online 9 May 2019Source: Aquatic ToxicologyAuthor(s): Guixiang Wang, Qiong Zhang, Jialiang Li, Xiangyan Chen, Qiaolin Lang, Shaoping Kuang Multiple antibiotics are simultaneously detected in aquatic environment, so it is extremely important to study the combined effects of their mixtures. In this study, we investigated the toxic effects of erythromycin (ERY) and enrofloxacin (ENR), added individually or in combination, on Chlorella vulgaris and explored the toxic mechanisms. Results showed that the 96 h-EC50 values of ERY, ENR and ERY-ENR mixture to C. vulgaris were 85.7, 124.5 and 39.9 μg L-1 respectively, and combined toxicity assessment found that joint effect of the two antibiotics was synergism, which was proven by the chlorophyll content in algae. Antioxidant defense system and photosynthesis were involved in toxic mechanisms and the results revealed that both the activities of antioxidant enzymes, and the malondialdehyde (MDA) and glutathione (GSH) contents increased in antibiotic treatments. In addition, the increase was more significant in joint exposure treatment, which implied that the antioxidant defense system was synergistically affected. RT-PCR showed that ERY and ENR upregulated the transcript abundance of psaB, psbC and chlB at low concentrations and the transcription abundance was synergistically increased in combined treatment. Therefore, the risk of the toxicity of antibiotics to aquatic organisms in real environment both at organismal and molecular level increases as a result of their combined presence.
       
  • Parental Gemfibrozil Exposure Impacts Zebrafish F1 Offspring, But Not
           Subsequent Generations
    • Abstract: Publication date: Available online 9 May 2019Source: Aquatic ToxicologyAuthor(s): Shamaila Fraz, Abigail H. Lee, Simon Pollard, Krishna Srinivasan, Abhilasha Vermani, Joanna Y. Wilson Gemfibrozil (GEM) is a fibrate lipid regulator and one of the most commonly occurring fresh water pharmaceuticals. The negative effects of fibrates including GEM on fish reproduction have been frequently reported including effects of F0 GEM exposure on reproduction of the unexposed F1 offspring. We predicted that chronic, direct exposure of zebrafish with low concentrations of GEM would adversely affect parental male reproduction and unexposed offspring for multiple generations. Adult zebrafish were exposed to 10 μg/L GEM for 6 weeks and a range of reproductive indices were analyzed. The F1–F4 offspring were reared in clean water from 3 distinct lineages where only a single or both parents were exposed and compared to a control lineage where parents were unexposed. Reproductive indices were examined in unexposed F1–F4 offspring to test the hypothesis of multi- or trans- generational impacts. Exposure to GEM caused a decline in breeding success and mean embryo production in F0 parents and a reduction in whole body 11-ketotestosterone (11-KT), altered male courtship, aggression and sperm morphology. Our results indicate that paternal exposure alone is sufficient to result in reproductive effects in unexposed male offspring but that effects are mostly limited to F1. We suggest that GEM may act as a reproductive endocrine disruptor in fish and that chronic exposure reduced male reproductive fitness but not over multiple generations.
       
  • Hypoxia and Reduced Salinity Exacerbate the Effects of Oil Exposure on
           Sheepshead Minnow (Cyprinodon variegatus) Reproduction
    • Abstract: Publication date: Available online 9 May 2019Source: Aquatic ToxicologyAuthor(s): Lindsay Jasperse, Milton Levin, Kara Rogers, Christopher Perkins, Thijs Bosker, Robert J. Griffitt, Marisol Sepúlveda, Sylvain De Guise Estuaries of the northern Gulf of Mexico are dynamic environments, with fluctuations in salinity and dissolved oxygen, including areas of seasonal hypoxia. Fish that reside and reproduce in these estuaries, including sheepshead minnow (Cyprinodon variegatus; SHM), were at significant risk of oil exposure following the Deepwater Horizon oil spill incident. It is poorly understood how differences in environmental conditions during oil exposure impact its toxicity. The present study investigated the effects of crude oil high-energy water accommodated fraction (HEWAF) on SHM reproduction in three environmental scenarios (normoxic (NORM), hypoxic (HYP), and hypoxic with low salinity (HYP-LS)) to determine if differences in salinity (brackish vs low salinity) and dissolved oxygen (normoxia vs hypoxia) could exacerbate the effects of HEWAF-derived polycyclic aromatic hydrocarbons (PAHs). We observed that HEWAF exposure significantly increased liver somatic index of SHM compared to control, but this effect was not exacerbated by hypoxia or low salinity. HEWAF exposure also significantly decreased egg production and egg fertilization rate, and the HYP and HYP-LS scenarios exacerbated these effects. A significant correlation existed between body burdens of PAHs and reproductive endpoints, providing substantial evidence that oil exposure reduced reproductive capacity in SHM, across a range of environmental conditions. These data suggest that oil spill risk assessments that fail to consider other environmental stressors (i.e. hypoxia and salinity) may be underestimating risk.
       
  • The dynamic changes of arsenic bioaccumulation and antioxidant responses
           in the marine medaka Oryzias melastigma during chronic exposure
    • Abstract: Publication date: Available online 7 May 2019Source: Aquatic ToxicologyAuthor(s): Lizhao Chen, Dongdong Song, Wei Zhang, Canchuan Zhang, Li Zhang Arsenic (As) is a highly toxic metalloid to aquatic organisms, but the effects of low-dose chronic inorganic As exposure on marine fish are still unclear. A 28-day study was conducted on chronic exposure of 100 µg/L inorganic As [As(III) and As(V)] in the marine medaka Oryzias melastigma to quantify the effects of chronic inorganic As exposure on its bioaccumulation, biotransformation, oxidative stress, and antioxidant enzymes response. During the exposure period, chronic inorganic As exposure had no significant effect on the total As bioaccumulation except at 7 d for As(V) treatment. Based on the toxicokinetic data, the low As bioaccumulation was caused by low dissolved uptake (ku), internal transfer (k12, k21) and high efflux (ke1). The organic As were the predominated species (77 − 80%) and remained constant, while the inorganic As increased 35% (from 0.26 μg/g to 0.35 μg/g) during the initial 4-d exposure and then recovered. The increased inorganic As could be covered by the high contribution of organic As especially arsenobetaine (AsB) to the total As accumulation. Coincidently, the malondialdehyde (MDA) levels followed similar trends as the inorganic As concentrations, indicating that inorganic As bioaccumulation induced oxidative stress at the initial stage. Both the contents of the nonenzymatic antioxidant (glutathione, GSH) and the activities of the enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione-S-transferase (GST)) increased initially and then decreased as the inorganic As concentrations, thus lowering the hydrogen peroxide (H2O2) levels and displaying a typical antioxidant defense mechanism. In summary, this study elucidated that although the marine medaka had a limited ability to accumulate waterborne As, the increase in the inorganic As at the early stage of exposure still caused toxic effects, which could be ignored by constant total As concentrations. Therefore, the toxicity of As could be underestimated if only the total As instead of the inorganic As is monitored in marine fish.
       
  • Physiological trade-offs, acid-base balance and ion-osmoregulatory
           plasticity in European sea bass (Dicentrarchus labrax) juveniles under
           complex scenarios of salinity variation, ocean acidification and high
           ammonia challenge
    • Abstract: Publication date: Available online 2 May 2019Source: Aquatic ToxicologyAuthor(s): Jyotsna Shrivastava, Moses Ndugwa, Warren Caneos, Gudrun De Boeck In this era of global climate change, ocean acidification is becoming a serious threat to the marine ecosystem. Despite this, it remains almost unknown how fish will respond to the co-occurrence of ocean acidification with other conventional environmental perturbations typically salinity fluctuation and high ammonia threat. Therefore, the present work evaluated the interactive effects of elevated pCO2, salinity reduction and high environmental ammonia (HEA) on the ecophysiological performance of European sea bass (Dicentrarchus labrax). Fish were progressively acclimated to seawater (32 ppt), to brackish water (10 ppt) and to hyposaline water (2.5 ppt). Following acclimation to different salinities for at least two weeks, fish were exposed to CO2-induced water acidification representing present-day (control pCO2, 400 μatm, LoCO2) and future (high pCO2, 1000 μatm, HiCO2) sea-surface CO2 level for 3, 7 and 21 days. At the end of each exposure period, fish were challenged with HEA for 6 h (1.18 mM representing 50% of 96 h LC50). Results show that, in response to the individual HiCO2 exposure, fish within each salinity compensated for blood acidosis. Fish subjected to HiCO2 were able to maintain ammonia excretion rate (Jamm) within control levels, suggesting that HiCO2 exposure alone had no impact on Jamm at any of the salinities. For 32 and 10 ppt fish, up-regulated expression of Na+/K+-ATPase was evident in all exposure groups (HEA, HiCO2 and HEA/HiCO2 co-exposed), whereas Na+/K+/2Cl− co-transporter was up-regulated mainly in HiCO2 group. Plasma glucose and lactate content were augmented in all exposure conditions for all salinity regimes. During HEA and HEA/HiCO2, Jamm was inhibited at different time points for all salinities, which resulted in a significant build-up of ammonia in plasma and muscle. Branchial expressions of Rhesus glycoproteins (Rhcg isoforms and Rhbg) were upregulated in response to HiCO2 as well as HEA at 10 ppt, with a more moderate response in 32 ppt groups. Overall, our findings denote that the adverse effect of single exposures of ocean acidification or HEA is exacerbated when present together, and suggests that fish are more vulnerable to these environmental threats at low salinities.
       
  • Systematic analysis of freshwater metal toxicity with
           WHAM-F TOX
    • Abstract: Publication date: Available online 1 May 2019Source: Aquatic ToxicologyAuthor(s): E Tipping, A Stockdale, S Lofts We used the WHAM chemical speciation model and the WHAM-FTOX toxicity model to analyse the published results of laboratory toxicity experiments covering 52 different freshwater biological test species and 24 different metals, a total of 2037 determinations of EC50 with accompanying data on solution composition. The key extracted parameter was αM, the parameter in WHAM-FTOX that characterises the toxic potency of a metal on the basis of its estimated metabolically active body burden. For 16 data sets applying to metal-test species pairs with appreciable variations in solution composition, values of EC50 back-calculated from averaged values of αM showed significantly (p 
       
  • Evaluating sub-lethal stress from Roundup® exposure in Artemia
           franciscana using 1H NMR and GC-MS
    • Abstract: Publication date: Available online 1 May 2019Source: Aquatic ToxicologyAuthor(s): Melissa A. Morgan, Corey M. Griffith, Meredith Dinges, Yana Lyon, Ryan Julian, Cynthia K. Larive Global salinization trends present an urgent need for methods to monitor aquatic ecosystem health and characterize known and emerging stressors for water bodies that are becoming increasingly saline. Environmental metabolomics methods that combine quantitative measurements of metabolite levels and multivariate statistical analysis are powerful tools for ascertaining biological impacts and identifying potential biomarkers of exposure. We propose the use of the saltwater aquatic crustacean, Artemia franciscana, as a model organism for environmental metabolomics in saltwater ecosystems. Artemia are a good choice for ecotoxicity assays and metabolomics analysis because they have a short life cycle, their hemolymph is rich in metabolites and they tolerate a wide salinity range. In this work we explore the potential of Artemia franciscana for environmental metabolomics through exposure to the broad-spectrum herbicide, glyphosate. The LC50 for a 48 hr exposure of Roundup® was determined to be 237 ± 23 ppm glyphosate in the Roundup® formulation. Artemia cysts were hatched and exposed to sub-lethal glyphosate concentrations of 1.00, 10.0, 50.0, or 100 ppm glyphosate in Roundup®. We profiled 48 hr old Artemia extracts using 1H NMR and GC-MS. Dose-dependent metabolic perturbation was evident for several metabolites using univariate and multivariate analyses. Metabolites significantly affected by Roundup® exposure included aspartate, formate, betaine, glucose, tyrosine, phenylalanine, gadusol, and isopropylamine. Biochemical pathway analysis with the KEGG database suggests impairment of carbohydrate and energy metabolism, folate-mediated one-carbon metabolism, Artemia molting and development, and microbial metabolism.
       
  • Trophic transfer of Paralytic Shellfish Toxin (PST): Physiological and
           reproductive effects in the carnivorous gastropod Acanthina monodon
           (Pallas, 1774)
    • Abstract: Publication date: Available online 30 April 2019Source: Aquatic ToxicologyAuthor(s): Paola V. Andrade-Villagrán, Jorge M. Navarro, Samyra Aliste, Oscar R. Chaparro, Alejandro OrtízABSTRACTHarmful algal blooms can adversely affect different levels of the trophic chain, from primary consumers, such as bivalve molluscs, to higher links such as large fish, birds and mammals, including humans. Among secondary consumers, it has been described that carnivorous gastropods can accumulate these toxins when they prey on bivalves that have been exposed to toxic microalgae; these could also harm human health. In Chile, frequent events of harmful algal blooms caused by the dinoflagellate Alexandrium catenella have been described. This organism produces paralytic shellfish toxin (PST) which has been identified in some carnivorous gastropods. The objective of this research was to identify the physiological and reproductive response of the carnivorous gastropod Acanthina monodon fed on the Mytilid Perumytilus purpuratus, which had previously been maintained on a diet containing PST. Specimens of A. monodon showed a decrease in ingestion and absorption rate when they consumed PST indirectly through their diet. The oxygen consumption rate was also affected by the diet-time interaction. The variations of these parameters were reflected in the scope for growth, since the available energy was lower in gastropods exposed to toxic diet. Consumption of PST had a negative effect on the reproduction of A. monodon, since intoxicated adults presented lower egg-masses and delayed start of oviposition. We observed a delay in the development of the embryos inside the capsules, and a lower number of hatched juveniles, although these few juveniles from intoxicated parents accomplished higher growth rates during the next 6 months. We may therefore suggest that toxin transfer, from harmful microalgae through the trophic chain, can generate deleterious effects on the physiological energetics of the organisms that consume them, affecting their reproductive capacity and early ontogenetic development.
       
  • Aroclor 1254 inhibits vasotocinergic pathways related to osmoregulatory
           and stress functions in the gilthead sea bream (Sparus aurata, Linnaeus
           1758)
    • Abstract: Publication date: Available online 29 April 2019Source: Aquatic ToxicologyAuthor(s): Arleta Krystyna Skrzynska, Gonzalo Martínez-Rodríguez, Magdalena Gozdowska, Ewa Kulczykowska, Juan Miguel Mancera, Juan Antonio MartosSitcha The present study assesses the response of vasotocinergic system in the gilthead sea bream (Sparus aurata) after administering two doses of the polychlorinated biphenyl Aroclor 1254 (15 or 50 μg g-1 fresh body mass). Seven days post-administration, eight fish of each experimental group were sampled, and the remaining animals were challenged with a hyperosmotic stress by being transferred from seawater (36 ppt) to high salinity water (55 ppt) and being sampled 3 days post-transfer. Aroclor 1254 affected gene expression of avt, together with Avt concentrations in pituitary and plasma, inhibiting the stimulation observed in vasotocinergic system after hyperosmotic challenge. This was noted by the accumulation of Avt at hypophyseal level as well as by its undetectable values in plasma. Hyperosmotic transfer significantly changed branchial avtrv1a, avtrv2, atp1a and cftr mRNA expression levels in control fish, while in Aroclor 1254-treated fish they remained mostly unchanged. This desensitization also occurred for avtrs in hypothalamus, caudal kidney and liver. In addition, an enhancement in plasma cortisol concentration, together with the orchestration of several players of the Hypothalamic-Pituitary-Interrenal axis (crh, crhbp, trh, star), was also observed mostly at the highest dose used (50 μg g-1 body mass), affecting plasma and hepatic metabolites. Our results demonstrated that Aroclor 1254 compromises the hypoosmoregulatory function of vasotocinergic system in S. aurata, also inducing a concomitant stress response. In summary, this study demonstrates that Aroclor 1254 can be considered an important endocrine disruptor in relation with the correct arrangement of vasotocinergic, metabolic and stress pathways after their stimulation by transfer to hyperosmotic environments.
       
  • Exposure pathway dependent effects of titanium dioxide and silver
           nanoparticles on the benthic amphipod Gammarus fossarum
    • Abstract: Publication date: Available online 29 April 2019Source: Aquatic ToxicologyAuthor(s): Simon Lüderwald, Theresa Schell, Kymberly Newton, Rashidat Salau, Frank Seitz, Ricki R. Rosenfeldt, Vera Dackermann, George Metreveli, Ralf Schulz, Mirco Bundschuh The increasing production of engineered inorganic nanoparticles (EINPs) elevates their release into aquatic ecosystems raising concerns about associated environmental risks. Numerous investigations indicate sediments as the final sink, facilitating the exposure of benthic species to EINPs. Although reports of sub-lethal EINP effects on benthic species are increasing, the importance of exposure pathways (either waterborne or dietary) is poorly understood. This study investigates the influence of two EINPs, namely titanium dioxide (nTiO2) and silver (nAg), on the benthic model organism Gammarus fossarum specifically addressing the relative relevance of these pathways. For each type of EINP an individual 30-day long bioassay was conducted, applying a two-factorial test design. The factors include the presence or absence of the EINPs (nTiO2: ˜80 nm, 4 mg/L or nAg: ˜30 nm, 0.125 mg/L; n = 30) in the water phase (waterborne), combined with a preceding 6-day long aging of their diet (black alder leaves) also in presence or absence of the EINPs (dietary). Response variables were mortality, food consumption, feces production and energy assimilation. Additionally, the physiological fitness was examined using lipid content and dry weight of the organisms as measures. Results revealed a significantly reduced energy assimilation (up to ˜30%) in G. fossarum induced by waterborne exposure towards nTiO2. In contrast, the dietary exposure towards nAg significantly increased the organisms’ energy assimilation (up to ˜50%). Hence, exposure pathway dependent effects of EINPs cannot be generalized and remain particle specific resting upon their intrinsic properties affecting their potential to interact with the surrounding environment. As a result of the different properties of the EINPs used in this study, we clearly demonstrated variations in type and direction of observed effects in G. fossarum. The results of the present study are thus supporting current approaches for nano-specific grouping that might enable an enhanced accuracy in predicting EINP effects facilitating their environmental risk assessment.
       
  • Differential in vivo hemocyte responses to nano titanium dioxide in
           mussels: effects of particle size
    • Abstract: Publication date: Available online 27 April 2019Source: Aquatic ToxicologyAuthor(s): Ting Wang, Xizhi Huang, Xiaoyu Jiang, Menghong Hu, Wei Huang, Youji Wang Titanium dioxide nanoparticles (TiO2 NPs) are widely used in various products and inevitably released with different sizes and forms into aquatic environment. The purpose of this study was to assess the differential immune toxicity of TiO2 NPs with size difference on mussel hemocytes using flow cytometry (FCM) assays. Hemocyte parameters, including total hemocyte count (THC), hemocyte mortality (HM), phagocytosis activity (PA), lysosomal content (LC), esterase activity (EA), mitochondrial number (MN), mitochondrial membrane potential (MMP) and reactive oxygen species content (ROS) were evaluated in the mussels Mytilus coruscus exposed to two types of TiO2 NPs (25nm & 100nm: 0.1, 1, 10 mg/L, respectively). In general, size- and concentration-dependent toxicity was pronounced with 25nm-NP and highest concentration (10mg/L) being the most toxic. Alhough a slight recovery from the TiO2 exposure was observed, significant carry-over effects were still detected. These results highlight the importance of differential size effects of metal oxide NPs on toxicity mechanisms in aquatic animals.Graphical abstractGraphical abstract for this article
       
  • Medroxyprogesterone acetate affects sex differentiation and
           spermatogenesis in zebrafish
    • Abstract: Publication date: Available online 25 April 2019Source: Aquatic ToxicologyAuthor(s): Wen-Jun Shi, Dong-Dong Ma, Yu-Xia Jiang, Lingtian Xie, Jin-Na Zhang, Guo-Yong Huang, Hong-Xing Chen, Li-Ping Hou, You-Sheng Liu, Guang-Guo Ying Medroxyprogesterone acetate (MPA) is a widely used synthetic progestin and it has been frequently detected in aquatic environments. However, its effects on aquatic organisms remain largely unknown. Here we investigated the chronic effects of MPA on sex differentiation and gonad development in zebrafish. Zebrafish larvae at 20 days post fertilization (dpf) were exposed to 4.32, 42.0, and 424 ng L-1 of MPA until they reached 140 dpf. The results showed that chronic exposure to 42.0 ng L-1 of MPA caused 60% proportion of males as well as significant up-regulation of dmrt1 (˜1.79 fold) and hsd17b3 (˜1.92 fold). Histological analysis showed MPA significantly increased the frequency of immature spermatocytes accompanied with the increased transcription of dmrt1 (˜2.06 fold) and ar (˜1.73 fold) in the testes. Meanwhile, MPA exposure significantly increased the transcription of lhb at all exposure concentrations in the males. In contrast, it significantly suppressed the transcription of lhb (˜-8.06-fold) and fshb (˜-6.35-fold) at 42.0 ng L-1 in the females. Collectively our results demonstrated that MPA had androgenic activity, and could affect sex differentiation and spermatogenesis in zebrafish at environmentally relevant concentrations. The findings from this study suggest that MPA in the aquatic environment may pose potential androgenic risks to fish populations.Graphical abstractGraphical abstract for this article
       
  • Uptake and Efflux of Xenobiotic Transporter Substrates in Zebrafish Embryo
           Ionocytes
    • Abstract: Publication date: Available online 25 April 2019Source: Aquatic ToxicologyAuthor(s): Wei E. Gordon, Jose A. Espinoza, Dena M. Leerberg, Deborah Yelon, Amro Hamdoun Ionocytes are specialized cells in the epidermis of embryonic zebrafish (Danio rerio) that play important roles in ion homeostasis and have functional similarities to mammalian renal cells. Here, we examined whether these cells might also share another functional similarity with renal cells, which is the presence of efflux transporter activities useful for elimination of toxic small molecules. Xenobiotic transporters (XTs), including the ATP-Binding Cassette (ABC) family, are a major defense mechanism against diffusible toxic molecules in aquatic embryos, including zebrafish, but their activity in the ionocytes has not previously been studied. Using fluorescent small molecule substrates of XT, we observed that specific populations of ionocytes uptake and efflux fluorescent small molecules in a manner consistent with active transport. We specifically identified a P-gp/ABCB1 inhibitor-sensitive efflux activity in the H+-ATPase-rich (HR) ionocytes, and show that these cells exhibit enriched expression of the ABCB gene, abcb5. The results extend our understanding of the functional significance of zebrafish ionocytes and indicate that these cells could play an important role in protection of the fish embryo from harmful small molecules.
       
  • Fate and effects of triclosan in subtropical river biofilms
    • Abstract: Publication date: Available online 18 April 2019Source: Aquatic ToxicologyAuthor(s): Naisheng Zhang, Fengjiao Peng, Guang-Guo Ying, Paul J. Van den Brink Triclosan (TCS, 5-chloro-2-(2,4-dichlorophenoxy) phenol) is a broad-spectrum antimicrobial compound. Owing to its wide use, TCS has been frequently detected in river systems, especially in the (sub-)tropics. However, little information on its interaction with river biofilm in the (sub)tropics is currently available. In the present study, subtropical river biofilms were chronically exposed to TCS for 14 d at concentrations of 0.1-100 μg/L in artificial river water, which was followed by a 7 d recovery period. The results show that 100 μg/L TCS inhibited the growth of river biofilms and the no-observed-effect concentration (NOEC) of TCS on river biofilms was 10 μg/L. The affected biofilms did not completely recover within the 7 d of recovery period due to the adsorbed TCS which was not removed together with dissolved TCS. Exposure to TCS caused significant changes in prokaryotic species composition of river biofilms but no significant effects on eukaryotic species composition. In particular, the relative abundance of several TCS-tolerant bacterial species (e.g., Pseudoxanthomonas mexicana, Sphingopyxis alaskensis and Sphingomonas wittichii) in river biofilms increased following exposure to 10 and 100 μg/L TCS. River biofilm efficiently removed TCS from the liquid phase and the pH values of the aquatic system significantly affected the removal efficiency of TCS (from 36% at pH 6.5 to 60% at pH 8.5). No degradation products were detected in the liquid phase after 5 days of exposure, possibly due to strong adsorption of the hydrophobic degradation products to river biofilms and through biodegradation by bacteria utilizing TCS and its degradation products as source of carbon and energy for growth, such as Methyloversalitis universalis and Methylobacterium aquaticum.
       
  • The toxic mechanisms of BDE-47 to the marine diatom Thalassiosira
           pseudonana-a study based on multiple physiological processes
    • Abstract: Publication date: Available online 16 April 2019Source: Aquatic ToxicologyAuthor(s): Yirong Zhao, Xuexi Tang, Antonietta Quigg, Mengchen Lv, Yan Zhao Polybrominated diphenyl ethers (PBDEs), a series of highly persistent organic pollutants (POPs), are ubiquitous in marine ecosystems. As key primary producers, microalgae are of great importance on evaluating the environmental outcome of PBDEs pollution. In this study, the toxic mechanisms of BDE-47 on the marine diatom Thalassiosira pseudonana were evaluated by measuring multiple physiological processes. Three concentrations of BDE-47 (25, 15 and 5 μg L-1) were used along with two controls (blank: no BDE-47 or DMSO; negative control: only DMSO). Experiments lasted 144 hrs (6 days), in which the actual BDE-47 concentrations, cell densities, nutrient (nitrate and phosphate) uptake, pigment compositions, photosynthetic physiology, cell morphology and cellular contents (organic carbon and nitrogen) were measured at 12-48 h intervals. The toxic mechanisms of BDE-47 on T. pseudonana cells were evaluated by measuring multiple physiological processes including photosynthesis, nutrient uptake, cellular material synthesis and cell cycle progressions. The cell divisions of T. pseudonana were severely inhibited by the stress of BDE-47, but the photosynthetic parameters were much less declined and recovered earlier than the cell divisions in the same BDE-47 treatments. The unsuppressed uptake rates of nutrients, increased cell volume and cellular contents indicated the cellular material synthesis proceeded normally. Finally, we found that the cell cycle was arrested in G2/M phase under the stress of BDE-47, we thus concluded that the inhibition of cell divisions by BDE-47 was not due to the lack of energy or cellular materials, where the cell cycle arrest happened; this might be the most important toxicological outcome.
       
  • Multimetal tolerance mechanisms in bacteria: The resistance strategies
           acquired by bacteria that can be exploited to ‘clean-up’ heavy metals
           contaminants from water
    • Abstract: Publication date: Available online 16 April 2019Source: Aquatic ToxicologyAuthor(s): Manisha Nanda, Vinod Kumar, D.K. Sharma Heavy metal pollution is one of the major environmental concerns worldwide. Toxic heavy metals when untreated get accumulated in environment and can pose severe threats to living organisms. It is well known that metals play a major role either directly or indirectly in different metabolic processes of bacteria. This allows bacterial cells to grow even in the presence of some toxic heavy metals. Microbial biotechnology has thus emerged as an effective and eco friendly solution in recent years for bioremediation of heavy metals. Therefore, this review is focused on summarising bacterial adaptation mechanisms for various heavy metals. It also shares some applications of have metal tolerant bacteria in bioremediation. Bacteria have evolved a number of processes for heavy metal tolerance viz., transportation across cell membrane, accumulation on cell wall, intra as well as extracellular entrapment, formation of complexes and redox reactions which form the basis of different bioremediation strategies. The genetic determinants for most of these resistances are located on plasmids however some may be chromosomal as well. Bacterial cells can uptake heavy by both ATP dependent and ATP independent processes. Bacterial cell wall also plays a very important role in accumulating heavy metals by bacterial cells. Gram-positive bacteria accumulate much higher concentrations of heavy metals on their cell walls than that of metals gram -ve bacteria. The role of bacterial metallothioneins (MTs) in heavy metal has also been reported. Thus, heavy metal tolerant bacteria are important for bioremediation of heavy metal pollutants from areas containing high concentrations of particular heavy metals.
       
  • Joint effects of gamma radiation and cadmium on subcellular-, individual-
           and population-level endpoints of the green microalga Raphidocelis
           subcapitata
    • Abstract: Publication date: Available online 10 April 2019Source: Aquatic ToxicologyAuthor(s): Clare Bradshaw, Dina A. Meseh, Hiba Alasawi, Ma Qiang, Pauline Snoeijs-Leijonmalm, Francisco J.A. NascimentoABSTRACTInterpreting and predicting the combined effects of toxicants in the environment is an important challenge in ecotoxicology. How such effects are connected across different levels of biological organisation is an additional matter of uncertainty. Such knowledge gaps are particularly prominent with regards to how ionising radiation interacts with contaminants. We assessed the response of twelve endpoints at the subcellular, individual and population level in a green microalga when exposed singly and jointly to gamma radiation and cadmium (Cd). We used a fully factorial experimental design where observed effects were compared to those predicted by the Independent Action (IA) model for mixture toxicity to determine whether they deviated from additivity. Subcellular endpoints (e.g., catalase, thiamine diphosphate, xanthophyll cycle pigments) showed an increased antioxidant and/or photoprotective response. However, our results indicate that this protection was not sufficient to prevent lipid peroxidation, which also increased with dose. At ecologically relevant doses, most interactions between gamma radiation and Cd regarding subcellular-, individual- and population-level endpoints were additive as predicted by the IA model. However, exposure to binary mixtures displayed antagonistic interactions between gamma radiation and Cd at the higher end of the tested dose spectrum. No correlations were observed between subcellular endpoints and higher-level endpoints, but there were linkages between individual and population endpoints. Our results suggest that antagonistic interactions between gamma radiation and Cd can occur at higher doses and that these interactions seem to disseminate from subcellular and individual to population level. Possible consequences for aquatic primary production and food-web interactions are discussed.
       
  • Pollutants released from the pulp paper industry: Aquatic toxicity and
           their health hazards
    • Abstract: Publication date: Available online 10 April 2019Source: Aquatic ToxicologyAuthor(s): Ajay Kumar Singh, Ram Chandra The pulp paper industries release wastewater containing very complex organic and inorganic pollutants. These pollutants are discharged mainly pulping and bleaching process during paper manufacturing. The main gaseous pollutants hydrogen sulfides, sodium sulfide, methyl mercaptan, sulfur, and chlorine dioxide is reported for chronic, respiratory disorder and irritation to skin, eyes and cardiac problem along with nausea and headache. The major inorganic pollutants include ferrous, copper, zinc, nickel, and magnesium, which is reported for neurotoxicity, toxic to juvenile channel catfish (Ictalurus punctatus) and Accumulation to gill > liver > ovary > muscle. The detected major organic and inorganic pollutants are hexadecanoic acids, octacosane, β-sitosterol trimethylsilyl ether, 1-tetradecane, 2-methoxy phenol, trichlorocatechol, tetrachlorocatechol, chlorophenols, chloroguaiacols, chlorosyringols, chlorocatechols, terpenes, methanol, phenol, alkylated phenols, decalone, benzoic acid, abietic acid, and dehydroabietic acid. Several of these compounds are reported as endocrine-disrupting chemicals (EDCs). Therefore, direct toxicity of effluent to the reproductive system in aquatic flora and fauna are reported. Several reports have highlighted reduced gonad size, change in secondary sexual character, delayed maturity and suppression of sex hormone in fish rainbow trout (Oncorhynchus mykiss) and mosquitofish (Gambusia holbrooki) further the in-vitro studies of organic compounds on fish, Salmonella typhimurium, Vibrio fischeri, and Saccharomyces have shown inhibition in growth and luminescence properties. The presence of organic and inorganic pollutants in pulp paper industry wastewater causes phytotoxicity chromosomal aberration in Allium cepa. Thus the manuscript has concluded that detected pollutants produced foul odors and cause hermaphroditism in fish, hepatotoxicity and mutagenic effect. In addition, the growth of coliform bacteria in River and other aquatic resources has been reported due to contamination of PPI effluent. The studies also highlighted the presence of tannins, chlorophenols, dioxins, furans, biocide, fatty acids, and resin acids along with chlorolignine compounds as persistent organic pollutants (POP), which needs special attention for pollution prevention of rivers, lakes and other aquatic resources.
       
  • Bisphenol A and 17α-ethinylestradiol-induced transgenerational
           differences in expression of osmoregulatory genes in the gill of medaka
           fish (Oryzias latipes)
    • Abstract: Publication date: Available online 8 April 2019Source: Aquatic ToxicologyAuthor(s): Xuegeng Wang, Diamond Hill, Donald E. Tillitt, Ramji K. Bhandari Embryonic bisphenol A (BPA) and 17α-ethinylestradiol (EE2) exposure can have far reaching health effects in fish, including adult onset transgenerational reproductive abnormalities, anxiety, and cardiac disorders. It is unknown whether these two environmental estrogens can induce transgenerational abnormalities in the gill. The present study examined transgenerational effects of BPA or EE2 exposure on genes that are critical for osmoregulation in fish. Medaka (Oryzias latipes) embryos were exposed to either BPA (100 μg/L) or EE2 (0.05 μg/L) for the first 7 days of embryonic development and never thereafter for the remainder of that generation (F0) or in subsequent generations of this study (F1, F2, or F3). Expression of osmoregulatory genes (NKAa1a, NKAa1b, NKAa1c, NKAa3a, NKAa3b, NKCC1a, and CFTR) were examined in gills of the first-generation (F0) adults which were directly exposed as embryo and in the fourth-generation adults (F3), which were never exposed to either of these environmental estrogens. Significant alterations in expression of osmoregulatory genes were observed in both F0 and F3 generations. Within the F0 generation, a sex-specific expression pattern was observed with a downregulation of osmoregulatory genes in males and an upregulation of osmoregulatory genes in females. At the F3 generation, this pattern reversed with the majority of the osmoregulatory genes upregulated in males and downregulated in females, suggesting that exposure to BPA and EE2 during embryonic development induced transgenerational impairment in molecular events associated with osmoregulatory functions in subsequent generations. These adverse outcomes may have impacts on physiological functions related to osmoregulation of fish inhabiting contaminated aquatic environments.
       
  • Host-parasite interaction as a toxicity test endpoint using asymmetrical
           exposures
    • Abstract: Publication date: Available online 8 April 2019Source: Aquatic ToxicologyAuthor(s): Karel Douda, Shuran Zhao, Barbora Vodáková, Pavel Horký, Kateřina Grabicová, Kristýna Božková, Roman Grabic, Ondřej Slavík, Tomáš Randák Interspecific relationships frequently determine the effect a pollutant can have on an organism, and this is especially true in closely interacting species such as hosts and parasites. The high spatial and temporal variability of contaminant concentrations combined with the movement of aquatic biota can further influence the consequences that are associated with contamination. We used a full factorial design for the exposed and unexposed partners of the relationship between the parasitic larvae (glochidia) of the European freshwater mussel (Anodonta anatina) and its host fish (Squalius cephalus) to identify the sources of variation in the sublethal endpoints of species interaction (the intensity of parasite attachment, the spatial position of glochidia on the host body, and encapsulation success). We used the water-borne human pharmaceutical compounds methamphetamine (a central nervous system stimulant) and tramadol (an opioid) at environmentally relevant concentrations (˜ 6.7 and 3.8 nmol L-1 of methamphetamine and tramadol, respectively) as a proxy for contaminant exposure because these compounds are emerging aquatic stressors that are known for high spatial and temporal variability in their detected concentration levels. The relationship between the bivalve and the fish species was influenced by the preceding contact with both methamphetamine and tramadol, but this effect was highly asymmetric. Our experimental design enabled us to identify the specific changes in the relationship outcome that are elicited by the exposure of individual partners, such as the significant increase in glochidia infection success rate from 59.6 ± 3.9 % to 78.7 ± 2.8 % (means ± s.e.) that was associated with host exposure to methamphetamine. Additionally, the significant interaction effect of the exposure was demonstrated by the lowered proportion of glochidia attached to gills after the coexposure of both partners to tramadol. The impact of pharmaceuticals on wild aquatic host–parasite relationships provides an example of the risks that are associated with the unintentional discharge of biologically active compounds into freshwater habitats. Given the increasing evidence showing the ecological impact of waste pharmaceuticals, the use of multitrophic interaction endpoints after joint and unilateral exposures provides an important step towards the realistic risk assessment of these compounds.
       
  • Water-soluble fraction of crude oil affects variability and has
           transgenerational effects in Daphnia magna
    • Abstract: Publication date: Available online 6 April 2019Source: Aquatic ToxicologyAuthor(s): Mikko Nikinmaa, Emilie Suominen, Katja Anttila The importance of interindividual variability in environmental responses has been little studied, although the available information suggests that, e.g., changes in environmental temperature may be associated with changes in variability. We studied, if exposure to water-soluble fraction (WSF) of crude oil can be associated with changes in interindividual variability in phenotype in Daphnia magna, which reproduces parthenogenetically. By using these clonal organisms, we could exclude the possibility that the observed changes were caused by genetic variability. The results show that the variability of oxygen consumption rate decreased in 48 h 30% WSF-exposed animals as compared to 10% WSF-exposed or control animals without a change in the mean of oxygen consumption rate. The clonal Daphnia magna could also be used to study transgenerational effects without genetic contribution, as the different generations are genetically identical. We observed that the oxygen consumption rates in F1 and F2 generations of unexposed and 10% WSF-exposed Daphnia had decreased from parental F0 generation and were also lower than in offspring of 30% WSF-exposed specimens. The studies did not aim at environmental realism but were designed to show the possibility of variability changes without changes in the mean value of a parameter, and transgenerational effects as a result of environmental contamination.
       
  • Toxicity of binary mixtures of pesticides to the marine microalgae
           Tisochrysis lutea and Skeletonema marinoi: Substance interactions and
           physiological impacts
    • Abstract: Publication date: Available online 6 April 2019Source: Aquatic ToxicologyAuthor(s): Valentin Dupraz, Dominique Ménard, Farida Akcha, Hélène Budzinski, Sabine Stachowski-Haberkorn This study screened binary mixtures of pesticides for potential synergistic interaction effects on growth of the marine microalgae Tisochrysis lutea and Skeletonema marinoi. It also examined the single and combined effects of three of the most toxic substances on microalgal physiology.Single substances were first tested on each microalgal species to determine their respective EC50 and concentration-response relationships. The toxicity of six and seven binary mixtures was then evaluated in microplate experiments on the growth of T. lutea and S. marinoi, respectively, using two mixture modelling approaches: isobolograms and the MIXTOX tool, based on Concentration Addition (CA) or Independent Action (IA) models. Significant cases of antagonism (for both species) and synergism (for S. marinoi) were observed for the mixtures of isoproturon and spiroxamine, and isoproturon and metazachlor, respectively.These two mixtures, together with that of isoproturon and diuron, for which additivity was observed, were further studied for their impacts on the physiology of each species. Exposures were thus made in culture flasks at three concentrations, or concentration combinations for mixtures, selected to cause 25%, 50% and 75% growth rate inhibition. The effects of the selected pesticides singly and in combination were evaluated at three perceived effect concentrations on esterase metabolic activity, relative lipid content, cytoplasmic membrane potential and reactive oxygen species (ROS) content by flow cytometry, and on photosynthetic quantum yield (ϕ’M) by PAM-fluorescence.Isoproturon and diuron singly and in mixtures induced 20–40% decreases in ϕ’M which was in turn responsible for a significant decrease in relative lipid content for both species. Spiroxamine and metazachlor were individually responsible for an increase in relative lipid content (up to nearly 300% for metazachlor on S. marinoi), as well as cell depolarization and increased ROS content. The mixture of isoproturon and metazachlor tested on S. marinoi caused a 28–34% decrease in ϕ’M that was significantly higher than levels induced by each of substances when tested alone. This strong decrease in ϕ’M could be due to a combined effect of these substances on the photosynthetic apparatus, which is likely the cause of the synergy found for this mixture.
       
  • Effect of flavonoids isolated from Tridax procumbens on the growth and
           toxin production of Microcystis aeruginos
    • Abstract: Publication date: June 2019Source: Aquatic Toxicology, Volume 211Author(s): Gustavo Franciscatti Mecina, Mathias Ahii Chia, Micheline Kézia Cordeiro-Araújo, Maria do Carmo Bittencourt-Oliveira, Maria Varela Rosa, Ascensión Torres, José Maria Gonzales Molinillo, Francisco Antônio Macías, Regildo Márcio Gonçalves da Silva The excessive proliferation of toxin producing cyanobacteria constitutes a significant health risk to the environment and humans. This is due to the contamination of potable water and accumulation of cyanotoxins in plant and animal tissues. As a means of controlling bloom forming cyanobacteria, secondary metabolites with pro-oxidative activities from plants are used to treat water bodies contaminated with cyanobacterial blooms and their associated toxins. The objective of the present study was to evaluate the mechanism of action of extract, fractions and isolated flavonoids of Tridax procumbens L. on Microcystis aeruginosa (Kützing) Kützing. by monitoring changes in growth, oxidative stress, antioxidant response, and cyanatoxin microcystins (MCs) production. The extract, fraction 3 and the isolated flavonoids significantly reduced the cell density of the cyanobacterium. Furthermore, the extract and fraction 3 increased the production of reactive oxygen species, induced lipid peroxidation, and altered antioxidant enzyme activities of M. aeruginosa. The total MCs content of the cyanobacterium was negatively affected by the presence of the extract, fractions and isolated flavonoids. The present study show that T. procumbens has secondary metabolites that are capable of interfering with the physiology and microcystins production of M. aeruginosa. These characteristics are promising for the control of this noxious cyanobacterium in aquatic ecosystems.
       
  • Copper caused reproductive endocrine disruption in zebrafish (Danio
           rerio
    )
    • Abstract: Publication date: Available online 4 April 2019Source: Aquatic ToxicologyAuthor(s): Jinling Cao, Guodong Wang, Tianyu Wang, Jianjie Chen, Guo Wenjing, Panhong Wu, Xinjin He, Lingtian Xie Cu in surface waters has been demonstrated to affect aquatic animals at ecologically relevant concentrations. However, its effects on reproductive endocrine system and the underlying toxicological mechanisms are largely unknown. In this study, zebrafish (Danio rerio) were exposed to 0, 10, 20, 40 μg/L of Cu for 30 days. Growth, gonad histopathology, the hormone levels and the transcriptional profiles of genes in the hypothalamic-pituitary-gonadal (HPG) axis in both sexes were examined. The results indicated that body weight was significantly reduced, the gonadal development was affected, and the levels of E2, T and 11-KT were remarkably disturbed in Cu-exposed fish. Moreover, the expression profiles of steroidogenesis-related genes in gonad (3βhsd, 17βhsd, cyp11a1, cyp17, cyp19a, lhr, fshr, hmgra and star) and in brains (ar, cyp19b, erα, er2β, lhβ, fshβ, gnrh2, gnrh3, gnrhr1, gnrh2 and gnrh4) displayed alterations after exposure to Cu. These results demonstrated that Cu could suppress the growth of zebrafish and significantly affect the reproductive biology in both sexes by damaging the structure of the gonads, altering the steroid hormone levels and the expressions of endocrine-related genes in HPG of zebrafish. This study suggests that Cu adversely affects the reproductive endocrine system in zebrafish and could pose a potential threat to fish populations inhabiting Cu-contaminated waters.
       
  • Parental Exposure to Tebuconazole Causes Thyroid Endocrine Disruption in
           Zebrafish and Developmental Toxicity in Offspring
    • Abstract: Publication date: Available online 3 April 2019Source: Aquatic ToxicologyAuthor(s): Shuying Li, Qiong Wu, Qianqian Sun, Scott Coffin, Wenjun Gui, Guonian Zhu Azole fungicides are one class of the most extensively applied current-use pesticides. Tebuconazole is a common azole fungicide that has been frequently detected in aquatic ecosystems, thus raising concerns about its ecological safety. However, adverse effects of tebuconazole remain largely unknown, especially with regard to endocrine function in aquatic organisms. In the present study, sexually immature zebrafish were exposed to different concentrations of tebuconazole (0.05, 0.20 and 0.50 mg/L) for 60 days in order to test for transgenerational toxicity on the thyroid endocrine system. Thyroid hormone homeostasis, neuronal, and cardiovascular development were investigated in the F1 generation, which were reared in tebuconazole-free water. In the F0 generation, exposure to 0.20 and 0.50 mg/L tebuconazole reduced both thyroxine (T4) and 3,5,3’-triiodothyronine (T3) levels in females, while the T3 levels were unchanged in males. Decreased heart rate was found in F1 larvae, as well as diminished T4 levels in F1 eggs/larvae. We also observed significantly increased expression of ugt1ab mRNA in two generations of zebrafish. Moreover, expression of mRNA associated with neuronal development (e.g. α1-tubulin, mbp, gap43) and cardiovascular development (e.g. cacna1ab, tnncal) were significantly downregulated in F1 larvae at 5 and 10 dpf. In addition, tebuconazole was detected in F1 eggs following parental exposure, indicating maternal transfer. This study demonstrated that tebuconazole can be transferred to offspring from exposed parents, causing thyroid endocrine disruption and developmental toxicity.
       
  • Polyphenols obtained from Didymosphenia geminata (Lyngbye) Schmith altered
           the viability and proliferation of salmonids cells lines SHK-1 and
           CHSE-214
    • Abstract: Publication date: Available online 1 April 2019Source: Aquatic ToxicologyAuthor(s): Pamela Olivares-Ferretti, Claudia Hernandez, Matías Peredo-Parada, Viviana Chavez, Erico Carmona, Allisson Astuya, Jorge Parodi Didymosphenia geminata (Lyngbye) Schmidt, also referred to as Didymo, is an invasive diatom that forms nuisance mats. Since it was first reported in our country in approximately 2010, Didymo has expanded and colonized different rivers in the Zona Austral region of Chile. Its biology and effects on ecosystems are still being studied because Didymo is an invasive algal mat that forms in a range of systems from oligotrophic austral rivers to more subtropical systems. We aimed to evaluate the viability of two salmonid cell lines, CHSE-214 and SHK-1 (somatic and embryonic cell lines, respectively), in dilutions of river water alone and in river water contaminated with Didymo or polyphenols extracted from Didymo under controlled conditions. We developed an artificial river system (2 aquariums/replicate) from five different rivers from the central area (Bio-Bio) and Patagonia area (Futaleufú) of Chile to maintain Didymo in the benthic phase. The Didymo populations were maintained for six months in the water from the rivers, after which samples were obtained. Following the extraction of polyphenols from the Didymo samples maintained in the artificial rivers, toxicity assays (10 assays) were performed to determine cell viability. Our results indicated that the CHSE-214 cells were highly sensitive to increasing concentrations of Didymo extracts. We observed a 50% reduction in cell viability after 24 h of exposure to a 0.01 V/V dilution, and this treatment further reduced the proliferative capacity by 70% after 120 h. The SHK-1 cells were less responsive, showing only a 20% decrease in viability at 24 h and a lower cell proliferation rate (45%) after 120 h, which remained higher than that of the CHSE-214 cells. We conclude that certain cell types are sensitive to Didymo in rivers, suggesting that there are chronic effects on several aquatic species following exposure to these diatom substances. These effects should be further studied using this laboratory model to understand the full impact of Didymo on river ecosystems.
       
  • Biochemical and Molecular responses of cyprinids in two Mediterranean
           lacustrine ecosystems: opportunities for ecological assessment and
           biomonitoring
    • Abstract: Publication date: Available online 1 April 2019Source: Aquatic ToxicologyAuthor(s): Martha Kaloyianni, Konstantinos Feidantsis, Ioanna Nteli, Panagiota Stergiou, Thomai Tsoulia, Anastasia Dimitriadi, Efthimia Antonopoulou, Dimitra Bobori Lacustrine ecosystems have been altered by accelerating pollution, excessive nutrient and organic load, water abstraction, and are susceptible to climate change. Hence, suggesting sensitive and reliable biomarkers for early assessments of their status is of urgent need. In this study, two freshwater commercial fish species, Cyprinus carpio (carp) and Carassius gibelio (Prussian carp) from two lakes (i.e. Koronia and Volvi, Northern Greece) with different anthropogenic pressures were used and a battery of biochemical and molecular biomarkers related to stress response were analyzed in fish gills and liver. In parallel, water physicochemical parameters (T, DO, pH, conductivity, salinity), BOD5 and nutrient (N-NO3, N-NO2, N-NH4, P-PO4) concentrations were measured. Results showed that Lake Koronia had higher conductivity and salinity values, and N-NO2 concentrations. Levels of Heat Shock Response (HSR), MAPK phosphorylation, protein carbonylation, lipid peroxidation products, Bax/Bcl-2 ratio, ubiquitination and caspases were increased in gills and liver of both fish species sampled from Lake Koronia in relation to those of Lake Volvi. Likewise, liver lipid content was increased in both fish species sampled from Lake Koronia compared to those sampled from Lake Volvi. The results indicate and reflect the higher environmental degradation that prevails in Lake Koronia ecosystem in comparison to that of Lake Volvi. The fish species studied showed different susceptibility depending on the biomarkers examined. In addition, our results from both examined species provide insight into the mechanisms involved in acclimatization to stressful environments and support the role of the studied biomarkers as sensitive and reliable tools for ecological assessments of lake ecosystems in biomonitoring studies.Graphical abstractGraphical abstract for this article
       
  • Comparative studies of the response of sensitive and tolerant submerged
           macrophytes to high ammonium concentration stress
    • Abstract: Publication date: Available online 29 March 2019Source: Aquatic ToxicologyAuthor(s): Jingqing Gao, Peng Ren, Qingyang Zhou, Jingshen Zhang Three submerged macrophytes, Ceratophyllum demersum (CD), Myriophyllum spicatum (MS) and Myriophyllum aquaticum (MA), were treated with various concentrations of ammonia for different lengths of time. Ammonium ions (NH4+) in the medium severely inhibited plant growth and led to a reduction in total chlorophyll (chl a and b) in CD and MS. The addition of ammonia significantly decreased the soluble protein content and increased the free amino acid content of CD and MS in treatments with high concentrations of NH4+, but MA showed no significant physiological response. The antioxidant enzyme system of MA was activated, which in turn reduced the peroxidation level in the plant and maintained the plant’s normal physiological activities when the ammonia nitrogen in the culture fluid increased. The study continued to use higher concentrations (25, 50, 100, 200 and 400 mg/L) of ammonium nitrogen to treat and observe the peroxidation level and corresponding enzyme production for this species of MA in vivo to explore its resistance mechanism. The experiments show that MA can normally live for a period of time in a high-ammonia environment of up to 100 mg/L. The results of the present study will assist in studies of the detoxification of high ammonium ion contents in submersed macrophytes and the selection of plants suitable for macrophyte recovery.
       
  • Exposure to a nanosilver-enabled consumer product results in similar
           accumulation and toxicity of silver nanoparticles in the marine mussel
           Mytilus galloprovincialis
    • Abstract: Publication date: Available online 28 March 2019Source: Aquatic ToxicologyAuthor(s): Analía Ale, Giulia Liberatori, Maria Luisa Vannuccini, Elisa Bergami, Stefania Ancora, Giacomo Mariotti, Nicola Bianchi, Juan M. Galdopórpora, Martín F. Desimone, Jimena Cazenave, Ilaria Corsi The incorporation of silver nanoparticles (AgNPs) in commercial products is increasing rapidly. The consequent release of AgNPs into domestic and industrial wastewater raises environmental concerns due to their anti-microbial properties and toxicity to non-target aquatic organisms. The aim of the present study was to investigate the effects of nanArgen™ (Nanotek S.A.), a AgNP-enabled consumer product, in the marine bivalve Mytilus galloprovincialis. Two environmentally relevant concentrations of nanArgen™ (1 and 10 µg/L) were tested in vivo for 96 h, and Ag was quantified in mussel soft tissue and natural seawater (NSW). nanArgen™ suspensions were characterized via TEM, SEM, EDS, DLS, and UV-Vis optical analysis. Several molecular and biochemical responses were investigated in exposed mussels: lysosomal membrane stability by Neutral Red Retention Time (NRRT) assay; micronucleus (MN) frequency in hemocytes; metallothionein (MT) protein content and gene expression (mt10 and mt20); catalase (CAT) and glutathione-S-transferase (GST) activities; malondialdehyde (MDA) accumulation in digestive glands; and efflux activity of ATP-binding cassette transport proteins (ABC) in gill biopsies. SEM, TEM and DLS analyses confirmed the presence of well-defined AgNPs in nanArgen™ which were roughly spherical with an average particle size of approx. 30 ± 10 nm. DLS analysis revealed the formation of AgNP aggregates in nanArgen™ suspension in NSW (Z-average of 547.80 ± 90.23 nm; PDI of 0.044). A significant concentration-dependent accumulation of Ag was found in mussels’ whole soft tissue in agreement with a concentration-dependent decrease in NRRT and an increase of MN frequency in hemocytes and GST activities in digestive glands. A significant increase in MDA levels and MT via both molecular and biochemical tests, were also observed but only at the highest nanArgen™ concentration (10 µg/L). No changes were observed in CAT activities. ABC efflux activities in gill biopsies showed a significant decrease (p 
       
  • Assessment of oxidative stress of paracetamol to Daphnia magna via
           determination of Nrf1 and genes related to antioxidant system
    • Abstract: Publication date: Available online 28 March 2019Source: Aquatic ToxicologyAuthor(s): Liu Sijia, Ding Rui, Nie Xiang Ping Paracetamol (APAP) is one of the most widely used anti-inflammatory and analgesic drugs in human being health care and has been universally detected in various aquatic environments. However, its potential adverse effects and toxic mechanisms on freshwater invertebrates still remain unclear. In the present study, the effects of APAP on the expressions of Nrf1 and the antioxidant related genes including GCLC, GST, GPX, CAT, TRX, TrxR and Prx1 in Daphnia magna (D. magna) were evaluated after 24, 48 and 96 h, and the changes of GPX, GST and CAT enzyme activities, as well as the GSH and MDA content under APAP exposure for 48 h were also determined. Results showed that paracetamol affected the expressions of Nrf1 and antioxidant related genes in D. magna, which were related to the exposure time and concentration of APAP. Nrf1 was inhibited at 48 h, but induced at 96 h under the APAP exposure, being about two fold of the control in 5.0 μg/L. CAT were significantly induced in all treatments. But Prx decreased in an concentration-dependent manner in all treatments. In comparison with the mRNA expression, antioxidant enzymes activity displayed less changes in D. magna. Overall, APAP exposure altered the expression of Nrf1 and genes related to antioxidant system and disturbed the redox homeostasis of D. magna.
       
  • Impact of salt-contaminated freshwater on osmoregulation and tracheal gill
           function in nymphs of the mayfly Hexagenia rigida
    • Abstract: Publication date: Available online 27 March 2019Source: Aquatic ToxicologyAuthor(s): Fargol Nowghani, Chun Chih Chen, Sima Jonusaite, Trudy Watson-Leung, Scott P. Kelly, Andrew Donini The impact of freshwater (FW) salinization on osmoregulation as well as tracheal gill morphology and function was examined in nymphs of the mayfly Hexagenia rigida following exposure to salt contaminated water (SCW, 7.25 g/L NaCl) for a 7-day period. Ionoregulatory homeostasis was perturbed in SCW exposed H. rigida nymphs as indicated by increased hemolymph Na+, K+ and Cl- levels as well as hemolymph pH and water content. Despite this, SCW did not alter gill Na+-K+-ATPase (NKA) or V-type H+-ATPase (VA) activity. In addition, NKA and VA immunolocalization in gill ionocytes did not show alterations in enzyme location or changes in ionocyte abundance. The latter observation was confirmed using scanning electron microscopy (SEM) to examine exposed tracheal gill ionocyte numbers. Ionocyte surface morphometrics also revealed that SCW did not change individual ionocyte surface area or ionocyte fractional surface area. Nevertheless, analysis of Na+ movement across the tracheal gill of mayfly nymphs using scanning ion-selective electrode technique indicated that FW nymphs acquired Na+ from surrounding water, while tracheal gills of SCW nymphs had the capacity to secrete Na+. Because Na+ secretion across the gill of SCW-exposed animals occurred in the absence of any change in (1) NKA and VA activity or (2) ionocyte numbers/surface exposure, it was reasoned that Na+ movement across the gill of SCW animals may be occurring, at least in part, through the paracellular pathway. The ultrastructure of tracheal gill septate junctions (SJs) supported this idea as they exhibited morphological alterations indicative of a leakier pathway. Data provide a first look at alterations in osmoregulatory mechanisms that allow H. rigida nymphs to tolerate sub-lethal salinization of their surroundings.
       
  • Ecotoxicological effects of lanthanum in Mytilus galloprovincialis:
           Biochemical and histopathological impacts
    • Abstract: Publication date: Available online 25 March 2019Source: Aquatic ToxicologyAuthor(s): João Pinto, Marcelo Costa, Carla Leite, Cláudia Borges, Francesca Coppola, Bruno Henriques, Rui Monteiro, Tania Russo, Anna Di Cosmo, Amadeu M.V.M. Soares, Gianluca Polese, Eduarda Pereira, Rosa FreitasSummaryInappropriate processing and disposal of electronic waste contributes to the contamination of aquatic systems by various types of pollutants such as the rare-earth elements (REE) in which lanthanum (La) is included. Knowledge on the toxicity of these elements in marine organisms is still scarce when compared to other metals such as mercury (Hg) and arsenic (As). Therefore, this study aims to assess the toxicity of La on the mussel Mytilus galloprovincialis, considered a good bioindicator of aquatic pollution, through the analysis of metabolic, oxidative stress, neurotoxicity and histopathological markers. Organisms were exposed to different concentrations of La for a period of 28 days (0, 0.1, 1, 10 mg/L) under controlled temperature (18 °C ± 1.0) and salinity (30 ± 1) conditions. La concentrations in mussels increased in higher exposure concentrations. La exposure demonstrated a biochemical response in mussels, evidenced by lowered metabolism and accumulation of energy reserves, activation of the antioxidant defences SOD and GPx as well as the biotransformation enzymes GSTs, especially at intermediate concentrations. Despite oxidative stress being shown by a decrease in GSH/GSSG, oxidative damage was avoided as evidenced by lower LPO and PC levels. Inhibition of the enzyme AChE demonstrated the neurotoxicity of La in this species. Histopathological indices were significantly different from the control group, indicating impacts gonads, in gills and digestive glands of mussels due to La. These results show that La can be considered a risk for marine organisms and as such its discharge in the environment should be supervised.Graphical Graphical abstract for this article
       
  • Influence of light intensity on cadmium uptake and toxicity in the
           cyanobacteria Synechocystis sp. PCC6803
    • Abstract: Publication date: Available online 25 March 2019Source: Aquatic ToxicologyAuthor(s): Juan Du, Baosheng Qiu, Marcelo Pedrosa Gomes, Philippe Juneau, Guozheng Dai The mechanisms of cadmium toxicity to cyanobacterial photosynthesis have been extensively studied, but the response mechanisms to combinations of different cadmium concentrations and different light intensities are not yet well understood. The two principal objectives of the present work were to: 1) study the short term (5 hour) toxic effects of cadmium on Synechocystis PCC6803 under three different culturing light intensity conditions; and, 2) investigate the effects of light history on Cd toxicity to Synechocystis. The maximal (ФM) and operational (Ф’M) photosystem II quantum yields, photosystem I quantum yield [Y (I)], cyclic electron flow, relative photochemical quenching (qPrel), relative non-photochemical quenching (qNrel), relative unquenched fluorescence (UQFrel), pigment contents, and cadmium uptake were evaluated when Synechocystis cells were treated with cadmium for 5 hours under three different light conditions. We demonstrated that cadmium toxicity was enhanced with increasing growth light intensities due to increased cadmium uptake under higher light exposures, and the photoprotective mechanisms could not cope with cadmium and light stress under high light conditions. We also investigated Cd toxicity to Synechocystis adapted to three growth light intensities and subsequently shifted to different light intensity conditions to compare the effects of light regime shift on cadmium toxicity. We observed increased cadmium toxicity when the cells were transferred from low light to high light conditions. Interestingly, Synechocystis cells grown at high light intensities were more tolerant to cadmium than cells grown at low light intensities after the same light regime shift, due to the development of photoprotective mechanisms.
       
  • Effect of copper nanoparticles and ions on spermatozoa motility of sea
           trout (Salmo trutta m. trutta L.)
    • Abstract: Publication date: Available online 20 March 2019Source: Aquatic ToxicologyAuthor(s): Monika Kowalska-Góralska, Katarzyna Dziewulska, Mateusz Kulasza Nanoproducts are being increasingly used in various industrial products, leading to a greater risk of water pollution through their discharge into environment as production byproducts. Increased levels of environmental pollution with nanoproducts pose a threat to all living organisms. Nanopollutants may have toxic effects on gametes and fertilization process in species with external fertilization, thereby reducing effectiveness of reproduction or greatly impairing it. The objective of the present study was to determine the effect of copper nanoparticles (Cu and CuO) and copper ions (CuSO4·5H2O) on the spermatozoa motility of sea trout and compare their harmful effects.Copper nanoparticles (NPs) of primary particle size
       
  • Whether warming magnifies the toxicity of a pesticide is strongly
           dependent on the concentration and the null model
    • Abstract: Publication date: Available online 20 March 2019Source: Aquatic ToxicologyAuthor(s): Vienna Delnat, Lizanne Janssens, Robby Stoks How global warming changes the toxicity of contaminants is a research priority at the intersection of global change biology and ecotoxicology. While many pesticides are more toxic at higher temperatures this is not always detected. We studied whether deviations from this general pattern can be explained by concentration-dependent interaction effects and by testing the interaction against the inappropriate null model. We exposed larvae of the mosquito Culex pipiens to three concentrations of the pesticide chlorpyrifos (absence, low and high) in the absence and presence of 4 °C warming. Both the low and high chlorpyrifos concentration were lethal and generated negative sublethal effects: activity of acetylcholinesterase (AChE) and total fat content decreased, and oxidative damage to lipids increased, yet growth rate increased. Warming was slightly lethal, yet had positive sublethal effects: growth rate, total fat content and metabolic rate increased, and oxidative damage decreased. For four out of seven response variables the independent action model identified the expected synergistic interaction between chlorpyrifos and warming. Notably, for three variables (survival, AChE and fat content) this was strongly dependent on the chlorpyrifos concentration, and for two of these (AChE and fat content) not associated with a significant interaction in the general(ized) linear models. For survival and fat content, warming only potentiated chlorpyrifos (CPF) toxicity at the low CPF concentration, while the opposite was true for AChE. Our results highlight that taking into account concentration-dependence and appropriate null model testing is crucial to improve our understanding of the toxicity of contaminants in a warming world.
       
  • Does intraspecific variability matter in ecological risk assessment'
           Investigation of genotypic variations in three macrophyte species exposed
           to copper
    • Abstract: Publication date: Available online 19 March 2019Source: Aquatic ToxicologyAuthor(s): Eva Roubeau Dumont, Camille Larue, Sophie Lorber, Hervé Gryta, Elise Billoir, Elisabeth Maria Gross, Arnaud ElgerABSTRACTTo limit anthropogenic impact on ecosystems, regulations have been implemented along with global awareness that human activities are harmful to the environment. Ecological risk assessment (ERA) is the main procedure which allows to assess potential impacts of stressors on the environment as a result of human activities. ERA is typically implemented through different steps of laboratory testing. The approaches taken for ERA evolve along with scientific knowledge, to improve predictions on ecological risks for ecosystems. We here address the importance of intraspecific variability as a potential source of error in the laboratory evaluation of pollutants. To answer this question, three aquatic macrophyte species with different life-history traits but with their leaves directly in contact with the water were chosen; Lemna minor and Myriophyllum spicatum, two OECD model species, and Ceratophyllum demersum. For each species, three or four genotypes were exposed to 7-8 copper concentrations (up to 1.9 mg/L, 2 mg/L or 36 mg/L for C. demersum, L. minor and M. spicatum, respectively). To assess species sensitivity, growth-related endpoints such as Relative Growth Rate (RGR), based either on biomass production or on length/frond production, and chlorophyll fluorescence Fv/Fm, were measured. For each endpoint, the effective concentration 50% (EC50) was calculated. Almost all endpoints were affected by Cu exposure, except Fv/Fm of M. spicatum, and resulted in significant differences among genotypes for Cu sensitivity. Genotypes of L. minor exhibited up to 35% of variation in EC50 values based on Fv/Fm, showing differential sensivity among genotypes. Significant differences in EC50 values were found for RGR based on length for M. spicatum, with up to 72% of variation. Finally, C. demersum demonstrated significant sensitivity differences among genotypes with up to 78 % variation for EC50 based on length. Overall, interspecific variation was higher than intraspecific variation, and explained 77% of the variation found among genotypes for RGR based on biomass, and 99% of the variation found for Fv/Fm. Our results highlight that depending on the endpoint, sensitivity can vary greatly within a species, and that pollutant- and species-specific endpoints should be considered in ERA.
       
  • The osmotic effect of hyper-saline hydraulic fracturing fluid on rainbow
           trout, Oncorhynchus mykiss
    • Abstract: Publication date: Available online 14 March 2019Source: Aquatic ToxicologyAuthor(s): P.L.M. Delompré, T.A Blewett, K.N. Snihur, S.L. Flynn, D.S. Alessi, C.N. Glover, G.G. Goss Flowback and produced water (FPW) is a complex, often brackish, solution formed during the process of hydraulic fracturing. Despite recent findings on the short-term toxicity of FPW on aquatic biota, longer-term impacts of FPW on fish have not yet been investigated and the mechanisms of chronic effects remain unknown. The aim of the present study was to observe the effect of a diluted FPW on ionoregulatory endpoints in the rainbow trout Oncorhynchus mykiss, following a 28-d sub-chronic exposure. A salinity-matched control solution (SW), recreating the salt content of the FPW, was used to differentiate the specific effect of the salts from the effects of the other FPW components (i.e. organics and metals). Overall, fish ionoregulation was not impacted by the chronic exposure. An accumulation of strontium (Sr) and bromide (Br) occurred in the plasma of the FPW-exposed fish only, however no change of plasma ions (Na, K, Cl, Ca, Mg) was observed in SW- or FPW-exposed fish. Similarly, exposures did not alter branchial activity of the osmoregulatory enzymes sodium/potassium ATPase and proton ATPase. Finally, FPW exposure resulted in modifications of gill morphology over time, with fish exposed to the fluid displaying shorter lamellae and increased interlamellar-cell mass. However, these effects were not distinct from morphological changes that also occurred in the gills of control groups.
       
  • The relative importance of waterborne and dietborne As exposure on
           survival and growth of juvenile fathead minnows
    • Abstract: Publication date: Available online 8 March 2019Source: Aquatic ToxicologyAuthor(s): Russell J. Erickson, David R. Mount, Terry L. Highland, J. Russell Hockett, Correne T. Jenson, Tylor J. Lahren The survival and growth of juvenile fathead minnows were investigated at various combinations of waterborne exposure to arsenate and of dietborne exposure to oligochaete worms which had been exposed to inorganic arsenic. Previous work with rainbow trout established that dietborne arsenic can reduce fish growth at environmentally relevant concentrations and could be more important than waterborne exposures. This was found to be less true for fathead minnows, which were less sensitive to dietborne exposures than rainbow trout, while being as or more sensitive to waterborne exposures. When assessed on the basis of accumulation of total As by the fish, further differences between fathead minnows and rainbow trout were evident. Fathead minnows accumulated relatively more arsenic from water versus diet than trout, and the accumulations at which growth effects occurred in minnows were different for dietborne and waterborne exposure, whereas they were the same for trout. These results suggest complex relationships involving arsenic speciation, toxicokinetics, and toxicodynamics, and underscore a need for care in relating effects information to real-world exposures. The present study also demonstrated the challenges in testing and interpreting growth effects in long-term exposures to fish, because the expression of toxicity can be confounded by the relationship of fish growth to size, the feeding regime, and wet weight versus dry weight relationships.
       
  • Control of Invasive Sea Lampreys Using the Piscicides TFM and Niclosamide:
           Toxicology, Successes & Future Prospects
    • Abstract: Publication date: Available online 21 December 2018Source: Aquatic ToxicologyAuthor(s): Michael P. Wilkie, Terrance D. Hubert, Michael A. Boogaard, Oana Birceanu The invasion of the Laurentian Great Lakes of North America by sea lampreys (Petromyzon marinus) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10 % of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys, and in non-target invertebrates and vertebrates, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, likely works in a similar manner, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible “next-generation” strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.
       
 
 
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