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1.
Toxins (Basel) ; 13(2)2021 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-33572944

RESUMO

Cyanobacterial blooms and the associated release of cyanotoxins pose problems for many conventional water treatment plants due to their limited removal by typical unit operations. In this study, a conventional water treatment process consisting of coagulation, flocculation, sedimentation, filtration, and sludge dewatering was assessed in lab-scale experiments to measure the removal of microcystin-LR and Microcystis aeruginosa cells using liquid chromatography with mass spectrometer (LC-MS) and a hemacytometer, respectively. The overall goal was to determine the effect of recycling cyanotoxin-laden dewatered sludge supernatant on treated water quality. The lab-scale experimental system was able to maintain the effluent water quality below relevant the United States Environmental Protection Agency (US EPA) and World Health Organisation (WHO) standards for every parameter analyzed at influent concentrations of M. aeruginosa above 106 cells/mL. However, substantial increases of 0.171 NTU (Nephelometric Turbidity Unit), 7 × 104 cells/L, and 0.26 µg/L in turbidity, cyanobacteria cell counts, and microcystin-LR concentration were observed at the time of dewatered supernatant injection. Microcystin-LR concentrations of 1.55 µg/L and 0.25 µg/L were still observed in the dewatering process over 24 and 48 h, respectively, after the initial addition of M.aeruginosa cells, suggesting the possibility that a single cyanobacterial bloom may affect the filtered water quality long after the bloom has dissipated when sludge supernatant recycling is practiced.

2.
PLoS One ; 15(9): e0239358, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32970715

RESUMO

There is an extensive literature establishing, validating, and quantifying a wide range of responses of fishes to fasting. Our study complements this work by comparing fed and unfed treatments of hatchery-raised Delta Smelt (Hypomesus transpacificus)-an imperiled fish that is endemic to the San Francisco Estuary and its tributaries in California, USA-across a diverse suite of endpoints over a two-month time series. The experiment was conducted at 15.9°C, and individuals were sampled at 12 time points as starvation became increasingly severe. We found that hepatosomatic index and condition factor were relatively sensitive to starvation, becoming significantly depressed at Day 4 and 7, respectively. Histological analysis of liver showed elevated cytoplasmic inclusion bodies at Day 7, followed by increased glycogen depletion, single cell necrosis, and hydropic vacuolar degeneration at Day 14, 21, and 28, respectively. Of four antioxidants measured, glutathione decreased at Day 4, superoxide dismutase increased at Day 14, catalase increased at Day 56, and glutathione peroxidase was not affected by starvation. The net result was a ~2-fold increase in lipid peroxidation (malondialdehyde) in fasted fish that was highly inconsistent through time. RNA to DNA ratio and triglycerides in muscle were relatively insensitive to starvation, only consistently decreasing with fasting after mortality began increasing in the 'No Feeding' treatment, at Day 21. Together, these results suggest that Delta Smelt mobilize hepatic energy stores far more rapidly than lipids in muscle when subjected to fasting, leading to rapid atrophy of liver and the development of cytoplasmic inclusion bodies-possibly autophagosomes-in hepatocytes.


Assuntos
Osmeriformes/metabolismo , Inanição , Animais , Catalase/metabolismo , Glutationa/metabolismo , Glicogênio/metabolismo , Corpos de Inclusão/metabolismo , Fígado/metabolismo , Fígado/patologia , Malondialdeído/metabolismo , Músculos/metabolismo , Músculos/patologia , Necrose , Osmeriformes/crescimento & desenvolvimento , Superóxido Dismutase/metabolismo , Fatores de Tempo
3.
Sci Total Environ ; 726: 138333, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32315843

RESUMO

The Delta Smelt (Hypomesus transpacificus) is an imperiled, annual fish endemic to the Sacramento-San Joaquin Delta and San Francisco Estuary. This study examined the severity and prevalence of liver and gill lesions of juvenile through adult Delta Smelt from 2011 through 2017 collected from five regions throughout its habitat (n = 1,053). The first and last years of the study were wet, but bracketed an extreme drought in CA (2012-2016), during which the Delta Smelt population reached historical lows. Overall, the three most common lesions were gill ionocyte hyperplasia, liver lipidosis, and gill aneurysm. Individuals with higher fork lengths exhibited increased gill and liver lesion score (summations of the severity scores), suggesting that Delta Smelt accumulate lesions through their lives, and that larger individuals were more tolerant of liver and gill lesions. Liver lesion score showed significant regional differences, while salinity was a better predictor of gill lesions than region, with lower gill lesion scores associated with higher salinities. Largely consistent with previously reported histopathology patterns, Delta Smelt collected from the Confluence and Suisun Marsh had the lowest liver lesion score, while Delta Smelt collected from Cache Slough and Suisun Bay had the highest lesion scores, and Suisun Marsh had the lowest glycogen depletion, suggesting heterogeneous levels of exposure to environmental stressors across regions. Gill and liver lesion score also varied significantly with year-class. The highest gill lesion score occurred in the 2015/16 year-class, and the lowest occurred in the 2017/18 year-class, a 2.8-fold difference. Controlling for size and regional effects, individuals with comparatively high liver lesion scores were prevalent in the population until the 2014/15 year-class. In the two subsequent year-classes, Delta Smelt livers were in the best condition, coinciding with peak drought conditions and record low abundances.


Assuntos
Osmeriformes , Animais , Espécies em Perigo de Extinção , Estuários , Salinidade , São Francisco
4.
Environ Toxicol Chem ; 39(7): 1375-1381, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32289178

RESUMO

Herbicides have recently been designated as one of the most frequently detected chemical types in aquatic systems. We evaluated the effect of the herbicide formulations Clearcast® (active ingredient imazamox) and Galleon® SC (active ingredient penoxsulam), in conjunction with the adjuvant Agri-dex®, on the diatom Thalassiosira pseudonana and the copepod Eurytemora affinis and whether their application in invasive aquatic weed control has acutely negative effects on important delta food web species. Herbicide-adjuvant mixtures were more toxic than herbicide formulations alone. For the diatom, 50% inhibition concentration (IC50) were 84.4 mg/L for Clearcast, >100 mg/L for Galleon SC, and 38.5 mg/L for Agri-dex. In the herbicide mixture diatom tests, IC50s decreased to 2.8 mg/L for Clearcast + 64 mg/L Agri-dex and to 6.6 mg/L for Galleon SC + 41 mg/L Agri-dex. In the copepod tests, 50% effect concentrations (EC50s) were 45.4 mg/L for Agri-dex, 31.2 mg/L for Galleon SC, and >100 mg/L for Clearcast. When tested together, EC50s were reduced to 24.1 for Galleon SC and 67.6 mg/L for Clearcast in the presence of 50 mg/L Agri-dex. Environmentally relevant herbicide-adjuvant mixture ratios were at the no-observed-effect level. Mixture interactions between herbicides and adjuvants indicate the potential for increased toxicity in herbicide formulations and tank mixes, especially in consideration of the unlisted, proprietary ingredients which are included in herbicide formulations, making predicting nontarget effects challenging. Environ Toxicol Chem 2020;39:1375-1381. © 2020 SETAC.

5.
Toxins (Basel) ; 12(3)2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32183091

RESUMO

Harmful cyanobacterial blooms compromise human and environmental health, mainly due to the cyanotoxins they often produce. Microcystins (MCs) are the most commonly measured group of cyanotoxins and are hepatotoxic, neurotoxic, and cytotoxic. Due to MCs ability to covalently bind to proteins, quantification in complex matrices is difficult. To analyze bound and unbound MCs, analytical methods were optimized for analysis in sediment and clam tissues. A clean up step was incorporated to remove lipids, improving percent yield. This method was then applied to sediment and clam samples collected from the Sacramento-San Joaquin River Delta (Delta) in the spring and fall of 2017. Water samples were also tested for intracellular and extracellular MCs. These analyses were used to quantify the partitioning of MCs among sediment, clams, and water, and to examine whether MCs persist during non-summer months. Toxin analysis revealed that multiple sediment samples collected in the Delta were positive for MCs, with a majority of the positive samples from sites in the San Joaquin River, even while water samples from the same location were below detection limit. These data highlight the importance of analyzing MCs in complex matrices to accurately evaluate environmental risk.

6.
Artigo em Inglês | MEDLINE | ID: mdl-31642727

RESUMO

The herbicides glyphosate, imazamox and fluridone are herbicides, with low toxicity towards fish and invertebrates, which are applied to waterways to control invasive aquatic weeds. However, the effects of these herbicides on natural isolates of phytoplankton and cyanobacteria are unknown. Three species of microalgae found in the San Francisco Estuary (SFE)/Sacramento-San Joaquin River Delta (Delta) (Microcystis aeruginosa, Chlamydomonas debaryana, and Thalassiosira pseudonana) were exposed to the three herbicides at a range of concentrations in 96-well plates for 5-8 days. All three algal species were the most sensitive to fluridone, with IC50 of 46.9, 21, and 109 µg L-1 for M. aeruginosa, T. pseudonana and C. debaryana, respectively. Imazamox inhibited M. aeruginosa and T. pseudonana growth at 3.6 × 104 µg L-1 or higher, and inhibited C. debaryana growth at 1.0 × 105 µg L-1 or higher. Glyphosate inhibited growth in all species at ca. 7.0 × 104 µg L-1 or higher. Fluridone was the only herbicide that inhibited the microalgae at environmentally relevant concentrations in this study and susceptibility to the herbicide depended on the species. Thus, the application of fluridone may affect cyanobacteria and phytoplankton community composition in water bodies where it is applied.


Assuntos
Cianobactérias/efeitos dos fármacos , Estuários , Herbicidas/toxicidade , Fitoplâncton/efeitos dos fármacos , Rios/química , Poluentes Químicos da Água/toxicidade , Animais , California , Cianobactérias/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Fitoplâncton/crescimento & desenvolvimento , Especificidade da Espécie
7.
Sci Total Environ ; 700: 134495, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31693955

RESUMO

The herbicide fluridone is intensively applied to control invasive aquatic plants globally, including in the Sacramento and San Joaquin Delta (the Delta), California, USA. Our previous study revealed that the adult stage of Delta Smelt showed acute and sub-lethal adverse effects following 6 h of exposure to environmentally relevant concentrations of fluridone. To further investigate mechanisms of toxicity of fluridone and to assess its toxicity to early life stages of fish, we performed additional exposures using the fish model Japanese Medaka (Oryzias latipes). Male and female Medaka embryos were exposed to concentrations of fluridone for 14 d and showed reduced hatching success in a dose dependent manner. The half maximal effective concentration for the hatching success was 2.3 mg L-1. In addition, male and female Medaka larvae were acute exposed to fluridone for 6 h to assess their swimming behavior and gene expression patterns. Fish exposed to fluridone at 4.2 mg L-1 or higher became lethargic and showed abnormal swimming behavior. The response to the stimuli was significantly impaired by fluridone at 21 mg L-1 and above in males, and at 104 mg L-1 in females. Transcriptome analysis identified a total of 799 genes that were significantly differentially expressed, comprising 555 up-regulated and 244 down-regulated genes in males exposed to 21 mg L-1 of fluridone. The gene set enrichment analysis indicated a number of biological processes altered by fluridone. Among the genes involved in those biological processes, the expression of the genes, acetylcholinesterase, retinoic acid receptor, insulin receptor substrate, glutathione reductase, and glutathione S transferase, exhibited dose- and sex-dependent responses to fluridone. The study indicated that fluridone exposure led to detrimental toxic effects at early developmental stages of fish, by disturbing the biological processes of growth and development, and the nervous system, inducing oxidative stress and endocrine disruption.


Assuntos
Disruptores Endócrinos/toxicidade , Oryzias/fisiologia , Piridonas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Embrião não Mamífero , Herbicidas/toxicidade
8.
Environ Manage ; 63(6): 703-717, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30944966

RESUMO

The San Francisco Estuary (California, USA) had abundant pelagic fish in the late 1960s, but has few pelagic fish today. A primary cause for this decline in fish is thought to be a trophic cascade, triggered by declining phytoplankton. Here, we describe the changes in pelagic community structure of the San Francisco Estuary. Then, we examine whether changes in hydrodynamics due to freshwater exports, which increased exponentially beginning in 1967, in addition to the 1986 invasion by the clam Potamocorbula amurensis, explain the phytoplankton loss. Hydrodynamic variables were reconstructed back to 1956 using statistical models fit to, and cross-validated against, output from a hydrodynamic model. Then, we regressed mean summer/fall chlorophyll a-the season with the largest phytoplankton decline-against the reconstructed hydrodynamic variables and the presence/absence of P. amurensis for 1969-2014. The regression model, which explained 78% of the interannual variation in chlorophyll a, was then used to quantify the influence of P. amurensis and exports on chlorophyll a. Based on monitoring data, chlorophyll a declined 22-fold from 1969-2014, zooplankton declined 32-fold from 1972-2014, and pelagic fish declined 92-fold from 1968-2014. Averaged over 1990-2014, the chlorophyll a model ascribed an 88% decline in chlorophyll a to P. amurensis, a 74% decline to exports (at minimum), and a 97% decline to the combined influence of P. amurensis and exports (at minimum). Thus, the decline in pelagic productivity in the San Francisco Estuary has occurred largely due to the combined impacts of the P. amurensis invasion and increased freshwater exports.


Assuntos
Bivalves , Estuários , Animais , Clorofila , Clorofila A , Água Doce , Hidrodinâmica , Fitoplâncton , São Francisco
9.
PLoS One ; 13(9): e0203953, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30248115

RESUMO

Blooms of Microcystis and other harmful cyanobacteria can degrade water quality by producing cyanotoxins or other toxic compounds. The goals of this study were (1) to facilitate understanding of community structure for various aquatic microorganisms in brackish water and freshwater regions with emphasis on cyanobacteria, and (2) to test a hypothesis that Microcystis genotypes that tolerate higher salinity were blooming in brackish water environments during the severe drought, 2014. Shotgun metagenomic analysis revealed that cyanobacteria dominated the brackish water region while bacteria dominated the freshwater region. A group of cyanobacteria (e.g., Aphanizomenon, Microcystis, Planktothrix, Pseudanabaena), bacteria (e.g., Bacillus, Porphyrobacter), and diatoms (Phaeodactylum and Thalassiosira) were abundant in the brackish water region. In contrast, Hassallia (cyanobacteria) and green algae (Nannochloropsis, Chlamydomonas, and Volvox) were abundant in the landward freshwater region. Station variation was also apparent. One landward sampling station located downstream of an urbanized area differed substantially from the other stations in terms of both water chemistry and community structure, with a higher percentage of arthropods, green algae, and eukaryotes. Screening of the Microcystis internal transcribed spacer region revealed six representative genotypes, and two of which were successfully quantified using qPCR (Genotypes I and VI). Both genotypes occurred predominantly in the freshwater region, so the data from this study did not support the hypothesis that salinity tolerant Microcystis genotypes bloomed in the brackish water region in 2014.


Assuntos
Cianobactérias/genética , Cianobactérias/isolamento & purificação , Microbiologia da Água , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Clorófitas/classificação , Clorófitas/genética , Cianobactérias/classificação , DNA Bacteriano/genética , Diatomáceas/classificação , Diatomáceas/genética , Diatomáceas/isolamento & purificação , Estuários , Água Doce/microbiologia , Genótipo , Proliferação Nociva de Algas , Metagenômica , Microcystis/genética , Microcystis/isolamento & purificação , Filogenia , Reação em Cadeia da Polimerase , Águas Salinas , Salinidade , São Francisco , Análise Espaço-Temporal
10.
Aquat Toxicol ; 197: 79-88, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29448126

RESUMO

Concerns regarding non-target toxicity of new herbicides used to control invasive aquatic weeds in the San Francisco Estuary led us to compare sub-lethal toxicity of four herbicides (penoxsulam, imazamox, fluridone, and glyphosate) on an endangered fish species Delta Smelt (Hypomesus transpacificus). We measured 17ß-estradiol (E2) and glutathione (GSH) concentrations in liver, and acetylcholinesterase (AChE) activity in brain of female and male fish after 6 h of exposure to each of the four herbicides. Our results indicate that fluridone and glyphosate disrupted the E2 concentration and decreased glutathione concentration in liver, whereas penoxsulam, imazamox, and fluridone inhibited brain AChE activity. E2 concentrations were significantly increased in female and male fish exposed to 0.21 µM of fluridone and in male fish exposed to 0.46, 4.2, and 5300 µM of glyphosate. GSH concentrations decreased in males exposed to fluridone at 2.8 µM and higher, and glyphosate at 4.2 µM. AChE activity was significantly inhibited in both sexes exposed to penoxsulam, imazamox, and fluridone, and more pronounced inhibition was observed in females. The present study demonstrates the potential detrimental effects of these commonly used herbicides on Delta Smelt.


Assuntos
Glicina/análogos & derivados , Herbicidas/toxicidade , Imidazóis/toxicidade , Osmeriformes/fisiologia , Piridonas/toxicidade , Sulfonamidas/toxicidade , Uridina/análogos & derivados , Acetilcolinesterase/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/enzimologia , Estradiol/metabolismo , Feminino , Glutationa/metabolismo , Glicina/toxicidade , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Testes de Toxicidade Aguda , Uridina/toxicidade , Poluentes Químicos da Água/toxicidade
11.
PLoS One ; 12(11): e0187664, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29108004

RESUMO

We examined whether environmentally relevant concentrations of different types of microplastics, with or without PCBs, directly affect freshwater prey and indirectly affect their predators. Asian clams (Corbicula fluminea) were exposed to environmentally relevant concentrations of polyethylene terephthalate (PET), polyethylene, polyvinylchloride (PVC) or polystyrene with and without polychlorinated biphenyls (PCBs) for 28 days. Their predators, white sturgeon (Acipenser transmontanus), were exposed to clams from each treatment for 28 days. In both species, we examined bioaccumulation of PCBs and effects (i.e., immunohistochemistry, histology, behavior, condition, mortality) across several levels of biological organization. PCBs were not detected in prey or predator, and thus differences in bioaccumulation of PCBs among polymers and biomagnification in predators could not be measured. One of the main objectives of this study was to test the hypothesis that bioaccumulation of PCBs would differ among polymer types. Because we could not answer this question experimentally, a bioaccumulation model was run and predicted that concentrations of PCBs in clams exposed to polyethylene and polystyrene would be greater than PET and PVC. Observed effects, although subtle, seemed to be due to microplastics rather than PCBs alone. For example, histopathology showed tubular dilation in clams exposed to microplastics with PCBs, with only mild effects in clams exposed to PCBs alone.


Assuntos
Corbicula , Peixes/fisiologia , Plásticos/toxicidade , Bifenilos Policlorados/toxicidade , Comportamento Predatório , Poluentes Químicos da Água/toxicidade , Animais , Peixes/metabolismo , Água Doce , Plásticos/metabolismo , Bifenilos Policlorados/metabolismo , Poluentes Químicos da Água/metabolismo
12.
Artigo em Inglês | MEDLINE | ID: mdl-28529176

RESUMO

Increasing aluminum (Al) concentrations in aquatic habitats as a result of anthropogenic acidification and industrialization is a global issue. Moreover, in extensive areas of the humid tropics and subtropics, high Al concentrations in freshwater are observed because of both naturally low pH and high Al concentrations in soil. Al increases production of reactive oxygen species and enhances oxidative damage in mammals. However, no studies have examined the effect of environmentally relevant concentrations of Al at low pH on oxidative stress in fish. This study assessed Al-induced effects on enzymatic and non-enzymatic antioxidants, lipid peroxidation, and on expression of oxidative stress-related genes at low pH using Japanese Medaka (Oryzias latipes). Larval fish were exposed to dissolved Al concentrations of 0, 1.7, 6.2 and 16.7µgL-1 for 4days at pH5.3 in soft water. Al caused a significant reduction in activity of glutathione peroxidase at 6.2 and 16.7µgL-1, and of glutathione reductase at 16.7µgL-1 in whole body homogenates. No changes were observed in the expression of the glutathione peroxidase gene, and expression levels of the glutathione reductase gene were too low to be quantitated. Even though there was an overall decrease in the activity of catalase and in the concentration of glutathione, differences were not significant compared to the control. Changes in lipid peroxidation were not found. This study showed that exposure to environmentally relevant concentrations of Al at low pH impairs antioxidant defense mechanisms of Medaka.


Assuntos
Alumínio/toxicidade , Antioxidantes/metabolismo , Oryzias/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Catalase/metabolismo , Ecotoxicologia/métodos , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Concentração de Íons de Hidrogênio , Larva/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Testes de Toxicidade Aguda/métodos , Poluentes Químicos da Água/toxicidade
13.
Chemosphere ; 181: 304-312, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28448912

RESUMO

Extreme weather events like drought are expected to increase with climate change, which will increase exposure of freshwater fish to ultraviolet (UV) radiation. Compared to fully grown adult fish, fish in early life stages are more susceptible to UV radiation due to the lack of well-developed pigmentation. Even though several studies have described affectation of fish health after exposure to UV radiation, most of the studies have used intensities that are only found on the surface of the earth crust or at shallow depths in water bodies, and little is known about impacts of weaker UV radiation, which can be found in deep water. This study showed effects on the antioxidant system of Japanese Medaka after 7 days of exposure to very low intensities of UV radiation, levels that can be found at deep locations in lakes and rivers. Exposure to UV radiation (UVA: 360.1 ± 18.4 µW cm-2 for a dose of 21.6 ± 1.2 mJ cm-2 min-1, and UVB: 6.3 ± 0.5 µW cm-2 for a dose of 0.38 ± 0.03 mJ cm-2 min-1) caused a reduction in the catalase activity (over 50%) and enhanced oxidative damage to lipids. Results of this study showed that environmentally relevant, low levels of UV radiation affect mechanisms by which fish deal with enhanced production of reactive oxygen species and oxidative damage. The results raise concerns about early life stages of fish under scenarios of increased exposure to solar light, such as in tropic regions or during summer in temperate regions.


Assuntos
Antioxidantes/efeitos da radiação , Oryzias/metabolismo , Luz Solar/efeitos adversos , Raios Ultravioleta/efeitos adversos , Animais , Mudança Climática , Oxirredução/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Espécies Reativas de Oxigênio/efeitos da radiação
14.
PLoS One ; 12(3): e0173497, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28291808

RESUMO

Diadromy affords fish access to productive ecosystems, increasing growth and ultimately fitness, but it is unclear whether these advantages persist for species migrating within highly altered habitat. Here, we compared the foraging success of wild Delta Smelt-an endangered, zooplanktivorous, annual, semi-anadromous fish that is endemic to the highly altered San Francisco Estuary (SFE)-collected from freshwater (<0.55 psu) and brackish habitat (≥0.55 psu). Stomach fullness, averaged across three generations of wild Delta Smelt sampled from juvenile through adult life stages (n = 1,318), was 1.5-fold higher in brackish than in freshwater habitat. However, salinity and season interacted, with higher fullness (1.7-fold) in freshwater than in brackish habitat in summer, but far higher fullness in brackish than freshwater habitat during fall/winter and winter/spring (1.8 and 2.0-fold, respectively). To examine potential causes of this interaction we compared mesozooplankton abundance, collected concurrently with the Delta Smelt, in freshwater and brackish habitat during summer and fall/winter, and the metabolic rate of sub-adult Delta Smelt acclimated to salinities of 0.4, 2.0, and 12.0 psu in a laboratory experiment. A seasonal peak in mesozooplankton density coincided with the summer peak in Delta Smelt foraging success in freshwater, and a pronounced decline in freshwater mesozooplankton abundance in the fall coincided with declining stomach fullness, which persisted for the remainder of the year (fall, winter and spring). In brackish habitat, greater foraging 'efficiency' (prey items in stomachs/mesozooplankton abundance) led to more prey items per fish and generally higher stomach fullness (i.e., a higher proportion of mesozooplankton detected in concurrent trawls were eaten by fish in brackish habitat). Delta Smelt exhibited no difference in metabolic rate across the three salinities, indicating that metabolic responses to salinity are unlikely to have caused the stomach fullness results. Adult migration and freshwater spawning therefore places young fish in a position to exploit higher densities of prey in freshwater in the late spring/summer, and subsequent movement downstream provides older fish more accessible prey in brackish habitat. Thus, despite endemism to a highly-altered estuary, semi-anadromy provided substantial foraging benefits to Delta Smelt, consistent with other temperate migratory fish.


Assuntos
Espécies em Perigo de Extinção , Estuários , Comportamento Alimentar , Osmeriformes/fisiologia , Animais , Salinidade , Estações do Ano
15.
Chemosphere ; 166: 511-520, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27710886

RESUMO

Pesticides in urban runoff are a major source of pollutants in aquatic ecosystems. Fipronil, a phenylpyrazole insecticide, found in structural pest control products, turf grass control, and home pet flea medication, has recently increased in use and is commonly detected in urban runoff. However, little is known about the effects of fipronil on aquatic organisms at early developmental stages. Here, we evaluated toxicity of fipronil to embryos of Japanese Medaka (Oryzias latipes, Qurt strain) using a high-throughput 96-well plate toxicity test. Male and female embryos (<6 h post fertilization) were exposed to concentrations of fipronil ranging from 0.1 to 910 µg L-1 for 14 days or until hatching. Embryos were subjected to gross and microscopic examinations of developmental adverse effects as well as transcriptome analysis using RNA-seq. Results indicated a positive dose-response in reduced hatching success, increased gross deformity (tail curvature) at a lowest-observed-effect concentration (LOEC) of 200 µg L-1 and delayed hatching (∼1 day at the highest concentration, LOEC = 600 µg L-1). The transcriptome analysis indicated that fipronil exposure enhanced expression of titin and telethonin, which are responsible for muscle development. It is therefore possible that the formation of a tail curvature is due to asymmetrical overgrowth of muscle. Our results indicate that sub-lethal effects occur in embryonic stages of an aquatic vertebrate following exposure to high concentrations of fipronil, although no adverse effects at the highest published environmentally relevant concentration (6.3 µg L-1) were observed.


Assuntos
Embrião não Mamífero/efeitos dos fármacos , Inseticidas/toxicidade , Oryzias/embriologia , Pirazóis/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Feminino , Masculino , Testes de Toxicidade
16.
Sci Total Environ ; 568: 26-32, 2016 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-27285793

RESUMO

Acidification in aquatic ecosystems is a major concern worldwide. In freshwater, although there are several publications reporting acute toxicity and adverse effects due to low pH, little is known about adverse effects on antioxidant mechanisms in fish after prolonged exposure. This study aimed to investigate how antioxidants are affected by raising larval Japanese Medaka (Oryzias latipes) in soft water at pH5.5, 6.0, and 6.5. After 18days of exposure, glutathione concentration and glutathione peroxidase activity in whole body homogenates increased as pH decreased, without changes in lipid peroxidation measured as thiobarbituric acid reactive substances. This study showed that prolonged exposure to low pH increased reactive oxygen species production and that fish cope with it by increasing levels of enzymatic and non-enzymatic antioxidants.


Assuntos
Antioxidantes/metabolismo , Proteínas de Peixes/genética , Expressão Gênica , Oryzias/metabolismo , Estresse Oxidativo , Animais , Feminino , Proteínas de Peixes/metabolismo , Glutationa , Glutationa Peroxidase/genética , Glutationa Peroxidase/metabolismo , Concentração de Íons de Hidrogênio , Masculino , Fatores de Tempo , Testes de Toxicidade Crônica
17.
Fish Physiol Biochem ; 42(1): 219-32, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26407957

RESUMO

Abiotic factors like salinity are relevant to survival of pelagic fishes of the San Francisco Bay Estuary. We tested the effects of 4 parts per thousand (ppt) salinity increases on Delta Smelt (DS) in a laboratory experiment simulating salinity increases that might occur around the low-salinity zone (LSZ) (<6 ppt). Adult DS, fed 2% body mass per day, starting at 0.5 ppt [freshwater (FW)], were exposed to weekly step-increases of 4 ppt to a maximum of 10 ppt saltwater (SW) over 19 days, and compared to FW controls. DS (n = 12/treatment per sampling) were sampled at 24, 72, and 96 h (1, 3, and 4 days) post-salinity increase for analyses of hematocrit, plasma osmolality, muscle water content, gill chloride cell (CC) Na(+)/K(+)-ATPase (NKA) and apoptosis after being weighed and measured (n = 3 tanks per treatment). No apparent increase in length or weight occurred nor did a difference in survival. Following step-increases in SW, hematocrit increased over time. Other fish responses generally showed a pattern; specifically plasma osmolality became elevated at 1 day and diminished over 4 days in SW. Percent muscle water content (%) did not show significant changes. CCs showed increased NKA, cell size and apoptosis over time in SW, indicating that CCs turnover in DS. The cell renewal process takes days, at least over 19 days. In summary, DS are affected by salinities of the LSZ and ≤10 ppt, though they employ physiological strategies to acclimate.


Assuntos
Osmeriformes/fisiologia , Salinidade , Aclimatação , Animais , Apoptose , Tamanho Corporal , Caspase 3/metabolismo , Caspase 7/metabolismo , Brânquias/metabolismo , Hematócrito , Músculos/metabolismo , Osmeriformes/anatomia & histologia , Osmeriformes/metabolismo , Simportadores de Cloreto de Sódio-Potássio/metabolismo , Água/metabolismo
18.
Aquat Toxicol ; 170: 152-161, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26655659

RESUMO

A common approach used to assess environmental impacts in aquatic environments is to measure indicators of stress (biomarkers) and condition of fish within ecosystems. Particularly in estuarine ecosystems with multiple stressors, it is often desirable to quantify a suite of biological endpoints that (1) reflect fish condition at several levels of biological organization and time scales and (2) are sensitive to a range of environmental stressors. However, established methods of preservation and processing of fish for specific endpoints are often incompatible. Here, we developed a novel flash-freezing approach for assessing the health of a small, sensitive fish, the endangered Delta Smelt (Hypomesus transpacificus) after collections from the San Francisco Estuary (SFE). We assess whether flash-freezing the entire fish ensures effective preservation of multiple tissues for subsequent biomarker analyses by comparing measurements of fresh to frozen tissue. Tissues included brain, gill, and liver for enzyme activity, kidney and spleen for pathogens, and gills, liver, and gonads for histopathology and reproduction. Although flash-freezing in liquid nitrogen altered the length, weight, and condition factor of Delta Smelt, the percent changes were small (<1.5%). Histological analyses of the cellular morphology of gills, liver, and gonads were similar between both methods. Freezing artefacts were observed in ovaries, but did not hinder the identification and interpretation of cell types and oocyte stages. Freezing did not alter bacterial isolation or the activities of ethoxyresorufin-0-deethylase (EROD) or acetylcholinesterase (AChE), but had a small, negative influence on sodium potassium adenosine triphosphatase (ATPase) activity. Thus, flash-freezing in the field is a versatile preservation method for Delta Smelt, allowing for multiple tissue collections and bioassays from an individual tiny fish exposed to a wide range of natural and anthropogenic stressors. Similar methodology may be applicable to other species for which a range of biological endpoints and histopathology data are needed.


Assuntos
Congelamento , Osmeriformes/metabolismo , Acetilcolinesterase/metabolismo , Animais , Biomarcadores/metabolismo , Encéfalo/enzimologia , Citocromo P-450 CYP1A1/metabolismo , Brânquias/enzimologia , Brânquias/patologia , Gônadas/patologia , Fígado/patologia , Oócitos/metabolismo , Oócitos/patologia , Osmeriformes/crescimento & desenvolvimento , ATPase Trocadora de Sódio-Potássio/metabolismo
19.
J Environ Sci (China) ; 38: 95-102, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26702972

RESUMO

Naturally-occurring and artificially-induced polyploids have been documented in various fish species but to date no comparison has been reported of the impacts of ploidy on fish biomarker responses to organic pollutants. This study describes effects of ploidy, gender, and dose on biliary fluorescent aromatic compound (FAC) concentrations, hepatic ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities in one of the most commonly cultured warm-water species, the African catfish Clarias gariepinus. Recently matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 5 or 25mg/kg benzo[a]pyrene (BaP) and liver and gallbladder were sampled 48hr later. No significant differences were found between ploidies in bile concentrations of 7,8 dihydrodiolbenzo[a]pyrene (7,8D BaP), 1-hydroxybenzo[a]pyrene (1-OH BaP) or 3-hydroxybenzo[a]pyrene (3-OH BaP). However, concentrations of the biliary FACs did differ between males and females at different dose of injection with generally higher concentrations in females at the low dose of BaP and higher concentrations in males at the higher BaP concentration. Hepatic EROD activity did not exhibit gender-dependent difference, whereas it was significantly higher in triploids than diploids. GST activities were not significantly influenced by any of the tested factors. This work advanced our understanding of the role of ploidy, gender, and dose in biotransformation of pollutants in fish.


Assuntos
Benzo(a)pireno/toxicidade , Biomarcadores/análise , Poluentes Químicos da Água/toxicidade , Animais , Peixes-Gato , Citocromo P-450 CYP1A1/metabolismo , Monitoramento Ambiental , Glutationa Transferase/metabolismo , Fígado/efeitos dos fármacos , Fígado/enzimologia , Masculino
20.
Sci Rep ; 5: 14340, 2015 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-26399762

RESUMO

The ubiquity of anthropogenic debris in hundreds of species of wildlife and the toxicity of chemicals associated with it has begun to raise concerns regarding the presence of anthropogenic debris in seafood. We assessed the presence of anthropogenic debris in fishes and shellfish on sale for human consumption. We sampled from markets in Makassar, Indonesia, and from California, USA. All fish and shellfish were identified to species where possible. Anthropogenic debris was extracted from the digestive tracts of fish and whole shellfish using a 10% KOH solution and quantified under a dissecting microscope. In Indonesia, anthropogenic debris was found in 28% of individual fish and in 55% of all species. Similarly, in the USA, anthropogenic debris was found in 25% of individual fish and in 67% of all species. Anthropogenic debris was also found in 33% of individual shellfish sampled. All of the anthropogenic debris recovered from fish in Indonesia was plastic, whereas anthropogenic debris recovered from fish in the USA was primarily fibers. Variations in debris types likely reflect different sources and waste management strategies between countries. We report some of the first findings of plastic debris in fishes directly sold for human consumption raising concerns regarding human health.


Assuntos
Contaminação de Alimentos/análise , Alimentos Marinhos/análise , Resíduos/efeitos adversos , Animais , Bivalves , Peixes , Humanos , Indonésia , Frutos do Mar , Estados Unidos
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