Home About us Contact
|
Home About us Contact | ||
|
|
||
Fish Health (fish + health)
Selected AbstractsHistopathological alterations in the liver of the sharptooth catfish Clarias gariepinus from polluted aquatic systems in South AfricaENVIRONMENTAL TOXICOLOGY, Issue 2 2009M. J. Marchand Abstract There is a need for sensitive bio-monitoring tools in toxicant impact assessment to indicate the effect of toxicants on fish health in polluted aquatic ecosystems. Histopathological assessment of fish tissue allows for early warning signs of disease and detection of long-term injury in cells, tissues, or organs. The aim of this study was to assess the degree of histopathological alterations in the liver of C. gariepinus from two dams in an urban nature reserve, (Gauteng, South Africa). Two dams (Dam 1 and Dam 2) were chosen for their suspected levels of toxicants. Water and sediments were sampled for metal and potential endocrine disrupting chemical analysis. A quantitative and qualitative histology-based health assessment protocol was employed to determine the adverse health effects in fish. The analysis of blood constituents, fish necropsy, calculation of condition factors, and hepatosomatic indices were employed to support the findings of the qualitative and quantitative histological assessment of liver tissue. Assessment of the liver tissue revealed marked histopathological alterations including: structural alterations (hepatic cord disarray) affecting 27% of field specimens; plasma alterations (granular degeneration 98% and fatty degeneration 25%) of hepatocytes; an increase in melanomacrophage centers (32%); hepatocyte nuclear alterations (90%); and necrosis of liver tissue (14%). The quantitative histological assessment indicated that livers of fish collected from Dam 1 were more affected than the fish livers collected from Dam 2. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] Long-term trends in liver neoplasms in brown bullhead in the Buffalo River, New York, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Darrel J. Lauren Abstract The Buffalo River area of concern (AOC) was assigned an impaired status for the fish tumors and other deformities beneficial use impairment category by the New York State Department of Environmental Protection in 1989. This was initially based on an inadequately documented brown bullhead (Ameiurus nebulosus) feeding study using river sediment extracts. The presence of liver tumors was subsequently supported by reports of a 19 to 27% prevalence in wild brown bullhead between 1983 and 1988 and a 4.8% prevalence in 1998. However, neither fish size (or age) nor sample locations were given, and histopathological definitions were inconsistent in these previous studies. Therefore, in 2008, we re-evaluated the prevalence of hepatocellular and chloangiocellular tumors (as well as other gross indicators of fish health) in brown bullhead averaging 25,cm in length collected from three reaches of the Buffalo River and recorded our collection sites by global positioning system. Among the 37 fish of appropriate size collected, only three exhibited liver tumors (8%). The tumors were evenly distributed within the three reaches, and only hepatocellular tumors were found. There were no differences in the prevalence of hepatic foci of alteration, body weight, length, or hepatosomatic index among the three reaches, but the conditions factor was significantly lower in fish from reach 2. Natural attenuation of water and sediment quality are the most likely causes for the decrease in liver tumors. The prevalence of liver tumors between 1998 and 2008 in the Buffalo River is similar to that found in recovery-stage AOCs and some Great Lakes reference areas. Environ. Toxicol. Chem. 2010; 29:1748,1754. © 2010 SETAC [source] Effects of pulp and paper mill effluent on fish: A temporal assessment of fish health across sampling cyclesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Timothy J. Barrett Abstract The Canadian environmental effects monitoring (EEM) program is a regulated, cyclical, industry-funded program designed to determine whether receiving water impacts exist when a mill is in compliance with its discharge limits. The results from three cycles of the fish monitoring program (1992 to 2004) are available from over 200 surveys of fish compared between sites located upstream and downstream of pulp and paper mill effluent outfalls. Previous meta-analyses have shown a national average response pattern across cycles characterized by an increase in endpoints measuring energy storage and growth and a decrease in a reproductive endpoint, consistent with a response of nutrient enrichment in combination with some form of metabolic disruption. Although the national average pattern of effects was temporally consistent, there was some variability in the magnitude of effects among cycles. Questions were raised as to whether the intercycle variability was due to changes in effluent quality or due, at least in part, to other factors. The present study compares responses over the first three cycles, and shows that the choice of sentinel species is likely to be a major contributing factor to the variability in observed effects. Subset analyses using studies from mills that used the same sentinel species across cycles reveal fairly uniform responses and little evidence of significant improvements in overall fish health from cycles one to three. However, a meta-analysis using 1991 data collected from 10 mills before the implementation of the EEM program and data from the same mills collected during cycles one to three of the program reveal significantly reduced effects on relative liver weight and potential improvements in other endpoints. Environ. Toxicol. Chem. 2010;29:440,452. © 2009 SETAC [source] Trout density and health in a stream with variable water temperatures and trace element concentrations: Does a cold-water source attract trout to increased metal exposure?ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2009David D. Harper Abstract A history of hard-rock mining has resulted in elevated concentrations of heavy metals in Prickly Pear Creek (MT, USA). Remediation has improved water quality; however, dissolved zinc and cadmium concentrations still exceed U.S. Environmental Protection Agency water-quality criteria. Physical habitat, salmonid density, fish health, and water quality were assessed, and metal concentrations in fish tissues, biofilm, and macroinvertebrates were determined to evaluate the existing condition in the watershed. Cadmium, zinc, and lead concentrations in fish tissues, biofilm, and invertebrates were significantly greater than those at the upstream reference site and an experimental site farther downstream of the confluence. Fish densities were greatest, and habitat quality for trout was better, downstream of the confluence, where water temperatures were relatively cool (16°C). Measures of fish health (tissue metal residues, histology, metallothionein concentrations, and necropsies), however, indicate that the health of trout at this site was negatively affected. Trout were in colder but more contaminated water and were subjected to increased trace element exposures and associated health effects. Maximum water temperatures in Prickly Pear Creek were significantly lower directly below Spring Creek (16°C) compared to those at an experimental site 10 km downstream (26°C). Trout will avoid dissolved metals at concentrations below those measured in Prickly Pear Creek; however, our results suggest that the preference of trout to use cool water temperatures may supersede behaviors to avoid heavy metals. [source] Effects of contaminated sediment on the epidermis of mummichog, Fundulus heteroclitusENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Laurent C. Mézin Abstract Secretion of mucus by epidermal goblet cells protects fish against many biological, physical, and chemical insults encountered in the environment. This study monitored changes in hemoglobin concentration in epidermal mucus and in the density, diameter, and mucus quality of epidermal goblet cells in the mummichog, Fundulus heteroclitus, following exposure to creosote-contaminated sediment from the Elizabeth River, Virginia, USA. Fish were exposed for 13 d in flow-through aquaria to either uncontaminated (US) or contaminated (CS) sediments and were sampled periodically. The condition index was lower and the mortality rate and the occurrence of epidermal lesions were higher in CS-exposed fish than in US-exposed fish. Hemoglobin contents in epidermal mucus from the former group were significantly higher than from the latter. Significant reductions in both size and density of goblet cells in CS-exposed fish suggested a mucus secretion rate exceeding its production rate. Significant changes in mucin types between treatments did not occur until day 13 and are not believed to be directly related to the creosote present in the contaminated sediment. These results all indicate that exposure to creosote-contaminated sediment had a profound and deleterious effect on fish health. [source] Evaluation of stress- and immune-response biomarkers in Atlantic salmon, Salmo salar L., fed different levels of genetically modified maize (Bt maize), compared with its near-isogenic parental line and a commercial suprex maizeJOURNAL OF FISH DISEASES, Issue 4 2007A Sagstad Abstract The present study was designed to evaluate if genetically modified (GM) maize (Bt maize, event MON810) compared with the near-isogenic non-modified (nGM) maize variety, added as a starch source at low or high inclusions, affected fish health of post-smolt Atlantic salmon, Salmo salar L. To evaluate the health impact, selected stress- and immune-response biomarkers were quantified at the gene transcript (mRNA) level, and some also at the protein level. The diets with low or high inclusions of GM maize, and its near-isogenic nGM parental line, were compared to a control diet containing GM-free suprex maize (reference diet) as the only starch source. Total superoxide dismutase (SOD) activity in liver and distal intestine was significantly higher in fish fed GM maize compared with fish fed nGM maize and with the reference diet group. Fish fed GM maize showed significantly lower catalase (CAT) activity in liver compared with fish fed nGM maize and to the reference diet group. In contrast, CAT activity in distal intestine was significantly higher for fish fed GM maize compared with fish fed reference diet. Protein level of heat shock protein 70 (HSP70) in liver was significantly higher in fish fed GM maize compared with fish fed the reference diet. No diet-related differences were found in normalized gene expression of SOD, CAT or HSP70 in liver or distal intestine. Normalized gene expression of interleukin-1 beta in spleen and head-kidney did not vary significantly between diet groups. Interestingly, fish fed high GM maize showed a significantly larger proportion of plasma granulocytes, a significantly larger sum of plasma granulocyte and monocyte proportions, but a significantly smaller proportion of plasma lymphocytes, compared with fish fed high nGM maize. In conclusion, Atlantic salmon fed GM maize showed some small changes in stress protein levels and activities, but none of these changes were comparable to the normalized gene expression levels analysed for these stress proteins. GM maize seemed to induce significant changes in white blood cell populations which are associated with an immune response. [source] A NEW LARVAL FISH BIOASSAY FOR TESTING THE PATHOGENICITY OF PFIESTERIA SPP. (DINOPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 3 2003Vincent J. Lovko Water quality, microbial contamination, prior fish health, and variable results have been major impediments to identifying the cause and mechanism of fish mortality in standard aquarium-format Pfiesteria bioassays. Therefore, we developed a sensitive 96-h larval fish bioassay for assessing Pfiesteria spp. pathogenicity using six-well tissue culture plates and 7-day-old larval cyprinodontid fish. We used the assay to test pathogenicity of several clonal lines of Pfiesteria piscicida Steidinger and Burkholder and P. shumwayae Glasgow and Burkholder that had been cultured with algal prey for 2 to 36 months. The P. shumwayae cultures exhibited 80%,100% cumulative mortality in less than 96 h at initial zoospore densities of approximately 1000 cells·mL,1. No fish mortalities occurred with P. piscicida at identical densities or in controls. In a dose-response assay, we demonstrated a strong positive correlation between dinospore density and fish mortality in a highly pathogenic culture of P. shumwayae, generating a 96-h LD50 of 108 zoospores·mL,1. Additionally, we applied the assay to evaluate a 38-L P. shumwayae bioassay that was actively killing fish and compared results with those from exposures of juvenile tilapia (Oreochromis niloticus) in a 500-mL assay system. Water from the fish-killing 38-L assay was filtered and centrifuged to produce fractions dominated by dinoflagellates, bacteria, or presumed ichthyotoxin (cell-free fraction). After 96 h, the larval fish assay exhibited 50%,100% cumulative mortality only in fractions containing dinoflagellates, with no mortalities occurring in the other fractions. The 500-mL bioassay with tilapia produced inconsistent results and demonstrated no clear correlation between mortality and treatment. The new larval fish bioassay was demonstrated as a highly effective method to verify and evaluate dinoflagellate pathogenicity. [source] Toward Improved Public Confidence in Farmed Fish Quality: A Canadian Perspective on the Consequences of Diet SelectionJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2010Anthony P. Farrell Marine fish oils (MFO) are used in salmon diets to mimic the natural diet, to ensure that essential fatty acid requirements for good fish growth and health are met, and to provide salmon flesh with an omega-3 highly unsaturated fatty acid content that can benefit human health. However, an extensive use of MFO in formulated salmonid diets is perceived as an unsustainable use of wild marine fish stocks. In addition, MFOs have a background level of persistent organic pollutants (POPs) unrelated to aquaculture practices. This review considers recently completed studies using alternative lipid sources of terrestrial origin as replacements for MFO and shows that the composition of conventional finfish diets can be altered to reduce the reliance on MFO while concurrently maintaining fish health as well as reducing background levels of POPs. A challenge still ahead is the need for a concerted and sustained outreach to ensure that the public is aware of such improvements to seafood quality so that the preoccupation of the news media with presenting negative images of fish culture to the public is combated. [source] Effects of a natural parasitical infection (Lernanthropus kroyeri) on the immune system of European sea bass, Dicentrarchus labrax LPARASITE IMMUNOLOGY, Issue 12 2009M. A. HENRY Summary The immune response of European sea bass, Dicentrarchus labrax, to a natural infection by the copepod parasite Lernanthropus kroyeri was evaluated for the first time in vivo. The results clearly demonstrated the triggering of the fish immune system by the parasite. Lysozyme activity and alternative complement pathway were involved in the early action against the parasitical infection, whilst classical complement and respiratory burst (RB) activity took over in the later stages of infection. It was hypothesized that the levels of alternative and classical complement and RB stimulation indexes may determine the resistance capacity of the fish to the parasite. It is not clear how parasites can survive despite the strong immunological arsenal deployed by the fish. The continual increase of prevalence and severity of parasite infection suggested that the parasite's mechanism of evasion of the immune system was extremely successful. The contrasting decrease in the negative effects of parasites on the fish health (such as gills anaemia) suggested that an equilibrium between the parasites and their hosts was reached in chronic infection. These dynamic interactions between parasites and fish hosts were probably the main determinant of host specificity. [source] Maximum limits of organic and inorganic mercury in fish feedAQUACULTURE NUTRITION, Issue 2 2004M.H.G. Berntssen Abstract The relatively high levels of mercury found in fish feeds might form a fish health and food safety risk. The present study aims to establish sublethal toxic threshold levels in fish and assess feed-fillet transfer of dietary mercury. Atlantic salmon (Salmo salar L.) parr were fed for 4 months on fish meal-based diets supplemented with mercuric chloride (0, 0.1, 1, 10 or 100 mg Hg kg,1 dry weight (DW)) or methylmercuric chloride (0, 0.1, 0.5, 5 or 10 mg MeHg kg,1 DW). At the end of the experiment, dietary inorganic mercury mainly accumulated in intestine (80% of body burden) and assimilation was low (6%). In contrast, methylmercury readily accumulated in internal organs and muscle (80% of body burden) and had a relatively high assimilation (23%). Highest accumulation of dietary inorganic mercury was observed in the gut and kidney. Fish fed 10 mg Hg kg,1 had an early (after 2 months) significant increase in renal metallothionein (MT) level and intestinal cell proliferation, followed by intestinal pathological conditions after 4 months of exposure. At 100 mg Hg kg,1, intestinal and renal function were reduced as seen from the significantly reduced protein and glycogen digestibility and increased plasma creatinine levels. For dietary methylmercury (MeHg), highest accumulation was found in blood and muscle. Intestinal cell proliferation and liver MT significantly increased at 5 mg MeHg kg,1 after 2 months of exposure. At the end of the experiment, blood haematology was significantly affected in fish fed 5 mg MeHg kg,1 and these fish exceeded the current food safety limit for mercury. Tissue MT induction and intestinal cell proliferation appeared to be useful and quantifiable early indicators of toxic mercury exposures. Based on the absence of induction of these early biological markers such as MT and cell proliferation, nonobserved effect levels (NOELs) could be set to 0.5 mg Hg kg,1 for dietary methylmercury and 1 mg Hg kg,1 for inorganic mercury. Lowest observed effect levels (LOELs) levels could be set to 5 mg kg,1 for methylmercury and 10 mg Hg kg,1 for inorganic mercury. [source] Effects of the probiotic, Lactobacillus acidophilus, on the growth performance, haematology parameters and immunoglobulin concentration in African Catfish (Clarias gariepinus, Burchell 1822) fingerlingAQUACULTURE RESEARCH, Issue 14 2009Mohammed Abdullah Al-Dohail Abstract This experiment was carried out to evaluate the effects of the probiotic, Lactobacillus acidophilus, on the growth performance, haematology parameters and immunoglobulin concentration in African catfish Clarias gariepinus fingerling. Two experimental diets were formulated to contain 35 g kg,1 crude protein and 10 g kg,1 lipids accordingly and fed three times daily for 12 weeks to 25 C. gariepinus fingerlings per fibreglass tank in 12 replicates each. The control diet was prepared with no probiotic supplementation whereas the second diet was prepared supplemented with a probiotic, L. acidophilus, containing about 3.01 × 107 colonies/g of diet. The results show that growth performance [specific growth rate (SGR) and relative growth rate (RGR)], nutrient utilization [protein efficiency ratio (PER) and feed conversion ratio (FCR)] and survival were significantly (P<0.05) higher in fish maintained on the probiotic-supplemented diet compared with those on the control diet. Haematology parameters (packed cell volume, haemoglobin, erythrocyte sedimentation rate, red blood cell and white blood cell, total serum protein, Ca2+, Mg2+, Cl,, glucose and cholesterol) and total immunoglobulin concentrations were also significantly better in fish fed the probiotic-supplemented diet than in the control. Although the water quality parameters monitored were better in the fish fed the probiotic-supplemented diet than in the control, the parameters were not significantly different (P>0.05). From the results of this experiment, we conclude that L. acidophilus can be used as a probiotic agent in African catfish culture, to enhance fish health, survival and better feed efficiency and growth performance. [source] | |||||||||||||