Browsing by Subject "herring"

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  • Raubenheimer, Marie-Claire (Helsingin yliopisto, 2020)
    Oil spillages represent a serious environmental hazard for flora and fauna of marine and coastal ecosystems. Though marine oil spills have decreased since the 1970s, the increasing production of petroleum goods remains a potential source of pollution due to its use and transportation. When aquatic organisms, including fish, are exposed to toxic oil compounds, this can cause sublethal morphological changes and increase mortality. In this context, herring have been frequently studied, and results suggest that particularly herrings eggs and larvae are highly susceptible to oil toxicity. In this thesis, a Bayesian meta-analysis was conducted to investigate the effects of crude and fuel oil on the mortality of herring eggs from the genus Clupea. Observations from laboratory studies, collected during a literature review, served as input for the statistical analysis. To this end, Bayesian inference modeling was applied to generate posterior probability distributions for additional mortality caused by exposure to oil mixtures. Also, oil concentration, oil type, exposure time, and temperature were analyzed to study possible correlations with mortality impacts. The results of this study suggest that acute mortality of exposed herring eggs is similar to mortality observed for individuals exposed to only small concentrations or none at all. Of all evaluated oil types, medium grade crude oil caused the most significant change in instantaneous mortality with increasing oil concentration. Generally, distinct oil types had a greater influence on mortality outcomes than temperatures at the given concentrations. For the lowest temperatures, some correlations for increased mortality were found. Overall, the unexplained variability between the reviewed studies has a relatively small influence on mortality outcomes. In conclusion, the mortality of exposed herrings eggs is most likely delayed due to sublethal effects, rather than immediate, at the modeled concentrations. Altogether, uncertainty amongst the posterior probability distributions is high, indicating a wide possibility range for the monitored parameters' actual values. The reasons for elevated uncertainty likely stem from diverse experimental setups, biological differences between tested species, relatively small sample sizes, and model-related issues. Thus, future research could consider additional variables, information from observational studies and other fish species to reduce uncertainty in mortality outcomes.
  • Lyhs, Ulrike; Korkeala, Hannu; Vandamme, Peter; Björkroth, Johanna (Elsevier, 2001)
    Spoilage characterised by bulging of lids and gas formation affected various product lots of different marinated herring types. Microbiological analyses resulted in growth on MRS and Rogosa SL agar. Altogether, 206 randomly selected colonies from two unspoiled and ten spoiled samples were characterised using phenotypical key tests and a 16123S rRNA gene-based RFLP identification database. L. alimentarius was found to be the specific spoilage organism in all samples. All isolates obtained from the different product types were of the same clonal type. The slight rise in pH value together with marked gas production suggested a rare lactic acid bacteria spoilage type called ‘protein swell’. L. alimentarius has not been previously associated with herring spoilage.
  • Lyhs, Ulrike; Koort, Joanna M.K.; Lundström, Hanna-Saara; Björkroth, K. Johanna (Elsevier, 2003)
    Spoilage characterised by strong slime and gas formation affected some manufacture lots of 2 an acetic-acid Baltic herring (Culpea haerengus membras) preserve after few weeks’ storage 3 at 0-6°C. The product consisted of herring filets in acetic acid marinade containing sugar, 4 salt, allspice and carrot slices. Microbiological analyses of the spoiled product showed high 5 lactic acid bacterium (LAB) levels ranging from 4.5 ×108 to 2.4 × 109 CFU/g. Yeasts were 6 not detected in any of the herring samples. Since LAB contaminants seldom are associated 7 with fresh fish, LAB populations associated with marinade ingredients (carrots, allspice) 8 were also analysed. The highest LAB levels exceeding 107 CFU/g were detected in 9 equilibrium modified atmosphere packaged baby carrots whereas the levels detected in the 10 allspice samples did nor exceed 4.3 × 105. A total of 176 randomly selected LAB isolates 11 originating from herring, carrot and allspice samples were further identified to species level 12 using a 16 and 23S rRNA gene RFLP (ribotyping) database. Leuconostoc gelidum and 13 Leuconostoc gasicomitatum strains dominated both in the spoiled herring and carrot samples. 14 These species are heterofermentative producing CO2 from glucose and they also produce 15 dextran from sucrose. Inoculation of some commercial herring products with spoilage- 16 associated L. gelidum and L. gasicomitatum strains verified that these strains have the 17 capability of producing slime and gas in herring preserves although slime formation was not 18 as strong as in the original samples. Since L. gelidum and L. gasicomitatum strains were 19 commonly detected in carrots, carrot slices used for the fish marinade were considered to be 20 the probable source of these specific spoilage organisms. 21
  • Teacher, Amber G. F.; Andre, Carl; Jonsson, Per R.; Merila, Juha (2013)