Mercury and selenium in free-ranging brown trout (Salmo trutta) in the River Skienselva watercourse, Southern Norway

A Quantitative Assessment and Biomagnification of Mercury and Its Associated Health Risks from Fish Consumption in Freshwater Lakes of Azad Kashmir, Pakistan

Issues regarding biomagnification of mercury (Hg) due to its persistence, bioaccumulation, and toxicity in freshwater lakes have gained much attention in the last two decades especially in remote regions of the world where anthropogenic inputs are considered as negligible. In this study, spatial distribution of total mercury (THg), interspecific accumulation patterns, trophic transfer, and associated health risks in fish of freshwater lakes (357-3107 masl) in Azad Kashmir, Pakistan, were investigated. THg concentrations in the regions were 0.20 ± 0.08 μg g^-1 in glacial, 0.54 ± 0.21 μg g^-1 in rural, and 1.35 ± 0.46 μg g^-1 in urban region. Omnivorous, herbivorous, and carnivorous fish showed THg concentrations of 0.94, 0.85, and 0.49 μg g^-1. Regional, lake, trophic level, and specie-specific differences of THg accumulation were found significant in the study. Among growth parameters, length and age varied significantly among species, trophic levels, and lakes, whereas weight showed significant variation among lakes as well. Condition factor (K) showed significant differences within species, lakes, and trophic levels. Biomagnification was observed in all lakes with the trophic magnification slopes (TMS) ranging from 0.03 to 0.20 with an average of 0.094 ± 0.07. Isotopic values of nitrogen (δ¹⁵N) and condition factor were found to dominate THg accumulation trends; however, no significant health risks were found in the study.

Study of Heavy Metals Pollution and Vitellogenin Levels in Brown Trout (Salmo trutta trutta) Wild Fish Populations

The objectives of this research were, first, to determine the concentrations of certain heavy metals in the edible tissue of wild brown trout (Salmo trutta trutta) from two different rivers located in the Abruzzi region (Italy), and then, to investigate the levels of variation in vitellogenin (VTG) associated with the presence of metalloestrogens. VTG is an effective indicator for endocrine disturbance, and an increase in the vitellogenin levels in male fish is widely employed as a biomarker of estrogenic contamination in the aquatic environment. The muscles of the trout were analyzed for As, Cd, Co, Cr, Ni, Pb, Al, and Zn using an inductively coupled plasma-mass spectrometer (ICP-MS), and Hg was measured using a direct mercury analyzer (DMA-80). The calculated values of the condition factor confirmed a healthy status for this species, indicating that the aquatic habit in both rivers is suitable for brown trout life. No significant difference in the concentrations of each metal were reported between the trout from the two rivers, and no significant difference for VTG levels were found between male and female fish. It is interesting to note the high concentrations of Al/Zn, while the Pb, Cd, and Hg concentrations in all of the samples were lower than those established by the European Commission.