Browsing by Author "Deb, Aruna Rani"

Since mercury (Hg) may biomagnify in food webs and bioaccumulate in living things, it is considered a dangerous element globally. The two most toxic forms of mercury are methyl mercury (MgHg) and dimethyl mercury (DMgHg). The dietary Hg consumed by fish is mostly removed through the intestine, but some of the MeHg bioaccumulates and is delivered to various organs, such as the liver, kidney, muscle, or gonad. The perch (Perca fluviatilis), the national fish of Finland serves as both a popular food fish and a monitoring species for assessing the chemical health of lakes. Fish tissue exhibits seasonal variations in mercury levels, which are thought to be produced by growth dilution in the summer, which is related to rapid somatic growth during the growing season, and hunger in the winter, which condenses mercury in the muscle as well as during spawning since gonad development requires significant energy expenditure. There has been a considerable study on Hg concentration in fish but currently lack knowledge regarding potential seasonal variation in patterns of Hg content and bioaccumulation to understand the dynamics of Hg content and bioaccumulation. This study investigates (Q1): Does mercury content change in muscle, liver and gonad tissues of males and females of perch over the four seasons? (Q2): How does mercury bioaccumulation change seasonally in different organs between male and female perch? (Q3): How does the mercury content relationship among different organs (muscle, liver, and gonads) vary seasonally and between sexes? Materials were collected monthly from Lake Pääjärvi from April 2020 to March 2021, and categorized into four seasons: winter (January -March), spring (April-Jun), summer (July-September), and autumn (October-December). Each fish was taken of its length, weight, sex, and other tissues too. Total mercury (Hg) concentrations were determined in three organs (muscle, liver and gonad) in male and female perch separately. Using analysis of variance, the annual length-corrected THg content variation and simple linear regression analysis were used to examine the annual THg bioaccumulation variation and to test the relationships in Hg concentrations among three tissues separately in males and females. Seasonal THg levels in female perch significantly varied in muscle and gonads, not in the liver. Females had consistently higher THg in muscle and liver, while males had higher levels in gonads throughout the season. THg bioaccumulation peaked in spring and winter for both sexes in muscle, but lowest in autumn. Liver THg slope was highest in early summer for females and lowest in autumn. Gonads showed the highest slopes in summer for both sexes. The highest slopes between muscle and liver THg for females were in summer and for males in spring. Similar patterns were seen in both muscle-gonad and liver-gonad THg relationships. Female perch showed significant differences only in summer, while in males, the highest slopes were in autumn and lowest in summer. Long-term monitoring is crucial to understanding THg variation in fish.