Histophysiological responses in ovary and liver of Cyprinus carpio after short term exposure to safe concentration of mercuric chloride and recovery pattern.

Effect of short term (7 days) exposure to safe concentration of HgCl2 (0.5 ppm) and changes 7 days after withdrawl of the treatment on histophysiology of ovary and liver in yearlings of Cyprinus carpio were assessed during active phase of reproductive cycle. Noticeable degenerative histophysiological changes were observed in both ovary and liver after exposure which were more prominent in the group with abnormal behaviour. After withdrawl of the HgCl2 treatment the recovery was apparent in both organs but was more appreciable in liver. These observations indicated that even safe concentration of HgCl2 might not be fully devoid of deleterious influence on reproductive functions in Cyprinus carpio.

Behavioural and hematological responses of Cyprinus carpio exposed to mercurial chloride.

The static bioassay experiments were conducted to study the hematological and behavioural responses of Cyprinus carpio after exposure to mercuric chloride. Three different concentrations i.e. 0.5, 1.0 and 1.5 ppm of mercuric chloride (HgCl2) were used for 8, 16, 24, 48, 72, 96 and 124 hrs for evaluating behavioural responses. Hematological responses were assessed after 60 days exposure to 0.1 ppm of HgCl2. The changes in body colour, movement, sluggishness or activeness, disbalance etc. constituted the observations on behavioural responses. Hematological parameters included total erythrocyte (TEC) and leukocyte (TLC) counts and hemoglobin (Hb) levels. Body colour had changed in all groups after 48 hours. The fish exposed to 0.5 ppm HgCl2 did not show any abnormal activity except colour change throughout the experiment. Though no sign of distress was observed initially in groups exposed to 1.0 and 1.5 ppm HgCl2 but abnormal posturing, disbalance and sluggishness became apparent after 72 hrs and all specimens of 1.5 ppm group had died within 124 hours. TEC and Hb levels decreased whereas TLC increased in both male and female specimens of C. carpio after exposure to 0.1 ppm HgCl2 for 60 days. These observations indicated that mercurial toxicity even at low levels, caused adverse effects on body colour, behavioural responses and hematological parameters like TEC, TLC and hemoglobin levels in C. carpio.