Exposure to Sublethal Concentrations of Copper Affecting Ion Balance in Tilapia Larvae (Oreochromis Mossambicus)

Abstract

將孵化一天的吳郭魚(Oreochromis mossambicus)仔魚以0及100μg/L之銅處理11天，分別在0、l、3、5、7、12、24、48、96、120、168、240、264小時等不同之時間點，測定仔魚體內鈣及鈉離子含量的變化。結果顯示：當仔魚暴露銅水中，12小時內其體內之鈉離子尚無明顯之變化，但是12小時～11日之間，處理組顯著的低於對照組，從5～11日鈉離子之降低幅度趨緩，雖有回升但仍舊比對照組低，無法恢復正常之濃度，同時亦沒有死亡的現象產生。至於鈣離子之變化，在銅處理後第2～11日，處理組之仔魚體內鈣離子濃度開始顯著的低於對照組，隨著暴露時間之延長，處理組與對照組之鈣離子濃度的差距維持在一定之範圍，而且有再現性。我們推論在亞致死濃度之銅處理下之吳郭魚仔魚，於短時間內（12小時～2日）其鈣及鈉離子濃度處在一個調節階段，當延長銅暴露時間時。仔魚成長雖然受到抑制，但是它仍然可維持體內在低鈣(hypo-calcium)及低鈉狀態(hypo-sodium)下而存活在銅水中。

Tilapia larvae (post-hatch. 1-day stage) ere exposed with 0 (control) and 100 μg/L (treatment) for 11 days, and the hole body of the calcium and sodium content as detected after copper exposure at 0, 1, 3, 5, 7, 12 hr and 1, 2, 5, 7, 10, 11 days. The present data show it didn't undergo significant change during 0~12 hr and 0~48 hr of copper exposure for the sodium content and calcium content, respectively. The sodium content was significantly decreased to compare with the control group 12 hr after copper exposure. It was still lower on treatment than the control group. However, the range of the sodium content between treatment and control became narrower during 5~11 days of copper exposure. Besides, the range of the calcium content as smaller and smaller following the copper exposure time. No larvae died during this study, but both the Ca(superscript 2+) and Na(superscript +) levels increased gradually following the larvae growth. According to these data, we suggest that the larvae acclimated in the hypo-sodium and hypo-calcium states, awl even the growth rate of the larvae as inhibited by ambient copper.