3.2. Morphological examination in the acidic treatments
When first tested, T. lalius showed morphological differences
based on SEM and histological sections in the 1st and 4th gill arches
(Figs. 1 and 2). Within 1 day (data not shown), the lamellae in the 1st
gill arch were thicker in the acidic group than in the control group
(Fig. 1A and B). More variations were found on day 2 (data not
shown). The most severe variation was on day 4 (Fig. 1E and F) before
the gill arch returned to a rather normal appearance on day 7 (Fig. 1I
and J). On day 4, we could easily find two filaments or several lamellae
merged. Similar profiles of morphological changes were also found in
the 4th gill. The lamellae were thicker within 1 day (data not shown)
than the control group (Fig. 2A and B), and there were more variations
on day 2 (data not shown), most severe on day 4 (Fig. 2E and F), and
returned to normal on day 7 (Fig. 2I and J).