3.2. Combination of different sulfide concentrations and
hypoxia
When sulfide concentration under normoxic conditions
was gradually increased, tamoata´ started to lose equilibrium at 52 AM, and at 82 AM 100% of the individuals had lost
their equilibrium. The graphical interpolation showed that
the sulfide lethal limit for this species was about 70 AM
(Fig. 2a). Under hypoxic conditions, fish started to lose
equilibrium at 85 AM. At 93 AM all fish had lost their
equilibrium. The sulfide lethal limit under hypoxic condition
was then calculated as 87 AM (Fig. 2b).
Fig. 3a shows the fRA of tamoata´ exposed to gradual
increases in sulfide concentrations under normoxic conditions.
The fRA increased significantly at 15 AM and
remained nearly constant in the subsequent experimental
sulfide concentrations. Under hypoxia, the fRA increased
significantly at 3.0 AM and remained constant in the
following sulfide concentrations (Fig. 3b).