concentration of hydrogen ions (pH) can affect the organisms that
live in water.
Aquatic organisms have adapted over time to survive
and reproduce in a relatively narrow range of hydrogen ion concentrations.
Some bacteria can withstand environments that have high hydrogen
ion concentrations (pH = 2 or 3); other bacteria can live at very
low hydrogen ion concentrations (pH = 12 or 13). However,
most fish can only survive and reproduce in a water that is not
very acidic or basic, but is water that is "just right".
Most fish survive best in water that is close to "neutral"
or, in terms of pH, at a pH between 6.5 and 8.2. Immature
stages of aquatic insects (mayfly nymphs, stonefly nymphs, caddis
larvae), snails, tadpoles, and crayfish are also very sensitive
to changes in hydrogen ion concentration and seem to reproduce and
survive best under "neutral" conditions (pH = 6 to 8).
In water that is very acidic (low pH values), the concentration
of heavy metals ions (copper, aluminum, etc.) increases and, this
in turn, has negative effects on the health of aquatic organisms.
In general, more acidic conditions tend to cause
animals to become less excitable and, in extreme conditions, can
lapse into a coma. More basic conditions can lead to animals
becoming hyper excitable (over excited).
to see how acid rain affects certain organisms, such as trout.
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