CLIMATE CHANGE AND OCEAN ACIDIFICATION - Marine Pollution: What Everyone Needs to Know - page 178

because the farther away they go, the more likely they are
to get eaten by predators. Furthermore, Philip Munday and
colleagues studying coral reefs next to natural seeps near
New Guinea (where carbon dioxide bubbles are made by vol-
canic activity), have found that fish lose their fear of preda-
tors. Living in this acidic environment makes small reef fish
become attracted to the smell of their potential predators. In
another example of reduced olfactory behavior, homing abil-
ity is impaired in cardinalfish in low pH. All these modified
behaviors can increase mortality. But predatory behavior can
also be impaired. The brown dottyback (a coral reef fish) in
elevated CO 2 levels shifted their behavior from preference to
avoidance of the smell of injured prey, and decreased their
feeding activity.
The Chilean abalone, a snail that adheres to rocks along
wave-swept shores, quickly rights and reattaches itself when
it is dislodged, an important skill. But when CO 2 levels were
increased (pH decreased), snails were slow to right them-
selves or did not do so at all. Responses of hermit crabs to food
odors were disrupted under reduced pH. Crabs in reduced
pH seawater had lower antennular flicking rates (the sniffing
response), were less successful in locating an odor source, and
had reduced activity compared to those in untreated seawater.
Since there is great variation in sensitivity to OA, we can
expect that some species will thrive while others will diminish
greatly, thus causing major changes in marine communities.
For example, some large crustaceans such as crabs and lobsters
do not seem to be impaired by excess CO 2 , but instead seem
to grow larger, despite their need for calcium in their shells.
Under high CO 2 , they have been found to molt faster. After
molting, they undergo a growth spurt while in the soft-shell
stage. Extra carbon speeds the molt cycle so that they become
bigger, potentially less vulnerable to predators and possibly
better predators themselves. These studies are all preliminary,
and much work needs to be done to understand effects in a
variety of organisms. In acidified conditions mollusks grow