Environmental Engineering Reference
In-Depth Information
impact on fi sh community, which will rely on geographic gradient, species-
specifi c plasticity and the strength of community interactions (Roessig et
al. 2004).
Effects of other climate-driven changes in aquatic systems
Besides temperature rising, several abiotic changes have permeated the
marine ecosystems as a result of global climate change. These include
increase of atmospheric CO
2
concentration, ocean deoxygenation, enhanced
occurrence of extreme weather events, and changes in ocean circulation
patterns.
CO
2
increase.
The increase of CO
2
emission has generated an increase
on the concentration of CO
2
in the world's oceans, which is evidenced
by a reduction of seawater pH and ocean acidifi cation (e.g., Caldeira
and Wickett 2003, Orr et al. 2005, Wootton et al. 2008). Lower ocean pH
impacts negatively on calcifying organisms such as phytoplankton, corals,
mollusks and crustaceans (Orr et al. 2005); produces severe tissue damage
of fi sh larvae (Frommel et al. 2011), and impairs food quality and transfer
efficiency in aquatic communities (Rossoll et al. 2012). Physiological
responses of aquatic organisms to decreasing seawater pH remains almost
unknown, however, recent studies demonstrated that olfactory and auditory
capacity of fi shes can be disrupted when exposed to pH levels close to the
ones expected to occur in 2100. Tropical fi sh larvae proved to be unable
to discriminate olfactory and auditory cues for detecting predators and
suitable settlement habitats when exposed to lower pH levels (Munday
et al. 2009, 2010, Simpson et al. 2011). The modifi cation of such essential
behavioral trait during early life history stages might ultimately lead to
reduced adult survival and species recruitment. Additionally, fi sh otoliths
are vulnerable to increasing CO
2
concentration as they are composed of
aragonite. These constituent of fi sh ears are essential to adequately detecting
external auditory stimuli and body orientation, and when exposed to high
CO
2
concentrations, otolith become overcalcifi ed and lose functionality
(Checkley et al. 2009, Manjela et al. 2012a, Munday et al. 2011).
Brain function is also affected by the concentration of CO
2
by altering
fi sh lateralization, which is a key mechanism involved in behavioral
activities including predator avoidance (Domenici et al. 2012). Moreover,
the swimming behavior of the Atlantic cod was also shown to respond
to increasing CO
2
concentration (Manjela et al. 2012b). Behavioral shifts
after high CO
2
exposures might decrease predator avoidance and species
fi tness.
Deoxygenation.
Deoxygenation of certain oceanic regions is expected to
occur as a consequence of a decrease in oxygen solubility due to elevated
