Environmental Engineering Reference
In-Depth Information
silicate by non-calcifying organisms). Furthermore, the activity of bacteria
(which produce CO 2 ) and the zooplankton (which consume phytoplankton)
might also be affected by pH, resulting in changes in the structure and
functioning of the marine ecosystem as a whole.
Effects on early developmental stages. Ocean acidifi cation can also produce
effects on early developmental stages, and studies on this subject are very
important since larvae and juveniles are generally more vulnerable to
environmental perturbations, and their survival will largely determine
population abundance, distribution and community confi guration. For
instance, Kawaguchi et al. (2011) found that high concentrations of CO 2
impacted severely on the embryonic development of krill ( E. superba )
embryos and larvae experimentally exposed to different pCO 2 . They found
that at high concentrations development was disrupted before gastrulation
in 90% of embryos, and no larvae hatched successfully. In addition, they
pointed out an urgent need for understanding the pCO 2 -response of later
stages of krill, in order to predict the possible fate of this key species in the
Southern Ocean ecosystems.
Mac Donald et al. (2009) studied the effect of pH on planktonic larval
stages of the barnacle Amphibalanus amphitrite , and revealed no effects
of reduced pH on larval condition, cyprid size, cyprid attachment and
metamorphosis, juvenile to adult growth or egg production. However,
barnacles exposed to pH 7.4 showed overcalcifi cation at the lower, active
growth regions of the wall shells. Despite this enhanced calcification, further
studies revealed that the central shell wall plates required significantly less
force to be penetrated than those of individuals raised at pH 8.2. Therefore,
barnacles with weakened wall shells are more vulnerable to predators.
Some copepod species appear more tolerant to increased CO 2 than
other marine organisms (i.e., sea urchins, bivalves, barnacles, amphipods).
Kurihara and Ishimatsu (2008) found that high CO 2 exposure through all life
stages of the 1st generation of Acartia tsunesis copepods did not signifi cantly
affect survival, body size or developmental speed. Egg production and
hatching rates were also not signifi cantly different between the initial
generation of females exposed to high CO 2 concentration and the 1st and
2nd generation females developed from eggs to maturity in high CO 2 . Mayor
et al. (2007) also found that ocean acidifi cation did not affect the survival
of Calanus fi nmarchicus adults. In fact, growth and egg production of adult
females was not affected by experimentally-simulated ocean acidifi cation.
In contrast, a maximum of only 4% of the eggs successfully yielded nauplii
after 72 h in the experimental treatment. The authors demonstrated that
environmental risk assessments for marine CO 2 disposal must look beyond
adult mortality as an endpoint. Furthermore, they conclude that if CO 2 is to
be disposed of in the deep sea, the location and timing of such activities must
take into consideration the overwintering populations of C. fi nmarchicus.
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