Publisher :
Place of publication :
Publication year : 2008
Thematic : Marine Resources
Language : English
Note
Ocean warming and acidification occur at global scales and, in the case of temperature,
have already caused shifts in marine ecosystem composition and function. In the case of CO2-induced
ocean hypercapnia and acidification, however, effects may still be so small that evidence for changes
in the field is largely lacking. Future scenarios indicate that marine life forms are threatened by the
specific or synergistic effects of factors involved in these processes. The present paper builds on the
view that development of a cause and effect understanding is required beyond empirical observations,
for a more accurate projection of ecosystem effects and for quantitative scenarios. Identification
of the mechanisms through which temperature- and CO2-related ocean physicochemistry affect
organism fitness, survival and success, is crucial with this research strategy. I suggest operation of
unifying physiological principles, not only of temperature but also CO2 effects, across animal groups
and phyla. Thermal windows of optimized performance emerge as a basic character defining species
fitness and survival, including their capacity to interact with other species. Through effects on performance
at the level of reproduction, behaviour and growth, ocean acidification acts especially on
lower marine invertebrates, which are characterized by a low capacity to compensate for disturbances
in extracellular ion and acid–base status and sensitivity of metabolism to such disturbances.
Available data suggest that one key consequence of these features is a narrowing of thermal tolerance
windows, as well as a reduced scope for performance at ecosystem level. These changes in
bioenvelopes may have major implications for the ranges of geographical distribution of these organisms
and in species interactions.
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Encoded by : Pauline Carmel Joy Eje
