Environmental Engineering Reference
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environmental warming. The shift occurred at every level of organization.
At the individual-level, the authors found that the fi nal size of adults was
lower at higher temperatures. At the population level, a dual response was
found, since intra-specifi c size changed negatively with warming and the
age-structure of the population also modifi ed by an increase in the number
of juveniles. In addition, temperature can shape the population structure by
infl uencing the reproductive traits, for instance, the spawning period, age at
sexual maturity, and egg and larval size are determined by temperature in
most species (e.g., Crozier et al. 2008, Hutchings and Myers 1994, Jonsson
and Jonsson 2004). Finally, at the community-level warming benefi ted the
smaller species over the bigger, leading to a shift on the community structure
(Daufresne et al. 2009).
Special attention has been given recently to the interplay between
climate warming and the occurrence of marine diseases and parasitism.
Warmer temperatures are expected to benefi t the development, dispersal
and transmission of pathogens (Harvell et al. 2002, Parmesan 2006, Walther
et al. 2009), while climate-driven changes and human activities are expected
to accelerate the emergence and geographical expansion of infectious
diseases and parasitism (Brooks and Hoberg 2007). However, the long-
term response of pathogens to climate warming in marine systems seems
to involve several species-specifi c and host-specifi c aspects and is under
considerable debate (e.g., Ward and Lafferty 2004).
Changes in community abundance, structure and phenology. Temperature might
have a direct infl uence on population abundance by affecting individualĀ“s
physiology. Furthermore, population abundance and biomass are indirectly
infl uenced by temperature since it determines the magnitude of growth and
recruitment rate, as well as the geographical distribution of species. Also,
by changing the distribution and availability of plankton, climate warming
might change carrying capacity of an ecosystem, leading to changes in
the abundance and structure of local fi sh communities (Beaugrand et al.
2008). For example, temperature infl uences the population abundance of
the Atlantic cod ( Gadus morhua ) by affecting larval recruitment, however, as
temperature rises cod stocks increase in the lower temperature range and
decrease in the upper temperature range (e.g., Sundby 2000). On the other
hand, the long-term temperature increase had a net positive effect on the
recruitment of pipefi sh ( Entelurus aequoreus ) in the Northeastern Atlantic
since 2002, probably as a result of the benefi cial effect on the reproductive
trait of the species (Kirby et al. 2006).
The occurrence of community reorganization and ecological regime
shifts has also been associated to climate change (Stenseth et al. 2002). Fish
communities on the North Sea have experienced profound modifi cations
since 1970, given that smaller species benefi ted by climate warming and
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