Environmental Engineering Reference
In-Depth Information
partially replaced bigger species (Hiddink and Hofstede 2008). Community
reorganization may also occur as a result of the positive effects of climate
warming on diverse marine organisms, for example, in the last decades
an apparent increase in jellyfi sh blooms and a shift from fi sh-dominated
to jellyfi sh-dominated trophic webs has been registered in many aquatic
habitats (e.g., Mills 2001). The factors leading to this shift include climate
variations, overfi shing, eutrophication and habitat modifi cation (Purcell et
al. 2007). One of the most concerning consequences of jellyfi sh outbreaks
and the replacement of top predators, is that the carbon of planktonic
origin is rerouted into respiration instead of being effi ciently transferred
into upper trophic levels (Condon et al. 2011). Thus, the reorganization of
local food webs as a consequence of global warming, increasing climatic
uncertainty and anthropogenic activities, might lead to profound ecosystem
modifi cations by altering the functioning of the biological pump.
The seasonal recurring cycle or phenology of marine organisms is
mainly driven by environmental signals and the seasonal pattern of
resources availability, and is already being modifi ed by climate change
(Edwards and Richardson 2004). Plankton represents a key food item for
early stages of fi shes, thus the trophic coupling between early stages of fi shes
and mass productivity events in aquatic ecosystems sets the magnitude of
annual recruitment and population abundance and determines the survival
success of fi sh species. Changes in the plankton phenology as a consequence
of temperature shifts lead to trophic mismatch and subsequently, to larval
starvation and decreasing recruitment (Cushing 1990, Durant et al. 2007,
Edwards and Richardson 2004). The trophic mismatch occurs after the
temporal decoupling cannot be overcome by phenotypic plasticity of
predators, and results in prey biomass accumulation due to ineffi cient
exploitation (Donnelly et al. 2012). Hence, the effects of climate change on
the timing of primary producers can be transferred up in the food chain,
impairing the effi ciency of local food webs.
Changes in the distribution range.
Climate change is gradually changing
the mapping of ocean biodiversity as a consequence of changes in species
distribution. As temperature continues to rise, marine species will migrate
pole-ward in search for suitable environmental conditions and resources
(Parmesan and Yohe 2003). Functional traits and adaptability of species
will set the potential for colonizing new geographic areas, and many will
inevitably face local extinction (e.g., Root et al. 2003, Thomas et al. 2004,
Cheung et al. 2009). Fish species are highly susceptible to experience
distributional shifts as a result of climate warming given that their spreading
ability is promoted by the migratory capacity of juveniles and adults, eggs
and larval dispersal strategies and the lack of geographical barriers in oceans
(Metcalfe et al. 2002). Those species with short developmental times and
