Environmental Engineering Reference
In-Depth Information
small body size are particularly well adapted to change their distributional
range (Perry et al. 2005). Behavioral adaptation of fi sh species to climate
warming also includes vertical migration in the water column in order to
encounter deeper and colder waters (Perry et al. 2005, Dulvy et al. 2008).
Several fi sh species have already extended their range distribution in
response to climate warming. For instance, in the North Sea temperature
rising matched with an increase of species richness, as a result of a range
expansion of small species from lower latitudes (e.g., Brander et al. 2003,
Wynn et al. 2007, Hiddink and Hofstede 2008). In the southern hemisphere
(Tasmania, southeastern Australia), several inshore species experienced
pole-ward movements since 1970 in response to sea temperature rising (Last
et al. 2011). Species from cold waters in high latitudes are also undergoing
distributional shifts. For example, as a result of sea ice retreat in the Bering
Sea, a new habitat has emerged northward which used to be permanently
covered by ice, and has been colonized by several invertebrate and fi sh
species (Mueter and Litzow 2008). The distribution and diversity of top
predators in the North Pacifi c are expected to change under the current
climate trend, since some predator species (e.g., the shark guild) might be
impaired by habitat compression, while others (e.g., tuna) might benefi t
by gaining core habitat (Hazen et al. 2012). However, the synergistic effect
of climate change and human activities might exacerbate population
vulnerability and lead to irreversible shift on community confi guration.
Besides the direct effect of temperature, the shifts in the geographical
pattern of preys as a result of climate driven changes, may indirectly affect
the range distribution of many fi shes. Due to their small size and rapid
turnover rates, phyto- and zooplankton experience rapid response to
warming. Many studies conducted in diverse habitats have registered shifts
on the distribution map of diverse planktonic communities (e.g., Mackas et
al. 2007, Richardson and Schoeman 2004, Beaugrand et al. 2002) as well as
changes in the pattern of ocean productivity (Behrenfeld et al. 2006). These
major changes permeate the entire ecosystem through cascading effects in
the trophic web, and determine the fate of fi sheries worldwide (Brown et
al. 2010). In the North Sea, the abundance and survival of cod larvae (
Gadus
morhua
), are directly linked to the cold water copepod
Calanus fi nmarchicus
(Beaugrand and Kirby 2010). However, in recent years this species have
retracted toward the North Pole and is thought of as highly vulnerable
to climate stress due to shrinkage of its ecological niche (Helaouët et al.
2011). This copepod species represents a key food item for various fi sh
species, including the cod, and it has been hypothesized that the reduced
geographical availability of copepods leads to enhanced cod larvae mortality
in the North Sea (Beaugrand et al. 2003). In the future, the cumulative and
probably intensifi ed effects of climate warming will have an increased
