Environmental Engineering Reference
In-Depth Information
levels in pelagic ecosystems implies that the impact of future climate change
will permeate the entire marine food webs. Ocean temperature is likely to
be further affected by anthropogenic climate change. The IPCC predicts
a rise in temperature of between 2 and 4°C in the northeast Atlantic by
2100 (Richardson and Schoeman 2012). The effect of climate change will
have severe impacts on phytoplankton community, herbivorous copepods
and carnivorous zooplankton, thereby affecting ecosystem services, such
as oxygen production, carbon sequestration, and biogeochemical cycling
(Richardson and Schoeman 2012). Finally, fi shes, seabirds, and marine
mammals will need to adapt to a changing spatial distribution of primary
and secondary production within pelagic marine ecosystems (Richardson
and Schoeman 2012).
Changes in zooplankton distributional ranges.
Distributions and/or abundances
of numerous species have been extensively altered by human activities
(e.g.
,
habitat loss, ecosystem alteration) (Hughes 2000). However, some
distributional shifts are explained more by an association with changing
climatic conditions, especially when the shift has been towards the poles
(Hughes 2000). Fossil evidence shows that marine organisms shifted
polewards as sea surface temperatures raised, e.g.
,
during the Pleistocene-
Holocene transition (Harley et al. 2006). Although relatively few in number,
long-term ocean biological data indicate that zooplanktonic organisms
exhibit fast and large shifts in their ranges in response to global warming
(Richardson 2008). Most cases correspond to species whose distributions
are mainly driven by climate or organisms that are highly mobile at some
stage of their life cycle (Hughes 2000).
Several copepod species have already modifi ed their habitat ranges
in response to climate warming. Most of the examples are from the North
Atlantic, where the Continuous Plankton Recorder survey (CPR) has been
operating since 1931 (Richardson et al. 2006). The CPR survey provides
a unique long-term dataset of oceanic plankton abundance in the North
Atlantic and North Sea (Warner and Hays 1994). It has been running for
almost 70 years sampling at a depth of 10 meters. In 1998,
Calanus hyperboreus
was recorded at its farthest southern limit in the CPR survey, 39°N, off the
Georges Bank shelf edge (Johns et al. 2001). These authors suggested a direct
response of this species to a cooling of the surrounding environment. Ocean
climate in the Northwest Atlantic is driven by thermohaline mechanisms,
and these infl uence the south-fl owing Labrador Current (Richardson
2008). The Labrador-Newfoundland area experienced abnormally cold
temperatures during the late 1980s and early 1990s (Prinsenberg et al.
1997)
which increased the production of Labrador seawater and thus the strength
of the Labrador Current (Dickson 1997). This cold water has spread farther
