Environmental Engineering Reference
In-Depth Information
invasive species, development, hunting, and climate change (Davidson et
al. 2012). Marine mammals accumulate large concentrations of contaminants
in organs and tissue, such as organochlorine contaminants (OCs), heavy
metals and polycyclic aromatic hydrocarbons (PAHs) (Leonzio et al. 1992,
Marcovecchio et al. 1994, Fossi and Marsili 1997, Lailson-Brito et al. 2008).
Evidence links pollutants exposure to several biological effects in marine
mammals, such as, immune and endocrine system dysfunction, increased
risk of infection or diffi culties in reproduction (De Guise 1995, Jepson et
al. 2005, Hall et al. 2006).
These changes in the marine environment in turn have direct and
indirect potential impacts on marine mammals. Direct impacts include the
mentioned effects of reduced sea ice and rising sea levels on seal haul-out
sites, while indirect impacts include changes in prey availability affecting
distribution, abundance and migration patterns, community structure,
susceptibility to disease and contaminants (Learmonth et al. 2006).
Moreover, rapid climate change is likely to impose strong selection
pressures on traits important for fi tness (Gienapp et al. 2008). One of the
potential long term effects of climate change will be alterations of the
genetic structure of wildlife populations (Lynch and Lande 1993). The
knowledge of current genetic structure and the effect of past climate
on patterns of geographical differentiation at the molecular level may
reveal valuable information on the underlying evolutionary processes
and past demographic events (Milá et al. 2000) and would light up on
the future genetic consequences of present climate change (Waltari et al.
2007). Molecular markers, such as mitochondrial DNA genes and nuclear
microsatellites, have been extensively used in marine mammals in the last
decade for the study of these topics (Trujillo et al. 2004, Weber et al. 2004,
Baker et al. 2005, Hoffman et al. 2006, 2009, Matthee et al. 2006, Fontaine et
al. 2007, Túnez et al. 2007, 2010).
The earth's climate is changing, the planet is warming, sea ice and
glaciers are in retreat, sea level is rising, and pollutants are accumulating
in the environment and within organisms (Moore 2008). The severity of
damaging human-induced climate change that takes place due to increase
in carbon dioxide concentration is largely irreversible (Solomon et al. 2009).
All these changes affect marine ecosystem and the different marine species
suffer the consequences. All those species that depend upon the ice, such
as polar bear (
Ursus maritimus
) and the ringed seal (
Phoca hispida
) are good
examples of these changes and they are very sensitive at population level
to climate change. Carnivores are the clearest examples, and the response
of cetaceans to climate change are more diffi cult to evaluate because they
are more extended in their home range and are totally aquatics, besides
bears and seals which depend upon ice or land to complete their life cycles.
The use of marine mammals as ecosystem sentinels is a function of their
