Environmental Engineering Reference
In-Depth Information
fairly recent major impact to coastal ecosystems, whose effects are most
remarkable due to the synergy established with previous impacts that have
been taking place for longer historical periods. In our discussion, we will
demonstrate that the enchainment of these factors produces major impacts
on coastal ecosystems.
Biodiversity: Defi nitions and Conceptual Approaches
Biological diversity or
biodiversity
(a term introduced a few decades ago)
comprises the variety of life on Earth, from genes and organisms to larger
units such as ecosystems and landscapes. This concept not only encompasses
the biotic components of ecosystems, but also makes reference to specifi c
temporal and spatial dimensions and the complex species interactions that
arise as a product of natural selection, adaptation and other evolutionary
processes.
As much as a quantifi cation of the intrinsic value of biodiversity
would contribute to the argumentation for its conservation, assigning a
value to biodiversity is a diffi cult task and it necessarily implies a value
assessment from a multidimensional perspective (González Barberá and
López Bermúdez 2000). Numerous studies indicate the fundamental role
of biodiversity in the modulation of ecosystem functioning and stability
(Emmerson et al. 2001, Singh 2002, Hooper et al. 2005).
The
ecosystem approach
is a perspective that emerged from 1992 Rio's
Earth Summit, which deals with ecosystem functioning and management
from a holistic perspective (Beaumont et al. 2007). Biodiversity clearly
affects the way ecosystems function (Hooper et al. 2005), and in that sense,
identifying
ecosystem services
facilitates the incorporation of biodiversity into
management discussions and planning. Simply put, such services are the
benefi ts that humans obtain from ecosystems. These include
provisioning
services
such as food and water;
regulating
services
that affect climate, fl oods,
and water quality;
cultural
services
that provide recreational, aesthetic, and
spiritual benefi ts; and
supporting
services
such as soil formation, primary
productivity, and nutrient cycling. Most, if not all, human endeavors are
directly or indirectly dependent upon ecosystem services (Hooper et al.
2005, UN Millennium Ecosystem Assessment 2007).
Despite some successful conservation efforts (mostly at local scales)
biodiversity continues to decline (Rands et al. 2010). Marine ecosystems
are not exempt to this global trend, and despite their adaptive nature,
they are vulnerable to rapid changes in diversity and function (Palumbi
et al. 2008). To name a few examples, the increasing pressure on marine
biodiversity is evidenced by the steep declines in fi sh populations and
loss of marine habitats that resulted from overexploitation of fi sh protein
from the top of the food chain; poorly managed aquaculture practices;
