Environmental Engineering Reference
In-Depth Information
￿ Benthic organisms are also important members of the lower food
web, consuming organic matter and phytoplankton. Constituting a
source of food for larger organisms such as many fi sh, shorebird and
marine mammal species, they link primary production with higher
trophic levels (Carlson et al . 1997). In addition, a number of benthic
invertebrates, particularly clams, are consumed by humans and are
used for recreational purposes such as fi shing bait (McLachlan et al.
1996, Thrush and Dayton 2002).
￿ The infauna of nutrient-poor tropical carbonate sediments play a crucial
role in bioturbation, oxygenation, nutrient cycling and transport, and
processing of pollutants (Snelgrove 1997, 1998, Uthicke and Klumpp
1998, Uthicke 1999). Many benthic organisms, including fi lter feeders
like clams, scallops and mussels, obtain their food by taking in sea
water. As the water fl ows through their bodies, sediments, organic
matter, and pollutants are fi ltered out and ingested.
￿ The interest in benthic indicators for soft-bottom marine communities
has increased dramatically as the need for new tools to assess the status
of marine waters has grown (Dauvin 2012). There are a number of
advantages of using benthic invertebrate fauna for assessing ecological
quality: they are sedentary; they have relatively long life-spans; they
comprise diverse species that exhibit different sensitivities or tolerances
to stress; and they play an important role in the cycling of nutrients
and materials between bed sediments and the overlying water column
(Borja et al . 2000, 2009, Rees et al . 2006, Dauvin 2007, Dean 2008).
Descriptions of benthic variability and its relation to climate change
and other global stressors are still evolving as more evidence and time-
series observations are becoming available. Climate change may modify
population dynamics over time and space and change the geographical
distribution of communities, sometimes resulting in habitat loss and species
extinction, with repercussions for ecosystem functioning and biodiversity
(Birchenough et al . 2011).
Effects of Increasing Temperatures
Temperature affects all biological structures and physiological processes
ranging from protein damage and membrane fl uidity to organ function
(Hochachka and Somero 2002). Organisms may have to pay a high toll for
their thermal sensitivities, particularly in terms of repairing and replacing
heat-denatured proteins and in the adaptive alterations of cellular structures
and processes during acclimatization (Somero 2002). The biological
importance of rising temperature varies within and among species and
it is known that different ontogenetic stages are differently susceptible
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