Environmental Engineering Reference
In-Depth Information
Sandin et al. ( 2008 ) surveyed coral reefs on de-
serted islands in the northern Line Islands to pro-
vide a baseline of reef community structure, and
on increasingly populated islands to document
changes associated with human activities.
salinity, seasonal cycle, and carbon dioxide
concentration on bacterial community structure
in the polar and alpine ecosystems. The results
suggest that the spatial distribution of genetic
variation and, hence, comparative rates of evolu-
tion, colonization, and extinction are particularly
important when considering the response of mi-
crobial communities to climate change. Although
the direct effect of a change in, e.g., temperature
is known for very few Antarctic microorganisms,
molecular and genomic techniques are starting to
give us an insight into what the potential effects
of climate change might be at the molecular/cel-
lular level (Friedmann 1993 ).
4.3.3
Climate Change
Effects of climate change on biodiversity (such
as changing distribution, migration, and repro-
ductive patterns) are already observable. Average
temperature is expected to rise between 2 and
6.3 ᄚC by the year 2100. Predicted impacts asso-
ciated with such temperature increase include a
further rise in global mean sea level of 9-88 cm,
more precipitation in temperate regions and
Southeast Asia, in turn a higher probability of
floods (Nardini et al. 2010 ). On the contrary Cen-
tral Asia, the Mediterranean region, Africa, parts
of Australia and New Zealand will get less pre-
cipitation which can result in greater probability
of droughts, more frequent and powerful extreme
climatic events, such as heat waves, storms, and
hurricanes, an prolonged range of some danger-
ous “vector-borne diseases”, such as malaria, and
further warming of the Arctic region (Nardini
et al. 2010 ). Pollution from nutrients such as
nitrogen, introduction of invasive species, over
harvesting of wild animals can all reduce resil-
ience of ecosystems. In the atmosphere, green-
house gases such as water vapor, carbon dioxide,
ozone, and methane act like the glass roof of a
greenhouse by trapping heat and warming the
planet. The natural levels of greenhouse gases are
being supplemented by emissions resulting from
human activities, such as the burning of fossil
fuels, farming activities, and land-use changes.
As a result, the Earth's surface and lower atmo-
sphere are warming. This will have profound ef-
fects on the biodiversity.
4.4
Utility of Microbial Diversity
Microbial diversity existing in natural ecosys-
tems has the following major applications:
4.4.1
Biogeochemical Cycling
of Matter
Soil acts as the source of nutrition for the growth
of a spectrum of microorganisms which have re-
markable ability to degrade a vast variety of com-
plex organic compounds due to their metabolic
bioremediation agents. They also play a vital role
in providing conditions for functions of humans
and animals and for the continuation of all life-
forms on Earth. Many microorganisms carry out
unique geochemical processes critical to the op-
eration of the biosphere (Gruber and Galloway
2008 ) and no geochemical cycle is carrying out
without their involvement. Metabolic variety
of microbes is enormous, ranging from being
photo- and chemosynthetic and to degrade vari-
ous anthropogenic xenobiotic compounds. For
example, the global nitrogen cycle in nature is
dependent on microorganisms. Unique processes
carried out by microorganisms include nitrogen
fixation, oxidation of ammonia and nitrite to
nitrate, and nitrate reduction with formation of
dinitrogen and nitrous oxide gases (Gruber and
Galloway 2008 ). Similar important and unique
roles are played in other cycles, such as the sul-
fur and carbon cycles. In addition, microbes run
4.3.4
Effect of Temperature on
Microbial Communities
Pearce ( 2008 ) and Rodriguez-Blanco et al. 2009
has demonstrated the effects of factors such
as temperature, nutrient availability, grazing,
 
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