Changes
in the algal community composition can be used as indicator factor for
environmental change. Algae can be used in laboratory bioassays to monitor the
quality of water for their safe drinking and other purposes. Algae can also be
used in paleoecological studies to investigate the changes in water quality of
lakes over time. These two methodologies can be used to detect the instances of
climate change affecting the lake or ocean algal change.
Bioassay
is a procedure that uses the organisms and their responses to estimate the
effects of physical and chemical agents in the environment. Algal bioassay is
widely used to monitor the nutrients that promote
the development of algal bloom and the
substances that are toxic to algae and other organisms. Algae are effective in
bioassays because they are more sensitive than animals to some pollutants,
including detergents, dyes, textile manufacturing effluents, herbicides etc.
The
Biology Laboratory conducts Algal Growth Potential and Limiting Nutrient algal
assays. Algal Growth Potential (AGP) tests and Limiting-Nutrient assays are the
most direct and effective ways to determine the amount of nutrients available
to organisms in surface waters, and the eutrophication potential of an aquatic
system. These methods provide information on the biologically-available
nutrients in the water. Algal Growth Potential (AGP) assays determine the
maximum amount of algal growth that the nutrients in a water sample can
support. This test provides a better indication of the potential for algal
blooms than can be determined by chemical measurement of nutrient
concentrations, because all nutrients in the water are not in a form that can
be used by algae. There may be substances present in the water that inhibit
algal growth. In nature, other factors than nutrient availability can limit the
growth of algae, such as the amount of light available, water temperature, or
the amount of algal being consumed by algae-eating organisms. However, the AGP
assay alerts officials to the potential for algal blooms. AGP within the watersheds
have shown the impact on water quality of human activities such as agriculture
and urbanization.
Paleoecological indicators are examined as to their
accuracy in reconstructing past biotic communities and environmental
conditions, their utility in answering important questions about such
communities and conditions, and the temporal and spatial scales over which they
are effective. When the algae die, their decay resistant remains may accumulate
in the lake or ocean sediments. It is estimated that 20-25% of the entire organic
carbon fixation on Earth; via photosynthesis, is attributable to diatoms - in
large due to their great abundance. Together with diatoms, calcified scales of
coccolithophorid algae, silica skeletions of silicoflagellates, decay
resistance cysts of dinoflagellates persist in ocean sediment for millions of
years. This layering of algal fossils in sediments, along with other
information, allows paleolimnologists to infer the relative age of sedimentary
deposits. The database of relationship between measured environmental variables
and modern diatoms can be used to infer the ecological conditions that were
present in the past.
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