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Download PHYTOPLANKTON: Role in fresh water ecosystem and water quality
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PHYTOPLANKTON: Role in fresh water ecosystem and water quality NSERC-IRC Program. Department of Biology. University of Victoria Phytoplankton • Phytoplankton are organisms that live in the water column • Phytoplankton are divided into several major groups based on their evolutionary relationship. In general, different groups have different pigments Green algae Golden-brown algae Blue-green algae Why is phytoplankton important ? • Like plants, phytoplankton produce oxygen during photosynthesis. It has been estimated that, on a global scale, 50 – 60 % of all photosynthesis is performed by phytoplankton (Campbell, 1999) • Phytoplankton are at the base of the food web supporting higher organisms within water ecosystem Assessing phytoplankton abundance in water • Phytoplankton diversity and abundance are estimated by counting and measuring phytoplankton in lake water samples • A sample representing phytoplankton distribution in the lake is whole water • The sample is preserved in Lugols – a solution that stains all phytoplankton species brown • A light microscope is used to view the preserved sample and identify the species • Because the identification of phytoplankton species often relies on features that cannot be seen in preserved samples due to loss of pigmentation, a qualitative fresh water sample from the same lake is viewed (if possible) before the actual count to determine which groups of algae are dominant • A computer program allows for measurements of length and width of each individual organism. It uses these measurements to calculate the biomass of each species found in the water Phytoplankton and water quality: • Some fresh water phytoplankton are toxic and many species contribute to the taste and odor of water • When there is an abundance of algae, water quality diminishes because water filtration process becomes more difficult as filters get clogged more easily. • Increase in algae also increases chlorine demand and disinfection byproducts formation. Image of live Crucigenia rectangularis Image of preserved Crucigenia rectangularia In this picture, water in the enclosure is of distinct green color because of abundance of algae Some of taste and odor causing phytoplankton species are: Anabaena sp. Synura sp. Image of live Cyclotella sp. Image of preserved Cyclotella sp.
