diatoms: stream monitoring and ecological...
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DIATOMS: DIATOMS: Stream Monitoring and Stream Monitoring and
Ecological StudiesEcological Studies
Karthick B, M K Mahesh* and T V Ramachandra
Energy and Wetlands Research Group, Centre for Ecological Sciences
*Dept of Botany, Yuvaraja’s College, Mysore
Biomonitoring & ……Biomonitoring & ……Role of Diatom in BiomonitoringRole of Diatom in Biomonitoring
What is living in the stream?What is living in the stream?
What is a biological indicator?
The fundamental principle behind biological indicator theory is that organisms provide information about their habitats. A biological indicator (or bioindicator) is a taxon/taxa selected based on its sensitivity to a particular attribute, and then assessed to make inferences about that attribute.
Why indicator species? Bioindicators make a broad and intangible concept such as biodiversity or ecosystem monitoring manageable by breaking it down into a specific set of quantifiable indicators. Inference through biological indicators replaces direct measurement when such measurements are not possible, too expensive/difficult, or too direct. Some historical events are impossible to observe directly, but can be inferred via bioindicators, such as reconstruction of lake pH using diatom communities in lake sediments from known dates
A bioindicator is an anthropogenically-induced response in biomolecular, biochemical, or physiological parameters that has been causally linked to biological effects at one or more of the organism, population, community, or ecosystem levels of biological organization.
Choose among the many !Choose among the many !
Photos: S Ali, Gururaja K V, Sreekantha & me
BacillariophyceaeBacillariophyceae
Diatoms are unicellularDiatoms are unicellularmicroscopicalmicroscopicalphotosyntheticphotosyntheticeukaryoteeukaryotefreefree--livingliving
What are diatoms ?What are diatoms ?
Abundant BeautyAbundant Beauty
Different components of the cell wallDifferent components of the cell wall
Hallmark of diatoms Hallmark of diatoms : SILICIFIED CELL : SILICIFIED CELL WALLWALLbasic component basic component SiOSiO22 (60%)(60%)completely closed completely closed ‘‘box & coverbox & covercontains 2 large, contains 2 large, heavily sculptured heavily sculptured units: units: VALVESVALVES
upper valve = upper valve = EPIVALVE EPIVALVE (“cover”)(“cover”)lower valve = lower valve = HYPOVALVE HYPOVALVE (“box”)(“box”)
1. Epivalve1. Epivalve2. Epicingulum2. Epicingulum3. Hypocingulum3. Hypocingulum4. Hypovalve4. Hypovalve5. FRUSTULE
EpithecaEpitheca
HypothecaHypotheca
6. Frustule6. Frustule
5. FRUSTULE
Pennate
SEM SEM –– PHOTOGRAPHY OF A PENNATE DIATOM PHOTOGRAPHY OF A PENNATE DIATOM
Why Diatom ???Diatoms constitute a water quality monitoring tool widely accepted
They provide a wide range of ecological information (T°, pH, salinity, trophy, organic load, etc…)
Omnipresence in aquatic systems (even in extreme environments)
Very high diversity (up to 10000 taxons known in fresh and brackish waters)
Other methods (Invertebrates) are difficult to apply (unaccessibility due to depth and lack of some habitats)
Sampling and preparation are quick, easy and standardized
Storage and "traceability" of results (permanent slides)
Taxonomic and ecological data are abundant
Relative low cost for implementation &……
Here, there & EverywhereHere, there & Everywhere
Different forms & their homesDifferent forms & their homes
Fig. 1 and Fig. 2 show a thick layer of diatom cells attached to boulders.
Fig. 3 shows a layer ofdiatom cells growing both on sediment and on pebbles.
Fig. 4 shows diatoms growing thickly aroundsubmerged tree branches.
Fig. 5 shows the film of diatoms to be found on the submerged stems
Fig. 6 shows diatoms inhabiting sediments.
Different forms & their homesDifferent forms & their homes
The diatom The diatom biofilmbiofilm can be found growing can be found growing on many surfaces in running waters ….on many surfaces in running waters ….
rocks
Fine sediments
Rocks plus filamentous algae
Submerged macrophytes
Emergent macrophytes
Man-made surfaces
Source for Collection Source for Collection –– Artificial substratesArtificial substrates
Treatment & Preparation of Permanent Slides of benthic diatom samples from rivers for water quality assessment
100 times
1000 times
It might look very exciting, it is a complex 3-dimensional community of which diatoms are typically the most abundant group of photosynthetic organisms exhibiting a range of ecological strategies.
Stalked taxa, e.g. Synedra
Polysaccharide matrix Plankton
Motile taxa, e.g. Nitzschia
20 µm
Diatoms are very important in the world
Primary production through the photosynthesis processLungs of the earth
through the respiration/oxygen-production in the oceans
Study and understanding of diatoms is therefore very important!!!
DIATOMS ARE FOREVER !!!
THANKS