Introduction

Sahyadri e-news is CES-ENVIS's quarterly newsletter, covering the issues related to Western Ghats biodiversity. Western Ghats is rich in diversity of life. Due to unplanned developmental activities, its ecological resource base is under threat, with extensive destruction of natural habitats, widespread degradation of ecosystems and a growing burden of air and water pollution. Simultaneously, knowledge base of uses of biodiversity is also being eroded, with the present generation becoming increasingly alienated from the natural world.

We need to carefully plan on conserving, sustainably using and restoring the biological diversity of the Western Ghats. We also need to conserve and benefit from the knowledge of uses and the traditions of conservation of this biological diversity. Also, we must ensure that benefits flowing from our heritage of biodiversity and related folk knowledge percolate down to the people at the grass-roots.

Biological communities reflect the overall ecological integrity by integrating various stresses, thus providing a broad measure of their synergistic impacts. Aquatic communities, both plants and animals, integrate and reflect the effects of chemical and physical disturbances that occur over extended periods of time. Monitoring procedures based on the biota measure the health of a river and the ability of aquatic ecosystems to support life as opposed to simply characterising the chemical and physical components of a particular system. Biological evaluations provide a description of the water quality that is often not achievable from elemental analyses alone. A biological indicator (or bioindicator) is a taxon or taxa selected based on its sensitivity to a particular attribute, and then assessed to make inferences about that attribute. In other words, they are a substitute for directly measuring abiotic features or other biota. Bioindicators are evaluated through presence or absence, condition, relative abundance, reproductive success, community structure (i.e. composition and diversity), community function (i.e. trophic structure), or any combination thereof. Diatoms are widely used as biological indicators of environmental health in the aquatic ecosystem because algae occupy the most basic level in the transfer of energy through natural aquatic systems. The distribution of algae in an aquatic ecosystem is directly related to the fundamental factors such as physical, chemical and biological constituents. This issue introduces diatoms including taxonomic aspects. Second article highlights the contributions by Professor Hemendrakumar Prithivraj Gandhi, the legend in the field of Indian diatoms> Prof Gandhi has the unique distinction of pioneering diatomological research in India . Recently Prof H P Gandhi donated his vast collection of samples, slides and literature, including reprints, reports and books on diatoms to SAHYADRI - Environmental Information System (ENVIS) centre on Western Ghats Biological Diversity located at the Centre for Ecological Sciences, Indian Institute of Science, Bangalore. The details about his work and publications are available at: http://wgbis.ces.iisc.ernet.in/biodiversity/

Collections of Prof. Gandhi are kept in the diatom museum at the Centre for Ecological Sciences, which constitute a much awaited resource for diatom researchers. The flourishing research and interests in diatomology in India bears a testimony to the legacy of H P Gandhi and undoubtedly he is the father of freshwater diatomology in India .