Local Knowledge and Conservation of Seagrasses in the Tamil Nadu State of India

Key words: local health and nutrition, traditional ecological knowledge (TEK), conservation and natural resources management, consensus, ethnomedicine, ethnotaxa, cultural heritageSeagrasses are an artificial grouping of grass-like plants that grow in or around aquatic marine ecosystems. The name seagrass is purely descriptive as is the name seaweed with respect to marine algae [1]. Despite popular misunderstanding of the taxonomic relation of seagrasses to the grass family (Poaceae), seagrasses in fact have no relation to grasses as supported by systematic and phylogenetic evidence. However, the term seagrass aptly defines a group of angiosperms that are specially adapted to grow in estuaries and marine ecosystems. As such, this group of plants includes 13 genera and approximately 72 species that belong to the families Zosteraceae, Potamogetonaceae, Posidoniaceae, Cymodoceaceae, Hydrocharitaceae and Ruppiaceae [2,3].Seagrasses have adapted to grow in coastal marine environments in both tropical and temperate regions on almost every continent in the world [2,4]. In tropical seas, genera such as Cymodocea, Enhalus, Halodule, Halophila, Syringodium, Thalassia and Thalassodendron are represented. However, some species of these genera are also found in temperate regions, whereas species of Amphibolis, Heterozostera, Phyllospadix, Posidonia, Pseudalthenia and Zostera are usually restricted only to temperate seas [5-7]. Growing erect from rhizomes embedded in the sediment and debris on the ocean floor, seagrasses are the only angiosperms that are able to thrive underwater in marine environments [2]. In general seagrasses inhabit the tidal and subtidal zones of shallow and sheltered localities of seas, gulfs, bays, backwaters, lagoons and estuaries. They usually prefer muddy, sandy, clayey and coral rubble substrate, but they also grow on rocks and in crevices. They are found to grow either homogenously or heterogeneously, forming thick and dense meadows that produce consi