Scientists suspect hidden seagrass habitat in Muttukadu

Chennai: Below the murky waters of Muttukadu, there could be a hidden seagrass habitat protecting the coast. Last week, researchers from Sathyabama University found seagrass washed ashore near Akkarai Beach. They now believe it may have drifted from the estuary 9km away at Muttukadu, a location where seagrass presence has not been formally documented."We have not observed seagrasses on Chennai beaches for at least the past 10 years," said Prof Amit Kumar, centre for climate change studies, Sathyabama University. "It is common to find water hyacinth washed ashore on city beaches, but for the first time, we observed a lot of seagrasses along with it," he added.The team collected samples and identified three different seagrass species — Halophila ovalis (paddle weed or spoon grass), Halodule pinifolia (needle seagrass), and Ruppia brevipedunculata (widgeon grass or ditch grass) — all typically found in estuarine waters where rivers meet the sea. With no formal records from Muttukadu backwaters, researchers suspect a patch of undetected estuarine meadow may have been uprooted and carried northward by coastal currents."We think the major source would be the Muttukadu estuary. Otherwise, there is no nearby patch. In Muttukadu, the water is so murky that we cannot study it underwater using remote sensing," the professor said.He pointed to two possible triggers — the recent heavy flow of currents from rain and the manual or natural removal of water hyacinth that may have disturbed the bottom substrate, uprooting the seagrass. "At this time of the year, the sea current goes from south to north in Chennai, and that may be why these seagrasses are coming back to the shore," he said.Seagrass beds are known to provide multiple ecological services: They form critical feeding habitats for endangered dugongs and act as natural buffers against coastal erosion by reducing wave energy and anchoring sediments. Studies indicate that Tamil Nadu's shores support nearly 13 different seagrass species. Palk Bay and the Gulf of Mannar alone host significant meadows with 10 species identified in Chinnapalam, a fishing village in the Gulf of Mannar, and nine species in Devipattinam, a coastal town in Ramanathapuram district, and Manoli Island in the Gulf of Mannar.