Estuaries & Lagoons of Sri Lanka

Tuesday, November 24th, 2020 | Blog

The coasts of Sri Lanka are usually well supplied with lagoons and estuaries. On the castern and southern coasts, they form a more or less interconnected chain running from Point Pedro to Dondra Head, their topography constantly changing under the influence of weather and tide. These transition zones between sea and land, where the salinity of the water varies with time and place, host a variety of complex ccosystems – mangrove forests, salt marshes, sea-grass beds and mudflats – which contain a diversity of living species. Some of these bodies of water have a continuous connection with the sea; in others, the connection sometimes fails during dry seasons, depriving the local marine ecosystem of nutrients and making it less attractive to life.

Lagoons and estuaries attract marine mammals, which come to feed off their bounty. Dolphins, dugongs and whales have all been sighted among the estuaries and lagoons of Sri Lanka, feeding, resting, at play and even giving birth.

One of the largest estuarine waters is Jaffna Lagoon, 450km? in area. Opening westward into Palk Bay, which lies cradled between the Jaffna peninsula and the island of Mannar, it is mostly landlocked, rarely over 3 m deep and partly dry during the hot season. Not surprisingly, it is of no interest to marine mammal enthusiasts.

By contrast, the 475km’ extent of the Puttalam Archipelago is a paradise for dolphin watchers and other nature lovers. A biodiversity hotspot that plays host to unnumbered species of fish, crustaceans, and marine mammals, as well as seabirds, Puttalam Lagoon and nearby Dutch Bay, are shallow, though still navigable due to the presence of deeper channels. The offshore waters beyond Kalpitiya Peninsula are among the best places in Sri Lanka to see dolphins and whales.

Batticaloa Lagoon, at 168km?, is the largest of the chain of lagoons and inlets that stretches down the east coast of Sri Lanka. It is fed by eight separate rivers and is open to the sea at both its northern and southern extremities – though sand, accumulating at the lagoon mouths during the dry season, now restricts the exchange of salt and fresh water. The average depth of the lagoon, earlier put at about 17m, seems to have declined in recent times and was recently found to be nearer 5m. Dolphin sightings in Batticaloa Lagoon were once frequent, but none have been recorded there recently.

Text by Howard Martenstyn, Out of the Blue