Hikkaduwa National Park is one of the three marine national parks in Sri Lanka. The national park contains a fringing coral reef of high degree of biodiversity. The area was declared a wildlife sanctuary on May 18, 1979, and then on August 14, 1988, upgraded to a nature reserve with extended land area. The growth of the number of visitors in the next 25 years increased the degradation of the coral reef. To reduce the effects to the ecosystem, the reef was declared a national park on September 19, 2002.
Hikkaduwa coral reef is a typical shallow fringing reef with an average depth of around 5 metres (16 ft). The coral reef reduces the coastal erosion and forms a natural breakwater. The coast of the national park extends four km. Generally the coast is narrow, ranging from 5–50 m according to the climatic conditions of the year. Scuba diving is a popular recreation here.
The national park situated in the wet zone and receives a 2,000 millimetres (79 in) of annual rainfall. The rain is received in both southwestern and northeastern monsoon seasons, in April–June and September–November respectively. Inter-monsoon season is a dry period which is considered the best season to visit the park. The temperature of the water ranges from 28.0°-30.0°C while the mean annual temperature is 27°C of the atmosphere.
Flora and Fauna:
Foliaceous Montipora species dominate the coral reef. Encrusting and branching species are also present. Faviidae and Poritidae corals are contained in the inshore areas of the reef in massive colonies. Staghorn, elkhorn, cabbage, brain, table and star corals are all present in the reef. Corals of 60 species belonging to 31 genera are recorded from the reef. The reef also recorded over 170 species of reef fish belonging to 76 genera.
Seagrass and marine algae belonging to genera Halimeda and Caulerpa are common in the seabed depth ranging from 5–10 m. Seagrasses provide habitat to Dugong and sea turtles. Some species of prawns feed on the seagrass. Eight species of ornamental fishes also inhabit the reef, along with many vertebrates and invertebrates including crabs, prawns, shrimps, oysters and sea worms. Porites desilveri is an endemic coral species of Sri Lanka. Chlorurus rhakoura and Pomacentrus proteus are two reef fish species confined to Sri Lanka. Blacktip reef shark are found along the outer slope of the reef. Three sea turtles which have been categorized threatened visit the coral reef: the hawksbill turtle, green turtle, and Olive Ridley.
The reef has suffered high degradation due to both natural and human activities. The live coral cover was decreased from 47 percent to 13 percent in a coral bleaching event in 1998, induced by the 1998 El Niño. It has been suggested that at least 30-40 percent of coral reef should be restored in order for it to be capable of sustaining itself. Despite being designated as a protected area, the coral reef has been subject to constant exploitation including removal of breeding ornamental fish for the commercial market.
Boxing Day Tsunami:
The two marine national parks of Sri Lanka, Hikkaduwa and Pigeon Island, received little direct impact from the Boxing day tsunami. However they suffered from secondary impacts, particularly from terrestrial debris being deposited on the reefs. A collaboration work of conservation groups and volunteers was carried out to clean up the beach and the reef debris, including two large fishing nets stuck on the outer edge of the reef.