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By W.T.J.S. Kaviratne-Ambalangoda Special Correspondent A three day workshop-seminar on coastal ecology was held recently at Coral Gardens Hotel, Hikkaduwa for the Wildlife Officers following the Diploma in Wildlife Management at the University of Colombo. During the three day programme, Wildlife Officers attended the lectures, interactive work and field work on Mangrove ecosystems Rocky shore, Sandy shore and Coral Reef Ecosystems, on the South coast covering the areas of Hikkaduwa, Weligama, Tangalla and Rakawa. Professor Suki Ekaratne, the Director, Staff Development Centre, Department of Zoology, Colombo University, conducted this three-day program. Professor Ekaratne speaking on Coral Reef Ecosystems said that coral reef was a microcosm of different communities, each separate but linked to the next by a complex web of ecological interactions. These communities of corals were distinctive because on a single reef, they form a series of narrow zones having a particular place in any array of rapidly changing environmental gradients. He said that the most important factors controlling the composition of coral community were the availability of life, wave action, sediment load, salinity and tidal range. These factors were clearly interrelated and the wave action affected the sediment load which in turn affected the availability of light. Referring to the formation of corals, he said that there were hundreds of different species of corals and they were made up of small animals called ‘polyps’. There were three main varieties of corals such as hard corals, horny corals and soft corals, he said. One of the most basic factors controlling reef development he said was the relationship between the rate of reef growth and the rate of the sea-level change. Speaking on how coral species were particularly sensitive to temperature increase bringing about coral bleaching and mortality, Professor Ekaratne revealed the research findings he and his team collected on the ecological implications of the bleaching of the Hikkaduwa Reef Ecosystem. Bleaching of corals took place in April 1998, followed by extensive coral mortality. This was brought about by increased seawater temperature. The coral bleaching and mortality occurred on an unprecedented scale, he said. The primary impact on the Coral Reef Ecosystem had been the loss of reef diversity, structure and ecosystem processes that enabled the proper functioning of the reef ecosystem. Speaking on how the temperature affected coral reproduction, he said that the primary mechanism for maintaining and renewing population size had suffered drastically with coral reproduction continuing to be reduced almost three years after bleaching. He said that the increase of temperature would result in reduced diversity and population size of coral species in the marine sanctuary of Hikkaduwa, over a long-time scale. The changes brought about in coral abundance and species assemblage had resulted in changed ecological roles in the reef ecosystem. Loss of the three dimensional protective structure through reef disintegration had resulted in coral nestling fish losing their abodes and in their depressed reproduction and populations. In addition, reef break-up, he said had led to increased wave force with possible implications on coastal erosion of the area. Referring to effects of coral bleaching in the Hikkaduwa Marine Sanctuary, and its direct impact on ‘reef - associated fish’ he said that prior to bleaching, there were 55 species of fish belonging to 23 families. Before bleaching, the dominant fish species found at Hikkaduwa Marine Sanctuary were ‘angel fish’, ‘butterfly fish’, ‘surgeon fish’ and ‘wrasses’, he revealed. Just after bleaching of coral formations, the total number of fish decreased by 23 per cent. Butterfly fish and wrasses were replaced by ‘parrot fish’ and again after nine months, ‘angel fish’ and ‘surgeon fish’ remained as dominant fish groups in the Marine Sanctuary of Hikkaduwa he said, in accordance with the findings of the research activities carried out by him. Coral mortality was followed by increased algal growth on the dead reef structure of Hikkaduwa. Herbivorous fish species had increased and coroll-ivoroues butterfly fish species and their abundance had gradually decreased. Invertebrate species such as ‘sponges’, ‘dideminds’, ‘tube-worms’ had undergone dynamic changes, he said as a result of the bleaching of corals in the Hikkaduwa Marine Sanctuary. During the discussions on the proposed management plan for Hikkaduwa marine sanctuary, numerous issues related to marine sanctuary were identified. Lack of Visitor Centres to regulate visitor numbers, increased visitor pressure was identified as one of the major problems. Increased ‘glass bottom boats’ had caused damage to corals and reef ecology he said. Feeding fish living in the sanctuary area continued unabated by the boat operators using bread and during night these tamed fish were caught. Effluents from beach-side hotels and filling up of the reef lagoon with sand due to ‘breakwaters’ of the adjoining ‘Fisheries Harbour’ were some other issues affecting the marine sanctuary of Hikkaduwa, discussed during the workshop. In order to resolve the above-mentioned environmental constraints which have cropped up at the Hikkaduwa Marine Sanctuary, the following recommendations were made:
It was also suggested that glass bottom boats should not be allowed to operate in the Marine Sanctuary during the months of June to August when the South-West monsoon was heavy. Environmentally unfriendly activities such as feeding fish by boat operators should be banned within the Marine Sanctuary. Steps should be taken to expedite the installation of the sewage system to regulate effluents from hotels. To overcome the ill-effects of coral bleaching, a programme of coral rehabilitation be started with the involvement of Wildlife Officers. The Hikkaduwa Wildlife Office is housed in a small room threatening to collapse at any moment. A new building having all modern facilities should be made available for the Wildlife Officers operating at Hikkaduwa. A management committee for the Hikkaduwa Marine Sanctuary should be established with all stakeholders including local government officials, hoteliers, glass bottom boat operators, diving school operators, vendors, community representatives and the scientists. A research programme should also be started involving the staff of the Department of Wildlife at the Hikkaduwa Marine Sanctuary so that a better understanding and monitoring of the ecological processes would take place. Professor Ekaratne and his team of research workers were engaged in replanting corals in the marine sanctuary and he said it proved to be a great success. With the approval of the Wildlife Department, a number of boards carrying instructions to visitors to the Marine Sanctuary at Hikkaduwa had been constructed but due to unknown reasons, the officials attached to the Wildlife Office at Hikkaduwa had not allowed to fix them he revealed. R.K. Somadasa De Silva who is an international diving instructor operating at Hikkaduwa for the last 30 years said that illegal methods of fishing using dynamite was taking place daily. Dumping garbage at the Marine Sanctuary by the beach side hoteliers was a daily occurrence he further said. He said so far no action was taken by the Wildlife Officials operating at Hikkaduwa to resolve these issues. Field observations were conducted at Hikkaduwa, Weligama, Thangalla and Rekawa beach stretches on different ecosystems.
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