The Impact of Human Activities on Coral Reefs

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Case study

based on Coral Reefs of Sri Lanka: HumanDisturbance and Management Issues


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Sri Lanka is situated between 5 and 10degrees north of the equator and south of theIndian subcontinent and has a total land areaof 65 000 km2. The coastline of the island,which is about 1585 km, supports highlyproductive ecosystems such as coral reefs,mangroves, sea-grass beds and marshylands. The continental shelf of Sri Lanka isrelatively narrow averaging only a few km inwidth.


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The reefs of Sri Lanka are divided into threecategories:

true coral reefs; sandstone reefs;

boulder reefs of crystalline rock


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Reefs are a valuable resource for the peopleof Sri Lanka, in particular to the coastalcommunities. Coastal reefs have forcenturies, been utilized as a source of food

and building materials. In the past two tothree decades, the collection and export ofcoral reef associated organisms havecontributed substantially to the foreign-exchange earnings of the country


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Coastal tourism, which has been developed toa limited extent, has a tremendous potentialfor further expansion. However, properplanning and management steps must be

taken to ensure that the sustainability ofreefs is not compromised for short-termbenefits. In Sri Lanka, the use of coastal reefsas a resource has often led to over-exploitation and destruction


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Major causes of reef degradation are habitatloss due to destructive fishing methods suchas the use of explosives and bottom-set nets,mining coral from the sea for lime

production, uncontrolled harvesting,including the collection of ornamental fishand invertebrate species. Sedimentation dueto unplanned land


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clearance practices, pollution from industrialdevelopment as well as agricultural runoff,and discharge of untreated sewage have alsohad negative effects on nearshore reefs.


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Much of the recent research on Sri Lankanreefs has focused on reef monitoringprograms that are essential to addressenvironmental and management issues.

The first investigations geared towards themanagement of coral reefs were carried out

at Hikkaduwa and Rajasuriya


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Coral Mining Coral- mining from the sea forlime production

Fishing includes1. Blast fishing2. Overharvesting3. Bottom-set nets to catch spiny lobsters and

reef fish4. Using nonselective fishing gear5. Indiscriminate netting in reef areas


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Ornamental Fish1. Collection Uncontrolled collection of live

marine organisms for the aquarium trade

2.

Using 'moxy nets' for omamental fish.collection

3. Excessive collection of shells and otherinvertebrates


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Pollution1. Pollution from land-based sources

2. Sewage disposal Pollution from shipping

Sedimentation1. Sedimentation due to unplanned land

clearance practices and coastal erosion

2. Sedimentation due to construction of ports

and harbours


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Boats1. Damage caused by boats and anchors

2. Glass-bottom boats and fishing craftscolliding against reefs

3. Discharging waste oil and bilge water fromboats;


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Coral-reef resources are important forthe fisheries industry in Sri Lanka.Photo: A. Rajasuriya


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An undamaged area of the coral reefswithin the Bar Reef Marine Sanctuary.

Implementation of sanctuaryregulations is needed to prevent reefdegradation due to human activitiesand other natural causes.


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Loss of reef habitat has the greatest impact onabundance and diversity of marine species in SriLanka. Therefore, conservation of reef habitatsshould be given prime consideration.

- Destructive gear such as the bottom-set netsused in reef fishery and the moxy nets used tocatch ornamental species should be bannedunder the Fisheries Ordinance.

- All users of reef resources should be licensed

by the Department of Fisheries and AquaticResources Development through their respectiveprovincial councils.


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Coral mining needs to be addressed through acomprehensive program that will providealternatives to the use of lime and to makedolomite-based lime available in the coastal

region at a subsidized rate. Artificial reefs should be introduced within the

buffer zones of sanctuaries and other areas inorder to prevent overfishing, and to divert fishing

activities from sensitive habitats. They could alsobe used to restore habitats lost due to coral min-ing and destructive fishing


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1. Rajasuriya, A. 1991. Location and condition of reefsalong Sri Lanka's coast. Proc. Seminar on Causes ofCoastal Erosion in Sri Lanka. Coast ConservationDepartment, Colombo, Sri Lanka, pp. 203-210.

2. Swan, B. 1983. An Introduction to the CoastalGeomorphology of Sri Lanka. National Museums of Sri

Lanka, Colombo, 182 pp.3. Ormand, R. 1985. Status of critical marine habitats in the

Indian Ocean. In: IOCI UNESCO Workshop on RegionalCo-operation in Marine Science in the Central In- dianOcean and Adjacent Seas and Gulfs. Colombo 1985.Unesco Worshop report No. 37, pp. 167-193.

4. Gomez, E.D. 1988. Overview of environmental problemsin East Asian Seas region. Ambio 17, 166-169.


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5. Pauly, D. and Chua, Thia-Eng. 1988. The overfishing of marineresources: socio-eco- nomic background in Southeast Asia. Ambio17, 200-206.6.Wells, S.M. 1993. Coral reef conservation and management,progress in the South and Southeast Asian regions. CoastalManagement in Tropical Asia. No. 1, Coastal Re- sources Centre,

University of Rhode Island, USA, pp. 8-13. Hatcher, B.G., Johannes,R.E. and Robertson, A.I. 1989. Review of research relevant to theconservation of shallow tropical marine ecosystems. Oceanogr. Mar.Biol. Ann. Rev. 27, 337-414.7. Linden, 0. 1990. Human impact on tropical coastal zones. Nat.Resour. 26, 3-11.8. Lundin, C.G. and Linden, 0. 1993. Coastal ecosystems: attempts tomanage a threat- ened resource. Ambio 22, 468-473. 10. Ridley, S.O.

1883. The coral faunas of Ceylon with descriptions of new species.Ann. Mag. Nat. Hist. 11, 250-262.

The Impact of Human Activities on Coral Reefs

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