1.

Use of destructive fishing methods

Physical damage is caused to the coral structure of the reef from many fishery related activities. These include the use of explosives (dynamite fishing), entanglement of bottom set nets and the “moxy” a net used by the ornamental fish collectors. The ornamental fish collectors cause additional and usually avoidable damage as they break up and over turn coral boulders to collect fish and invertebrates hidden below or within them.  The lost pieces of synthetic fishing nets cause degradation of corals by binding onto corals and rubbing on them, referred to as ghost nets they also continue to trap marine organisms.

2.

Over fishing and unmanaged selective collection

The ornamental aquarium fishery, shellfish and holothurians export trade and  spear fishing have had an impact on the reef communities in selectively removing species and individuals of specific size categories.  (Extraction of breeders, new recruits etc.) This could lead to alteration of the balance of the ecosystem as  key trophic / community elements are affected.

3.

Removal of reef coral for the lime trade

Coral mining for lime is carried out on some reef areas such as Akurala and Rekawa and constitutes a serious but localized threat to coral reefs, as the basic reef structure is lost the chances of re-colonization of the reef is also lost.

4.

Un-regulated tourism

Tourism impact on the  reefs when the number of visitors to an area exceeds the carrying capacity of the reef to absorb incidental damage by visitors; such as walking, touching and striking coral with swim fins etc. The coastal developers/hoteliers  infringe on the coastal dynamics by building close to or on marine areas, and release sewage and refuse into the waters close to the coral reef.  Extraction of coral and other shellfish etc. for the souvenir trade  also contribute to the tourism impact on the reefs.

5.

Collection of marine organisms for souvenirs

The collection of coral, Shells and other reef organisms has become a significant threat to reefs in some areas. Though the act of picking up a dead shell on a beach does not cause significant harm, commercial collection  of souvenirs for sale  and  excessive collection by groups on localized sites (eg. At school field trips) can lead to harmful levels of extraction if not controlled.

6.

Unplanned and inappropriate coastal Development

Development of harbors, revetments, Groins, sea walls and other coastal structures impact the coral reefs directly by building over coral areas and through changes to the coastal sand transport by increasing sedimentation and accretion within coral reefs.

Some planned major development schemes in the South coast such as the proposed Galle harbor development envisaged to build over a rich coral reef  leading to extermination of the reef.

The construction of a breakwater at the fishery harbor in Hikkaduwa is believed to be the cause for sand filling of both the Hikkaduwa Marine Sanctuary and the Akurala reef.

The warmed water plumes released by coastal power plants (eg. Proposed Norochchole, and the Trincomale coal thermal plants.) could damage coral reefs in the area as the sea water temperature would be elevated by several degrees over a long period of time, which could trigger local bleaching events and reef death.

7.

Boat and anchor  damage

Use of coral reef lagoons as anchorages for small and medium sized boats has affected reefs as the heavy anchors and dragging anchor chains break, abrade and over-turn coral colonies (e.g. Hikkaduwa, Kapparathota) . The fishing craft anchorages  further affected the reef as  fish off-loading and cleaning operations also contribute to pollution of the surrounding areas. Unauthorized channel blasting over the reef flat/crest by fishermen to open access channels  for the boats also destroy reef sections.  Glass bottom boats damage the reef as the boats are regularly rammed on to the reef to provide better viewing opportunities for the visitors.

8.

Pollution (Coastal, Sewage, Sedimentation, River runoff, Petrochemicals,  etc.)

The degradation of the coastal marine environment is steadily increasing as rivers and canals carry heavier loads of untreated domestic sewage , industrial pollution and sediment  into the coastal seas. The development of the coastal belt and tourism has also contributed to the addition of non bio-degradable plastics and other solid waste into  the waters. Waste from tourist hotels on the coastline, petrochemicals from boats, bilge water pumping and tank cleaning by tanker ships and spills. fishery spoils, coastal industry  and sedimentation from river run off cause serious adverse impacts on the reef. This may also contribute significantly in disrupting the ecological balance of the reef and may be causative in increasing coral diseases and triggering attacks by invasive reef organisms.

9.

Natural disasters

The effects of natural processors and climatic events are becoming a growing threat to coral reefs as the intensity and frequency of such events are steadily on the increase. Currently they are overtaking in importance as the major factor in reef destruction over the normal human causes.

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Sand filling

Though coral reefs are a primary agent in acting as a wave barrier in stabilizing eroding shorelines. They are at the mercy of sand filling (accretion) events. The 1997 beach accretion event at Akurala smothered and completely buried the shallow Akurala coral reef under several feet of sand within a time span of about one month. The Hikkaduwa Marine Park is also gradually filling up and is at risk of disappearing under the sand if no remedial action is taken.

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Global warming/ Coral bleaching

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Storms

Storms  and associated wave surges are known to damage reefs periodically, often these affect the shallower more exposed sections of reefs. Storms damage  coral reefs as the wave force  causes  coral breakage,  move coral debris and sand on reefs. They can also cause significant re-modeling of reef environments;  changing the current patterns. The incidence and intensity of Storms are on the increase with the changes to global climate. On the positive side storms of moderate intensity can help in clearing surface debris from a reef and leaving reef surfaces cleaner and available for new coral settlement.

·

Tsunami

The 26th December 2004 Tsunami is the only properly identified Tidal wave on record in Sri Lanka. The damage to submarine environments from Tidal waves differs from storms in its mechanics. The location, geography both coastal and under water affect the way the reefs are impacted. During the 2004 Tsunami the reefs in the direct path of the tidal wave;  especially in the east coast seem to have suffered heavier physical damage, while the Southern and Western reefs received less direct damage as the wave approached the coast more as an accelerated tide. Indirect damage may be caused by erosion from the strong currents created by the receding tidal waters and through the large masses of debris washed off from land areas and being deposited on the reefs causing abrasion and smothering.

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Infestations /Reef Invasive species

Due to yet unidentified reasons,  sudden increase in the population of normally insignificant reef organisms spread fast over the reef surfaces at an accelerated speed killing off live coral cover in competition for reef space. The species include both algae and faunal groups ranging from simple sponges to the Crown of thorns sea-star. The reason or triggers for these population bursts are unexplained and may be the result of reduction of predatory species or creation of conditions that favor increased survival of larvae of invasive species.