Anthropogenic Impacts (originating in human activity). The Curio trade is a global business with huge numbers of marine organisms collected and exported for sale as souvenirs or in the aquarium trade. This has lead to local extinctions resulting in an alteration of the ecological balance in many areas. Sedimentation is a major problem for coral reefs smothering corals with disastrous effects. When covered by sediment the coral polyps will release a mucous to remove the sediment, which diverts energy away from other vital processes. Poor land management and deforestation is leading to increased run-off and higher levels of sediment accumulating on coral reefs. This increased particulate matter serves to reduce light penetration in the water altering vertical plant distribution.
Pollution is a problem frequently associated with areas of increased human activity. Agricultural chemicals such as pesticides and fertilisers are pumped into watenivays and find their way to coastal waters where they damage reef communities. Industrial activities release heavy metals into the marine environment along with hydrocarbons that are known to affect cell structure and growth rate of corals.
Nutrient loading results from the discharge of materials from agriculture and aquaculture. Organic compoundsbuild up in coastal waters leading to oxygen depletion through eutrophication. Coral reef communities survive in an environment where nutrient levels are finely balanced. lf these levels rise they are quickly outcompeted by algae resulting in a decline in the amount of coral and a shift towards an algal dominated community. Further loading of nutrients from sewage serves to assist increased algal growth.
Coastal development can be particularly destructive to coral reefs and is of significant importance in relation to Bali. Development brings with it associated coral reef stressors such as increased sedimentation from dredging and runoff, nutrient loading from sewage discharge, and physical damage from tourism related activities. Already many of the reefs in southern Bali have been damaged beyond repair.
Overfishing is a problem for coral reefs around the world. In Bali over 11,000 tons of fish are imported each year just to satisfy the demand for seafood from the tourist industry. The overexploitation of large predatory fish can lead to wide scale ecosystem changes. Similarly, by targeting herbivorous grazers algae quickly begins to dominate once healthy reef systems. Continued overexploitation will also lead to a reduction in the size of fish species.
Destructive fishing practices are common throughout SE Asia. There are numerous techniques with dynamite fishing and cyanide fishing the most widespread. Dynamite fishing in particular is an extremely damaging, non selective technique that decimates large areas of coral reef.
Mining of coral reefs used to be commonplace and still occurs in parts of Indonesia. Apart from the obvious destruction of the reef itself and the dispersal of reef organisms, mining can have a significant affection the surrounding coastline. A good example is Candi Dasa on BaIi’s east coast where mining the coral reef for construction led to sever beach erosion.
Text from Chris Mason – Parke; MSc g
R. O.L.E. Foundation Marine Biologist .
www. rolefounda tion. org