With increasing reports on global warming and ocean acidification, the reefs in Brunei too, are not omitted from such devastation. Comparison between Reef Check surveys done in 2012 to 2016 shows a slight decrease in live coral cover from 40% to 34%. Aside from the global threats from climate change and ocean acidification, coral reefs damage is largely attributed to local threats that could have otherwise been prevented through stringent management. Some of the local threats are as followed:

 

1. Overfishing

• Overfishing contributed to the main cause of threat to our marine ecosystem. It affects the ecological balance of reef communities, over harvesting of herbivore fishes and other key reef species that are able to control algal biomass within the ocean. Fishing practices that are unsustainable may also cause effects that are far beyond the directly overfished population, thus, negative affects the overall food chain of the reef communities.

 

2. Pollution

• This may include pollution from industrial waste, sewage, oil pollutions as well as human waste product. Pollutants may alter the chemical composition of seawater and cause a spike in nitrogen level. This causes an overgrowth of algae or termed ‘algal bloom’ that may cover over a large proportion of the corals and cut off sunlight that are harvested by the ‘zooxanthellae’ for photosynthesis and coral growth. Increase in nutrient input from river run-off may also alter the phytoplankton in the sea; the main food source for predatory larvae, Crown of Thorns. Other human waste such as ghost nets and fishing materials that are left on corals may result in a large pool of unintentional bycatch of larger species such as turtles and sharks. These ghost nets trap the large fauna as they get tangled up on the lines, reducing their ability to swim back up to shore to breath.

 

3. Destructive fishing practices

• This includes practices such traditional fish bombings, cyanide fishing, ghost fishing, bycatch and bottom trawling. The use of explosives and poisons is common in both fresh and salt water fishing. Although cheap and easy to purchase, the results of such practices are usually devastating as they kill not just the target fish but also the surrounding fauna and flora. Bottom trawling make use of enormous nets that are weighted down with heavy ballast and dragged along sea floor, raking and crushing everything along the way. The overall reconstruction of coral reef may take long, if not, decades to recover.

 

Anthropogenic threats are as followed:

 

1. Climate change

• Increased in water temperature may cause stress to corals, resulting in ‘bleaching’; a phenomenon where colorful, symbiotic algae (zooxanthellae) expulses itself from corals, leading to a whitening or ‘bleached’ corals. These zooxanthellae are responsible for the survival, growth and reproduction of corals. While most corals can withstand from bleaching events, it is predicted that there may be an increased in frequency and severity of coral bleaching, reducing the ability for the already stressed coral reefs from recovering.

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2. Ocean acidification

• The ocean is a great source of carbon sink that can absorb at least a quarter of the CO2 released into the atmosphere every year. When the atmospheric CO2 increases, the effects is proportionate to the amount of CO2 that is dissolved in the ocean. The downside of such effect is an increased ocean acidity and lowering of carbonate concentration that is useful for most calcifying marine organisms. This includes corals and shell fishes that make use of calcium carbonate to build their skeleton. Increased emission of CO2 may further dampens the ability of corals to grow and recover bleaching and other stresses, thus, can be lethal to survival of corals in the ocean.

 

There may be other form of stresses and threats to the survival of coral reefs including careless tourism, coral mining and sedimentation. Although less reported in Brunei Darussalam, these practices are still widely reported in our neighbouring countries including Sabah and Sarawak.

 

If you have seen any of these practices, please report them back to us!