Save our corals!

"If you get people diving on a coral reef, they're going to become more respectful of the outdoors and more concerned with the threats that place faces" - Tim Cahill, Australian Athlete

One of the best things I did on my gap year was learn to dive; breathing underwater and being surrounded by a vast array of organisms in a coral reef is an unforgettable experience. However global warming is making these environments a rarity.

Figure 1: Cartoon displaying the effects of increased sea temperatures on the underwater environment - Source: Steve Sack

What causes coral bleaching and ocean acidification?

The ocean has absorbed approximately 30% of all carbon dioxide released by anthropogenic activity since 1800's. The uptake of co2 decreases the ph of ocean water as it is converted to carbonic acid, placing coral reefs at extreme risk. Reef building corals and calcifying algae use carbonate to produce the calcium carbonate skeletons which build the reefs. Hydrogen ions released by carbonic acid bind to calcium carbonate, decreasing its concentration and form bicarbonate changing the ocean chemistry affecting the process of calcification, consequently affecting coral reef growth. 

Ocean acidification also effects crucial reef building animals through weakening their calcium carbonate shells, and changes ecosystem dynamics. Furthermore, ocean acidification is reported to a bleaching agent for corals.

Video 1: Dr. Triona McGrath explains how the oceans are changing due to ocean acidification and how it will impact the marine life 

 Coral bleaching is mainly caused by warmer ocean temperatures. When water is too warm, corals expel zooxanthellae causing them to turn completely white. Upon bleaching, the coral isn't necessarily dead, but it is under more stress and is more likely to die.  Mass coral bleaching events are directly related to my previous post about the El Niño-Southern Oscillation event.

Video 1: Explains the process of coral bleaching in more depth

Figure 2: Table highlighting the effects of many Climate variables and their influence on coral bleaching, specifically reiterating my point about ENSO  - Source: Great Barrier Reef Marine Park Authorities

Video 2: 360-degree video showing the extent of coral bleaching in the Great Barrier Reef - Source: Climate Central 

Ocean acidification and Pacific reefs

Ocean acidification is extremely far reaching and effects many aspects of the environment; corals being one of them. By 2034, a 5% decrease in calcification is predicted for all reefs as a result of decreases in ph of 0.06 units per decade in the tropical Pacific. Ocean acidification is predicted to have important socioeconomic and ecological implications for the region including damage to fisheries, tourism and ecosystems.

Coral bleaching globally and the pacific

Coral bleaching is becoming a more frequent occurrence and now more than 70% of coral reefs globally have experienced heat stress potentially leading to bleaching or mortality. 

Figure 4: Map highlighting all the coral bleaching events globally between 1979 and 2010 - Source: Chumkiew, Jaroensutasinee and Jaroensutasinee, 2011

Video 3: Displays the severity of coral bleaching globally

The Pacific Ocean's temperature has increased by 0.31 degrees since the 1950s. Currently, 50% of Pacific reefs are classified as threatened and 20% were highly threatened. This figure is due to rise to 90% by 2030. By geographic region, the eastern pacific region has experienced the most bleaching, while Micronesia, Melanesia and Polynesian reefs the least. Furthermore, bleaching events are projected to become more frequent in the future, with prediction suggesting, they could occur annually in Micronesia by 2040.

Figure 5: Highlights the extent of bleaching in the pacific between the 9th of November and today! - Source: NOAA

Figure 6: The current threat to coral reefs in the Pacific region - Source:  Status on Coral Reefs of the Pacific and Outlook 2011

The Coral Triangle

The Western Pacific is known as the 'Coral Triangle' which comprises of the Solomon Islands, Papua NewGuinea, Timor Leste and several Asian countries. The region is a marine biodiversity hotspot containing 75% of all known coral species and provides shelter for 40% of the world's reef fish.

Figure 7: Map of the Coral Triangle - Source: Hossain et al., 2016

Figure 8: Coral Triangle atlas interactive map! Very interesting tool, please have a play! - Source:http://ctatlas.reefbase.org/atlas/default.aspx?layers=8,68,24&zoom=4&lat=7.46260404298648&lng=125.86914062500001&maptype=terrain

The Coral Triangle Initiative (CTI)

The CTI is a multilateral agreement among six nations to protect a global biodiversity hotspot regarding its coral reefs, fisheries and food security . The region is approximately 5.7 million Km² and directly supports the livelihoods and food security of 100 million people. Additionally, commercial fisheries alone provide USD 3 billion annually to the regional economies, highlighting its great importance.

Figure 9: Map displaying all 612 marine protected areas within the Coral Triangle - Source: Venegas-Li et al 2016

Figure 10: Goals and targets of the Coral Triangle Initiative, many of which will improve the effects of social issues caused by global warming in the Pacific Islands involved - Source: Berdej, Andrachuk and Armitage, 2015

Why is coral so important?

1.  Reefs only make-up 1% of the world's marine environments, but they provide a home for 25% of marine species 
2.  A decrease in the number of coral reefs saw over 75% of reef fish species decline, 50% of which decreased to less than half of their original number
3. Pacific islands have a strong dependence on fishing with fish being an important source of protein
4. Coral reefs reduce wave energy by 97% which would otherwise impact the shoreline
5. Provide substantial economic benefit through tourism and exports
6. Medicinal purposes

Mitigation techniques

A number of techniques have been developed to reduce the effects of coral bleaching 

• Shading of coral
• Connecting coral reefs 
• Building coral tolerance to bleaching
• Marine protected areas 
• 3D printed corals
• Microfragmentation

Figure 11: Diagram displaying coral bleaching mitigation techniques, many of which, particularly the "support human adaptive capacity" and "protect resistance" sections relate directly to the goals of the coral triangle initiative - Source: NOAA

Corals reefs in the Pacific are extremely important to everyday life, through providing sustenance, economic benefits and protection. Our moral obligation as global citizens to protect planet provide further reasoning as to why we should protect these natural phenomena globally as well as in the Pacific for future generations to enjoy!

Wells