THE GREAT BARRIER REEF!

The title says it all folks


Budget: AUD$18-22 per night (Gilligan's hostel, Cairns, QLD) + groceries ($5 per meal) + SCUBA costs

The live-aboard cost about $300USD for six dives and two days spent out on the boat which was the cheapest (and most amazing!!) deal that we could find. Definitely worth it to experience world-class diving.



Here's a humble attempt to showcase what it's like to experience the Great Barrier Reef. I can assure you that this in no way does the job, and the diversity and color of this ocean habitat is beyond imagination.


That being said, threats to this beautiful reef, as well as many reefs like it are very real.


While on the live-aboard that took me out to the reef, I listened to an interesting discussion between our boat's captain and some of the passengers over the validity of human activity as an imposing threat to ocean systems. He presented some interesting arguments from his observations of returning to this same reef for 20 years, noting that he watched the corals bleach and regrow annually as evidence to debunk the climate change argument.


His argument was compelling, but it ignored and misunderstood a lot of trends observed in scientific literature that suggest that rising sea surface temperatures may be a significant factor in the changing appearance of reefs. Because some of the things he mentioned were unclear on the biology behind corals, here's a friendly list of some widely accepted truths*º:


1) Corals are reef-building animals (hard corals, there are also soft corals and sea fans)! They share the same phylum (Cnidaria) as jellyfish and sea anemones, to name a few. As colonial animals, hard corals deposit a hard skeleton made out of calcium carbonate that forms what we think of as "coral reefs."


2) Corals, as well as some other cnidarians, have a happy little relationship with a single-celled algae called Symbiodinium or zooxanthellae. This alga, a type of dinoflagellate, lives within the coral's cells, and trades oxygen (made by photosynthesis!) and carbon for a home and food from the coral (Muscatine and Cernichiari, 1969).


3) Heard of coral bleaching? No, this does not consist of people throwing Clorox at the ocean like I pictured as a kid. Those little algal friends, the zooxanthellae, are what give the coral its beautiful colors. When corals become stressed (me too) by things like excess UV, increased water temperature, and water pollution, their zooxanthellae buds start to turn less friendly, producing chemical compounds that hurt the coral. As anyone should when someone is being rude in your home, the corals kick the zooxanthellae out. While this is a good temporary solution, corals rely on that oxygen input from the algae, and can die if left too long without them (Baker, 2003).


4) Corals aren't completely doomed after a bleaching spell. They can pick zooxanthellae (remember, its a single-celled dinoflagellate algae) out of the water and return to their happy partnership. However this is not a perfect solution, and bleaching generally leads to death (Baker, 2003).


5) The theory isn't that all corals are bleaching. Like the reef I visited off of Cairns, I can imagine that many places have been able to maintain their biodiversity and health. That being said, what seems to be happening with the of majority reefs is that places like the Great Barrier Reef as a whole, are seeing increased bleaching events, sustained over longer periods of time that usual in response to more intense weather patterns like El Niño. As I mentioned, a number of factors can stress a coral and cause it to bleach. What is important to note is the current trend of higher average temperatures making these preexisting problems worse.


6) We aren't doomed. Obviously none of this is good news; however this might not mean a complete destruction of corals, as is sometimes suggested. We understand that corals can uptake new algae, and it has been observed that they can swap out, or shuffle their zooxanthellae friends for different types that may be better at withstanding things like higher temperatures, increased UV rays, or pollution. This could mean that we won't necessarily see a complete destruction of coral reefs, but rather a change in what corals can live in this newly altered environment.


So what can you do?

1) Small things like reducing your carbon emissions are always going to help. Public transportation is awesome! It reduces the number of cars on the road and it’s also fun. Always go for the local public transportation if possible when visiting new places. Renting a bike and cycling around to explore is also a fun and carbon neutral way to see the world!


2) When traveling to places where coral is present, be sure to use the right kind of sunscreen! Sun protection is important (especially over here in Australia where the ozone layer is the thinnest!), and sunscreens often use a combination of oxybenzone and octinoxate that can accumulate on reefs in high densities and change the way coral babies develop (Downs et al. 2016). Always look for "reef safe" sunscreens that don't contain these chemicals. 100% zinc is the way to go! Also be sure to apply sunscreen one hour before entering the water so you can be sure it is nicely incorporated into your body and not onto the corals.


3) Watch what you eat. Herbivorous fishes are extremely important on coral-dominated reefs because they make sure that algae doesn't steal the space from corals or shade it out. Grazers like parrot fish act as growth checks on algae (T. P. Hughes et. al 2003), but unfortunately they are heavily fished. They're easy to catch, but resist the temptation if you're a recreational angler or spearfisher and think of what an important role they play in keeping that beautiful reef beautiful. It is also good practice to look for sustainable fish when consuming ocean products, since the fish that eats the parrot fish is important in this chain too! (See the SEAFOOD WATCH app by Monterey Bay Aquarium).


4) Stay up to date on the latest research! While direct scientific literature can sometimes be difficult to read and understand if you don't have the background, there are many news and public scientific sources that act as a bridge between the researchers and the general public. Update yourself regularly on the latest findings by poking around the internet. Sources like National Geographic that write their stories directly based on the latest literature are accurate and fun to read (NatGeo literally has a snapchat article every day, you have no excuse).


Here's a list of cool websites and journals to check out if reading direct scientific literature isn't your thing:


Coral colors and protection from the sun:

http://theconversation.com/revealed-why-some-corals-are-more-colourful-than-others-36866

Bridging a Gap between Scientists and the Public:

https://www.huffingtonpost.com/albert-einstein-college-of-medicine/bridging-a-gap-between-sc_b_11535268.html

Ways for young scientists and others to keep up on the literature:

https://www.sciencemag.org/careers/2016/11/how-keep-scientific-literature

Why we need to bridge the gap between science and the public:

https://www.huffingtonpost.com/albert-einstein-college-of-medicine/bridging-a-gap-between-sc_b_11535268.html

Importance of parrotfish and herbivores

https://blog.nationalgeographic.org/2014/07/02/to-save-coral-reefs-start-with-parrotfish/


Below are some peer reviewed papers on current understanding of coral reefs and how they are influenced by human stressors:


Recent Advances in Understanding the Effects of Climate Change on Coral Reefs

https://www.mdpi.com/1424-2818/8/2/12/htm


FLEXIBILITY AND SPECIFICITY IN CORAL-ALGAL SYMBIOSIS: Diversity, Ecology, and Biogeography of Symbiodinium

-This is a general review of the symbiosis, with an entire section regarding bleaching, symbiont shuffling, and shifting community composition.

Climate Change, Human Impacts, and the Resilience of Coral Reefs

http://science.sciencemag.org/content/301/5635/929?casa_token=aRsReCiYz4EAAAAA:ZT_znxhLuV0vdCsRmh6PjwZTsytf8i12dM0ZsihdhiTVs3-uEkB4g89um5xmO-dqxZpGxNd72FDB6wc

-This broadly outlines the concept of compositional change of communities rather than the complete die-off of corals as an organism.


Thanks for reading this long (and hopefully informative) post about something that I'm super stoked on and I hope you now will be too!


Cheers mates!


*theories based on many tested and falsifiable hypotheses, tested many times with adequate repetition and peer reviewed by fellow experts in the field

ºwhile these are the facts of today, science is a constantly evolving field that builds and tests itself every day. What we once knew as truth may very well change so it’s important to not become hung up on changes that occur within science. That being said, today's truths are tested with the most modern techniques possible and very well should be used to influence policy in areas where science is relevant (basically everywhere!)

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