Great Barrier Reef

Arguably, the most famous tourist attraction in Australia is the Great Barrier Reef (GBR). Varying from 5 to 75 miles off Australia’s east coast, it extends thousands of miles from Cairns to near Sydney. Really a collection of reefs, this massive organic superstructure is easily visible from space. (Jen Note: Until coming here, I imagined the reef as one big underwater wall, which is definitely not the case.) It is called a barrier reef because it blocks the majority of the surf coming from the Pacific Ocean. This creates the long stretches of calm beach, which are present all down the east coast.
The basis for the GBR is the coral. These colonial organisms build skeletons of calcium carbonate in their pursuit of sunlight. These skeletons, both living and dead, provide the base upon which an enormous interconnected ecosystem rests. The GBR is so large that is has a very real impact on the coastal weather. For example, the Daintree rainforest gets over 30% of its rainfall from cloud systems generated by the GBR.  During hot days, the coral in the GBR releases sulphur-gas compounds into the water.  These create low-lying cloud cover, protecting the coral from overheating in the shallow warm seas. So the rainforests on the mainland may not exist without the living coral reefs!

We took a day cruise to snorkel a few sites near Port Douglas, Queensland. Before I get to the cool wildlife pics, I need to get a few things out of the way.

First, I have a terrible farmer's tan. No, I don’t sit out on beaches trying to crisp my skin.  The UV here is ridiculous.
  

Second, Everyone (and I really mean everyone) looks ridiculous in a snorkel and mask. 


Third, It is hard to get a feel for the scale of things with underwater photos.  Many of these corals are hundreds (if not nearly a thousand) years old.  The large coral in the photo behind Jen is almost 10 feet across. 


Fourth, the GBR is dying.  Corals are very sensitive to water temperature. The aggressive and never-before-seen warming of the planet due to greenhouse gas emissions has pushed many of these reefs to the limit.  Just two degrees Fahrenheit increase in water temperature causes mass bleaching events.  If the temps don’t go back down in a week, the coral will die.  It can takes decades, or hundreds of years, for reefs to recover.

To start out, the great fear of mean, sharks. Sharks are really not dangerous at all, even the great whites. Of course, Jaws would have you thinking differently. This is one of several species of reef shark, which is about 5 feet long. 
 









Hey, look, its Nemo….  One of a large variety of anemonefish.  The biggest one is the dominant female.  So Nemo’s dad, actually turned into his mom (they are hermaphroditic). They have also started being hunted agressively for aquariums since that movie came out.
























This is one of many species of parrotfish. They graze on algae which grows on corals, but also on the dead chunks of corals themselves. The leftover coral skeleton is excreted. Those beautiful white sand beaches in the Caribbean? Yep, they are fish poop.


Corals get most of their energy needs from symbiotic algae which they host inside their bodies.  This means a healthy coral is a dull brown/green color.  When corals are stressed they produce extra antioxidants to protect against the algae's oxygen production. This makes them a vibrant blue, orange, or purple color.  The early stages of bleaching also look this way, before fading to a chalky white, and finally a dead coral.  The coral in the photo below is recovering from a stress event, probably high water temps, or similar.


The variety of coral shapes and sizes is staggering.




These are younger giant clams.  Only about a foot across, they are anchored to the coral base, filtering water for food.  They never stop growing, and can exceed 4ft in diameter after a hundred years or more.


This is a sea cucumber.  The vacuum cleaner of the reef, they slowly crawl over the sandy bottom, sucking up the sand, and eating any organic material it contains.


This is one of the more common species of sea turtle, known as a Green Turtle.  Interestingly they are not green on the outside.  Instead it is their green fat which gives them this name.  Diving for over 30 minutes at time, they often migrate thousands of miles a year for feeding and breeding. This one is about 30 years old, and has a 30 inch long shell.



This is probably the smartest creature on the reef, the cuttlefish. A distant relative of the squid, they can change the color and texture of their skin at will, making them nearly invisible.  They can also swim forwards or backwards if they so desire.