Good evening and welcome a more ancient world, the world of biodiversity. Tonight let's take a tour of one of the great wonders of this world, the great barrier reef. I had the great privilege of spending a day snorkeling on the reef in May 2009. It was also the first time I used the underwater housing for my camera. Let's learn a bit about the reef and put away the cares of the day.
Coral reefs are a fascinating phenomenon. Warm water holds less dissolved oxygen gas than does cold water. The clarity of the tropical ocean is partly due to the paucity of plankton in the oxygen poor water. Coral takes advantage of the water clarity to live like a plant as well as an animal. The coral provides food, directly or indirectly and structure for a great host of creatures. The pictures above and below show the spatial complexity of the coral habitat. If the open ocean is a desert, the coral reef is a rain forest.
The indopacific region (Australia/SE Asia) is the most diverse marine area on earth, the Amazon basin of the ocean.
The day we went out the tide was low and the water calm. It was ideal snorkeling conditions except that in places it was difficult to get around to coral as it came right up to the surface.
The great diversity of fishes on the reef can be seen in this photo. The eye is naturally drawn to the large parrot fish in the center. This is the equivalent of an elephant, literally eating the forest it lives in (parrot fish eat coral and excrete sand). You might also notice the large numbers o f pale green damsel fish.
A close up of the area in the lower left reveals four or five species of fish.
To the right of the parrot fish is an angel fish.
A bit further to the right is surgeon fish.
The areas between the coral is also home to fishes such as this sweet lips
And this lizard fish
Mixed in with the coral are their close relatives the sea anemones. Living amidst the anemone were clown fish. A classic example of a mutualistic relationship as we discussed a few weeks ago.
Other fish feed in and around the coral. I don't know the name of this species.
This is a Fox-faced Rabbitfish,an example of a species with toxic spines.
Here is another example of the details that can be missed. A nice bit of coral scenery.
Looking closer you can see the individual coral polyps. Each of these is like a tiny sea anemone with organisms called zooxanthellae living inside. The zooxanthellae are capable of photosynthesis. The polyps build a calcium shell that forms the reef. Ocean acidification caused by increasing CO2 levels in the atmosphere interfere with reef formation.
These blue damsel fish live among the branches this particular kind of coral. I saw them several places during the day.
Next time we'll look at some of the invertebrates on the reef.