Well we're here just in the water
straight off the reef crest and you're in a region here where we're starting get some
waves
pounding on the reef crest. Now, one of the important functions
that coral reefs have, is to dissipate that
energy that's coming from waves and storms, and what you can see in terms of
the coral community around me,
are a lot of very tough corals,
that are hanging on for dear life here as these waves come in.
Now it's a relatively calm day but I'm still having trouble hanging on.
As you can see there are waves breaking over the top here and it's this wave-
stress environment at which we begin our journey
down the reef slope, to the end of the end of the reef. So let's go a little bit deeper
and see what we find.
Well here we are
we're now at
10 meters below the surface. We're coming down the reef slope
and we're at a point where there's luxurious coral growth.
You can see there's far more branching coral, and
it is this part of the reef which is really growing at the fastest and most
productive
rate. As we saw in the shallows,
corals are struggling against wave action but down here
you've got ideal light, you've got oceanic water very low in
nutrients and sediments, and it's really the best place for corals to grow.
So if you look at the platform reef of Heron Island you'll see that
this is where it's growing this is the most actively growing part of the atoll.
But as we keep on going down the reef slope,
we'll start to lose light, there will be less and less coral
until we get to the great sandy expanses which is where the coral reef part of the
reef
has finished. So lets go have a look at that.
Well I can see things as I'm getting
deeper here, things are changing. There's
a lot less coral, there's a lot of other organisms, there's soft corals
and I'm getting to a point where corals are probably
not growing as prolifically as I saw at 10 metres,
but there are some other interesting creatures here we have a really large sea
anemone,
right in front of us here. This one looks like it's doing very well.
You can see tiny little
percula clownfish swimming through the tentacles,
of course the brown colour is zooxanthellae,
the symbiotic dinoflagellates.
Oh! this is an interesting one,
here's another
solitary coral.
This is another species which lives
independently of the bottom, so
it's mobile like that. It doesn't tend to go anywhere,
but it's got a different growth form,
as you would appreciate, to those that we've seen so far.
Well here we are
we're at 20 metres below the surface, the light levels are
getting
lower, the amount of coral is
giving way to sandy expanses so we no longer have the
rich coral habitats we have behind us, but of course we have a whole series of new
habitats
as we head out into the great sandy expenses between
the reef systems, between the platform reefs.
And so if I keep going that way,
it'll slowly get deeper until it will no longer be accessible by scuba diving.
At that point, you have to switch over to submarines
and remotely operated vehicles.
and that's exactly what we've been doing at the University of Queensland to
understand these systems.