The weather has been a bit of a mixed bag over the last week, but with the wind turning to the south-west the bay has gradually clouded up, reducing the visibility a little, and we’ve had some reasonable sized surf outside the reef.
So what’s been happening in our bays?
As I was exploring part of the outer reef, I noticed a Paragoniastrea australensis (a type of brain coral) covered in long filaments with white tips. At first I thought these were some kind of eggs that had been laid all over the coral. But a few quick enquiries to a very helpful coral expert (Joe Rowlett, author of the impressive tome Indo-Pacific Corals) informed me that these are sweeper tentacles. It is the first time I’ve seen these in action. They are used in aggression against nearby corals so the platygyra can assert itself and ensure it has the necessary space to grow. The white tips contain a concentration of stinging cells (nematcysts). You can see the tissue damage to the adjoining coral colony in the first image. I keep saying it, but it really is like Days of Our Lives down there! Above is another photo Paragoniastrea australensis, which has done a really good job of maintaining its space.
On a different day, I witnessed an inscribed wrasse, Notolabrus inscriptus, being watched by a small chub as it ate. The inscribed wrasse was a large terminal male and as I didn’t have a photo of one at that stage of maturity, I paused to get a few shots. The ensuing images are hilarious. The look on both their faces is priceless when they realise I am watching them! The chub then appears to be incredulous when the wrasse dives back in for more. The wrasse finally comes back up and gives me a very indignant look before swimming away. I made a little video of the stills for a bit of fun, here.
As I mentioned previously, the aatuti (banded scalyfin or Parma polylepsis), like many of the fish in the bays, have been in breeding mode. I know these aren’t really pretty or anything, but still, I do find some of their behaviours fascinating. They are great little gardeners aggressively guarding their little patch of algae all year round. I took a photo of an aatuti this morning guarding its algae patch, and in this case some eggs as well (the lighter patch). I was convinced I had a photo on file of the same fish this time last year. Sure enough, exactly one year apart to the day (15 July 2020), there it was doing the same thing – guarding its egg patch! The algae patch has grown slightly bigger in that time. If you are interested, I wrote a blog post about the aatuti, here.
On a final, and more sombre, note. We have quite a few instances of white syndrome in the bay. I keep an eye on just a couple of the patches and photograph them. These photos (below) show the disease moving across a coral colony over the space of a couple of months. This is not a good. Scientists aren’t exactly sure of the cause of this disease, but it is thought that algal overgrowth of the coral may be the main cause. I have sent my images, along with others as I have taken them, to Australian Marine Parks for their records.
You can see the white syndrome in the bottom leaf of coral on the left. In the photo on the right you can see it has spread very rapidly across the rest of the colony.
