Reef Report for Friday, May 2, 2003
Nudibranchs: Colorful Residents of the Reef
We are all motivated by seeing different things when we go diving, but if it wasn’t for there size and inconspicuous habits Nudibranchs would be considered a main attraction on the Great Barrier Reef.
I have covered Nudibranchs in earlier articles but as a scuba diver I really enjoy seeing these amazing little creatures.
You have to really look hard to spot a Nudibranch, which are pretty common on coral reefs. A good place to start looking is among algae, sponges and soft corals, which are their favorite food sources being algae. When you go diving next time try and see how many you spot. You will be surprised!
Nudibranchs form one of the main divisions with the molluscs group. In particular the Nudibranch featured is a Chromodoris. If I have picked the particular species correctly it is a Harlequin Nudibranch (Doridaceans). They are characterised by a combination of a pair of tentacles (rhinophores) on the top of the head and a tuft of feathery gills on the rear part of the back. Carrying no shell Nudibranchs protect themselves from predators by having very toxic flesh, making them not a very tasty meal. Their bright color patterns act as a warning to any looming predators to think twice before attacking, or to at least remember not to eat the next distinctly and brightly colored Nudibranch they come across!
Northern Reefs/Coral Sea
Sometimes just one dive can help you appreciate the sheer diversity of the Great Barrier Reef. Passengers on Diversity on the weekend unanimously declared Steve's Bommie their favourite dive of the trip. In diver language it was "going off". Sightings included 2 resting green turtles, decorator crabs, candy crabs, a large Dogtooth Tuna, a school of buffalo parrot fish, trevally and mantis shrimp. Also sighted were lionfish, a Coral Cod and a small Reef Shark. Steve’s Bommie is a small pinnacle about 30m high, situated off Ribbon reef No.3, around 65 nautical miles north of Port Douglas. Divers start the dive at the base and slowly circle their way around the bommie to the surface. Definitely a must do for all divers.
Passengers on TAKA II reported water temperature at 24 degrees with plenty of sunshine and winds around 15 knots at the Ribbon reefs and Coral Sea. Some of the sightings witnessed this week were 5 huge potato cod coming in for a feed, Maori wrasse and red bass. There were also a couple of sharks around.
Including both white tips and a Bull Shark. At Challenger Bay they saw garden eels, manta rays and a green sea turtle. The shark feed at Osprey was very exciting with over 15 sharks thrashing about for the passengers. There were also massive schools of dogtooth tuna and chevron barracuda. Also spotted on the dive trip were a Leopard Flounder, a White-mouthed Moray Eel and a couple of Lionfish fighting over breeding territory.
Onboard Passions of Paradise passengers enjoyed a great day out to Paradise Reef. Everyone enjoyed 15m visibility and calm surface conditions. Introductory divers reported seeing bicolour angel fish and lots of moorish idols, while certified divers were lucky enough to spot a White-tip Reef Shark.
The diving reports I have received from Poseidon out of Port Douglas is that diving and snorkeling conditions have been very exciting, with very favourable tides producing some fantastic drift diving on the Agincourt Reefs. Sightings reported ranged from eagle rays to anemone fish laying eggs. With the water temperatures now starting to drop more new sightings of unusual critters can be anticipated.
It is not uncommon to experience stronger winds during the months April to June and this weekend is not going to be any different. Expect some bumpy rides but all in all under the water will still produce some great diving. 1
As always safe diving! Steve Brady
This weekly reef report was written by Steve Brady of Pro Dive Cairns, who compiles them from the dive trips he takes, as well as the many conversations he has with divers, dive instructors, captains, and others in the Cairns dive community. The report is published weekly in the Cairn Post, the local daily paper and appears here thanks to the courtesy of
Pro Dive Cairns.
Index of all reef reports.