COMMENTS & OBSERVATIONS

An early start again saw Li’l Mischief arriving at Mudjimba Island as the dawn broke. Surface conditions were ideal and just a small swell was running. I was the only boat at the island when I entered the water but there were three dozen on the eastern side alone when I resurfaced. It was a big day on the water out of Mooloolaba. More and more vessels arrived including dive charter boats on the souther side of the island. The species count is a little lower than recent excursions. Goniobranchus splendidus were everywhere across the substrate, however, interestingly, most of the other species were sighted congregated in a quite small area, on both dives. Ceratosoma tenue and Trapania vitta are worth a special mention.

Taxonomic Diversity:
18 of the 20 species sighted were nudibranchs, with 14 being dorids comprising 3 x phanerobranchs (non-retractile gill), 2 x porostomes (suctorial feeders – all of the Phyllidiidae family), 9 x cryptobranchs (retractable gill – all bar one, belonging to the Chromodorididae family) and 4 x cladobranchs comprising 1 x aeolid, 1 x arminid and 2 x dendronotinids. One each of Sacoglossa and Cephalaspidea rounds out the species numbers. If diet is considered then 12 of the 20 species sighted are spongivores.

Our Historical Data:
– This excursion brings the number of survey dives to 17 at this site since we commenced fully recording data here on 05/06/2010.
– 112 species have been recorded at this site.
– The most regularly recorded species at this site are: Doriprismatica atromarginata (94%), Goniobranchus splendidus (94%), Hypselodoris jacksoni (88%) and Phyllidiella pustulosa (83%).
– This is the first time we have recorded Gymnodoris sp. 09 and Dermatobranchus sp. 08 at this site.
– The number of Goniobranchus splendidus specimens continues to rise.
– The line graph shows a steady decline in the number of species recorded at this site, but more data and close comparison of the nature of each of the previous surveys is needed before any definite conclusions can be drawn. One factor may be that the last four surveys (dives) have been undertaken by a single surveyor rather than the two, three or even four previously. The large spike in the number of organisms recorded on dives 14 & 15 is directly related to the swarm of pteropods, sea-butterflies, that were present then, skewing the data. (See Image Gallery below)
– This site last surveyed on 29/11/2022.
(Historical data courtesy of Terry Farr, who extracts it from his comprehensive database.)

Key to symbols
+++ New Species
+ First time sighted at this site
# Most commonly sighted at this site with %

TOTAL SPECIES SIGHTED: 20

DIVE IMAGES GALLERY

PUT CURSOR ON IMAGE FOR SPECIES NAME
CLICK IMAGE TO ENLARGE & SCROLL