COMMENTS & OBSERVATIONS

We had not previously dived any of the inshore reefs off Bowen that were not shore accessible. We had heard good reports of the coral cover at Innaminka Rock so took the opportunity to explore. For the first dive we anchored in the sand on the western side of the rock as it offered some protection from the light easterly winds and also looked like it would be sheltered a bit from any current associated with the tide. From the anchor we swam up over coral rubble towards the rock and shallower water. We never made it to the shallows and the coral because of the large number of species, particularly Phyllidiidae, that we found.

For the second dive, we were going to anchor on the northern side of the rock but there appeared to be some current flow there so we opted to anchor just south of the site of our first dive. Visibility was again relatively poor and we followed a similar plan to that of the first dive. This time however, we made it to the shallows where there was a lot of coral growth. Disappointingly there was also a lot of coral bleaching. We did however find plenty of critters in the rubble in the slightly deeper water and were pleased to see the number of dorids that we did.

This was an enjoyable outing and we recorded more heterobranch species than we have recorded on any of our previous excursions up here. No doubt the site will get a lot more attention from us in the future.

Innaminka Rock is located 1 km north of Horseshoe Bay beach or 700 m north of the tip of the headland that forms the western shore of Horseshoe Bay in the Edgcumbe Heights Recreational Reserve at Bowen. The rock is named after the steamship Innamincka, reported to have struck the rock in October of 1899, but subsequently made lighter and floated off by removal of some cargo.

Taxonomic Diversity:
All twenty-four of the sighted species were nudibranchs, with 22 being dorids comprising 1 x phanerobranch (non-retractile gill), 10 x porostomes (suctorial feeders – all of the Phyllidiidae family), 11 x cryptobranchs (retractable gill – 10 belonging to the Chromodorididae family) and 2 were cladobranchs comprising 2 x aeolids, 0 x arminids and 0 x dendronotinids. If diet is considered then 21 of the 24 species sighted are spongivores. Interestingly, only nudibranchs were sighted across the two dives, the members of the other sea slug orders being absent or, more likely, managed to escape our attention. 56 specimens in total were recorded.

Our Historical Data:
– These are our first surveys at Innaminka Rock off Bowen.
– This is the first time we have recorded: Mexichromis trilineata, Gymnodoris impudica, Goniobranchus daphne, Hypselodoris sp. 11, Noumeaella rehderi, Phyllidia sp. 04, Phyllidiella sp. 06, Thorunna sp. 08, and Verconia sp. 02 in the Whitsundays.

Notes on some new species:
– Hypselodoris sp. 11:  This species, with a little imagination, might represent Hypselodoris emma, the main feature of similarity being the three longitudinal purple lines on the dorsum. The margin, however, has submarginal purple spots rather than a thin marginal line and lacks even any hint of the broad brown lines on the notum.
– Thorunna sp. 08: This species, with a little imagination, might represent Thorunna flores but does not have any yellow in the lines on the notum and the gills and rhinophores are merely tipped in red.

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

TOTAL SPECIES SIGHTED: 24

DIVE IMAGES GALLERY

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