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Dive Reports

22-02-2024 Wobby Rock

DAY/DATE

Thursday

22/02/2024

SITE/S

Wobby Rock
Outer Gneerings 

 

PARTICIPANTS

Harvey & David 

 

TYPE

Subtidal

 

MODE

Boat Dives

 

VESSEL

Li’l Mischief

 

DIVE

1

2

SITE/S

Wobby Rock

Wobby Rock

SPECIES #

12

9

DURATION

65 Min

65 Min

DEPTH/RANGE

15-19 m

15-19 m

TEMP.

27 C

27 C

VIS.

8-10 m

8-10 m

SURGE

Moderate

Moderate

CURRENT

Slight

Moderate

COMMENTS & OBSERVATIONS

Following all the rain and wind we’ve experienced of late I was keen to dive a site where perhaps we would only have one of the two circumstances that can make a dive most unpleasant. I’m talking about very low viz and a swell that delivers a heavy surge down under. I can handle one but not both at the same time. The choice was Wobby Rock on the Outer Gneerings not far from the Blinker. Out there, it was hoped, we might be far enough offshore that the viz might be acceptable and the depth ameliorate somewhat the surge. The top 10 metres was green and murky but below that the viz opened out to 8-10 metres. The surge was there and made close-up photography challenging, but perseverance between the surges saw some nice sea slugs recorded. Nudies of Note include: Ardeadoris tomsmithi, Hypselodoris zephyra, Glossodoris sp. 04,  Marionia sp. 06 and Mexichromis macropus. The wind had dropped a little by the end of the second dive but a vicious little surface current certainly made its presence known as we reboarded the boat to head back to Australia.

Comment on Ardeadoris tomsmithi: Relatively common in Hawaii and known across the Northern Pacific from Hawaii to Okinawa. Other reports are scant and scattered from such disparate regions as Exmouth, WA; Lord Howe Island and Sunshine Coast Qld. Harvey has a record of it previously from Flinders Reef, off Cape Moreton in 2018, but the find here on the Gneering Shoals was a first for David.

Taxonomic Diversity:
Eighteen of the nineteen sighted species were nudibranchs, with 14 being dorids comprising 2 x phanerobranchs (non-retractile gill), 4 x porostomes (suctorial feeders of the Phyllidiidae family), 8 x cryptobranchs (retractable gill – all 8 belonging to the Chromodorididae family) and 4 were cladobranchs comprising 3 x aeolids, 0 x arminid and 1 x dendronotinid. A single sacoglossan completes the species count. If diet is considered then 13 of the 19 species sighted are spongivores. 23 specimens in total were recorded.

Our Historical Data:
– This excursion brings the number of survey dives to 32 at Wobby Rock since we commenced fully recording data here on 23/10/2010.
– 115 species have been recorded at this site.
– Of interest is that 6 of the species were recorded for the first time at this site. These are: Ardeadoris tomsmithi (Although this species has been recorded on the Sunshine Coast previously, this is our first record of the species), Cratena simba, Diversidoris sp. 2, Glossodoris sp. 4, Gymnodoris sp. 9 and, Marionia sp. 6 ;
– In addition, this is only the second time 4 of the species – Bulbaeolidia alba, Hypselodoris zephyra, Mexichromis macropus  and, Tenellia sibogae – have been recorded by us at this site;
– Although the overall number of organisms recorded on this survey is at the lower range of what we usually find here, the number of species recorded is around average – see graph below;
– The graphs below in the image gallery seem to indicate that the abundance of Phyllidia varicosa and Phyllidia pustulosa seems to peak around May and June respectively. However, the relatively small number of dives each month makes any definitive conclusions risky;
– Our most commonly recorded species at Wobby Rock are Phyllidiella pustulosa (93%), Doriprismatica atromarginata (90%), Thuridilla cf. splendens (87%) and Chromodoris elisabethina (60%) – all sighted on this excursion but mostly singletons.
– Our last survey at Wobby Rock was on 23/03/2022
(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: 19

 

SPECIES LIST – ALPHABETICAL

Aegires citrinus 1/-
Ardeadoris tomsmithi -/1 +++
Bulbaeolidia alba -/1
Cratena simba 1/- +
Chromodoris elisabethina -/1 #60%
Diversidoris sp. 02 1/- +
Doriprismatica atromarginata 1/- #90%
Glossodoris sp. 04 -/1 +
Goniobranchus splendidus 3/-
Gymnodoris sp. 09 -/1 +
Hypselodoris zephyra -/1
Marionia sp. 06 1/- +
Mexichromis macropus -/1
Phyllidia elegans 1/-
Phyllidia varicosa 1/1
Phyllidiella lizae 1/-
Phyllidiella pustulosa 1/1 #93%
Tenellia sibogae 1/-
Thuridilla cf. splendens 1/- #87%

SPECIES GROUPED BY ORDER

Nudibranchia
Dorids
Phanerobranchs
Aegires citrinus 1/-
Gymnodoris sp. 09 -/1
Cryptobranchs
Ardeadoris tomsmithi -/1
Chromodoris elisabethina -/1 
Diversidoris sp. 02 1/-
Doriprismatica atromarginata 1/- 
Glossodoris sp. 04 -/1
Goniobranchus splendidus 3/-
Hypselodoris zephyra -/1
Mexichromis macropus -/1
Porostomes
Phyllidia elegans 1/-
Phyllidia varicosa 1/1
Phyllidiella lizae 1/-
Phyllidiella pustulosa 1/1 

Cladobranchs
Aeolids
Bulbaeolidia alba -/1
Cratena simba 1/-
Tenellia sibogae 1/-
Arminids

Dendronotinids
Marionia sp. 06 1/-

Cephalaspidea
– 

Pteropoda

Sacoglossa
Thuridilla cf. splendens 1/-

Umbraculoidea

Pleurobranchoidea

Anaspidea

DIVE IMAGES GALLERY

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