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Dive Reports

09-04-2024 Middle Island

DAY/DATE

Tuesday

09/04/2024

SITE/S

Middle Island
Bowen 

 

PARTICIPANTS

Terry & Julie

 

TYPE

Subtidal

 

MODE

Boat Dives

 

VESSEL

Rebel II

 

DIVE

1

2

3

SITE/S

Middle Is. South

Middle Is. South

Middle Is. West

SPECIES #

6

7

1

DURATION

63 Min

57 Min

57 Min

DEPTH/RANGE

6.4 m

8.8 m

7 m

TEMP.

29 C

29 C

29 C

VIS.

4 m

2 m

2 m

SURGE

Nil

Nil

Nil

CURRENT

Nil

Nil

Nil

COMMENTS & OBSERVATIONS

Finally getting a break in the weather, with less than 10 knots forecast just for 1 day, the Whitsunday team headed out in the boat to check out some near shore areas. After jumping in on snorkel at a few locations and deciding the substrate was not suitable, we motored up to Innamincka Rocks. Unfortunately with the large tidal range, there appeared to be too much current running for us, so we headed over to Middle Island as we had not been there for a while.

Visibility was ordinary but we completed 2 dives on the southern side, heading west and then east, each side having different substrate and this is where we found the bulk of the critters. We then moved around to the western side where the visibility was no better and the silt loading higher. We scoured the sand whilst heading into the area of coral bommies with no luck so went back to the anchor where we found the one and only nudibranch for this site – the little Ceratosoma tenue.

Taxonomic Diversity:
All of the 12 species sighted were nudibranchs and all were dorids comprising 8 x porostomes (suctorial feeders – all of the Phyllidiidae family), 2 x phanerobranchs (non-retractile gill), 2 x cryptobranch (retractable gill – belonging to the Chromodorididae family). If diet is considered then 11 of the 12 species sighted are spongivores.

Our Historical Data:
– We have now completed 9 surveys at Middle Is South and 3 at Middle Island West where we have recorded 26 species and 3 species respectively. There is no data on the Phyllidiids included in this report as we are currently working through our classification of these species.
– This is the first time we have recorded Hypselodoris whitei and Gymnodoris citrina at Middle Island and the first time we have recorded Ceratosoma tenue in the Whitsundays;
– The species prevalence and species abundance at Middle Island South is consistent with our previous records at this site;
– We last surveyed Middle Is South on 12/04/2023 and Middle Is West on 2/03/2023.
(Historical data courtesy of Terry Farr, who extracts it from his comprehensive database.)

Note: All the Phyllidiella species listed below relate to the species delineated, although not formally named, in the paper:
Papu, et al. (2022). Phyllidiidae (Nudibranchia, Heterobranchia, Gastropoda): an integrative taxonomic approach including chemical analyses. Organisms Diversity & Evolution. Published online:
https://doi.org/10.1007/s13127-021-00535-7
We are currently interpreting the paper against our records.

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

TOTAL SPECIES SIGHTED: 12

 

SPECIES LIST – ALPHABETICAL

Aegires gardineri -/1/-
Ceratosoma tenue -/-/1 +
Gymnodoris citrina 1/-/-
Hypselodoris whitei -/2/-
Phyllidia coelestis 2/2/-
Phyllidia haegeli -/1/-
Phyllidia picta 2/-/-
Phyllidia varicosa 2/1/-
Phyllidiella cf. pustulosa -/1/-
Phyllidiella sp. a -/1/-
Phyllidiella sp. c-1 1/-/-
Phyllidiella sp. d 1/-/-

SPECIES GROUPED BY ORDER

Nudibranchia
Dorids
Phanerobranchs
Aegires gardineri -/1/-
Gymnodoris citrina 1/-/-
Cryptobranchs
Ceratosoma tenue -/-/1
Hypselodoris whitei -/2/-
Porostomes
Phyllidia coelestis 2/2/-
Phyllidia haegeli -/1/-
Phyllidia picta 2/-/-
Phyllidia varicosa 2/1/-
Phyllidiella cf. pustulosa -/1/-
Phyllidiella sp. a -/1/-
Phyllidiella sp. c-1 1/-/-
Phyllidiella sp. d 1/-/-

Cladobranchs
Aeolids

Arminids

Dendronotinids

Cephalaspidea
– 

Pteropoda

Sacoglossa

Umbraculoidea

Pleurobranchoidea

Anaspidea

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