DAY/DATE
Monday
13/02/2023
SITE/S
Middle Island
Bowen
PARTICIPANTS
Terry, Sue & Julie
TYPE
Subtidal
MODE
Boat Dives
VESSEL
Rebel II
DIVE
1
2
SITE/S
Middle Is. West
Middle Is. South
SPECIES #
1
10
DURATION
93 Min
91 Min
DEPTH/RANGE
10.7 m
14.9 m
TEMP.
29 C
29 C
VIS.
4 m
To 5 m
SURGE
Nil
Nil
CURRENT
Nil
Nil
COMMENTS & OBSERVATIONS
We decided to take advantage of the reasonable conditions and headed out to Middle island. Surface conditions were a little lumpy but quite manageable. We anchored in 8m of water at Middle Island West, after passing over the drop off. We descended to a silty sandy bottom, with scattered algae and sea grasses and the occasional sponge and ascidian. The site was very reminiscent of Low Isles so we knew Sue would be in her element. The site hosted an array of critters including decorator crabs, pygmy squid, fish, isopods, solitary corals and one lone nudibranch (but a new species for us). We moved for our surface interval to the more protected south side of the island (it was blowing NW). After driving over reef in 8m of water, we pulled back and anchored in 14m. As we descended the darkness ensued and visibility was almost non-existent. We had dropped the anchor near a large black coral that looked like a tree branch. We reeled up into the shallows and as we did so the visibility improved. This site has scattered corals and rubble, with numerous fish species and a reasonable count of nudibranchs, considering we did not venture too far. Unfortunately as we had reeled out, we had to descend back into the gloom to retrieve the reel and ascend the anchor line by feel until we had risen a couple of metres.
Taxonomic Diversity:
9 of the 11 species sighted were nudibranchs, with 7 being dorids, comprising 0 x phanerobranchs (non-retractile gill), 4 x porostomes (suctorial feeders – all of the Phyllidiidae family), 3 x cryptobranchs (retractable gill – all belonging to the Chromodorididae family). 2 x cladobranchs comprising 1 x dendronotinid & 1 x arminid completes the nudibranch finds. A single sacoglossan plus a single cephalaspidean rounds out the species numbers. If diet is considered then 7 of the 11 species sighted are spongivores.
Our Historical Data:
– There is insufficient historical data at this stage.
– However, of the species recorded, two are new sightings for us in Australia and two we have not sighted anywhere before.
Key to symbols
+++ New Species
+ First time sighted at this site
# Most commonly sighted at this site with %
TOTAL SPECIES SIGHTED: 11
SPECIES LIST – ALPHABETICAL
Elysia sp. 34 1/- +++ (first time we have sighted anywhere)
Chelidonura pallida -/3 +++ (first time we have sighted in Australia)
Dermatobranchus sp.15 -/2 +++ (first time we have sighted anywhere)
Glossodoris buko -/2 +++ (first time we have sighted in Australia)
Hypselodoris roo -/1
Hypselodoris sp. 02 -/1
Phyllidia picta -/1
Phyllidia varicosa -/3
Phyllidiella pustulosa -/1
Phyllidiopsis burni -/3
Tritoniopsis elegans -/1
SPECIES GROUPED BY ORDER
Nudibranchia
Dorids
Phanerobranchs
–
Cryptobranchs
Glossodoris buko -/2 (first time we have sighted in Australia)
Hypselodoris roo -/1
Hypselodoris sp. 02 -/1
Porostomes
Phyllidia picta -/1
Phyllidia varicosa -/3
Phyllidiella pustulosa -/1
Phyllidiopsis burni -/3
Cladobranchs
Aeolids
–
Arminids
Dermatobranchus sp.15 -/2 (first time we have sighted anywhere)
Dendronotinids
Tritoniopsis elegans -/1
Cephalaspidea
Chelidonura pallida -/3 (first time we have sighted in Australia)
Pteropoda
–
Sacoglossa
Elysia sp. 34 1/- (first time we have sighted anywhere)
Umbraculoidea
–
Pleurobranchoidea
–
Anaspidea
–