DAY/DATE
Monday
17/10/2022
SITE/S
North West Reef
Mudjimba Island
PARTICIPANTS
David
TYPE
Subtidal
MODE
Boat Dive
VESSEL
Li’l Mischief
DIVE
1
SITE/S
North West Reef
SPECIES #
13
DURATION
68 Min
DEPTH/RANGE
11 m
TEMP.
22 C
VIS.
8 m
SURGE
Slight
CURRENT
Nil
COMMENTS & OBSERVATIONS
Escape from the Court through the build-up of surfer’s cars was effected not a moment too late. Single-handed set-up and launch of Li’l Mischief went without incident and a short and pleasant 25 knot voyage to Old Woman Island was enjoyed thanks to the almost perfect surface conditions. Gear-up as well as water entry and exit all proceeded as planned. The only hiccup was discovering my first stage o-ring seat was damaged and it would not seal for the second dive, that then had to be abandoned. It is surmised that this was latent damage from a mishap during a recent Bali trip when the regulator was damaged by a careless diving attendant and “repaired”. Although only one dive was conducted by a single surveyor the sea slug population has certainly improved at this site since June of this year when only 8 species were recorded across two dives with two surveyors. This improvement was foreshadowed by the increased Bornella Reef (also at Mudjimba Island) sightings late last month. (Note: A video taken on this excursion of Verconia norba has been placed on its Species Profile page.)
Taxonomic Diversity:
11 of the 13 species sighted were nudibranchs, 8 being dorids comprising 1 x phanerobranch (non-retractile gill), 1 x porostome (suctorial feeder the Phyllidiidae family) and 6 x cryptobranchs (retractable gill) all bar one belonging to the Chromodorididae family. The other three nudibranchs were cladobranchs – one each, aeolid, arminid and dendronotid. The other two non-nudibranch sea slug species were a pleurobranchid (side-gilled slug) and one sacoglossan. If diet is considered then 9 of the 13 species sighted are spongivores.
Our Historical Data:
– This excursion brings the survey number to 48 at this site since we commenced fully recording data here on 12/06/2010.
– 164 species have been recorded at this site.
– Our most common sightings at this site are: Doriprismatica atromarginata (98%), Thuridilla cf. splendens (96%),
Goniobranchus splendidus (94%) and Phyllidiella pustulosa (92%) all of which were recorded on this survey.
– This site last surveyed on 14/06/2022.
– In reviewing the graphical representation (see image gallery below) of both species and total organisms, there seems to have been a gradual decline in the number of both recorded on each survey performed here. The reason for this trend (or the impression of a trend) will need to be examined in relation to other factors.
Key to symbols
+++ New Species
+ First time sighted at this site
# Most commonly sighted at this site with %
TOTAL SPECIES SIGHTED: 13
SPECIES LIST – ALPHABETICAL
Bulbaeolidia alba -1
Dermatobranchus tuberculatus -1
Doriprismatica atromarginata -3 #98%
Goniobranchus splendidus -10 #94%
Hexabranchus sanguineus -1
Hypselodoris jacksoni -2
Hypselodoris obscura -5
Jorunna sp. 03 -2
Phyllidiella pustulosa -1 #92%
Pleurobranchus peronii -1
Thuridilla cf. splendens -1 #96%
Tritoniopsis elegans -1
Verconia norba -2
SPECIES GROUPED BY ORDER
Nudibranchia
Bulbaeolidia alba -1
Dermatobranchus tuberculatus -1
Doriprismatica atromarginata -3
Goniobranchus splendidus -10
Hexabranchus sanguineus -1
Hypselodoris jacksoni -2
Hypselodoris obscura -5
Jorunna sp. 03 -2
Phyllidiella pustulosa -1
Tritoniopsis elegans -1
Verconia norba -2
Cephalaspidea
–
Sacoglossa
Thuridilla cf. splendens -1
Umbraculoidea
–
Pleurobranchoidea
Pleurobranchus peronii -1
Anaspidea
–