COMMENTS & OBSERVATIONS

A favourable forecast meant it was time to take the boat for a run so off to Holbourne Island we went. Surface conditions were a little lumpy on the way up but the closer we got to the island the calmer it got and we were greeted by glassy conditions and blue water. We decided to investigate the shallows today and spent a lot of time scanning the rubble and sand, trying not to be distracted by the beautiful fish and corals.

Terry started out strong, finding 4 different species on one small rock, but things slowed down and our least favourite critters (phyllidiids) dominated the finds. We did find some nice subjects though and after searching intently for Plakobranchus which are generally on the sand and large enough to see, we managed to find some on rocks but they were tiny, around 3 mm long.

Taxonomic Diversity:
Fourteen of the nineteen species sighted were nudibranchs, thirteen being dorids comprising 9 x porostome (suctorial feeders), 0 x phanerobranchs (non-retractile gill), 4 x cryptobranchs (retractable gill); and one cladobranch comprising 0 x aeolids, 1 x arminids and 0 x dendronotinids. Five sacoglossans complete the count. A total of 35 specimens were sighted.

Our Historical Data:
– We have now completed 10 surveys at Manta Reef since our first survey here on 13/03/2023.
 – We have now recorded 63 species at this site.
 – This is the first occasion on which we have sighted Diversidoris crocea, Glossodoris buko, Hypselodoris tryoni, Phyllidia ocellata, Phyllidiella pustulosa, or Phyllidiella sp. e (complex) at this site.
 – This is the first time we have recorded Plakobranchus sp. 05 on any of our dives. (This specimen was very small – 3 mm – and it is possible that it is a juvenile of some described species, but we have not been able to make the link.)
 – Our last survey at this site was on 31/08/2024.

Note: The large number of phyllidiid species in the lists below reflects the work that has identified taxonomic-cryptic species delineated in the paper: Papu, A., Bogdanov, A., Bara, R., Kehraus, S., Konig, G., Yonow, N. & Wagele, H. (2022). Phyllidiidae (Nudibranchia, Heterobranchia, Gastropoda): an integrative taxonomic approach including chemical analyses. Organisms Diversity & Evolution. https://doi.org/10.1007/s13127-021-00535-7 At the time of publishing this report we are in the process of reviewing all of our phyllidiid records to align them with the findings of the above paper.

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

TOTAL SPECIES SIGHTED: 19

DIVE IMAGES GALLERY

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