Sea slugs ready to dazzle as Coffs organisers aim for census species record

A marine slug with colourful skin in pink, yellow and white nodulesJanolus species of nudibranch (credit Steve Smith).

A Southern Cross University marine scientist is anticipating divers and rockpool ramblers will find a record number of nudibranch species at this year’s Coffs Coast Sea Slug Census.

‘Sea slug’ is the common name for molluscs with reduced or absent shells which includes the nudibranchs. While they resemble terrestrial slugs in form and size, nudibranchs are much more flamboyant and dazzling in colour, shape and behaviour.

“We’ve got strong registration numbers and if we get the right conditions this weekend I’m confident we can find more nudibranch species than in any other census,” said Professor Steve Smith.

“We know the species are out there. The abundance of sheltered rockpools along the Coffs coastline combined with the underwater habitat diversity around the Solitary Islands provide a fantastic combination of suitable conditions for a large range of species.”

The highest number of species found in any single census is 138 at Nelson Bay in December 2015.

With the support of the local diving group, Professor Smith created the first Sea Slug Census in 2013 at Nelson Bay, north of Newcastle. Since then, in conjunction with local naturalist and diving groups, the event has expanded to sites from Gold Coast to Melbourne and offshore at Lord Howe Island.

“Participants simply find and photograph as many species of sea slug as possible and note the location. It’s a citizen science program that offers fun, adventure and opportunities to learn about our remarkable marine biodiversity,” Professor Smith said.

Over its seven-year history along the east coast, the Sea Slug Census has recorded 627 species with the help of 2035 participants.

Interestingly, of those 627 species:

232 individual species have been photographed only once

263 are undescribed species

An undescribed species is one that may have already been discovered but is yet to receive a species name and a detailed description in a formal scientific publication.

“Engagement with the public has been incredibly important in documenting undescribed species, as well as tracking changing distribution patterns along Australia’s east coast,” Professor Smith said.

“These results provide evidence to support for the importance of ongoing taxonomic (classification) work for sea slugs locally. Most taxonomy for this group is currently being done in the US or Europe, with some also in Western Australia. We need to beef up our taxonomic capabilities in Australia.”

2021 Coffs Coast Sea Slug Census

This is the third annual Coffs Coast Sea Slug Census which is held in conjunction with SURG, the Solitary Island Underwater Research Group Inc.

The event runs from Friday January 29 to Sunday 31. The area surveyed includes the entire Solitary Islands Marine Park as well as coastal waters to Brooms Head in the north and Sawtell in the south.

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