Nelson bay is a sea slug hot-spot with more than 250 species so far identified but these volunteer divers aren’t here to simply admire their beauty.

As sensitive as they are striking, the Sea Slugs are a reliable indicator of ocean health, so the census plays an important role in preserving the port’s 98,000 hectare marine park.

And anyone can take part.

“We have such an incredible diversity of Sea Slugs in Port Stephens that people travel from Sydney and as far north as Coffs Harbour to take part,” Danny Eather, destination marketing manager for Destination Port Stephens said.

“The project is all about generating awareness of these beautiful creatures and the valuable contribution they make to monitoring and preserving the health of our greatest natural asset.”

Each year, the census attracts more divers and sees more species added to the list – many of them as yet unclassified.

Sea Slug spotters buddy-up to capture the colourful creatures on underwater cameras by diving or snorkelling.

Even rock pools are explored during the hunt.

“This is undoubtedly one of the most prolific and diverse populations of Nudibranch specimens in NSW and one of the most accessible, because it’s in an estuary,” diving guru Tom Davis said.

He joined forces with the Combined Hunter Underwater Group (CHUG) in 2013 to get the census underway as part of a PHD in marine biodiversity in Port Stephens at Southern Cross University.

“We wanted to get the community on board with the collection of data on the local marine ecology,” Mr Davis said.

“Sea slugs are so visually striking, they appeal to a lot of recreational divers with a keen interest in photography, so the census was a great way to engage the local diving community.”

Other-worldly in appearance, the high visibility of the slow moving Sea Slugs makes them relatively easy to monitor according to divers and ideal subjects for keen photographers.

“Stand-out discoveries include the identification of 2 invasive species to Australia, at Nelson Bay; Godiva Quadricolour and Spurilla Braziliana, as well as the identification of 12 southern range extensions, which was published in a scientific paper,” Mr Davis.

“We are working with Professor Steve Smith from SCU on how our ‘citizen scientists’ can collect valuable data on distributions of marine species like this.”

Census guidelines:

1. Photos for the census must be taken in Port Stephens on Saturday, September 9, 2017.

2. Each team should send in one photo for each species of sea slug they encounter on census day. You don’t need to identify the slugs, just take their photos.

3. Photos should be cropped around the slug, shrunk to around 640x480 pixels, and submitted by email or dropbox to seaslugcensus@gmail.com by Sunday, September 17.

4. Emails must give the names of the team, and details of the sites where photos were taken.

5. To get involved, register now by email: seaslugcensus@gmail.com

The census starts on the high tide, at 10.11am on September 9 with a post-dive lunch planned for Fly Point from 11:30-1pm (BYO food and drink).

Participants in this sea slug census for your chance to win some great prizes from Let's Go Adventures!