Diving for Worms

On Tuesday 18 March 2014, five Australian Museum divers took the plunge at Inscription Point in Botany Bay.

Twelve months ago we discovered a northern range extension of the exotic marine worm Sabella spallanzanii in Botany Bay (see the paper  and The Conversation). This species is a known pest with a high invasion potential and capable of significant impacts to the local environment.

It can form dense colonies and prevent native species from settling. Additionally, it seems likely the species contains compounds that make it unpalatable to potential predators, so once established it appears to have no natural predators.

This week we returned to the same site to confirm the worm is still established in this location. The visibility during our dive was pretty bad but this didn’t stop Pat Hutchings from finding a specimen and carefully digging it out of the substrate using her dive knife (video above).

A second dive was made to the same location two days later. The video below shows the results.

Individual worms live in a muddy tube that sits upright and have a featherduster/fan-like branchial crown which they extend into the water current from the top of the tube, collecting small food particles and obtaining oxygen. The worm Pat collected had the base of the tube anchored to some shell fragments which were embedded in the algal turf covering rocks at a depth of about 13 m.

All the specimen have been preserved and lodged with others in the Australian Museum Marine Invertebrate collection for future research, including genetic study to determine the source of the population in Botany Bay.