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Research Projects

Rehabilitation of Busselton Jetty’s Pile Marine Life

In March and April 2015 the City of Busselton commenced a maintenance program to prevent the progression of the molluscan wood borer Teredo sp. from burrowing into submerged timber piles beneath Busselton Jetty. This burrowing activity by the Teredo worms eventually weakens the structural integrity of the piles. Many timber piles were treated with a denso wrap system involving scraping off sessile marine invertebrates, adhering a grease layer to the exposed wood and then covering the greased pile with layers of PVC wrap and finally an outer meshed layer.

Due to the ecological diversity and importance of the marine environment beneath the end of Busselton Jetty, where the most established communities lived, this method caused some controversy amongst scientists, divers and tourism operators – as the area was cleared of sensitive marine organisms.

The opportunity was taken by myself to investigate the colonisation of the PVC material and the ability of sponges and soft corals to regrow after being disturbed from their substrate. The initial rehabilitation program began in April 2015, using collected fragments of invertebrates (mostly sea sponges and soft corals) which were latticed securely against the treated piles. Over the next 12 months the survival and growth of these fragments was monitored and recorded using a photo log.

Interestingly by the third month, the first new organisms which were new colonisers had secured themselves amongst the rehabilitated areas. This new colonisation occurred at a faster rate where established marine invertebrates occurred compared to colonisation on the treated piles which were not rehabilitated.

Due to the success of this experiment, it is hoped that future rehabilitation on other treated piles under Busselton Jetty can be carried out in the future.

 

Click below to see a time lapse video of the growth of the invertebrate fragments



Sophie Teede

Underwater Observatory Manager