Environment

Will Rottnest’s sea grass survive another summer?

Rottnest Island is pumping investment into Perth’s island escape to draw in more tourism dollars but with increased patronage comes new environmental considerations. 

B-shed in Fremantle. One of the departure points to travel to Rottnest. Photo:Connor Sheehan.

A study conducted by ECU in 2016 found 48,000 square metres of sea grass had been stripped from the bays surrounding the holiday island.

Since the study took place Rottnest Island has expanded by eight new buildings as well as an extension and rebranding of their hotel, The Quokka Arms.

The culprit was identified as the 900 mooring chains used by recreational boats within the bays.

The bays, known for being calm, are the perfect place for the growth of sea grass, but boats choose to moor here for the same reason.

The bays at Rottnest where sea grass grows.

The bays most affected were Bickley, Porpoise, Longreach and Geordie.

Lead researcher Dr Oscar Serrano said the sea grass is an incredibly efficient filter of carbon dioxide and is integral to the reduction of greenhouse gases and climate change.

“Sea grass is important in particular, when you lose that, you lose that canopy and the sediments become exposed to oxygen. Then microbes and bacteria attack them and release the carbon dioxide back into the atmosphere,

“Even driving (a boat) on top of sea grass can rip up the sea grass and damage and disturb the sediment.”

Sea Grass also provides shelter for local sea life and pushes back against rising sea levels.

Rottnest Island Authority media manager Kent Acott said they were in the process of finishing their Marine Conservation Action Plan.

This will include the monitoring of sea grass which, according to their research, finds the loss represented by the ECU study is only one percent of the sea grass in the Rottnest Marine Reserve.

Boating operators Jaden Charters said professional charters aren’t allowed to use the moorings inside the bays.

“We wish that we could use the moorings at Rottnest, our staff who operate the charters are highly trained and would know not to moor on top of sea grass.”

Most of the damage that was observed was from tourist boats using the moorings within the bays.