Cooks algae trial a success - Chamber of Commerce

Transcript

A trial to scrape algae out of the Muri lagoon in the Cook Islands, has been declared a success.

The lagoon has been plagued by unsightly algae which in turn affected tourism in the area.

The Chamber of Commerce President Steve Lyon told Koro Vaka'uta the trial used an excavator with a rake bucket to remove algae.

STEVE LYON: It actually worked better than we expected. The algae has managed to trap a whole bunch of fine sediments within it and cores of muddy ooze immediately beneath the algae which the rhizomes, I guess the algal roots, run through and beneath that it is still the white sand of the lagoon. The excavator was actually able to scoop through that layer, remove the algae and that anoxic mud but almost immediately you could see the change in the white sand. It was exposed again underneath.

KORO VAKA'UTA: Were there any negative impacts from this type of removal?

SL: We didn't specifically for negative impacts. We just generally monitored. From what I understand from our marine resource department that did water quality sampling, they didn't find any difference in water quality between when the work was occurring and when it was not occurring. Long-term, I mean more than a few days, there is no impact. You cannot see that any work has been done. During the work, there is a sediment plume, so while the excavator is working, some of these fine muds, and in fact we shake as the excavator brings up a bucket of material, it shakes it out to get the sand out of it. That of course creates sediment plume and that exists for about 75 metres downstream and it persists for about two or three hours but within one tidal cycle it is completely flushed through. The lagoon flushes itself about every 12 hours anyway.  Where the machine was operating is a high traffic area anyway, there is a lot of foot traffic there. There's been tractors on the beach actually removing algae that has washed up on the beach and we mapped out the areas where there were no coral heads or no centres of habitat. So we have literally only worked where the algae is growing on the bottom.

KV: As it stands now, how much of the algae is cleared?

SL: We really have only just scratched the surface. In total there is probably around about four and half to six hectares of algal dead and we have only removed in the vicinity of a quarter to half of a hectare. So this was a trial and it was done so it could inform an environmental impact assessment so that the work can be approved.

KV: If this was to tick all the boxes, if you like, how long would it take to do a major clear using this message?

SL: We've estimated it would take around about a month, maybe six weeks, but it is dependent, more so than we expected actually, on sea conditions and water height and other bits and pieces.               

KV: How about long-term?  What's the long-term solution here?

SL: The conversation for a long time has been around the need for reticulated septic systems and it's a conversation that people have really not wanted to have because of potential costs. Also because there has already been a New Zealand aid-funded project upgrading septic systems but because of the public awareness through this issue, all the powers that be are now seriously considering reticulation. Rather than saying 'do we or don't we', the question is now becoming 'how do we do it?'

Steve Lyon says the matter is now in government hands and the onus is on them to move the initiative on.