A new way to manage mulch, left after mangroves are mechanically removed, was trialled on Friday at Waikareao estuary.

During the mangrove removal process. File photo.

The trial is the first step to investigate different ways to manage or remove the mulch as part of the wider mangrove removal project.

Bay of Plenty Regional Council chairman John Cronin said the trial was timely as concerns had been raised recently that mangrove mulch was not being flushed from some areas as quickly as hoped.

'I'm pleased today's trial went ahead as this season's work has just begun and it's important to alleviate any concerns that the mulch is causing a smothering effect."

"We hope that by removing mulched material the estuary bed will revert to open mudflats quicker.”

The trial involved the purpose-built mechanical mangrove mulcher being followed by a beach groomer, used to remove sea lettuce from Mount Maunganui beach. The mulch will be taken off-site as green waste to be composted.

'This has been a good learning experience," John says. "We should be able to improve a couple of equipment issues which will help in the long-term."

The results of the trial will be considered by the council and if successful, will continue in other areas where mangroves will be removed this year. Firm ground and good access are expected to affect where this method can be used effectively.

Anoxic conditions will develop regardless of the mulch being removed as the mud below mangroves is already anoxic and contains very high levels of organic matter.

Stories and photographic evidence from the locals around Waikareao show that the older mulched areas have been heavily frequented by birdlife including banded rail, ducks, stilts, and herons.

Last season about 80 hectares of mangroves were mechanically removed from around Tauranga Harbour. This season about 30 hectares of mangroves will be cleared in the Waimapu, Welcome Bay and Wainui estuaries.