Letters to the Editor

 

It's great to see a heightened community dialogue happening regarding our Mangawhai estuary and its mangrove population. For far to long, the information base used to determine local mangrove management has been restricted to data supplied on overseas mangroves, residing in tropical and sub tropical environs.

Two letters published Mangawhai Focus (May 13) reflected much of this earlier available information, which is now being challenged by scientific research programmes, conducted not only on the unique New Zealand mangrove, but importantly on our own Mangawhai mangrove. Everyone loves that Mangawhai is so different to anywhere else and our mangroves are no exception.

Scientific studies now provide evidence that the New Zealand mangrove is of a different species to its well-known tropical cousins, and importantly our own are not imbued with the same beneficial environment characteristics. Not only is the New Zealand mangrove different, current research identifies that their performance characteristics are site specific, influenced by local tidal extremes, water quality, and local silt run-off. Such is the case in Mangawhai.

Current and ongoing scientific research, coupled with knowledgeable local hands-on experience supports the evidence that the New Zealand mangrove does not provide an environmental dependency for fish, marine invertebrates or bird life. This knowledge enables better-informed decisions to be made when considering and implementing mangrove management programs.

New Zealand is the only country where the mangrove is expanding its area of occupation. This rapid expansion is coming at the expense of other natural habitats, notably for us shellfish beds, seagrass beds, flounder and wading bird environs, not to mention the loss of enjoyed sandy beaches.

Margaret B. Hicks of Ruakaka (Letters to the Editor, May 13) states that Julia Wade appears to be a victim of misinformation when writing on mangroves. I believe Margaret's concerns are unwarranted, and welcome Julia and others challenging historical teachings.

NZ Fairy Tern Charitable Trust convenor Heather Rogan has good reason for support, but with some clarifications that recognise updated research.

Her comment that no one wants to see large machines in the harbour causing damage to the sea bed is certainly shared by all, but consideration must be given to the downside: If this channel clearance of our estuary flow systems was not happening in its planned and responsible manner the estuary would quickly revert to its pre Big Dig day – a toxic dormant mess. 

Heather challenges the Mangawhai Harbour Restoration Society (MHRS) to use its resources to implement a concerted riparian planting program. Firstly, for those unaware, the MRHS was established following the Big Dig estuary salvation initiative, its role is that of guardian for the ‘wellness' of our harbour estuary and coastal surrounds. This includes grass planting to inhibit movement of our sand spit and dunes, approved removal of juvenile mangroves on the coastal side of the estuary causeway bridge, plus the monitoring of coastal sand removal by commercial operators and much more.

Heather, MHRS protocol includes supporting recognised riparian planting programs. I am sure if you were to provide them with a well-founded program for extensive riparian planting it would be welcomed for consideration by the MHRS committee.

Ken Rayward
MHRS Committee Member
(Abridged)