Thursday, March 4, 2010

Response to Mangrove eradication in New Zealand

This is Prof Gordon Maxwell, now back in NZ again for a spell and I will outline the main aspects of the new anti-mangrove paradigm that is rapidly gaining favour as a fashionable way of approaching our sole species/subspecies of mangrove in New Zealand, Avicennia marina sub sp resinifera. I made a BIG mention of this disturbing paradigm at the Pacific Science/ ISME Conference in Okinawa in June ,2006. Please ask ISME ( for more.
1. Excess available sediment arriving in many estuaries is the fundamental 'cause' of the mangrove expansion over the past 40 years.This sediment is in land based runoff associated with inadequate catchment management e.g. due to excavations,soil disturbance,forestry operations.The NZ mangroves are opportunistically colinizing the expanding 'mud-flats' that develop.The process is,of course not at all new, but has accelerated over the past 4-5 decades.
2.Marinas are popular with many ( by no means all ) people who reside or have holiday homes in coastal zones, especially in the populated areas of the North Island of NZ and north of the biogeographiclly important "mangrove line" which lies ~ 38 Deg.South in the Eastern Bay of Plenty, N.Is., NZ. The marinas want open access to coastal areas and mangrove vegetation can be seen as an obstacle to such access.Hence the efforts to destroy mangroves.
3. There has been a move by some to have NZ mangroves defined as a " weed " species and this way neutralise the Resource Mangagement Act ( RMA) which seeks to protect native plants, animals....ecological resources.Some UNiversity people have joined this trend and use incomplete geological data ( pollen in sediments ) to hint that the NZ mangrove is not a 'real' native species ( and can, therefore be killed...this is the implication! ).The same people quietly accept the notion of 'self-introduced' bird species arriving in the past 5-10 decades from overseas.Yes, we have hints of science being contaminated by fashion and social pressure.The fact that we have a Maori name for our species of mangrove,"MANAWA" seems to matter very little.The historical linguistic aspects of this do not attract the moment !
4. To please the pro-marina lobby, many " Environmental management agencies" especially Regional Councils like Environment Bay of Plenty based at Tauranga, are falling in with the anti-mangrove voices.Some have enticed local iwi ( Maori tribal organisations ) to accept their anti-mangrove viwepoints,by suggesting that mangroves destroy their shell and fin fish resources !
5.This paradigm, stands in stark contrast to the pro-mangrove viewpoint,once common in NZ ,that looked upon these ecosystems as nursaries for fin fish and protectors of sheltered coastal habitats.I was a key scientist working within this model back in the 1970's when the Hauraki Catchment Board ( now part of Environment Waikato ) wanted to save mangrove stands: they were economically important protectors of stopbanks along side the twin Rivers of the Hauraki Plains ( Piako and Waihou Rivers).As such, the mangrove belts protected valuable dairying farmland from estuarine tidal invasion.This viewpoint is being lost these days as the fashion to which I made reference above gains momentum.Sad but true.
I will cc this outline to ISME and may be they can source some other papers ( including mine ) which may help further. I am still re-organising my library after my latest stint os a Prof in Hong Kong. Thanks in anticipation to Prof Baba and his staff at ISME Head Office, Okinawa, Japan.
Best wishes, GMax ( Prof Gordon S.Maxwell, FLS ).

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