Na­tion’s wet­lands ‘in cri­sis’


The huge degra­da­tion of New Zealand’s wet­lands has led to a cri­sis sit­u­a­tion, says For­est & Bird, which is us­ing Fri­day’s World Wet­lands Day to urge re­gional coun­cils to pro­vide more pro­tec­tion.

The en­vi­ron­men­tal group has re­leased maps, based on his­toric soil anal­y­sis, that show the ex­tent of wet­land loss since hu­man set­tle­ment be­gan, and the few rem­nants that are left.

Its fresh­wa­ter ad­vo­cate Anna­beth Co­hen said 90 per cent of pre-set­tle­ment wet­lands had been de­stroyed by agri­cul­tural and ur­ban de­vel­op­ment.

‘‘And we aren’t do­ing a very good job of pro­tect­ing what’s left.’’

Wet­lands played a vi­tal eco­log­i­cal role, she said. As well as pro­vid­ing unique habi­tat for threat­ened plants, birds, and fish, they also im­proved water qual­ity, and re­duced flood risks to nearby com­mu­ni­ties.

‘‘The trou­ble is, our orig­i­nal wet­lands have been drained for agri­cul­ture, and the now rare rem­nants can’t cope with the huge amounts of nutri­ent and sed­i­ment-loaded runoff, which de­grades the qual­ity of the water, mak­ing it very dif­fi­cult for white­bait, eels, and other na­tive fresh­wa­ter species to sur­vive there.’’

Be­fore hu­man oc­cu­pa­tion, New Zealand had an es­ti­mated 2.47 mil­lion hectares of wet­land ecosys­tems. To­day it has less than 250,000ha.

New Zealand has six wet­lands recog­nised in­ter­na­tion­ally by the Ram­sar Con­ven­tion. These were the Firth of Thames, Whanga­marino and Kop­u­atai Peat Dome in Waikato; Farewell Spit in Nel­son; Awarua Wet­land/ Waituna La­goon in South­land; and the Manawatu River Es­tu­ary.

‘‘Wet­lands can oc­cur in many places, from es­tu­ar­ies to moun­tain­tops, but very few of these spe­cial ecosys­tems re­main,’’ Co­hen said. ‘‘Those that do re­main are of­ten iso­lated and don’t pro­vide the con­nec­tion that wildlife need.’’

She pointed out that, in Hawke’s Bay, it took the Supreme Court to save a rare oxbow wet­land from the Ru­atani­wha water stor­age dam.

‘‘The Depart­ment of Con­ser­va­tion is re­spon­si­ble for man­ag­ing our Ram­sar sites, but in cases like the vast Whanga­marino wet­land in the Waikato, their ef­forts are ham­pered by poor man­age­ment from [the] re­gional coun­cil.’’

The Whanga­marino wet­land is af­fected by sed­i­ment from a num­ber of sources, in­clud­ing ad­ja­cent farm­land.

‘‘If an in­ter­na­tion­ally recog­nised Ram­sar wet­land like Whanga­marino is in such bad shape, what hope do our other wet­lands have?

‘‘Re­gional coun­cils must do more to pro­tect wet­lands, and that means bet­ter man­age­ment of sur­round­ing agri­cul­ture, en­forc­ing rules to pre­vent il­le­gal veg­e­ta­tion clear­ance and wet­land drainage, and work­ing with com­mu­nity, iwi, and DOC to re­store wet­lands that have be­come de­graded,’’ Co­hen said.

In Welling­ton, there were an es­ti­mated 122,804 hectares of wet­land ecosys­tem be­fore hu­man habi­ta­tion. Only 2774 ha, or just over 2 per cent, re­main.

The Hutt Val­ley was once marsh­land and swamp for­est. At the time of Euro­pean ar­rival, swampy marsh­lands ex­tended sev­eral kilo­me­tres up the val­ley from the river mouth.

Wet­land species such as raupo, flax and toe­toe dom­i­nated. Be­yond this, kahikatea, matai, puketea and rimu for­est grew ex­ten­sively on the val­ley floor. Most of the val­ley floor has since been cleared of the orig­i­nal for­est cover, with only a few small rem­nant stands and trees re­main­ing.

Sig­nif­i­cant re­main­ing


Hectares of wet­land, pre­hu­man and now: Nel­son: 769; 6 (99.2 per cent lost) Gis­borne: 67,008; 936 (98.6 per cent lost) Hawke’s Bay: 113,362; 2458 (97.8 per cent lost) Welling­ton: 122,804; 2774 (97.7 per cent lost) Manawatu: 264,511; 6983 (97.4 per cent lost) Auck­land: 57,851; 2639 (95.4 per cent lost) Taranaki: 40,278; 3046 (92.4 per cent lost) North­land: 258,451; 14,114 (94.5 per cent lost) Bay of Plenty: 43,089; 3304 (92.3 per cent lost) Waikato: 356,516; 28,226 (92.1 per cent lost) South­land: 450,984; 47,231 (89.5 per cent lost) Can­ter­bury: 187,115; 19,851 (89.4 per cent lost) Marl­bor­ough: 12,785; 1545 (87.9 per cent lost) Tas­man: 26,570; 5219 (80.4 per cent lost) West Coast: 358,182; 84396 (76.4 per cent lost) Otago: 110,804; 27,050 (75.6 per cent lost) TO­TAL: 2,471,080; 249,776 (89.9 per cent lost) wet­lands in the Welling­ton re­gion in­clude Pen­car­row lakes, Waikanae es­tu­ary, and Pau­ata­hanui in­let. For­est & Bird’s Kapiti-Mana branch has put a lot of work into restor­ing the Pau­ata­hanui Wildlife Re­serve at Pau­ata­hanui in­let.

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