6. West coast harbours of the North Island
Map ID Number: 6
Location: Includes Whangape, Hokianga, Kaipara, Manukau, Waikato River, Raglan, Aotea, and Kawhia harbours and the adjacent coastline.
Approximate area: 1,375km2(summation of the surface area's of the above esturies at high water) 7
Biological attributes:
The west coast estuaries are highly productive ecosystems, and are of significant environmental and economic importance. A range of habitat types are found in and around the west coast estuaries, including coastal shrublands and forest, freshwater wetlands, saltmarsh, mangroves, seagrass, sand and mud flats, rocky reefs and tidal channels. The extensive estuarine intertidal flats support abundant and diverse communities of benthic invertebrates, which are an important food source for many fi sh and birds, as well as having other significant ecological functions.
The intertidal sand and mudflats of the west coast harbours are important feeding grounds, and breeding and roosting sites for large numbers of wading birds and shorebirds – including internationally migratory and New Zealand endemic species and a number of threatened species. The vegetated margins of these estuaries also provide habitat for threatened coastal fringe birds, particularly where areas of adjoining terrestrial vegetation provides shelter for roosting and breeding.The estuaries are important feeding and breeding areas for a number of fish species and are also important migration pathways between marine and freshwater habitats for a variety of native freshwater fish. The dunes, open coast beaches and rocky cliffs and platforms also comprise important and complex habitat for a variety of plant and animal communities.
Criteria applied:
Species diversity; species richness; dependency for other species; trophic/ functional diversity; conservation status/threat classification both nationally and globally; cultural values; degree of disturbance; special conditions and specialised organisms; habitat complexity/diversity.
Status and management:
The west coast harbours have come under significant threat as a result of catchment activities which, in particular, have been responsible for increased rates of sedimentation. These estuaries are also under threat from coastal development (reclamation and infilling, foreshore structures, roading, etc.), stock grazing, introduced species etc. Many of the west coast harbours have been designated as “Areas of Significant Conservation Value” under regional council coastal plans. Improved catchment management (minimising erosion, reducing runoff and nutrient leaching) will help to protect estuaries. Regional councils, in conjunction with the Minister of Conservation, are responsible under the Resource Management Act 1991 for the management of the effects of activities in the coastal marine area. Territorial authorities are responsible for managing land-use effects above mean high water springs.
State of information:
Variable for the different harbours. For example, there is considerable information available for the Manukau Harbour; but for some of the other harbours there is relatively limited information available.
References and further reading:
Auckland Regional Council (2003), Grange (1979), Pridmore et al. (1990), Turner et al. (1995)
7Source for estuarine areas:http://finz.niwa.co.nz/NewZealand/viewer.htm