Physical Environment
The Whangaroa Harbour is an estuarine embayment 8 km long, into which the Kaeo, Pupuke and Iwitawa rivers flow from the south. The harbour covers an area of 19 km 2 , of which approximately 26 percent is mudflats. Mudflats occupy 573 hectares, mangroves 418 hectares, saltmarsh 45 hectares, and Zostera (eelgrass), 18 hectares. The northern and western shores of the harbour (including the headlands at the entrance) comprise high volcanic breccia outcrops and sheer cliffs dropping steeply into the water. In contrast, the southern and eastern shores comprise gentle hills composed of soft sedimental shales.
The shoreline of the harbour (particularly the inner harbour) has been highly modified by extensive reclamation for agriculture, road causeways, refuse landfills, timber mill and wharves. Siltation of the harbour is increasing the area of mangroves, but in the 1980's, this increase was exceeded by the loss of mangrove environment due to reclamation.
The habitat of the rare endemic plant Pseudopanax gilliesii on the northwestern head is of international importance, and other coastal forest and scrub areas, wetland and archaeological sites are nationally important.
Flora & Fauna
The estuarine nature of the inner Whangaroa Harbour has given rise to many areas of mangrove and saltmarsh - at the heads of Touwai Bay, Waitapu Bay, up the Kaeo River, in the head of the harbour between Ferguson and Taupuke Points, Waihapa Bay, and northwards along the western shore to Totara North. Juncus marsh is in general present on the landward side of the mangroves ( Avicennia marina var. resinifera ) and in Otangaroa Rd/Waihapa Bay area there is a transition into brackish marsh marked by increasing numbers of Typha and Leptospernum in the predominantly Leptocarpus marsh (Chapman, 1978). While the modification of the area by reclamation etc. has impacted on its ecological value, the upper harbour is still classified as having "moderate" wildlife values (DOC, 1991). Rare and endangered species found in the area include the banded rail, fernbird, NZ dotterel, and brown teal (present in low numbers). The diverse coastal vegetation in the northwestern head and shore of the harbour support the only known population of the rare plant Pseudopanax gilliesii . Kiwi also occur in this area, and penguins nest around the coast.
The harbour supports a wide variety of fish (snapper, trevally, kingfish, kahawai, mullet, parore, flounder) and shellfish - cockles, pipi, native rock oysters (tio) and Pacific oysters are found in the inner harbour, and scallops occur in the deeper channels in the vicinity of Peach Island.
References:
Chapman, V. J. 1978. Mangroves and salt-marshes of the Whangaroa and Whangaruru Harbours, and the Bay of Islands - A study with proposals for preservation of areas supporting the harbour ecosystem. Unpubl. report. Department of Lands and Survey.
Department of Conservation (DoC). 1991. Coastal wetland inventory: Volume 2: Coastal wetlands north of the Kaipara Harbour catchment (Draft). Department of Conservation, Wellington.
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