Hauraki Gulf tideways: Elements of their natural sciences

Abstract

GULF TIDEWAYS: AUCKLAND TO CAPE RODNEY.

The 60 km between Auckland and Cape Rodney is a special stretch of New Zealand Coast in which there are a dozen tideways, most of which still enrich the landscape with their variety and perform vital biological roles. They are of a size such that the eye can readily encompass their width, and of a depth sufficiently shallow to reveal the tidal rhythms. They are remarkable because, although set in a shallow coast, their incised embayments have, as yet, resisted the straightening which is the usual response of coastlines to natural forces. There is nothing quite like them in New Zealand. These Gulf Tideways have much in common. They share a geophysical background and similarities of flora and fauna, sufficient, perhaps, for them to be viewed as species of the same family. They are variously named Harbours, Rivers, Estuaries and Creeks. Unlike the common perception of an estuary their river components are relatively small. For convenience the term "tideway" has been used for all of them.

Research work on the tideways has been active but uneven. Thus Whangateau Harbour has, since the 1960s, been the subject of continuing investigation by postgraduate biology students of the University of Auckland, whose work on it has been facilitated by its manageable size. The Upper Waitemata Harbour received intensive attention by a special interdisciplinary study in the early 1980's. Certain aspects of the Mahurangi have been studied by students, engineering consultants and the Auckland Regional Water Board. Preliminary surveys have been carried out on the Matakana by the Auckland Regional Water Board and Bioresearches Ltd, and on the Waiwera by the Parks Board and the University. The University of Auckland's Leigh Marine Laboratory, a coastal observatory, has on record long time series of the coastal meteorology and oceanography of Gulf waters, which are common to all the tideways.

The research has been the work of specialists. The rapid development of their fields of study has meant that their attention has had to be concentrated on a relatively narrow front in a particular tideway. Furthermore, the results of their investigations have been published in a wide variety of scientific journals and reports, usually catering for a limited group and ordinarily not easily accessible. The consequence of this is that their work has not been as widely appreciated as it might have been, nor has it been viewed as part of a whole. It seemed worthwhile to try to redress these shortcomings. Treating the tideways as units within one book has meant concentrating on the important features and interrelationships, especially the conditioning of the biological by the geophysical. This has necessitated selection which has inevitably meant a sacrifice of depth of treatment of any one discipline, a shortcoming which, it is hoped, will be compensated for by the attempt to unify. The treatment is at the level of a primer. This approach could be of interest to specialist students and research workers who might value an introduction to disciplines other than their own, or to students of natural systems.

Most of the twelve tideways and their catchments are very great assets to the region. If, in keeping with the times, a new perception, based on respect for them as entities, were to take hold, they might have a future, though it is difficult to be optimistic.