Planning for Marine Protected Areas

1.1 Introduction

Tides have a major role in determining the location of the zones of plant and animal life on the shore. Tides vary in their physical character – their daily pattern, their energy, and the levels they reach on the shore. The West Coast, like the rest of New Zealand, has a dominantly twice-daily tide of a 2.4 hour cycle22. Due to the anticlockwise movement of the tidal wave around the New Zealand coast, the West Coast’s tides tend to become progressively later towards the south, with Jackson Bay tides lagging those at Karamea by about 75 minutes. Spring tides at Westport rise and fall by up to 3.7 metres, while the difference between high and low water at neap tides is as little as .2 metres23. The tidal range right along the West Coast is broadly similar to this, but a NIWA model (Figure 2.4) indicates that the tidal range is significantly greater in the north than in the south. areas.