Marlborough Sounds Resource Management Plan B Marine - D’Urville Island - Northern Cook Strait Collective Characteristics: Mainly Exposed Exposed; clear, cool oceanic waters; strong currents; off-shore reefs, stacks and islands; rich reef communities; bryozoan and horse mussel beds; massive tube worm colonies. A. The Physical Environment 1. Form/Geology Exposed shores are distinguished by their steeply sloping shores with extensive bedrock and boulder reefs extending into relatively deep water. The area is generally noted for the presence of numerous off-shore reefs, stacks and islands. Gravels and sands predominate off-shore of western D’Urville Island. Large sand masses occur off-shore in the larger outer bays, but mud/silt/shell remains the predominant soft bottom habitat elsewhere. A relatively narrow cobble (and in places bedrock) reef generally fringes the shores of the sheltered bays and inlets. 2. Dynamic Features and Processes, Including Climate Moderate to, in places, high exposure, though the large bays and inlets of the Outer Sounds and D’Urville Island offer a reasonable degree of protection from the open sea. 3. Water Clear oceanic waters with relatively low sedimentation levels. Relatively cool oceanic waters, particularly east of D’Urville Island. High current areas off headlands and between land masses. Moderate to high tidal range. B. The Biological Environment Distinctive Biota, Communities and Habitats Natural Biodiversity, Productivity and Biotic Patterns Near-shore and off-shore reefs support rich and abundant reef communities. Luxuriant stands of macro-algae extend into relatively deep water but some exposed water varieties (eg; Durvillea spp, Lessonia variegata) are noticeably absent. High diversity of fish and invertebrate species. The occurrence of large off-shore areas dominated by bryozoan corals and horse mussels are distinctive features of the area. The more sheltered bays and inlets support fewer conspicuous reef dwelling species and considerably less macro-algael cover. Coastal wetlands at heads of major bays and inlets. App Two - 64