Marlborough Sounds Resource Management Plan 3. Water Water quality is mostly very high. Notable features include: low sediment loadings in Queen Charlotte Sound and the Outer Sounds generally; moderate to high sediment levels in Pelorus Sound and Port Underwood; cooler waters in the east, warmer waters in the west; reduced salinities towards the head of Pelorus Sound; very complex and variable hydrodynamics; nutrients predominantly derived from sediment remineralisation, upwelling from Cook Strait, and river inflows; relatively poor water quality in the vicinity of Havelock and Picton. B. The Biological Environment 1. Natural Biodiversity Natural biodiversity of the Sounds as a whole is high as a result of the diverse range of environmental conditions traversing the Sounds. However, on a more localised scale biodiversity can range from the very diverse (eg reefs and off- shore rocks/stacks of the Outer Sounds) to the relatively simple (eg benthic communities of the more sheltered, enclosed bays). There is an overall gradient from the Inner to the Outer Sounds, with biodiversity generally increasing with proximity to the open ocean. 2. Productivity Productivity is variable, but generally moderate across the plan area. Some areas are distinguished by their very high productivity (eg. estuaries and exposed parts of the outer coast) whereas other areas can have relatively low productivity (eg. enclosed, sheltered bays with limited water exchange). 3. Ecological Features Ecological features which distinguish the Marlborough Sounds marine environment include: low energy rubble shores dominated by mobile and encrusting animal species and with little seaweed cover; extensive and relatively uniform mud bottom off-shore areas; high current communities in areas subjected to strong tidal currents; brachiopod dominated communities; bryozoan coral beds; horse mussel beds; off-shore reefs, rocks and stacks in the Outer Sounds; soft-bottom sponge communities; elephant fish spawning grounds; scallop beds; large tubeworm mounds in certain areas; Macrocystis beds in colder, sheltered eastern areas; a fish fauna noteworthy for the predominance of blue cod and spotties. A wide range of marine mammal species inhabit or migrate through Marlborough Sounds waters. Cook Strait is an important migratory route for several large whale species, including sperm, humpback, minke and southern right whales. Orca (killer whales) are regular visitors to the Marlborough Sounds and there are small resident populations of Hector’s and bottlenose dolphins. Dusky dolphins can be relatively numerous at times. New Zealand fur seals have established small haul-out colonies at various sites through the mid-Outer Sounds, with a large breeding colony present on Stephens Island. App Two - 12