The marine habitats in our coastal waters, harbours, and estuaries provide many benefits to New Zealanders. Some readily come to mind – swimming off our beaches, fishing and diving, and harvesting shellfish.
Other benefits are more subtle and involve complex functions of natural marine systems – also known as ecosystem services. Many people are unaware of these coastal marine ecosystem services. They include recycling nutrients and human wastes, trapping and stabilising sediments, producing oxygen that supports other marine life, and providing nursery grounds for fish.
Coastal marine habitats are particularly vulnerable to pressure from human activities because of their proximity to urban centres and ease of access to people and industry. Scientists who have assessed the human threats to New Zealand’s marine environment found that reef, sand, and mud habitats in harbours and estuaries and along our coastlines were the most highly threatened of the marine habitats in the EEZ and territorial sea (MacDiarmid et al, 2012a).
In this chapter we outline some of the main pressures on coastal marine habitats that come from land- and marine-based human activities and plastic and oil-based pollution, which come from activities on land and at sea.
Coastal marine habitats and ecosystems are degraded
Of all marine environments, our coastal environment is under the most pressure from humans because it is closest to where we live, work, and play. Over decades, coastal habitats have been destroyed or degraded – losing the abundance and diversity of marine life usually found in a natural ecosystem.
Why does it matter?
Biodiversity and the health of the ocean ecosystem depend on the functioning of coastal marine habitats – for example, as nurseries for fish. The degradation of coastal waters limits opportunities for recreation and compromises marine-based industries.
What are the big coastal pressures?
- Ocean acidification and climate change impacts (see Our oceans and the climate)
- Excess sedimentation
- Seabed trawling and dredging for fish and shellfish (see Our fisheries and the impact of fishing on marine ecosystems)
- Marine pests
- Excess nutrients carried down waterways.