New Zealand marine ecosystem services

Content Partner: Manaaki Whenua – Landcare Research. New Zealand's marine realm, including the Territorial Sea, Exclusive Economic Zone (EEZ), and Extended Continental Shelf, totals 5.7 M km2, an area about 21 times larger than New Zealand’s land mass and almost 1.7% of the world’s oceans. This enormous area is not uniform, and New Zealand has one of the most diverse ranges of marine habitats on the planet, with a rich and mostly endemic marine flora and fauna that provide at least 12 regulatory services, 5 provisioning services, and 9 non-consumptive services. Based on global estimates, marine ecosystems may provide about two-thirds of the value of services provided by New Zealand ecosystems annually. For instance, provisional estimates based on mapping of surface dissolved CO2 indicate that the New Zealand EEZ CO2 sink may be equivalent to about 5% of global ocean CO2 uptake, and is larger than that of New Zealand forests. In coastal regions terrestrial and marine ecosystems are closely linked. For example, in the Firth of Thames, local rivers contribute about 70% of the nitrogen supply that supports fisheries and aquaculture, with the remainder supplied by upwelling of slope-associated deep water, rich in nutrients, onto the shelf and into the coast. Denitrification processes can remove about 70% of the new nitrogen loaded to the system from land. Wild food support and provision is the ecosystem service that provides species targeted by humans for food. In New Zealand, human utilisation of marine living resources began with the arrival of Māori, increased during European settlement, and continues as one of New Zealand’s most significant primary industries with an annual catch of about 480 000 tonnes of fish and invertebrates worth over NZ$1.4 billion. One species, hoki (Macruronus novaezelandiae), comprises about 30% of the wild catch. It is very difficult to judge whether New Zealand marine ecosystem services are growing, stable, or declining. In part this is because we know little about the extent of marine habitats, and in part because the more remote and deeper marine ecosystems are difficult and expensive to monitor. Thus, for many habitats we have at best only a short time-series of information with which to judge trends in ecosystem services. Scaling for the size of New Zealand’s marine area of responsibility suggests that US$357 billion worth of services may be contributed each year by New Zealand’s marine ecosystems. Even if this estimate is ou