A new report on the state of New Zealand's marine environment warns of the serious effects of climate change and other issues on the unique life in our oceans and coasts.
Our marine environment 2019, a joint report by the Ministry for the Environment and Stats NZ, highlights the four most pressing issues facing our oceans and coasts. Adding to the effects of climate change, river sediment, waste, urban development, fishing, and shipping are harming - sometimes irreversibly - our native marine plants, animals and the habitats they live in.
"New Zealand's oceans act like a giant sponge against the effects of climate change. It's likely our seas take up more carbon dioxide than our forests, but there is only so much they and the life in them can take - and the limits aren't yet known," Secretary for the Environment Vicky Robertson said.
"The warmer the water gets, the less able it is to absorb gases like carbon dioxide. The growth of species in the oceans is affected, and coastal communities and habitats are at risk from flooding and sea-level rise."
On their own, each issue is challenging enough for the environment - but they accumulate, building on themselves and each other.
"New Zealand has one of the largest Exclusive Economic Zones in the world, yet we know less about our coasts and oceans than any other environmental domain. It may be challenging, but it is absolutely critical that we continue to extend our knowledge and understanding of our precious marine ecosystems - our oceans, estuaries, coasts, and harbours, and the life within them," Government Statistician Liz MacPherson said.
"We're expanding the breadth of our data with the help of community organisations and our treaty partners. For example, I'm especially pleased that this report includes, for the first time, data drawn from a citizen science project - the Sustainable Coastlines beach litter initiative. There is much more we can do to improve our understanding of the marine environment, but it's important we keep our focus on areas where the impact is likely to be greatest. We need to align, coordinate, and leverage efforts across knowledge and reporting systems, including te ao Māori."
Ms Robertson says our coasts and oceans are the places we play, relax, gather food, and earn a living.
"We trade on a reputation of pristine beaches and clean sparkling water, and visitors from other countries revere them, but we have seen in this report that this is not always the case. But by taking action now, collectively and even in small ways, we can hold on to that pride and protect our coasts and oceans for our mokopuna - our children and grandchildren."
The four issues identified in Our marine environment 2019 are:
Our native marine species and habitats are under threat
- Around 30 percent of Aotearoa New Zealand's biodiversity is in the sea, but many species are in trouble. Of the small number assessed, 22 percent of marine mammals, 90 percent of seabirds, and 80 percent of shorebirds are threatened with, or at risk of, extinction.
- The number of established non-native species is rising and now totals 214. Many non-native species can spread rapidly, and some affect native species and habitats.
- Nearly half of the world's dolphins, porpoises, and whales, some of which are endangered, have been recorded in New Zealand waters, so what we do matters for their future.
Our activities on land are polluting our marine environment
- Human settlement has brought large shifts in the patterns of sediments in most coastal environments. This includes changes in the rate it accumulates, increased muddiness, and the type and amount of contaminants that bind to sediments.
- Sediment is fine particles like silt, mud, and organic material that gets carried by and in water. Soil washed from pastures and from forests after felling moves along waterways and settles as sediment on streambeds. It also comes from urban development, where the footprint of erodible or impenetrable surfaces (and therefore surface run-off) is increased. It fills in the spaces used by fish and invertebrates for hiding and breeding, and makes their food harder to find or to eat.
- Sediment accumulation in estuaries is increasing in many parts of New Zealand, but there are big variations in the rate it accumulates, and some estuaries are worse than others.
- Litter and plastic debris are found everywhere in the marine environment.
- Plastic is the most commonly found litter on New Zealand beaches making up 61 percent. 11 percent of plastic litter comes from cigarettes. Having this knowledge helps us target our actions.
Our activities at sea are affecting the marine environment
- Almost all of our imports and exports move via shipping.
- While cargo and cruise shipping are great earners for New Zealand, they don't always bring welcome visitors. Non-native species likely hitched a ride to New Zealand on vessels. Once established, they compete with native species for resources. Ships can also collide with mammals causing death and injury.
- Seabed trawling and dredging have decreased in the last 20 years, but nearly a quarter of the fishable area has been trawled since 1990. This causes significant seabed disturbance and damage and takes time to recover - deepwater coral can take decades.
- What we do on land also has an impact. Activities such as agriculture, forestry, and the growth of cities and towns create pollutants, the load of which can be increased by land use change such as intensification, urban development, and draining wetlands.
Climate change is affecting marine ecosystems, taonga species, and us
- New Zealand's oceans play a huge role in limiting climate pollution. It's likely they take up more carbon dioxide than our forests.
- As a consequence, the water in New Zealand's oceans are warmer, more acidic, and expansive, causing sea levels to rise.
- Sea-level rise during the past 60 years was 2.4mm a year, double the rise during the previous 60 years.
- New Zealand coastal waters have warmed 0.2 degrees Celsius per decade on average. But the warmer the water gets, the less ability it has to absorb gases like carbon dioxide, reducing the ability to buffer the effects of climate change.
- Marine heat waves are occurring and have similar devastating effects as on land. During the unprecedented 2017/18 marine heatwave in the South Island, bull kelp suffered losses in Kaikōura and were completely lost from some reefs in Lyttelton.
For more information, including the full report, see Our marine environment 2019. Graphics from the report are available on request.
