NZ seas in trouble

Climate change, pollution and fishing are causing irreversible damage to New Zealand’s marine environment, a new report reveals.

Sustainable Seas Challenge manahautu¯ /deputy director Ma¯ ori Dr Linda Faulkner said the report’s detailed consequences of climate change, rising seas and biodiversity loss and their impact on Ma¯ori traditions and kaimoana could be significant. What troubled her most about the report – a joint project by the Ministry for the Environment and Stats NZ – was the uncertainty about the future and its impact on Ma¯ ori traditions.

‘‘Is it going to happen in my lifetime or in my children’s lifetime, and what can I do to prepare them for that?’’

Faulkner said Ma¯ori and Pacifica researchers were already well aware of the environmental challenges ahead.

‘‘In the Pacific region there are going to be massive implications and there is lots of knowledge of what is coming.’’

The large, cumulative effects of all the harms outlined by the report needed to be prepared for, she said.

National Institute for Water & Atmospheric Research (Niwa) principal scientist Dr Matt Pinkerton said the report should be a call to arms to protect the environment, before it was too late. ‘‘How did we get into this mess?’’

The past was an increasingly unreliable indication of the future and New Zealand needed to commit to improving scientific understanding of the threat, he said.

Secretary for the environment Vicky Robertson said oceans acted like a ‘‘giant sponge’’ against the effects of climate change. ‘‘It is likely our seas take up more carbon dioxide than our forests but there is only so much the oceans and the life in them can take.

‘‘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.’’

In the report, the life of the kuku (green lipped mussel) was followed to show the risks to the species from human activity.

Taonga species pa¯ ua, cockles, kuku, and kina have carbonate shells vulnerable to increased ocean acidity, just one of a raft of risks to species outlined in the report.

The kuku was believed to be everywhere on the coasts and doing well but that wasn’t the case, Ministry for the Environment marine science lead Constance Nutsford said. ‘‘The kuku is being largely lost from some areas due to fishing and an increase of sediment in the last century,’’ she said.

According to the report, 80 per cent of shorebirds, 90 per cent of seabirds and 22 per cent of marine mammals in New Zealand are threatened or at risk of extinction.

Sediment pollution

Activities on land, especially agriculture and forestry, and growing cities, are increasing the amount of sediment, nutrients, chemicals and plastics in New Zealand’s coast and oceans, the report says. Sediment travelling from waterways to coasts could smother animals and degrade habitats, affecting our ability to harvest kaimoana, swim and fish in our favourite local places.

Risk to culture

Due to climate change, some traditional Ma¯ ori tohu or marine indicators could no longer be used in the same way, the report said.

‘‘Ma¯ ori scientific knowledge is based on observation and is evolving in response to current changing seasonal patterns,’’ it says.

‘‘Traditionally when po¯hutukawa bloomed, it was time to harvest kina.

‘‘Today, the reproductive period of kina occurs at a different time due to changes in sea temperatures.’’

Sea level rise

Not only are sea levels rising, they are rising faster than before.

The report says the country’s rate of sea level rise has increased, with the average rate in the past 60 years (2.44 millimetres per year) being more than double the rate of the previous 60 years (1.22mm per year).

If the sea level rises by 1.5 metres, as is projected to occur by 2100, more than

6000 kilometres of drinking water, wastewater and stormwater pipes and

2000 kilometres of roads are at risk.

Marine heatwaves

80 per cent of shorebirds, 90 per cent of seabirds and 22 per cent of marine mammals in New Zealand are threatened or at risk of extinction.

Also on the rise are marine heatwaves, with extremely high sea-surface temperatures which can reduce the range of some species or cause them to disappear. Marine heatwaves also have implications for mitigating climate change. ‘‘The ocean has an important role in removing carbon dioxide from the atmosphere but as oceans warm, they lose their capacity to absorb as much carbon dioxide, which may result in further increases in atmospheric carbon dioxide concentrations,’’ the report says.

Plastic pollution

A litter count at 44 sites, led by Sustainable Coastlines, found 61 per cent of beach litter in the country is plastic. When birds eat plastic, it can reduce their intake of nutrients, decrease reproduction, cause poisoning and internal and external wounds, and block their digestive tracts.

Mussels have been proven to be ingesting microplastics, tiny plastic particles, the report says.

Extreme waves

Destructive extreme wave events are becoming more frequent.

In 2017, 17 extreme wave events exceeded the 8m threshold in coastal regions, and 15 of these were around the South Island.

‘‘Extreme wave events are affecting some coastal communities, infrastructure (bridges, road and rail), environments, and biodiversity.

‘‘It is very likely that increases in sea level will result in more frequent and extreme coastal flooding by 2050 and cause the loss of habitat in coastal regions.’’

Fishing

Since 2009, the country’s total commercial catch has remained stable at less than 450,000 tonnes per year. The report warned fishing still had long-term and wide-ranging effects on species and habitats but there was some good news.

‘‘In 2018, 84 per cent of routinely assessed stocks were considered to be fished within safe limits, an improvement from 81 per cent in 2009.’’

Seabed trawling and dredging have also decreased in the past 20 years.