Marine Data

This indicator measures the rise in annual mean coastal sea level relative to land. The national mean is derived from four long-term monitoring locations across New Zealand: Auckland, Wellington, Dunedin and Lyttelton. We also report the trends over time, from the beginning of our records until 2018. Relative sea-level rise includes the vertical land movement of the surrounding area (for example, a sinking landmass increases the rise in ocean sea level).

We report the change in annual mean coastal sea level to 2018 against the established baseline (mean sea level for 1986–2005) for the long-term sites plus an additional two sites: Moturiki (Mount Maunganui) and New Plymouth. These are not included in the national mean due to shorter records. We also measure the national annual sea-level rise for two time periods: the start of the records to 1960, and 1961–2018.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

Ocean acidification is the long-term decrease in the pH of our coastal waters and oceans. This indicator measures the change in pH in subantarctic surface waters at a station east of Otago from 1998 to 2017, and also the pH at selected coastal sites via the New Zealand Ocean Acidification Observing Network (NZOA-ON) from 2015 to 2017.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

Adapted by Ministry for the Environment and Stats NZ to provide for environmental reporting transparency. Dataset used to develop the "Ocean acidification" indicator (available at  www.stats.govt.nz/indicators/ocean-acidification).

This data set measures the pH at selected coastal sites via the New Zealand Ocean Acidification Observing Network (NZOA-ON) from 2015 to 2021.

Ocean acidification describes the long-term decrease in the pH of our oceans and coastal waters. This indicator measures:

• pH at selected coastal sites (New Zealand Ocean Acidification Observing Network, NZOA-ON) from 2015 to 2021.

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More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

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Adapted by Ministry for the Environment and Stats NZ to provide for environmental reporting transparency. Dataset used to develop the "Ocean acidification" indicator (available at  www.stats.govt.nz/indicators/ocean-acidification).

This data set measures the change in pH in subantarctic surface waters at a station east of Otago from 1998 to 2020.

Ocean acidification describes the long-term decrease in the pH of our oceans and coastal waters. This indicator measures:

• change in pH, acidity and pCO2 (a measure of dissolved carbon dioxide) in New Zealand’s subantarctic surface waters (Munida Transect) from 1998 to 2020.

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More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

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These data provide a snap shot of beach litter surveys submitted by Citizen Scientist ‘Monitoring Groups’ up to April, 2019. As defined by the United Nations Environment Programme (UNEP, 2009), marine litter is any persistent, manufactured or processed solid material discarded, disposed of, abandoned or lost in the marine and coastal environment. Marine litter washed onto beaches is one of the most obvious signs of marine pollution, and can have either land or sea-based origins. Land-based sources of marine litter include input from rivers, sewage and storm water outflows, tourism and recreation, illegal dumping, and waste disposal sites. Sea-based sources include commercial shipping, fisheries and aquaculture activities, recreational boating and offshore installations.

UNEP, 2009. Marine Litter: A Global Challenge. Nairobi: UNEP. 232 pp.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

The marine economy shows the contribution marine-based economic activities make to the New Zealand economy as measured by gross domestic product (GDP). Measuring the marine economy shows how New Zealand’s marine environment is used to generate economic activity and how this changes over time. However, these activities can be a source of pressure on New Zealand’s marine environment.

Estimates of the marine economy are often used globally as an indicator of the marine environment’s societal and economic importance (Kildow & McIlgorm, 2010; Suris-Regueiro et al, 2013).

This indicator measures the contribution of marine-related industries to New Zealand’s marine economy. Currently measurable activity categories are:

·         offshore minerals
·         shipping
·         fisheries and aquaculture
·         marine services
·         marine tourism and recreation
·         government and defence.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

New Zealand waters have at least 117 species of chondrichthyans (sharks, rays, and other cartilaginous fish species). They are particularly vulnerable to overfishing because they are long-lived, mature slowly, and have a low reproductive rate. Chondrichthyans are important for healthy ocean ecosystems, and reporting their commercial catch and bycatch helps us understand the sustainability of our fisheries.

The pH of New Zealand subantarctic waters is calculated from pCO2 (dissolved carbon dioxide) and alkalinity measurements using refitted Mehrbach constants (see Mehrbach et al, 1973; Dickson & Millero, 1987), and in-situ temperature taken from the Munida time-series transect off the Otago coast. Measurements of pCO2 are taken every two months.
The Munida transect, in the subantarctic waters off Otago, is the Southern Hemisphere’s longest-running record of pH measurements (NIWA, 2015).
More information on this dataset and how it relates to our Environmental reporting indicators and topics can be found in the attached data quality pdf.

Extreme wave events can damage marine ecosystems and affect coastal infrastructure, ocean-based industries, and other human activities.

Changing wave characteristics can have impacts on natural systems, as most coastal and near-shore biological communities can be damaged or destroyed by extreme wave action (Ummenhofer & Mehl, 2017). In another example, extreme waves can disrupt ferries such as those crossing the Cook Strait. Sailings are often cancelled when significant wave heights exceed six metres.

It is important to report on extreme waves to gain greater insight into their frequency, particularly as sea level and storm surges are projected to increase and can compound wave effects.

In this dataset, an extreme wave event is defined as a continuous 12-hour period during which the significant wave height equals or exceeds one of three height thresholds: four, six, or eight metres.

Four-metre-tall waves are considered extreme in the northern-most parts but are more common in the south. For the southern-most parts of New Zealand, eight-metre waves better represent extreme wave events.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.

Sea-level rise is a consequence of climate change. Increased global temperatures lead to rising sea-levels because warmer waters take up more space and glaciers and polar ice sheets melt into the ocean. Sea-level varies naturally from place to place due to local ocean circulation and temperatures and the movement of the land relative to the sea. For example, earthquakes can lift or drop the land.
Linear trends were provided by NIWA and Emeritus Professor John Hannah (previously University of Otago). Ideally, linear trends in sea level would be reported if there are at least 50 years of data to account for climate variability from climate oscillations such as the 20–30 year Interdecadal Pacific Oscillation (IPO) and the shorter ENSO cycle. Such climate variability can be seen in the increase in annual mean sea level in 1999–2000, when the IPO across the entire Pacific Ocean changed to a negative phase. While the Moturiki data cover 43 years, it was considered appropriate to apply a linear trend to further extend the number of reported sites. Further detail on the data processing (including adjustments for historic datum changes) and methods used for the trend analysis can be found in Hannah (1990), Hannah (2004), and Hannah and Bell (2012).
More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.