Information about past climate is obtained from piecing evidence together from various sources.

Temperature affects the number and type of animals and plants that live in a waterway.

Once eels become migrants (also known as tuna heke or tuna whakaheke) they stop feeding, and progressively develop the external features that clearly distinguish them from 'feeders'.

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Dissolved oxygen (DO) is a relative measure of the amount of oxygen (O2) dissolved in water.

How do nutrients from wastewater treatment enter waterways?

If you list all the historic rainfall totals for a particular month and for a specific location, rank these from lowest to highest, then divide the list into ten equal parts, you have identified the ten rainfall deciles for that month and for that location.

New Zealand’s forests and other land areas may be absorbing up to 60% more carbon dioxide than has been calculated, with much of this uptake likely occurring in native forests, NIWA scientists have discovered.

NIWA has recently created synthetic, multi-year, 10-minute wind datasets at 15 wind farm sites across New Zealand. These will be used by the Electricity Commission to model the impact of wind farms on the national grid.