Atmospheric analysis

Aquatic systems are under threat due to the introduction of invasive exotic species such as water weeds. Modelling work by NIWA has provided new information on which water bodies may be at greatest risk.

Deep (10s of metres), narrow, elongated basins which are largely subtidal - the estuary bed is still below water at low tide.

Very deep (up to 100s of metres), narrow, elongated basins which are largely subtidal.

Similar in some respects to Category E estuaries, these have shallow basins and narrow mouths, usually formed by a spit or sand barrier. However, Category F estuaries have complex shorelines and numerous arms leading off a main basin.

Shallow, circular to slightly elongated basins with simple shorelines and extensive intertidal area.

Shallow, circular or slightly elongated basins with simple shorelines and wide entrances that are open to the ocean.

These occur where the mouth of a main river channel connects to shallow lagoons.

Elongated basins of simple shape and several to ten metres depth.

Very shallow basins (several metres depth). They are often elongated and run parallel to the shore.

Formal identification keys are the scientifically accepted way to identify species. These will allow the identification of species which are unclear when using quick guides.

Compared to other countries, New Zealand has a sparse freshwater fish fauna of just over fifty species. But it is unique and comprises at least thirty-five native species of which thirty-one are found only in New Zealand.