A global census of marine biodiversity has portrayed New Zealand as a hotspot for life in the ocean, with a "particularly rich" range of plant and animal life in its waters, scientists say.
"New Zealand has a particularly rich marine flora and fauna," said a senior marine ecologist, Alison MacDiarmid.
"There are over 17,000 known living species within our exclusive economic zone (EEZ)".
This included over 4000 species which had been collected but not yet been scientifically described, "and we think there are at least another 17,000 species to be discovered in our waters".
Dr MacDiarmid, the principal scientist for marine ecology at state science company National Institute of Water and Atmospheric Research (Niwa), said that much of the nation's marine habitat was only just being explored for the first time - particularly ocean depths more than two kilometres below the surface.
"Whenever we go into these areas, we pick up lots of new species," she said.
Dr MacDiarmid was speaking on the release today of the results from the global Census of Marine Life, which has made an inventory over the past decade of species distribution and diversity in key global ocean areas.
Scientists worldwide combined information collected over centuries with data obtained during the decade-long ensus to create a roll call of species in 25 biologically representative regions - from the Antarctic through temperate oceans such as those around New Zealand, and tropical seas to the Arctic.
The papers published today will help set a baseline for measuring changes that humanity and nature cause.
And they will help guide future decisions on exploration of still poorly-explored waters, especially the abyssal depths, and provide a baseline for still thinly-studied forms, especially small animals.
Dr MacDiarmid participated in the census, and led a "taking stock" project that tried to describe changes to the nation's marine ecosystem since humans first settled about 750 years ago - work which was largely funded through the Ministry of Fisheries' biodiversity fund.
She said the most diverse groups in NZ waters were shellfish such as bivalves - including the familiar cockle, pipi, oyster and scallop - and other molluscs, such as cat's eye, limpet, paua and whelks among the more than 3600 species.
There were almost another 3000 species of arthropods - including crabs, lobsters, barnacles and shrimps - and over 700 species of sponges, and over 1000 cnidarians (CRRCT) such as corals, and jellyfish.
Dr MacDiarmid said about half of the species in local waters are endemic to New Zealand, but the "native" species varied. Sponge-type species were 95 percent endemic to New Zealand - not occurring elsewhere in the world - but the corals and jellyfish were only 21 percent. In between were the bivalves and molluscs at 84 percent and seasquirts at 75 percent, but only 16 percent of bony fish were endemic. About a third of the seaweeds are endemic.