One of the roundworms found in Porirua's Pāuatahanui Inlet as part of the NIWA study Photo: Supplied/NIWA
Scientists have discovered 26 new worm species, and evidence the creatures exist in stunning numbers.
To find the worms, samples were taken from a Porirua inlet for five years and analysed by the National Institute of Water and Atmospheric Research (NIWA).
NIWA marine biologist Dr Daniel Leduc said it was not a surprise to find new species as New Zealand worms had not been studied for very long. But he was surprised by how many of the marine worms were found in their samples.
The 26 new worms that had not been observed by scientists before are all roundworms, which are also called nematodes.
Roundworms are mostly about 1mm long and live in the soil or among sand grains on the beds of lakes and rivers or in the seabed. Some also live as parasites in plants and animals.
Leduc said they are one of the most successful groups of animals because because they had adapted to live in many varying conditions.
Along with the new species, the scientists found another 29 nematode species in the inlet which were known but had not been found there before, or had not been found in New Zealand before.
The samples collected showed nematodes probably make up about 40 percent of the inlet's known biodiversity - a surprising amount, Leduc said.
"Most of us will think about fish and birds and cockles and snails and things that we can see with the naked eye, and we think that's it - that's all there is to the environment - but there's actually a whole other world in between the sand grains."
The research samples were taken between 2016 and 2021 from Pāuatahanui Inlet, a wide shallow branch of Te Awarua-o-Porirua Harbour.
Porirua's Pāuatahanui Inlet Photo: Supplied/NIWA
The site was picked for both its ecological and cultural significance, Leduc said.
"The inlet is also subject to anthropogenic [human] impacts from land use changes and pollution, so a better knowledge of the nematode fauna will bring a more complete understanding of the value of this ecosystem and will facilitate monitoring in the future."
Working with worms was exciting partly because of how much knowledge there was still to be found, he said.
"We are still in the discovery phase for this group of animals, meaning we find species new to science pretty much everywhere we look.
He said the study had not covered the subtidal areas of the inlet, and it was safe to say there were still more unknown nematode species in Pāuatahanui Inlet yet to be found.
"There are of course many more discoveries to be made in the country's other inlets and multitude of marine habitats. It's pretty easy to find new species in this country if you are ready to spend some time looking down a microscope," Leduc said.
NIWA published the study in its latest Biodiversity Memoir.