Science Centres: Aquatic Biodiversity and Biosecurity

Endemic quillworts grow up to 30 cm tall, and reproduce by spores in the leaf base.

Quillworts grow as extensive underwater meadows in South Island lakes. They may look like a grass, but are more closely related to ferns. Here Mary de Winton swims over vegetation dominated by quillworts in Lake Wakatipu.

Quillworts (Isoetes species) are spiky-looking, submerged plants that form turfs in shallow, clear waters of lakes. Worldwide, there are about 200 species, and we believe the quillworts found here are unique to New Zealand.

These native plants are disappearing from some lakes due to alien weed invasions, poor water quality, and the resulting loss of habitat. Quillworts are already extinct in the upper North Island, and declining in the lower North Island, though they remain common in the South Island.

NIWA has been growing a variety collected from Northland (Lake Omapere) in 1997, but until now we haven’t been sure how different these plants are from other quillwort populations. In fact, overall it’s very hard to tell quillwort species apart, and that’s caused confusion over what species exist here, where they are found, and which populations need protection.

NIWA scientists Deborah Hofstra and Mary de Winton, and Chrissen Gemmill of Waikato University, sampled 300 plants from 20 lakes around the country, looking for genetic differences between regions, within lakes, and at different depths. They identified a separate South Island group of quillworts, and found that the Northland (Lake Omapere) plants are indeed genetically different from other North Island quillworts. As the Northland quillwort is almost certainly extinct at Lake Omapere, the finding makes NIWA’s work in preserving it even more important.

The scientists now plan further studies using different genetic markers to corroborate their findings. The research has been funded by the Foundation for Research, Science & Technology.