Whanganui City College Year 9 students got to spend a whole day learning about lakes - and Rotokawau/Virginia Lake in particular.

Seeing the tiny creatures that live in its water through a microscope was "cool as" for one student, who wanted to keep on looking.

Another boy, 14-year-old Anthony Rothery-Hughes, said it was pretty good to learn about the lake.

The Year 9 group focused on the lake on October 22. They first heard a talk from a group of seven visiting Lakes380 scientists, then went to the lake, heard an account of its origin and broke into groups for workshops.

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One group of students looked at core samples taken from nearby lakes Rotokare, Westmere and Moumahaki. Scientist Marcus Vandergoes explained how they can record 1000 years of lake history, showing what plants were growing nearby, when fire happened and how much algae was growing.


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Another group looked at DNA taken from organisms - either live or fossilised - in the cores. By comparing sections of DNA they could tell what the organisms were.

A third looked through a microscope at water taken from the lake that day. Some of the organisms they saw were water fleas, also known as daphnia, tiny crustaceans only just visible to the naked eye.

The lake also contained cyanobacteria - but not a major bloom - and lots of a more ordinary green algae.

Whanganui man Mike Paki told his family's story about how the lake was formed. It was about his ancestor Ranginui's love for a woman who loved another man.

Ranginui fought the other man and beat him. Then the woman's family sent a champion to fight him and, as they did so, tohunga [spiritual experts] called down rain, trapping Ranginui in mud and drowning him.

If his blood had been spilled the lake would have become tapu [taboo], Paki said, which would have stopped its being a source of food.

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The students got the chance to look at the lake with experts through their head of science Geoff Osborn, who visited it and took water samples every week for a year.

A tiny crustacean, known as a water flea, as seen through a microscope. Photo / Bevan Conley
A tiny crustacean, known as a water flea, as seen through a microscope. Photo / Bevan Conley

Sometimes students helped him, and he used findings from the samples in class work. He organised the visit by Lakes380 scientists through the Partnerships Through Collaboration Trust, which engages young people in a mix of science and indigenous knowledge.

Scientist Marcus Vandergoes tells students how the layers of sediment in a lake core can reveal its history. Photo / Bevan Conley
Scientist Marcus Vandergoes tells students how the layers of sediment in a lake core can reveal its history. Photo / Bevan Conley

Lakes380 is a five-year project to take sediment samples from 10 per cent of New Zealand's lakes, and use them to find out how and why the lakes are changing.

It will not take a core sample from the depths of Rotokawau, concentrating instead on lakes less studied.

Osborn took samples of Rotokawau's water and tested it on site and back in the school lab for temperature, pH, dissolved oxygen, turbidity, conductivity, nitrates, ammonium, phosphate, coliform bacteria and biological oxygen demand.

He recorded the results in a blog.

"My passion is trying to make science more relevant to the place that you come from," he said.

He wants to continue a school-wide focus on the lake into the future and "start counting some of the things you can count".