Lakes380 day with Whanganui City College Year Nine students

Dr Mike Paki tells the story of Tainui, Turere and Ranginui to begin the Lakes380 day at Rotokawau - Virginia lake with Year Nine students from Whanganui City College

Thirty Year Nine students led primarily by 9Hihi, hosted scientists from the Lakes380 team at Rotokawau - Virginia lake on Tuesday 22nd October, 2019.  The scientists are on a three year project to report on the state of health of the nation's lakes and their visit to nearby Westmere lake coincided with the work 9Hihi have been doing in class on water quality and lake eutrophication processes at Rotokawau - Virginia lake.  The coming together of the scientists and our students was arranged through the Partnership Through Collaboration trust and we are very grateful to them for organising this opportunity.

The day began with introductions and a presentation of the Lakes380 project to the students in the hall of Whanganui City College.   The students were then given the opportunity to work with the scientists at the lake side  to collect and analyse samples of water, mud and DNA  to better understand how the history of a lake can be built up from such original  data.   What amazed us all was when the scientists told us they were able to determine when eruptions occurred, when forests were felled and even when cyanobacteria and algae first appeared in a lake just by looking at the lake sediments.  Stories would go back many years as you will read later.

Collecting an algae sample from Rotokawau -Virginia lake

The scientist team showed the students how to collect and concentrate an algae sample (the green stuff in the lake) and then to analyse it to identify whether the green material was in fact, an algae  (microscopic plant) or a cyanobacteria ("blue-green algae").  Cyanobacteria are a bacteria that has evolved with the ability to photosynthesise and make its own food, just like a plant.  They are one of the earliest forms of life on Earth and produced the oxygen that made the atmosphere.  Unfortunately, some of them have cell contents that are toxic and cause nervous system and liver failure in animals which is why there is always concern when they are detected in waterways.

Our young scientists found out how to prepare a microscopic slide and identify an algae called....

Volvox

This image was taken from the microscope.  The air bubble can be ignored but what is amazing is the fact that this microscopic plant cell has the same chloroplasts (green spots) that are found in a leaf.  These have to be the smallest plants on the planet!

The cyanobacteria (Anabaena) that has been identified in the lake is not at dangerous levels according to the Lakes380 scientists.

Anabaena cyanobacteria from Rotokawau -Virginia lake collected during teacher lake study (2018-19)

And then we delved into the field of Forensic Biology!  Believe it or not but from a water sample or mud sample the scientists can find a section of DNA and replicate this in the laboratory with polymerase enzyme until there is enough  DNA to identify the organism and find out when it lived in the lake.   

Then we moved on to the studies that were being made into the lake sediments.  The Lakes380 Scientists informed us that a lake sediment core had not been extracted from Rotokawau - Virginia lake because this lake is reasonably well studied.  Instead the scientists had spent some time that week working on Lake Westmere - Rotomokoia, just up the road from Virginia on SH3.  Once upon a time Westmere water flowed into Virginia lake  to provide old Whanganui town with water.  Now it is surrounded by farmland and suffering from the same nutrient enrichment that has befallen Rotokawau - Virginia lake.

The centre core was taken from Westmere lake

The lake sediment corer

Students got to help with analysing the cores

After our boys and girls identified grasses and wood in the Westmere mud, it was explained to them that grasses only appeared once the land had been cleared of trees and since these dates were documented in historical sources in Whanganui it was possible to determine the rate of sedimentation in the lake and hence, how quickly the lake was being filled in.  This was scientific work with a strong historical and social connection.

The day continued along a cross-curricular theme when our young scientists interviewed the Lakes380 team to find out what their motivation was for being a scientist and working in lake science.  The English Department had small filming units recording the day and we are hoping to present this film to the Whanganui public at the City Library very soon, along with the work the students have done in Science and Social Studies.  This was a special day.  A big thank you to the Lakes380 scientists for sharing their knowledge and expertise, the PTC for arranging the day and the Whanganui Chronicle for taking an interest in our studies

A future kaitiaki (environmental guardian)  bids farewell to the Lakes380 team