Source: Environment Canterbury Regional Council
Dr Issie Barrett from Lincoln University and Enviroschools Selwyn facilitator Matt Stanford joined tamariki from Glentunnel School to test out some bug bags. When they arrived at Waikirikiri/Selwyn River, Matt had pre-collected water samples which contained invertebrates the children might find in their bug bags. This included mayflies and caddisflies, and the children were encouraged to use this information to guess what the quality of the water would be.
Tamariki then retrieved bags Matt had placed in the awa weeks before and opened them to see what invertebrates were inside. Unfortunately, the mesh the bags were made from seemed to have tightened as it absorbed water and the holes were too small for most bugs to get in.
Undeterred, Glentunnel School students returned to the classroom to create their bags, making theirs loose enough to capture bugs.
They returned to Waikirikiri that afternoon and secured their bug bags in the water with ropes and rocks, and plan to return in a few weeks to see what the invertebrates will tell them about the water quality of the awa.
“Invertebrates are food for fish and also feed on algae, so they’re really important,” Issie told the tamariki. “If anything happens to these bugs, the whole system can fall apart.”
Finding out about river health
Issie said, “there are lots of different types of bugs that can live in the river and what we want to see is lots of diversity, because that’s going to be the healthiest river.”
She explained that certain bugs were indicators of water quality – for instance, stoneflies are intolerant to pollution, so high numbers of stoneflies indicated better water quality. On the flip side, high numbers of invertebrates like snails and worms would suggest that the waterway might be polluted.
Bug bags collect freshwater bugs
Bug bags submerged in water for two to three weeks will collect invertebrates or bugs. They can be made from cotton or hemp (for the trial they were made from recycled coffee sacks!), or any material with small holes for the bugs to enter. We recommend filling them with items such as flax, rocks, and leaves, which act as a shelter for the invertebrates drifting downstream.
Bug bags are tied down with rope to nearby trees, roots or rocks and left in streams or awa for around two to three weeks. By the time they are retrieved, in theory, the bags should be filled with bugs from the awa.
Bug bags are easy for children to make, which allows them to express their creativity with the designs they bring to life.
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Retrieved: 10:24am, Fri 02 Aug 2024
https://www.ecan.govt.nz/get-involved/news-and-events/zone-news/selwyn-waihora/enviroschools-waitaha-deploys-tool-to-monitor-water-quality/
