Learnings From Shellfish
Each year Friends of Awa Matakanakana (FOAM) invites volunteers to identify, measure and count shellfish at Sandspit estuary. This was recently carried out in conjunction with students from Horizon School.
FOAM’s research focuses on the health of the catchment from the Glen Eden and Matakana rivers and the tributaries that flow from the hills, through land and villages, Sandspit estuary and into Kawau Bay. Counting shellfish provides an insight into the changes occurring in the rivers. The dominant shellfish inhabiting Sandspit estuary are tuangi (cockles), and others include whelks, nutshells, pipi, wedge and horn shells.
Mark Foster, FOAM committee member and relief teacher at Horizon School, says the students study ecology in science and geography. “I like involving young people and giving them exposure to estuary ecology, to the real environment where they need to be aware of some of the things that are going on.”
Prior to the student’s arrival, FOAM volunteers mark 20 GPS locations where shellfish data has been collected since 2013. The students were welcomed on arrival with a karakia to acknowledge the significance of the area to Ngāti Manuhiri, followed by a quick refresher on the methodology and health and safety. Heading out to the monitoring sites, some of which were only accessible for two hours before the tide turned, they dug 100-millimetre-deep samples of sand and placed them into sieve frames. The contents were rinsed in seawater, empty shells removed and then the various species of live shellfish were sorted into their groups before counting. The size and numbers of tuangi are recorded, which enables comparison with data from previous years.
Tuangi are filter feeders that help clean the estuary water and they are an important food for marine animals. They are sensitive to pollution, rising water temperatures, overharvesting, and excessive sediment.
Year 9 student, Harrison Andrew, found the experience quite different from what he expected. “You don’t really notice what is around until you start looking and find stuff,” says Harrison. “Then you realise there is a lot around that you didn’t know about before. It was a very new experience and it’s one of the ways of telling if the water, and its living creatures, are fine. Being able to help them and the ocean, rivers, lakes – it’s all very important.”
FOAM forwards its findings to Auckland Council so that scientists can examine the data. The results also contribute to the Hauraki Gulf Forum’s State of the Gulf report.