Waitahurangi (Avondale) Stream, one of the main branches of the Whau River catchment, was once an important travel route between the Waitemata and Manukau Harbours. Unfortunately, recent decades have put huge pressure on this catchment, with pollution from industry and urbanisation.
At the EcoMatters stream clean event, we saw a pile of rubbish that volunteers had pulled out of the stream the day before. Our Auckland Museum staff supported a guided walk along the riverbank near Olympic Park, and demonstrated water testing and freshwater invertebrate monitoring. This kind of work helps determine the overall health of a waterway – the healthier the water, the greater the abundance of life within it.
While the invertebrates found at this site were not as biodiverse as you would expect to find in an unpolluted stream, there were still freshwater shrimp, damselflies, and inanga (a whitebait species).
When organisms such as the ones found in the stream move through their environment, they shed little bits of themselves, leaving behind traces of DNA. Things such as dead skin cells, mucus, and faeces, all provide clues about the residents of the waterways. Scientists call the DNA found in this organic matter environmental DNA (eDNA). A selection of eDNA samples undertaken by EcoMatters show some very interesting species in this stream, including torrent fish and freshwater mussels.
This event was a great way for community, iwi, and professional organisations to share results. Volunteering and getting involved at your local stream could make a big difference, and keep these precious waterways from deteriorating.