How are the creatures in our waterways doing?

​New information has been released this week by Land, Air, Water Aotearoa (LAWA) to show how well macroinvertebrate communities in New Zealand’s waterways have been doing over the past 10 years.

Macroinvertebrates are small animals without backbones that live in freshwater and include iconic species such as mayflies and caddisflies.

Scientists measure their communities in rivers and streams by counting the number and different types of macroinvertebrates as this gives a good insight into what is happening with the water quality there.

The 10-year national trend summary shows that macroinvertebrates are likely or very likely improving at 26% of sites assessed, and likely or very likely degrading at 42% of sites assessed.

For Southland, the 10-year trend summary showed that macroinvertebrates are improving or likely improving at 28% of sites assessed, and likely or very likely degrading at 33% of sites assessed.

Environment Southland surface water quality scientist Roger Hodson said it’s extremely helpful to have this information. “We may not see them often but these creatures give us valuable information about what’s happening, and what’s been happening with water quality in our rivers and streams.”

“Even when improvements to water quality are made, it can take some time for sediment to shift, habitat to regenerate, and macroinvertebrate communities to come back, if at all. We also need them there as part of the ecosystem, to keep waterways healthy and to graze on algae, as well as feeding fish and birds. It’s important we keep our eye on how they are doing.”

Roger encouraged the community to take the opportunity to check the LAWA website which would allow them to not only see how well macroinvertebrates were doing in their local rivers and streams, but to also see what was happening overall at the catchment level.

This information is now available on the LAWA website and joins the eight other water quality parameters LAWA reports on annually, to produce the National River Water Quality 10-year Trend Summary (2008 – 2017).

The other measures that LAWA has worked out trends for include water clarity, turbidity, E. coli, total nitrogen, dissolved reactive phosphorus, and total phosphorus.

LAWA is a collaboration between New Zealand’s 16 regional and unitary councils, Cawthron Institute, and the Ministry for the Environment.