Uncovering estuary health with eDNA
Channel: Sustainable Seas National Science Challenge
Date: 2021-05-21

New research shows environmental DNA, or eDNA, can help scientists quickly detect ecosystem changes, helping us to manage our estuary health better. 

In this short video, lead author of the research Dana Clark explains what they did.

What is eDNA?
eDNA are the tiny traces of DNA that organisms like shellfish, worms, and bacteria leave behind in the waters of coasts and estuaries. Studying these traces is an important and cost-effective tool to detect changes in ecosystems. 

Learn more: https://www.sustainableseaschallenge.co.nz/tipping-points

Transcript //

Estuaries are really important ecosystems, but they're often undervalued.

It's really hard to get a clear idea of the overall health of New Zealand's estuaries and whether or not we're heading in the right direction.

We need good monitoring tools to track estuary health.

Traditionally when we're assessing estuary health, we tend to look at the animals that live within the sediments, so things like the shellfish and the worms.

They're a really valuable indicator of estuary health and we know a lot about them and how they respond to different types of stress.

But collecting and identifying these animals is expensive and time-consuming.

We know that there's changes occurring in other types of communities like bacteria which we can't see.

Our Tipping Points project looked at using environmental DNA (eDNA), which is faster and easier.

So as animals move through their environment, they're always shedding little parts of their bodies, their little skin cells and things are falling off into the environment. 

And they leave a trace of where they've been and so we can collect either water samples or sediment samples and find these little bits of DNA.

The team ran experiments by adding fertiliser to site in two Nelson estuaries. 

7 months later, they returned to collect samples containing eDNA of microbial communities. 

Samples were processed using eDNA metabarcoding.

They found this technique can detect microbial communities’ response to added fertiliser.

These smaller animals like bacteria have really quick turnover rates, so it means that they can respond really quickly to changing environmental conditions.

They're really good indicators of stress because they can pick up low levels of stress and act as early warning indicators.

This will help develop future monitoring tools that are better at detecting environmental changes, helping us to better manage our estuaries.