environmental DNA & Diver Surveys Reveal Different Signs of Reef Change
How do we know when a reef is changing?
When we think about monitoring reefs, we often picture divers counting fish or measuring kelp forests. But a healthy reef is far more than what we can see. It includes countless microscopic organisms, algae and invertebrates, each responding differently to environmental change.
A new study led by Dr Lara Denis-Roy from the University of Tasmania shows that no single monitoring method captures this full picture.
“Environmental DNA doesn't replace traditional reef surveys, it complements them. Every method reveals a different part of the story, and it's by bringing those methods together that we gain the most complete understanding of reef ecosystems."
- Lara Denis-Roy, lead author.
Looking Beyond What Divers Can See
The researchers compared traditional underwater visual surveys with environmental DNA (eDNA), tiny fragments of genetic material collected by swabbing different reef surfaces, including bare rock, coralline algae and brown algae.
They also examined different reef microhabitats, including seawater, bare rock and brown algal habitats, recognising that each supports distinct biological communities. Both approaches successfully detected changes in reef condition, but each revealed different components of the ecosystem.
While diver surveys documented visible organisms, eDNA identified shifts across different components of biodiversity, particularly microbial communities and other groups that are difficult to survey visually.
No Single Method Tells the Whole Story
The study found that different parts of the reef ecosystem respond differently to environmental pressures, meaning no single monitoring method tells the whole story.
Instead, the authors show that combining complementary approaches provides a more complete understanding of reef ecosystems and how they are changing.
The Future of Reef Monitoring
As our temperate reefs face growing pressures from climate change, marine heatwaves, harmful algal blooms and coastal development, understanding change across the whole ecosystem becomes increasingly important.
Studies like this show that the future of reef monitoring lies not in replacing divers with new technology, but in combining multiple tools to provide a more complete understanding of ecological change and better inform conservation and management.
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