Sea urchins blamed for kelp loss don't actually eat much kelp, research shows
Research shows long-spined sea urchins eat invertebrates and organic matter as much as kelp, challenging assumptions about forest decline.
Kelp forests along Australia's southeast coast have been shrinking, and sea urchins have long been blamed. New research is complicating the story.
Scientists examined the gut contents of 100 long-spined urchins from kelp forests and barrens off New South Wales and used stable isotope analysis to measure long-term diet. The urchins were eating invertebrates, kelp and particulate matter equally or in some cases more than kelp.
Even in dense kelp forests, urchins rely more heavily on other food sources. Meanwhile, urchin populations in NSW have remained stable over long periods.
In response to kelp decline, authorities have launched urchin control programs where divers remove them. But kelp prefers cold water and oceans are warming fast.
Urchins may be a symptom of change, not the cause.
- 100 long-spined sea urchins
- Sample examined
- Populations stable over long timeframes
- NSW urchin trend
- New South Wales kelp forests
- Location
Why it mattersIf ocean warming, not urchins, is the real cause of kelp loss, removal programs may not stop the decline. Understanding the actual threat means resources can be directed where they matter most.
AustraliaThis research could reshape how Australian marine authorities manage coastal ecosystems, potentially redirecting urchin control budgets toward addressing ocean warming and its effects on kelp species.
✓ Claims checked against the source and corrected before publish. checked 7 d ago
