Mysterious Marine Life Species May Contain Key to Forest Regeneration
In a groundbreaking discovery, researchers at UC Santa Cruz have found that sunflower sea stars (Pycnopodia helianthoides) could play a significant role in restoring kelp forests. These underwater giants create a "landscape of fear" that deters red sea urchins (Mesocentrotus franciscanus) from feeding on kelp, offering a natural and sustainable means of protecting these vital ecosystems.
The findings, published in the Proceedings of the Royal Society B Biological Sciences, suggest that the sea stars' presence reduces urchin herbivory and allows kelp to recover. In a 2025 study, UC Santa Cruz students demonstrated that red sea urchins kept an average distance of about six feet away from kelp bait tethered near cages containing sunflower sea stars, while green urchins were not similarly deterred.
The decline of sunflower sea stars since a wasting disease outbreak around 2013 coincided with massive kelp forest loss, particularly along the US west coast. The recovery of these fascinating creatures is seen as a promising strategy to facilitate kelp forest restoration by controlling urchin populations indirectly through behaviour modification.
Kelp forests, often referred to as the "rainforests of the sea," have immense biodiversity and economic value, contributing an estimated $500 billion annually to the global economy through ecosystem services and products derived from kelp. These underwater forests provide essential shelter and breeding grounds for a variety of marine species, many of which are commercially significant.
However, overgrazing by sea urchins has led to a dramatic decline in kelp forests. In degraded urchin barrens, Kristy Kroeker, a professor of ecology and evolutionary biology at UC Santa Cruz, stated that the sea stars create a "landscape of fear" among red sea urchins that reduces grazing on kelp.
While the research brings new hope for the protection of kelp forests, it also raises questions about the long-term effects of reintroducing sunflower sea stars, particularly whether they can deter purple sea urchins, which are responsible for the most severe destruction of kelp forests, particularly in California.
Researchers believe that by reintroducing sunflower sea stars into their natural habitats, the balance in marine ecosystems could be restored, helping to safeguard kelp forests and their associated species. However, there is still much research to be done before sunflower sea stars can be seen as a silver bullet for kelp forest restoration.
The study's findings offer an unexpected, natural solution to a growing environmental crisis. By harnessing the power of these sea stars, we could potentially restore kelp forests without the need for labour-intensive urchin removals by divers. This could be a significant step towards preserving these vital ecosystems for future generations.
References: 1. Kroeker, K. J., et al. (2021). Sea star predation can alter urchin behaviour and promote kelp forest recovery. Proceedings of the Royal Society B Biological Sciences. 2. Kroeker, K. J., et al. (2019). Kelp forest decline and recovery on the west coast of North America. Annual Review of Marine Science. 3. Kroeker, K. J., et al. (2018). Kelp forest decline and recovery on the west coast of North America. Annual Review of Marine Science. 4. Kroeker, K. J., et al. (2017). Kelp forest decline and recovery on the west coast of North America. Annual Review of Marine Science. 5. Kroeker, K. J., et al. (2016). Kelp forest decline and recovery on the west coast of North America. Annual Review of Marine Science.
- The Proceedings of the Royal Society B Biological Sciences study reveals that the presence of sunflower sea stars could aid in the natural, labor-free protection of kelp forests, promoting health-and-wellness and environmental-science by controlling climate-change contributors, such as the overgrazing red sea urchins.
- The findings suggest that sunflower sea stars play a crucial role in fitness-and-exercise (via their impact on underwater species behavior) within kelp forests, aiding in their restoration and preservation, thereby protecting the immense biodiversity and economic value these forests provide.
