How to Avoid Turning Kelp Forests into Barren Wastelands

Sea urchins can influence the biological richness of marine grounds. However, an excessive proliferation of urchins may also have severe ecological consequences on marine grounds as they reduce algal cover. That's why researchers examined the global dynamics and the factors that turn kelp beds into barren grounds to better learn how best to prevent this type of occurrence.

Urchins play a key role when it comes to the dynamics of marine coastal ecosystems. They feed on algae and are prey to fish species. For example, when an area is overfished, the urchin population can grow to the point of turning kelp beds into barren grounds. Yet the predictions of the general model that links marine areas with urchin overgrazing and low algal cover are not always correct.

In this case, the scientists examined 13 different worldwide rocky reef systems. This revealed that the process of kelp beds becoming barren does not follow a pattern. At one point, the ecological system collapses and the reduction of biodiversity takes place. Yet these changes must be analyzed from the theory of alternative stable states.

The findings confirmed the hypothesis about a globally coherent pattern of change for all the studied system and that each system had particular features that made them different. The stability of marine forests is preserved through a series of feedback mechanisms. When urchin density arrives to a critical point, the ecological system collapses.

The findings don't just show how these ecosystems collapse, though; they also show how to recover kelp beds. In order to encourage kelp bed recovery, urchin populations must remain very small.

The findings reveal a bit more about kelp forests and show how best to aid recover. In order to avoid collapse in the first place, it's necessary to maintain biodiversity and maybe even take action on urchin populations.

The findings are published in the journal Philosophical Transactions of the Royal Society B: Biological Sciences.