Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift
In Tasmania coastal waters are warming approximately 4 times higher than the average elsewhere. This has led to an increase in sea urchin levels which are causing deforestation of kelp beds and loss of biodiversity. These sea barrens are especially predominet in areas where fishing has wiped out sea urchin predators, specifically lobsters. The point of this research was to look at if areas in Tasmania with increased rates of fishing effected have a negative impact on the resilience of kelp beds and increase the amount of overgrazing by C. rogers a long-spined sea urchins. To test this theory, C. rogers were put in to reefs in Tasmania where there are no-take MPAs with large amounts of and other reefs that have open fishing and have low levels of sea urchin predators. In Australia C. Rodgers has had the highest damage of shallow reefs. The results showed that sea urchins were not able to grow their numbers as large in areas where there predators were present. It was also important that lobsters were large enough to be able to wrap around the sea urchins which is not found in most areas with fishing.
Ling, S. D., et al. “Overfishing Reduces Resilience of Kelp Beds to Climate-Driven Catastrophic Phase Shift.” PNAS, National Academy of Sciences, 29 Dec. 2009, www.pnas.org/content/106/52/22341.full.