Abstract

Echinoids play an important role in marine ecosystems structuring. Often, their population density experience markedly fluctuations that promote a state shift in the ecosystems they inhabit. Population increments of some sea urchins may cause catastrophic changes in temperate areas of the planet by decimating the erect macroalgae cover. These population increments results in unproductive and very stable assemblages, known as “blanquizales” (ericeras/moradales), or sea urchin barren ground. Macroalgae are the main ecosystem engineers in temperate areas and generate a suitable nursery and feeding habitat for fishes. These algae stands are also important zones for biofiltration of coastal waters and CO2 uptake. The main consequence of vegetated biomass lost is a trophic disequilibrium that generates important economic losses for artisanal fisheries and tourism. In tropical areas, sea urchin’s outbreaks can cause bioerosion in coral reefs. However, the most important event to highlight was the mass mortality occurred in the Caribbean during the 80’s. This event favored the development of algae communities that suffocated the coral reef ecosystem. Therefore, both in temperate and tropical areas of the planet, these boom-bust echinoids generate undesired ecosystems states. Very recently, various global scale collaborative papers have highlighted a clear anthropogenic cue. Human activity though overfishing or favoring global warming, weakens marine ecosystem resilience and promote these catastrophic ecosystem shifts. To mitigate the effects of these population changes different management strategies have been used. For instance, in temperate areas, sea urchin reduction actions (manually or by using quick lime), sea urchin harvesting or the implementation of marine reserves have been used, with contrasting results. In Caribbean coral reefs affected by urchin mass mortality, some sea urchin juvenile’s reintroduction plans have been used but with very low effectiveness. The more feasible ecosystem scale strategy due to its preventive nature, seems to be the implementation of protected areas. However, the impact of global warming will exceed our capacity to manage marine ecosystems locally and will required more efficient global actions to prevent undesired sea urchin fluctuations. Rev. Biol. Trop. 65(Suppl. 1): S23-S34. Epub 2017 November 01.

Keywords: sea urchins, population dynamics, community ecology, climate change, predation, marine reserves.