Effect of fish removal on the abundance and size structure of the sea urchinDiadema antillarum: A field experiment

Abstract

To cite this article: Ruber Rodríguez-Barreras, Alain Durán, Julián Lopéz-Morell & Alberto M. Sabat (2015): Effect of fish removal on the abundance and size structure of the sea urchin Diadema antillarum: A field experiment, Marine Biology Research, Abstract Three decades after its population collapse, the sea urchin Diadema antillarum has yet to return to pre-mortality densities in most Caribbean localities. Circumstantial evidence suggests high post-settlement mortality due to predation as a potential mechanism to explain the lack of, or the slow recovery of this sea urchin. In this study we experimentally reduced the densities of two reef fish, Thalassoma bifasciatum and Halichoeres bivittatus, at one site for one year and measured the effect of their removal in the abundances and size structures of D. antillarum in relation to that of a comparable control site. We hypothesized a significant increase in urchin abundance and a reduction in mean test diameter at the experimental site with respect to the control site after the reduction in fish abundance. Overall, the density of D. antillarum did not vary significantly between control and experimental sites for the different census periods. Fish removal had a significant effect on the size structure of D. antillarum and in the mean density of the medium size classes. Results suggest that removal of these two labrids can significantly increase the relative abundance of medium-sized sea urchins and modify its population structure. Efforts to recover D. antillarum populations would be strengthened if densities of T. bifasciatum and H. bivittatus remain low.

Mortality associated with ingestion of sea urchins in loggerhead sea turtles (Caretta caretta): A case series

“…Mass extraction of fish for human use is a major stressor on marine ecosystems [8]. In the last decades, some coasts around the world have suffered an increase of the sea urchin populations, possibly due to the decrease of natural predators, mainly due to overfishing [9,10].…”

Emergence of serranid pigment abnormality syndrome (SPAS) in wire netting cod (Epinephelus quoyanus) from Heron Island on the southern Great Barrier Reef

“…In the Caribbean, an acute large-scale epizootic in sea urchins (Diadema antillarum; see Lessios et al 1984;Lessios 1988) preceded phase shifts towards algal dominance in coral reefs in the early 1980s (Idjadi et al 2010). Although a disease agent was never identified as the cause of the initial mortality event, a microbial pathogen was suspected (Bauer and Agerter 1987) and it has taken nearly 30 years before sea urchin populations (and corals) in the affected regions began to recover (Idjadi et al 2010;Rodrı ´guez-Barreras et al 2015). Then, in 2000, spiny lobsters (Panulirus argus) in the Caribbean were found to be infected with a novel virus (Panulirus argus virus 1 (PaV1)) that caused disease and mortalities in juvenile lobsters (Behringer et al 2011).…”