Sea urchin Diadema africanum mass mortality in the subtropical eastern Atlantic: role of waterborne bacteria in a warming ocean

• Autor(a) principal: Clemente, S.
• Data de Publicação: 2014
• Outros Autores: Lorenzo-Morales, J., Mendoza, J. C., López, C., Sangil, C., Alves, F., Kaufmann, M., Hernández, J. C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.13/3704
• topic: Echinoids; Diadematid; Disease; Widespread die-off; Vibrio; Infection experiments; Canary Islands (Spain); Madeira (Portugal); .; Faculdade de Ciências da Vida

A widespread mass mortality event of the sea urchin Diadema africanum was detected in the subtropical eastern Atlantic, extending from Madeira to the Canary Islands, covering a straight line distance of >400 km. This is the first disease related die-off of a diadematid documented in the eastern Atlantic Ocean. Diseased individuals showed deterioration of the epidermis and water-vascular system, resulting in epidermal necrosis and release of spines. Despite some spatial heterogeneity in disease incidence at the study sites, there was a 65% overall reduction in urchin abundance after the mortality event compared to numbers pre-mortality. However, the reduction in urchin numbers did not compromise the species’ reproductive success; the settlement peak following the mortality event was of a similar magnitude to that in prior years. Bacterial isolation and cul ture techniques, and subsequent laboratory in fection experiments, strongly suggested that Vibrio alginolyticus was involved in the disease. We hypo thesize that the mass mortality event devel oped due to anomalously high seawater tempera tures recorded in the 2 studied archipelagos and that warmer temperatures enabled infection of D. africa - num by waterborne pathogenic bacteria. Fluctua tions in urchin populations are key in de termining the structure and functioning of benthic ecosystems: under the current seawater warming scenario, dis ease may result in more frequent phase shifts, aiding the persistence of macroalgae.