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Thermodependent bacterial pathogens and mass mortalities in temperate benthic communities: a new case of emerging disease linked to climate change

TitleThermodependent bacterial pathogens and mass mortalities in temperate benthic communities: a new case of emerging disease linked to climate change
Publication TypeJournal Article
Year of Publication2007
AuthorsBally, Garrabou
JournalGlobal Change Biology
Volume13
Keywordsbenthos, biodiversité, changement climatique, climate, climate change, disease, France, global warming, gorgonaire, gorgonian, habitat, Ile du Riou, infection, invertebrate, Marseille, Marseilles, mass mortality, Mediterranean sea, Méditerranée nord-occidentale, Méditerrannée occidentale, Mer Méditerranée, mortalité massive, mortality, north-western Mediterranean, Paramuricea clavata, pathogen, pathogène, Provence, réchauffement global, Riou Island, sea water temperature, temperature, température de l'eau de mer, threat, Vibrio corallilyticus, warming, western Mediterranean
Abstract

In the temperate north-western Mediterranean Sea, large-scale disease outbreaks in benthic invertebrate species have recently occurred during climatic anomalies characterized by elevated seawater temperatures. One of the most affected species was the red gorgonian Paramuricea clavata, a key species of highly diverse communities dwelling in dim-lit habitats in the Mediterranean. From diseased P. clavata colonies, we isolated culturable bacteria associated to tissue lesions in order to investigate their potential as pathogens. Inoculation of four bacterial isolates onto healthy P. clavata in aquaria caused disease signs similar to those observed during the 2003 mortality event. The infection process was dependent on elevated seawater temperatures, in a range of values consistent with recordings performed in the field during the climatic anomalies. Among the four isolates, we identified a Vibrio coralliilyticus strain that showed virulence to P. clavata. This strain was re-isolated from diseased colonies during the experimentations. V. coralliilyticus has been previously identified as a thermodependent pathogen of a tropical coral species, emphasizing a causal role of this infectious agent in the P. clavata disease. Taking into consideration predicted global warming over the coming decades, a better understanding of the factors and mechanisms that affect the disease process will be of critical importance in predicting future threats to temperate gorgonians communities in the Mediterranean Sea.

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