Review: Marine ecology - Emerging marine diseases - Climate links and anthropogenic factors

Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals , reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bl eaching in 1997-98 is coincident with high El Nino temperatures. Such clima te-mediated, physiological stresses may compromise host resistance and incr ease frequency of opportunistic diseases. Where documented, new diseases ty pically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populati ons.