Projections of climate conditions that increase coral disease susceptibility and pathogen abundance and virulence

Temperature-induced behavioral switches in a bacterial coral pathogen

“…Corals also provide an advantage in the context of facilitating in situ visualization because they host an important portion of their microbiome on their external surface (Garren and Azam 2012). It is also a timely choice of from an ecological perspective because disease has recently been identified as an under-appreciated driver of the future state of reefs (Maynard et al, 2015). Figure 5 Chemotactic response of V. coralliilyticus demonstrating the combined effect of temperature on pathogen motility and host physiology.…”

“…Maynard et al (2015) present climate model projections for the onset of increased pathogen virulence, which was defined as a doubling in the number of months at which sea temperatures are likely to induce heightened host-seeking behaviors (that is, 4historical mean monthly maximum, found experimentally to be~27°C). Under business as usual forecasts for greenhouse gas emissions, it is projected that pathogen virulence will increase for 440% of reefs worldwide by 2030 (Maynard et al, 2015).…”

“…Under business as usual forecasts for greenhouse gas emissions, it is projected that pathogen virulence will increase for 440% of reefs worldwide by 2030 (Maynard et al, 2015). Given that all currently known putative coral pathogens are motile (Garren et al, 2014) and that chemotaxis is both a common feature in the reef environment (Tout et al, 2015a) and implicated in the success of bacterial pathogens of corals (Banin et al, 2001;Meron et al, 2009), our observations that both chemotactic and chemokinetic behaviors of V. coralliilyticus are influenced by temperature add to our current understanding of coral disease to suggest that motility adaptations under future climate scenarios have the potential to favor bacterial pathogens over their coral hosts (Garren et al, 2014;Maynard et al, 2015).…”

“…Although we know that elevated seawater temperatures destabilize the coral-algal symbiosis that is critical for coral survival (Baker et al, 2008), we know far less about the linkages between warming waters and coral disease. Understanding how pathogen navigation and host-detection are influenced by changing environmental conditions is important to allow these processes to be accounted for in understanding coral heath and in forecasting areas of high risk for disease outbreaks (Maynard et al, 2015).…”

Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C

“…The assumption of a thermal adaptation of 0.4 • per decade appears very ambitious given the long creation times of reef-building corals and the consequently slow rate at which evolutionary adaptation occurs. Furthermore, additional environmental stressors such as ocean acidification (Caldeira, 2005) and disease spreading (Maynard et al, 2015) have to be expected to slow-down coral growth and to reduce the adaptive capacity of tropical coral reefs. As a consequence, this scenario should be seen as an absolute lower boundary for degradation of coral reefs globally.…”