DAO prepress abstract  -  DOI: https://doi.org/10.3354/dao03213

Influence of salinity and sedimentation on Vibrio infection of the Hawaiian coral Montipora capitata

A. Shore-Maggio*, G. S. Aeby, S. M. Callahan

*Email: asmaggio@umbc.edu

ABSTRACT: Environmental cofactors alter host–pathogen interactions and influence disease dynamics by impairing host resistance and/or increasing pathogen virulence. Terrestrial runoff is recognized as a major threat to coral reef health. However, the direct links between runoff and coral disease are not clear. Montipora white syndrome (MWS) is a coral disease that occurs in the Hawaiian archipelago, can be caused by various bacterial pathogens, including Vibrio species, and is linked to conditions associated with heavy rainfall and runoff. The objective of this study was to determine whether a short-term hypo-salinity stress (20 ppt for 24 h) or sedimentation stress (1000 g m-2 d-1) would influence bacterial infection of the coral, Montipora capitata. Hypo-salinity increased M. capitata susceptibility to infection by two MWS pathogens, Vibrio coralliilyticus strain OCN008 and Vibrio owensii strain OCN002. Specifically, hypo-salinity allowed OCN008 to infect at lower doses (106 CFU ml-1 compared to 108 CFU ml-1) and reduced the amount of time before onset of OCN002 infection at high doses (108 CFU ml-1). In contrast, short-term sedimentation stress did not affect M. capitata infection by either of these two pathogens. Although several studies have found a correlation between runoff and increased coral disease prevalence in field studies, this is the first study to show that one aspect of runoff (reduced salinity) enhances bacterial infection of coral using manipulative experiments.