Award: OCE-1015032

This is a collaborative research award to Rollins College and the University of Georgia. This outcomes report represents the Rollins College contribution to the collaborative award. Undergraduate training and professional development was a focus of this project. Five undergraduate students at Rollins College collaborated on this study. This project generated a seven-year data set (2010-2016) on the health and abundance of elkhorn coral (Acropora palmata) at seven reefs in the Florida Keys National Marine Sanctuary (FKNMS). We combined these data with our 2008-2009 data from these same reefs and with a historical annual 11-year (1994-2004) elkhorn coral survey conducted at an eighth reef in the FKNMS to generate a 22-year record of elkhorn coral health and abundance in the FKNMS. This long-term record (1994-2016) indicates that white pox disease (WPX) is a then (1994-2004) and now (2008-2016) disease in terms of etiology, severity, and contribution to whole colony mortality. Historical (1994-2004) WPX was a severe stressor that contributed to 97.8% whole colony mortality. Contemporary (2008-2016) WPX is a less severe recurring disease that causes only partial colony mortality. WPX prevalence showed a pronounced seasonal pattern with peak prevalence occurring in warmer spring and summer months. The range of WPX prevalence values through time was comparable for historical and contemporary elkhorn coral populations indicating that populations are equally as susceptible to WPX today as in the mid-1990?s. Through tracking over several years and seasons, we have identified that some elkhorn coral colonies are more prone to WPX than others suggesting that host or microbiome related factors may affect relative resistance to the disease. A form of WPX called acroporid serratiosis is diagnosed if and only if classic signs of WPX affecting the Acropora palmata host co-occur with the presence of the established bacterial pathogen Serratia marcescens. S. marcescens was identified with quantitative real-time PCR (qPCR) from lesions in 2012 and 2013, confirming acroporid serratiosis for these cases of WPX. The established pathogenic strain of S. marcescens, strain PDR60, was detected in apparently healthy non-host corals Porites porites and P. astreoides in 2012 using culture methods, identifying these non-host corals as reservoirs of acroporid serratiosis. All S. marcescens cultured from the reef environment during this study matched the pathogenic strain PDR60. The PDR60 strain was also found in untreated sewage in the Florida Keys during the same time period, supporting our earlier finding that human wastewater is a source of this pathogen. Presence of WPX signs during all years from 2009 to 2014 of our contemporary FKNMS-wide survey, and the lack of consistent confirmation of acroporid serratiosis supports the hypothesis that other pathogens or conditions also cause WPX. WPX etiology is a moving target for which we have hit the mark once with establishment of S. marcescens as one pathogen. Other forms of WPX not associated with S. marcescens also exist. Etiology of the alternate form(s) is unknown. The microbial communities of WPX- affected and unaffected elkhorn coral were examined to describe changes in the microbial community during WPX lesion onset and progression. We are using a modeling approach that combines our coral health and abundance data and our coral microbiome data with environmental data to elucidate local and global drivers of WPX. Our goal is to determine if etiology, severity, and lethality of WPX can be explained by (a) reduced virulence of the pathogen, (b) increased resistance of the host, (c) an altered host microbiome, and/or (d) environmental factors. Last Modified: 12/20/2016 Submitted by: Kathryn P Sutherland