Colony versus population variation in susceptibility and resistance to dark spot syndrome in the Caribbean coral Siderastrea siderea

Abstract

Scleractinian corals appear to be increasingly susceptible to pathogenic diseases, yet it is poorly understood why certain individuals, populations or species are more susceptible to diseases than others. Clearly an understanding of mechanisms of disease resistance in corals is essential to our understanding of patterns of disease incidence and virulence; this work must begin by examining the colony and population levels of organization. The Caribbean coral Siderastrea siderea exhibits variability in susceptibility to dark spot syndrome (DSS), a disease of unknown origin that can result in tissue necrosis. On the reef scale, variability in DSS prevalence in S. siderea occurred through time, but was not correlated with site, seawater temperature or depth. We monitored colonies of S. siderea affected by DSS, as well as their nearest neighbor controls, for 2 years in the Bahamas and found a marked decline in extent of DSS infection in October of both years. A preliminary survey of antimicrobial activity in S. siderea indicated selective activity against certain ecologically relevant bacteria. To assess whether changes in chemical defenses were responsible for the observed temporal variability in DSS prevalence, we sampled S. siderea for qualitative and quantitative analysis of chemical variability between resistant and susceptible colonies of S. siderea. These data suggest that phenotypic plasticity in antimicrobial activity may impact microbial settlement and/or survival.

Coral disease prevalence and host susceptibility on mid-depth and deep reefs in the United States Virgin Islands

“…This susceptibility pattern was similar to findings by Borger (2005) in Dominica, where S. siderea was the only species affected by dark spots disease, and by Gochfeld et al (2006) who also found that dark spots most frequently affects S. siderea. Although these results suggest the potential for degradation within S. siderea, another study by Borger (2003) found that the effects of dark spots disease on the coral community were low compared to the more virulent tissue eroding diseases white plague and black band disease.…”

Disease dynamics of Montipora white syndrome within Kaneohe Bay, Oahu, Hawaii: distribution, seasonality, virulence, and transmissibility

“…As such, MWS also has the potential to shift the coral community structure of the reefs within Kaneohe Bay towards coral species that are not susceptible to this disease. Differential disease susceptibility among coral genera has been found in a number of studies (Willis et al 2004, Gochfeld et al 2006, Aeby 2007, Vargas-Angel 2009, and individual coral dis-eases show variability in host specificity. For example, BBD has low host specificity and affects 19 Caribbean shallow-water coral species and 45 Indo-Pacific coral species (Sutherland et al 2004), whereas white band disease only affects Acropora sp.…”

Antibacterial chemical defenses in Hawaiian corals provide possible protection from disease

“…Differences in types and levels of defense vary among families, genera, and species and even at the level of the individual colony (Mullen et al 2004, Gochfeld et al 2006). These differences might enable particular populations, species, or genotypes to have an advantage over others in resisting invasion by pathogens.…”

“…Scleractinian corals have also been found to produce chemical defenses, although these are less well studied than those in soft-bodied invertebrates. Gochfeld (1997) demonstrated chemical defenses against predatory fish in 2 species of Hawaiian corals, and in one of the earliest studies on coral chemical defenses, Gunthorpe & Cameron (1990) documented antibacterial activity in 37 of 55 species of Australian corals. Likewise, Koh (1997) found that extracts from 100 Australian coral species inhibited growth of a marine cyanobacterium, and extracts from 8 species inhibited growth of marine bacteria.…”