Modeling the Impact of White-Plague Coral Disease in Climate Change Scenarios

Abstract

Coral reefs are in global decline, with coral diseases increasing both in prevalence and in space, a situation that is expected only to worsen as future thermal stressors increase. Through intense surveillance, we have collected a unique and highly resolved dataset from the coral reef of Eilat (Israel, Red Sea), that documents the spatiotemporal dynamics of a White Plague Disease (WPD) outbreak over the course of a full season. Based on modern statistical methodologies, we develop a novel spatial epidemiological model that uses a maximum-likelihood procedure to fit the data and assess the transmission pattern of WPD. We link the model to sea surface temperature (SST) and test the possible effect of increasing temperatures on disease dynamics. Our results reveal that the likelihood of a susceptible coral to become infected is governed both by SST and by its spatial location relative to nearby infected corals. The model shows that the magnitude of WPD epidemics strongly depends on demographic circumstances; under one extreme, when recruitment is free-space regulated and coral density remains relatively constant, even an increase of only 0.5°C in SST can cause epidemics to double in magnitude. In reality, however, the spatial nature of transmission can effectively protect the community, restricting the magnitude of annual epidemics. This is because the probability of susceptible corals to become infected is negatively associated with coral density. Based on our findings, we expect that infectious diseases having a significant spatial component, such as Red-Sea WPD, will never lead to a complete destruction of the coral community under increased thermal stress. However, this also implies that signs of recovery of local coral communities may be misleading; indicative more of spatial dynamics than true rehabilitation of these communities. In contrast to earlier generic models, our approach captures dynamics of WPD both in space and time, accounting for the highly seasonal nature of annual WPD outbreaks.

Unprecedented Disease-Related Coral Mortality in Southeastern Florida

“…The established pattern of high prevalence of white-plague disease following thermal anomalies suggests that thermal-stress events are the seasonal drivers of white-plague disease outbreaks, and that coral bleaching most likely enhances the severity of the disease. The above interpretation also suggests that the impact of coral diseases will increase with future global warming 4 38 .…”

Host size and proximity to diseased neighbours drive the spread of a coral disease outbreak in Hawai‘i

“…It is plausible, therefore, that discontinuities in mosaic marine habitats such as coral reefs, seagrass meadows and oyster reefs similarly affect disease spread in the ocean. In coral reefs, several studies have shown associations between colony configuration and clustering of disease cases [10][11][12][13], while other studies have found no evidence of disease clustering [4]; these opposing results probably reflect differences in modes of transmission for different diseases.…”

Occurrence of coral diseases at Akajima, Okinawa, Japan in 2010 and 2011

“…Information on the dispersal patterns of coral diseases is limited, although some researchers have analyzed the transmission pattern of diseased colonies using spatial analyses (Jolles et al 2002;Foley et al 2005;Zvuloni et al 2009;Lentz et al 2011;Zvuloni et al 2015). Coral diseases such as sea fan aspergillosis and yellow band disease have exhibited clustering at a small spatial scale .…”

“…These data are utilized to elucidate not only ecological factors contributing to the reduction of coral reefs on both global and regional scales (Osborne et al 2011;Ruiz-Moreno et al 2012), but also , Nobuhiro MANO 1 *, Yukio YANAGISAWA 1 , and Tsukasa MORI characteristics of the spread of infection in the population on regional and local scales (Miller et al 2003;Sato et al 2009;Pollock et al 2014;Lamb et al 2014). Some researchers have also focused on the pattern of spatial distribution of diseased colonies for analysis of infectious transmission on a local scale (Jolles et al 2002;Foley et al 2005;Zvuloni et al 2009;Lentz et al 2011;Zvuloni et al 2015).…”