Disease dynamics of Porites bleaching with tissue loss: prevalence, virulence, transmission, and environmental drivers

Abstract

The prevalence, number of species affected, and geographical extent of coral diseases have been increasing worldwide. We present ecological data on the coral disease Porites bleaching with tissue loss (PBTL) from Kaneohe Bay, Oahu (Hawaii, USA), affecting P. compressa. This disease is prevalent throughout the year, although it shows spatio-temporal variability with peak prevalence during the warmer summer months. Temporal variability in disease prevalence showed a strong positive relationship with elevated water temperature. Spatially, PBTL prevalence peaked in clearer waters (lower turbidity) with higher water flow and higher densities of parrotfish, together explaining approximately 26% of the spatial variability in PBTL prevalence. However, the relatively poor performance of the spatial model suggests that other, unmeasured factors may be more important in driving spatial prevalence. PBTL was not transmissible through direct contact or the water column in controlled aquaria experiments, suggesting that this disease may not be caused by a pathogen, is not highly infectious, or perhaps requires a vector for transmission. In general, PBTL results in partial tissue mortality of affected colonies; on average, onethird of the tissue is lost. This disease can affect the same colonies repeatedly, suggesting a potential for progressive damage which could cause increased tissue loss over time. P. compressa is the main framework-building species in Kaneohe Bay; PBTL therefore has the potential to negatively impact the structure of the reefs at this location. KEY WORDS: Porites compressa · Tissue mortality · Branching coral · Framework species · Coral reef ecology · Etiology · Coral disease · Water temperature Resale or republication not permitted without written consent of the publisherDis Aquat Org 113: [59][60][61][62][63][64][65][66][67][68] 2015 than the Caribbean, an increasing amount of evidence suggests that coral diseases are common (Sutherland et al. 2004, Willis et al. 2004, Raymundo et al. 2005, even at remote, uninhabited islands (Williams et al. 2008, 2011b, Vargas-Angel 2009, with the types of diseases and their prevalence varying across multiple spatial scales (Aeby et al. 2011a,b). In fact, the geographical extent, number of species affected, and incidence of new diseases are increasing globally (Harvell et al. 1999, Ward & Lafferty 2004, Sokolow 2009). Environmental stress, shifts in virulence of existing pathogens, introduction of novel pathogens from anthropogenic activities, and global climate change are associated with this increase (Harvell et al. 1999, Sokolow 2009.Coral disease prevalence can be expected to show intricate interactions with a variety of driving factors (Williams et al. 2010(Williams et al. , 2014. For example, an increase in temperature can lead to an increase in pathogen virulence or cause stress to the host, which can increase its susceptibility to disease (Harvell et al. 2002). Coral disease outbreaks and increases in disease prevalence and progression have been l...

Emerging coral diseases in Kāne‘ohe Bay, O‘ahu, Hawai‘i (USA): two major disease outbreaks of acute Montipora white syndrome

“…Other coral disease outbreaks have occurred in Hawai'i but not in the spatial extent or the number of cases found in the current study (Aeby 2005, Aeby et al 2010, 2015, Ross et al 2012. The large numbers of colonies affected (338 in 2010 and 1232 in 2012) and the spatial extent (spanning reefs across ~7.5 km from south to north Kā ne'ohe Bay) illustrate the scale and severity of these outbreaks.…”

“…An outbreak of black band disease was found on Kauai in 2011 (Aeby et al 2015), and now 2 disease outbreaks have occurred in Kā ne'ohe Bay, O'ahu (present study). The Caribbean offers an instructive cautionary contrast.…”

“…Comparatively low disease levels (usually <1% prevalence) have been consistently reported for most diseases (Aeby 2007, Aeby et al 2010, Williams et al 2010, Stimson 2011, Sudek et al 2015. However, in March of 2010 and January of 2012, M. capitata colonies on the reefs in Kā ne'ohe Bay experienced major outbreaks of a disease that caused rapid tissue loss (> 5 cm of recently denuded white skeleton; Fig.…”

“…Hawai'i (USA) is one of the most isolated archipelagos in the Indo-Pacific (Jokiel 1987), and the main Hawaiian Islands are under increasing human pressures from over fishing (Friedlander & DeMartini 2002), episodic sewage spills, and poor water quality (Friedlander et al 2008, Knee et al 2008, Dailer et al 2012. Coral diseases have been documented at low prevalence on reefs throughout the Hawaiian archipelago (VargasÁngel 2009, Aeby et al 2011), but recently disease outbreaks have occurred, predominantly in the common reef coral Montipora capitata Dana, 1846(Aeby et al 2010, 2015, Ross et al 2012.…”

“…Numerous coral diseases occur on the reefs in Kā ne'ohe Bay, including Porites trematodiasis (Aeby 2007), Porites growth anomalies (Stimson 2011), Porites bleaching with tissue loss (Sudek et al 2015), and Montipora white syndrome (Aeby et al 2010), among others. Comparatively low disease levels (usually <1% prevalence) have been consistently reported for most diseases (Aeby 2007, Aeby et al 2010, Williams et al 2010, Stimson 2011, Sudek et al 2015.…”