Threats listed in assessment
In the Gulf, the major threats to corals include extreme and increasing temperature variability due to climate change, as well as direct destruction and increased turbidity caused by coastal construction (Riegl et al. 2012). Although bleaching thresholds in the Gulf are the highest recorded in the world (Riegl et al. 2012), bleaching events in the UAE have resulted in significant mortality (such as in 1996-1998, 2002, 2010 and 2017) and slow recovery (Burt et al. 2008). In Abu Dhabi, the most recent coral bleaching event resulted in nearly 95% of corals bleaching, and by April 2018, mortality reached 73% (Burt et al. 2019). This event resulted in mass mortality of even the more stress-tolerant corals such as poritids and merulinids (Burt et al. 2019). Coastal development, particularly large-scale offshore real estate developments and sedimentation associated with reclamation, has directly buried coral reefs in the Gulf (Burt et al. 2008, 2013; Burt 2014; Burt and Bartholomew 2019). In the Sea of Oman, UAE reefs have experienced major hurricanes and harmful algal blooms that caused high coral mortality and shifted community structure (Bauman et al. 2010, Foster et al. 2011).The genus is not particularly susceptible to bleaching, but is more prone to disease than many other corals. Coral disease has emerged as a serious threat to coral reefs worldwide and is a major cause of reef deterioration (Weil 2006). The numbers of diseases and coral species affected, as well as the distribution of diseases have all increased dramatically within the last decade (Porter et al. 2001, Green and Bruckner 2000, Sutherland et al. 2004, Weil 2004). Coral disease epizootics have resulted in significant losses of coral cover and were implicated in the dramatic decline of acroporids in the Florida Keys (Aronson and Precht 2001, Porter et al. 2001, Patterson et al. 2002). In the Indo-Pacific, disease is also on the rise with disease outbreaks recently reported from the Great Barrier Reef (Willis et al. 2004), Marshall Islands (Jacobson 2006) and the northwestern Hawaiian Islands (Aeby et al. 2006). Increased coral disease levels on the Great Barrier Reef were correlated with increased ocean temperatures (Willis et al. 2004) supporting the prediction that disease levels will be increasing with higher sea surface temperatures. Escalating anthropogenic stressors combined with the threats associated with global climate change of increases in coral disease, frequency and duration of coral bleaching and ocean acidification place coral reefs in the Indo-Pacific at high risk of collapse.Globally, the major threat to corals is global climate change, in particular, temperature extremes leading to bleaching and increased susceptibility to disease, increased severity of ENSO events and storms, and ocean acidification. In addition to global climate change, corals are also threatened by a number of localized threats. Localized threats to corals include fisheries, human development (industry, settlement, tourism, and transportation), changes in native species dynamics (competitors, predators, pathogens and parasites), invasive species (competitors, predators, pathogens and parasites), dynamite fishing, chemical fishing, pollution from agriculture and industry, domestic pollution, sedimentation, and human recreation and tourism activities.
