Essay about Coral Reefs

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Coral reefs have been undergoing global degradation due to increasing natural and anthropogenic impacts for at least the last half-century. The intensity and frequency of stressors, including global climate change, have rapidly increased in number over recent years (Hughes & Connell 1999; Hoegh-Guldberg et al. 2007; Pandolfi et al. 2011). Frequent disturbances such as hurricanes/cyclones, predation outbreaks, diseases and mass bleaching events eat-away at the percent of living coral cover and without recovery, the available space is colonized by sponges, soft corals, and macroalgae. These alternative organisms are often competitive dominants in less than ideal conditions (Norström et al. 2009). The transition is termed a phase-shift from …show more content…
1993; Lirman 2001; Box & Mumby 2007), increased localized sedimentation (Nugues & Roberts 2003), interfering with the settlement of coral larvae through space preemption and/or biofilm production (Birrell et al. 2005; Birrell et al. 2008; Box & Mumby 2007; Vermeij et al. 2009), and allelopathy or chemically mediated competition (deNys et al. 1991, Morrow et al. 2011). Macroalgae can cause physical stress (Quan-Young & Espinoza-Avalos 2006) decreased photosynthetic abilities (Titlyanov et al. 2007), reduced fecundity (Foster et al. 2008), and harbor potential coral pathogens (Nugues et al. 2004). The ability of macroalgae to competitively damage stony corals also depends on the species of macroalgae (Maypa & Raymundo 2004; Birrell et al. 2008), and other compounding factors such as irradiance, sedimentation, dissolved nutrients, and level of herbivory on the reef.
Over the past several decades the incidence of coral disease has increased, with striking correlation to increasing macroalgal cover (Goreau et al. 1998; Harvell et al. 1999; Harvell 2004; Weil & Smith 2006). The enhanced need for disease research coupled with the massive advancements in molecular techniques made the study of coral-associated microbes more efficient and less cost prohibitive. Thus, we have recently recognized the significant role microorganisms play in the physiology of both healthy and diseased corals. The term holobiont was coined to describe the dynamic relationship
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