Fighting Current Real-World Threats to the Well-Being of Corals
Vega Thurber, R.L., Burkepile, D.E., Fuchs, C., Shantz, A.A., McMinds, R. and Zaneveld, J.R. 2014. Chronic nutrient enrichment increases prevalence and severity of coral disease and bleaching. Global Change Biology 20: 544-554.
Specifically, Vega Thurber et al. conducted "a long-term nutrient enrichment experiment on a coral reef in the Florida Keys, USA, designed to examine the impacts of anthropogenic nutrient loading on benthic community structure." There, over the course of three years, they continually added nitrogen and phosphorus to four nine-m2 enrichment plots that were paired with control plots subject to ambient levels of nutrients, after which - at the end of the experiment - they surveyed the coral community for signs of coral disease and bleaching.
The study revealed "Siderastrea siderea corals within enrichment plots had a two-fold increase in both the prevalence and severity of disease compared with corals in unenriched control plots," and "Agaricia spp. of corals exposed to nutrients suffered a 3.5-fold increase in bleaching frequency relative to control corals." But one year later, after nutrient enrichment had been terminated for ten months, they say "there were no differences in coral disease or coral bleaching prevalence between the previously enriched and control treatments."
In addition to demonstrating the debilitating effects of nutrient pollution of coastal waters on indigenous corals, and "given that coral disease and bleaching are some of the primary killers of corals worldwide (Bruno et al., 2007; Harvell et al., 2007)," according to Vega Thurber et al., their study's results reveal "conservation efforts that reduce nutrient loading and lower the prevalence and severity of disease and bleaching may be effective strategies for helping preserve reef ecosystems."
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