Danovaro, R., Bongiorni, L., Corinaldesi, C., Giovannelli, D., Damiani, E., Astolfi, P., Greci, L. and Pusceddu, A. 2008. Sunscreens cause coral bleaching by promoting viral infections. Environmental Health Perspectives 116: 441-447.
What was done
The authors conducted a series of independent in situ studies in different parts of the world, including the Pacific, Atlantic and Indian Oceans, in an effort to evaluate the impact of cosmetic sunscreens on hard corals (Acropora, Stylophora pistillata, and Millepora complanata) and their symbiotic algae. At each ocean location, coral branches were exposed to varying amounts of sunscreens and common ultra violet filters contained in them. The amount of subsequent coral bleaching was then determined via colorimetric analysis of digital photos taken at the beginning of the study and at various intervals throughout the experiment.
What was learned
At all study sites and at all sampling times, the addition of sunscreen, even at very low concentrations (10Ál/l), resulted in the release of large amounts of zooxanthellae and coral tissue within 18-48 hours, with complete bleaching of hard corals occurring within 96 hours. What is more, bleaching reportedly occurred at a faster rate in corals subjected to higher temperature, suggesting, in the researchers' words, "synergistic effects with this variable." Based on these results and conservative estimates of global sunscreen use and potential sunscreen release in and around tropical reefs, Danovaro et al. further calculated that approximately 10% of the world's coral reefs are at risk of sunscreen-induced bleaching.
What it means
There can be no escaping the fact that where people interact with corals, either directly or indirectly, corals suffer, either directly or indirectly (by becoming, for example, more susceptible to the deleterious effects of other stresses, such as higher water temperatures). Consequently, it is only to be expected that with ever more people using sunscreen lotion coming into contact with the world's coral reefs, ever more damage to those corals will be detected as time progresses. In addition, much of the damage that climate alarmists currently attribute to global warming may well be more validly laid at the feet of any number of increasing human population/coral reef interactions.