Field manual for investigating coral disease outbreaks

Coral reefs throughout their circumtropical range are declining at an accelerating rate. Recent predictions indicate that 20% of the world’s reefs have been degraded, another 24% are under imminent risk of collapse, and if current estimates hold, by 2030, 26% of the world’s reefs will be lost (Wilkinson 2004). Recent changes to these ecosystems have included losses of apex predators, reductions of important herbivorous fishes and invertebrates, and precipitous declines in living coral cover, with many reefs now dominated by macroalgae. Causes have been described in broad sweeping terms: global climate change, over-fishing and destructive fishing, land-based sources of pollution, sedimentation, hurricanes, mass bleaching events and disease. Recognition that corals can succumb to disease was first reported in the early 1970’s. Then it was a unique observation, with relatively few isolated reports until the mid 1990’s. Today disease has spread to over 150 species of coral, reported from 65 countries throughout all of the world’s tropical oceans (WCMC Global Coral Disease Database). While disease continues to increase in frequency and distribution throughout the world, definitive causes of coral diseases have remained elusive for the most part, with reef managers not sufficiently armed to combat it

Time-resolved fluorescence polarization anisotropy of multimodal samples: the asphaltene case

In this work we describe an application of the timeresolved fluorescence polarization anisotropy (TRFPA) technique to the analysis of asphaltenes, complex mixtures of highmolecular weight compounds, typically present in petroleum oils. Our asphaltene samples consist of nanometer-sized polydispersed particles, whose lighter fraction showed a relatively high fluorescence quantum yield. Most of the fluorescence intensity observed from the complex sample originated from a well defined sample fraction presenting a large fluorescence yield. Consequently, the TRFPA analysis only provided the average size of more fluorescing particles, that, in our case, were the smaller ones. Larger and less fluorescing aggregates did not significantly contribute to the TRFPA signal. Hence, to overcome intrinsic limitations of the TRFPA technique in characterizing multimodal samples, we preliminarily fractionated our complex samples by means of size exclusion chromatography (SEC), thus obtaining nearly monomodal fractions of the original samples. This procedure allowed to estimate also the size of less fluorescing and larger particles. A comparison of particle size estimate by means of TRFPA and SEC methods was also used to acquire information about occurrence of aggregation phenomena, and about the kind and strength of the chemical bonds linking chromophores to each other or to their parent particle