Heat Attenuation and Nutrient Delivery by Localized Upwelling Avoided Coral Bleaching Mortality in Northern Galapagos During 2015/2016 ENSO

Despite a very strong El Niño Southern Oscillation in 2015/2016, no coral mortality associated with bleaching was observed at the northern Galapagos (Ecuador) Islands of Darwin and Wolf. From March 2016 to March 2018, coral cover and health as well as water chemistry (NO3− and PO43−) and temperature were recorded. A marked heat anomaly reached 30 °C at Wolf in February 2016, but peak temperatures were attenuated after 2 d by a 4 °C drop. Temperature patterns at three depths (10, 15, and 20 m) and a subsequent and persistent phytoplankton bloom suggest topographically driven upwelling as the source of colder water and dissolved inorganic nutrients—both of which helped corals endure the heating episode. Consequently, no mortality and only partial bleaching were recorded in March 2016. Partially bleached corals contained numerous healthy zooxanthellae in deeper tissue layers. A continuous temperature record from 2012 to 2014 suggests that such upwelling events are common, inducing temperature fluctuations of up to 6 °C within 24 h during the observation period. Events at Wolf in 2016 suggest local upwelling reduced coral stress by relieving heat and by delivering nutrients required by corals to retain their regular temperature tolerance

Techno-Economic Analysis of a Glycerol Biorefinery

Biodiesel is an environmentally friendly alternative to fossil fuels, which is experiencing a steep growth in market size. Because the most common biodiesel production technology is based on the transesterification of triglycerides, a burgeoning amount of glycerol byproduct is obtained. In order to address this economic and ecologic drawback, several chemocatalytic technologies have been developed to exploit this compound to feed the market with added-value products. Lactic acid, acrylic acid, allyl alcohol, propanediols, and glycerol carbonate have emerged as the most relevant candidates for this purpose. In previous studies, an environmental and economic assessment of a glycerol biorefinery built on these valorization pathways has been performed, taking into account only the operating costs in relation to the economic aspects. This study evaluates for the first time the investment required by these glycerol valorization processes, based on the Guthrie, Taylor, and Aspen capital cost estimation methods, and then assesses the potential of a heat-integrated glycerol biorefinery. Glycerol carbonate stands out as the dominant product to maximize the profitability with respect to the glycerol utilized, while 1,2-propanediol and allyl alcohol are determined as target compounds to be included in the glycerol biorefinery product mix if further reductions of the environmental impact are sought after. This early stage techno-economic analysis provides a sounder basis toward the practical realization of an integrated facility sustainably upgrading waste streams from the processing of renewables into commodities, thus promoting the concept of circular economy

Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf

A severe bleaching event affected coral communities off the coast of Abu Dhabi, UAE in August/September, 2012. In Saadiyat and Ras Ghanada reefs ~. 40% of the corals showed signs of bleaching. In contrast, only 15% of the corals were affected on Delma reef. Bleaching threshold temperatures for these sites were established using remotely sensed sea surface temperature (SST) data recorded by MODIS-Aqua. The calculated threshold temperatures varied between locations (34.48 °C, 34.55 °C, 35.05 °C), resulting in site-specific deviations in the numbers of days during which these thresholds were exceeded. Hence, the less severe bleaching of Delma reef might be explained by the lower relative heat stress experienced by this coral community. However, the dominance of Porites spp. that is associated with the long-term exposure of Delma reef to elevated temperatures, as well as the more pristine setting may have additionally contributed to the higher coral bleaching threshold for this site