Ecology: Coral crisis captured
The Great Barrier Reef is the world's largest reef system, but is being increasingly affected by climate change. Terry Hughes and colleagues examine changes in the geographic footprint of mass bleaching events on the Great Barrier Reef over the last two decades, using aerial and underwater survey data combined with satellite-derived measurements of sea surface temperature. They show that the cumulative footprint of multiple bleaching events has expanded to encompass virtually all of the Great Barrier Reef, reducing the number and size of potential refuges. The 2016 bleaching event proved the most severe, affecting 91% of individual reefs. The authors call for immediate global action to reduce the magnitude of climate warming in order to secure a future for coral reefs.
Nesteretal A, A Novel Class of Cage-Like Polyketide from Marine-Derived Actinomycete Nesterenkonia halobia.
An intriguing cage-like polyhemiketal, nesteretal A (1), was isolated from the coral-derived actinomycete Nesterenkonia halobia. Its structure was established by extensive spectroscopic and computational methods. Nesteretal A is a highly oxygenated compound featuring an unprecedented 5/5/5/5 tetracyclic scaffold. A possible biosynthetic pathway of 1 from naturally occurring diacetyl was proposed. Compound 1 showed a weak retinoid X receptor-α (RXRα) transcriptional activation effect.
Computer simulations and theory of oceanographic fluorescence lidar signals: effect of sea surface structure.
A 3-D computer simulation model has been developed using geometrical optics suitable for analyzing the effect of sea surface structure on oceanographic fluorescence lidar signals. Depth-resolved and depth-integrated signals reveal a considerable dependence on the surface structure. The results obtained by simulation are confirmed by a theoretical approach based on the transformation of solid angles by curved boundaries. Using statistical assumptions about the distribution of curvatures of the ocean surface, a general expression for this influence is found.