Effects of a severe storm on seagrass meadows

Extreme environmental events can strongly affect coastal marine ecosystems but are typically unpredictable. Reliable data on benthic community conditions before such events are rarely available, making it difficult to measure their effects. At the end of October 2018, a severe storm hit the Ligurian coast (NW Mediterranean) producing damages to coastal infrastructures. Thanks to recent data collected just before the event on two Posidonia oceanica seagrass meadows hit by the storm, it has been possible to assess the impact of the event on one of the most valuable habitats of the Mediterranean Sea. By means of seagrass cover and depth data gathered along four depth transects positioned within the two meadows in areas differently exposed to the storm waves, and by using models (WW3® + SWAN + XBeach 1D) to evaluate wave height and bed shear stress, we showed that meadows experienced erosion and burial phenomena according to exposure. Paradoxically, meadows in good conditions suffered more damage as compared to those already suffering from previous local anthropogenic impacts. Besides the direct effect of waves in terms of plant uprooting, a major loss of P. oceanica was due to sediment burial in the deepest parts of the meadows. Overall, the loss of living P. oceanica cover amounted to about 50%. Considering that previous research showed that the loss of the original surface of P. oceanica meadows in 160 years due to anthropogenic pressures was similarly around 50%, the present study documented that an extreme environmental event can generate in a single day a loss of natural capital equal to that produced gradually by more than a century of human impact.

Fetal aortic root dilation: a prenatal feature of the Loeys-Dietz syndrome

Loeys-Dietz syndrome is a recently described autosomal dominant disorder with cardinal manifestations in cardiovascular, craniofacial and skeletal systems. Although the disease has some phenotypic overlap with Marfan syndrome, the disease, that is caused by mutations in the transforming growth factor beta-receptor 1 (TGFBR1) or transforming growth factor beta-receptor 2 (TGFBR2) genes, presents many distinctive features and a particularly aggressive cardiovascular course. We describe prenatal identification of an aortic root aneurysm in a fetus of 19 week of gestation as an early marker of Loeys-Dietz syndrome.