Highlights

  This project constitutes the first joint effort ever attempted to evaluate the effects of an extreme storm over the natural nearshore populations in the Mediterranean Sea. The first comprehensive assessment has been possible by comparing the ‘before and after’ conditions on a number of populations and communities monitored by several participant scientists.

For the first time, wave and surge reanalysis GOW 2.1 and GOS 2.1 has been used to obtain the wave -and current- induced bed shear stresses at the various stations studied with unprecedented spatial resolution of up to ~250 m, allowing to characterize the storm impact to the different communities.

Many mechanisms and modulating factors of damage on the major components of the coastal biota have been described, providing highly valuable information for further attempts to modelling the extent of the damage caused by extreme storms.

The accurate characterization of the ‘after event’ scenario made for some of the populations and communities represents a precious reference information for determining their resilience.

This project provides the first known attempt to assessing the response of nearshore soft and rocky bottom communities to changes in environmental parameters induced by strong and unpredictable meteorological events (Jordana et al., Villamor et al., Alcoverro et al., and Uriz et al.; Chapters 13, 11, 7, and 6, respectively). Until now, these biotic components had been mostly used in environmental quality assessment of coastal systems in relation to disturbances induced by human activities but not by natural perturbations.

This report presents the first study of the impact of an extreme event on shallow and deep algal communities and populations (Hereu et al., Navarro et al., Torras and Garcia-Rubies, Chapters 9, 10, and 8, respectively). The accurate assessment of the impact on sea urchin populations (see below), will allow to follow the temporal dynamics of the interaction between these two trophic levels with a crucial role in the structuring of hard-bottom ecosystem.

The assessment of the effect of this extreme event on fish species (highly targeted, other rocky assemblages, and cryptobenthic) is reported here for the first time. Furthermore, in some cases, this assessment is made comparing natural reserves vs. non protected areas (Garcia-Rubies et al.; Garcia-Rubies and Macpherson, Gordoa and Dimitriadis Chapters 14-15, 16, and 17, respectively).

The impact on sea urchin populations by an extreme (not predictable) storm has been assessed for the first time both for hard- and soft-bottom populations. Such a large and sudden mass mortality of Paracentrotus lividus had never been documented in the Mediterranean before as aconsequence of a single storm (Hereu and Garcia-Rubies; Alcoverro et al., Chapters 3 and 11, respectively).

The immediate mortality associated to an exceptional storm on the populations of the endangered giant mussel Pinna nobilis had never been investigated (Garcia-Rubies et al., Chapter 12). With the invaluable collaboration of the naturalist Pedro Lázaro and the Director of the Protected Area of the Medes Islands, Àlex Lorente, this project provides the most detailed study to date of the mortality rates (agents and factors) caused by the storm.

The study contributed with by Segura et al. (Chapter 18) represents a precious addition to the very scant information on the effects of extreme events on deep sea environments. The role of submarine canyons as preferential channels for matter transport from the shelf towards the deep slope during storms has been evidenced. Furthermore, the study presents strong evidences suggesting a severe punctual impact of the storm in the abundance and species composition of organisms captured in sediment traps (swimmers) as indicators of deep benthic fauna.