Temporal scales of variability for the partial pressure of CO 2 (pCO 2 ) in the surface waters of two stratified Mediterranean reservoirs were examined through the temporal decomposition of 5 month time series with hourly sampling frequency. pCO 2 time series included similar patterns of variability at daily, biweekly, and seasonal scales regardless of the difference in amplitude of the pCO 2 variation in the two reservoirs studied. Daily variability was strongly related to the day-night cycles of metabolic activity, accounting for about one third of the total amplitude in pCO 2 variation. At a biweekly scale, wind forcing led to higher rates of air-water CO 2 exchange and subsequently temporary partial mixing events associated to relevant increase of CO 2 concentration in surface waters. Seasonal variability accounted for one third of the amplitude of the pCO 2 variability and was coupled to the seasonal dynamics of water temperature and thermal stratification of the water column. Our results provide evidence that CO 2 emission from stratified water bodies shows significant variability at daily, biweekly, and seasonal scales; all of which should be taken into consideration in the analyses of the carbon fluxes. The wind-induced mixing events, operating at temporal scales between daily and seasonal cycles, may become a major factor controlling the pCO 2 dynamics. Hence, some of the most common models for computing CO 2 fluxes from pCO 2 were not able to reproduce the biweekly response patterns of CO 2 emissions to wind forcing.

At the Gulf of Cadiz (GoC), poleward currents leaning along the coast alternate with coastal upwelling jets of opposite direction. Here the patterns of these coastal countercurrents (CCCs) are derived from ADCP data collected during 7 deployments at a single location on the inner shelf. The multiyear (2008-2014) time-series, constituting ~18 months of hourly records, are further analysed together with wind data from several sources representing local and basin-scale conditions. During one deployment, temperature sensors were also installed near the mooring site to examine the vertical thermal stratification associated with periods of poleward flow. These observations indicate that the coastal circulation is mainly alongshore and barotropic. However, a baroclinic flow is often observed shortly at the time of flow inversion to poleward. CCCs develop all year-round and exclusively control the occurrence of warm coastal water during the upwelling season. On average, one poleward flow lasting 3 days was observed every week, corresponding to CCCs during ~40% of the time without seasonal variability. Thus, the studied region is distinct from typical upwelling systems where equatorward coastal upwelling jets largely predominate. CCCs often start to develop near the bed and are frequently associated with 2-layer cross-shore flows characteristic of downwelling conditions (offshore near the bed). In general, the action of alongshore wind stress alone does not justify the development of CCCs. The coastal circulation is best correlated and shows the highest coherence with south-eastward wind in the basin that proceed from the rotation of southward wind at the West coast of Portugal, hence suggesting a dominant control of large-scale wind conditions. In agreement, wavelet analyses indicate that CCCs are best correlated with alongshore wind occurring in a band period characteristic of the upwelling system (8-32 days). Furthermore, in the absence of wind coastal currents tend to be poleward during summer. This set of observations supports that CCCs develop in response to the unbalance of an alongshore pressure gradient during the relaxation of (system-scale) upwelling-favourable winds, oriented southeastward in the basin. The relaxation periods defined based on this wind direction show a good correspondence with the periods of poleward flow.

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12In the context of increased coastal hazards due to variability in storminess patterns, the 13 danger of coastal damages and/or morphological changes is related to the sum of sea 14 level conditions, storm surge, maximum wave height and run up values. In order to better 15 understand the physical processes that cause the variability of the above parameters a 44 16 years reanalysis record (HIPOCAS) was used. The HIPOCAS time-series was validated 17 with real wave and sea-level data using linear and vector correlation methods.

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White-Seabream (Diplodus sargus cadenati) is a species of commercial interest, but it shows high levels of intraspecific aggressiveness. In small groups of white-seabream, the monopolization and defence of resources affect directly the hierarchy structure of the group, as a result of the agonistic interactions.Groups show a linear hierarchy, where the dominant fish attacks selectively the next one in rank.The social organization of small groups into a hierarchy when the dominant fish is temporarily separated is described. The aggressiveness developed by the group doesn't show significant differences before and after the dominant fish was withdrawn and reintroduced, but the reintroduction of the first dominant fish after 24 hours of separation doesn't affect its status. After some aggressions, it recovers its social position.