Lluís Gómez-Pujol

Geomorphological characteristics and slope processes associated with different basins: Mallorca (Western Mediterranean)

Abstract We compare the different geomorphological processes which occurred in Pliocene–Quaternary times on two very similar slopes in Mallorca, one located at the Tramuntana Range and the other in the Llevant Ranges. Both slopes have the same geological structure, the same stratigraphic and lithological levels, and the same altitude and orientation. The different slope processes are due to the relationship between the accommodation space and the sedimentation rate in the adjacent basins: In the Valencia Trough (located N of the Tramuntana Range), the sedimentation rate has not been sufficient to fill the accommodation space, whereas in the Alcudia Basin (adjacent to the Llevant Ranges), the sedimentation rate has been sufficient to fill the accommodation space. This difference has resulted in major landslides on the Tramuntana slope, whereas the Llevant slope is characterized mainly by alluvial fans and debris screes.

Posidonia oceanica beach-cast litter in Mediterranean beaches: a coastal videomonitoring study

ABSTRACT Gómez-Pujol, L., Orfila, A., Álvarez-Ellacuría, A., Terrados, J. and Tintoré, J., 2013. Posidonia oceanica beach-caster litter in Mediterranean beaches: a coastal videomonitoring study. Mediterranean nearshore sandy and rocky bottoms are colonized by the endemic reef-building seagrass Posidonia oceanica. This species loses leaves in autumn that form large litter patches in the surf zone and huge litter banks on adjacent beaches, resulting in wedge and layered structures of few centimetres to several meters in thick (banquettes). Some authors pointed the importance of those banquettes for the protection of sandy beaches because they dissipate wave energy. By contrast other authors state that this effect is almost negligible. This work deals with the role of Posidonia oceanica accumulations in Mediterranean beach morphodynamics. By means of coastal video-monitoring and wave records we assess the marine conditions related to the formation and destruction of banquettes and evaluate their role in the protection of two sandy beaches (Cala Millor and Son Bou, Balearic Islands). Results indicate that banquettes are common beach features at the study sites although they are not persistent and experience complex construction and destruction dynamics throughout the year. Two different types of banquette construction can be differentiated over the year: one related to the reworking of older seagrass beach cast by alongshore currents and a second as a response to the incorporation of new volumes of dead leaves after energetic winter storms (Hs ~2 to 3 m). In both cases, seagrass cast accumulations are continuously built up and destroyed and rarely persist before the arrival of new sea storms. Therefore, at least for semi-enclosed sandy beaches, the protection role of seagrass banquettes should be reconsidered.

Spatial and seasonal variability of the macro-invertebrate community of a rocky coast in Mallorca (Balearic Islands): implications for bioerosion

The number of the main macro-invertebrate species grazing on the microalgal film on rocky coasts was evaluated at six closely located stations on Mallorca (Balearic Islands). The main bioerosive species at the sites studied were Melaraphe neritoides (L., 1758), Patella rustica (L., 1758), Monodonta turbinata (Born, 1780) and Lepidochitona corrugata (Reeve, 1848). The transects considered shared the same general environmental conditions and species pool. The aim of this study was to compare the effects exerted by the vertical gradient with those exerted by other sets of environmental variables. These sets were, namely, (1) inter-seasonal differences, (2) inter-transect differences (comprising degree of wave-exposure and lithological differences) and (3) effects of the micro-morphology (i.e., crevices, basin pools and other small-scale structures). The main null hypothesis verified was that species composition remains constant after assessing the effect of the vertical gradient. This hypothesis is largely rejected here. The main factor modelling the species composition was the vertical gradient (accounting for 31.6% of variability) whereas the percentages of variability yielded by the other sets individually were smaller but significant (P<0.001). Inter-transect differences (including degree of wave exposure and lithology) accounted for 24.9% of the variability. Seasonal differences accounted for 6.3%, small-scale morphology for 4.5%, and wave-height for 1.6%. The main conclusions obtained from these results are that the most basal strip of the coastline undergoes the largest bioerosive rates. Similarly, the sites exposed to wave action will undergo a larger bioerosive impact than the sheltered sites (possibly because they are more damp). These biotic and abiotic effects taken together would result in a maximisation of erosion rates in areas that are porous, exposed and located near the sea.

An Alert System for Beach Hazard Management in the Balearic Islands

A real-time beach hazard level associated with nearshore hydrodynamics is presented in this article. The suitability of the discussed alert system is illustrated via its application to fifteen beaches in the Balearic Islands (Western Mediterranean Sea) providing nearshore safety conditions for beach safety manager. The system provides daily forecasts of nearshore wave conditions using the deep water wave forecasts. The shallow water wave data (wave height, period, and direction) together with the morphology of the site (presence of bars, capes, beach type, etc.) are used to define a hazard level (low, medium, and high) associated with local conditions. The resulting hazard level is transmitted via SMS to lifeguards and local authorities for real-time beach management. The low computational cost of this system after the initial implementation and subsequent calibration results in a very suitable approach for beach management in order to mitigate risks related to local hydrodynamics.

Cave deposits and sedimentary processes in Cova des Pas de Vallgornera (Mallorca, Western Mediterranean)

In the above mentioned papers different types of sediments and genetic processes have been described as being the dominant mechanisms in producing the allochthonous in fillings that were carried into the caves mainly through surface entrances. The most frequent types are reddish-brown fine sediments mostly transported into the cave by surface runoff as in the case of Cova des Coll or Cova Genovesa (Gràcia et al., 2003, 2005), or by eolian processes as in the case of Cova de s’Ònix (Ginés et al., 2007), Cova de sa Font (Egozcue, 1971), Cova de sa Bassa Blanca (Ginés & Ginés, 1974), among others, or mixed eolian and runoff deposits as is the case of Galeria del Tragus in Cova des Pas de Vallgornera (Fornós et al., 2010). Autogenic processes have also been suggested for Cova de sa Gleda (Gràcia et al., 2007) and in the PirataPont-Piqueta system (Gràcia et al., 2006; Fornós et INTRODUCTION

Exploring rock coast bioerosion: rock fragment intestine transit time and erosion rates computation of the gastropod Monodonta articulata (Lamarck, 1822)

ABSTRACT Vidal, M., Fornós, J.J., Gómez-Pujol, L., Palmer, M., Pons, G.X., Balaguer, P., 2013. Exploring rock coast bioerosion: rock fragment intestine transit time and erosion rates computation of the gastropod Monodonta articulata (Lamarck, 1822) Coastal rock bioerosion research is well established. Otherwise there is the need to improve the way in which bioerosion rates are calculated. Since the findings of McLean (1967), it has been assumed that the dry weight of pellets collected after 24 hours provides an estimate of the amount of organism daily erosion. This is an assumption that relies largely on initial experimental procedures lacking any empirical ascertainment. This paper assess what is the transit time of the rock fragments through the intestine of the gastropod Monodonta articulata, and the implications of applicability of this temporal framework to the computation of a more precise estimation of the bioerosion throughout laboratory experiments. Our results suggest that for the gastropod Monodonta articulata, the major part of the eroded and ingested rock is defecated during feeding time. According to this, the confidence of bioerosion rates values calculated by means of faecal pellet collection based on 24-hour time frame can be concluded. Erosion rates for M. articulata activity in limestone rock samples have been estimated to range between 8.00 mg·ind−1·day−1 to 10.10 mg·ind−1·day−1.

The Impact of New Multi-platform Observing Systems in Science, Technology Development and Response to Society Needs; from Small to Large Scales…

New monitoring technologies are key components of ocean observatories, also called marine research infrastructures being implemented in the worlds oceans. As a result, new capabilities to characterise, in quasi-real time, the ocean state and its variability at small scales exist today. The challenge is the integration of theses multiplatform observing and forecasting systems to (a) monitor the variability at small scales (e.g. mesoscale/weeks) in order to (b) resolve the sub-basin/seasonal and inter-annual variability and by this (c) establish the decadal variability, understand the associated biases and correct them. The challenge is also to change focus and now monitor from small to large scales. SOCIB is leading this new small to large-scale multi-platform approach in ocean observation. Some examples are presented and discussed together with initial ideas on the optimal design of an observational network in the world oceans, responding to science priorities, technology development and response to strategic society needs.

Coastal karren features in temperate microtidal settings: spatial organization and temporal evolution

Basin pools are the diagnostic feature of coastal karren landscape in temperate settings. According to size and connectivity parameters four morphological zones are identified along limestone coastal profiles. Each zone reflects the balance between the effects of physical and chemical weathering-erosion agents. Broadly, marine abrasion, bioerosion, and biologically driven solution show a larger influence seaward, whereas non-biologically driven solution enhances its participation landward.

Beach Systems of Balearic Islands: Nature, Distribution and Processes

The Balearic Islands coast contains 867 beach systems covering 10% of the coast reflecting the different controls of waves, sediments, geological inheritance and human disturbance. The average length of theses beaches are 169 m, raging from 10 m to more than 5 km, which implies that physical boundaries play a major role in beach length and morphology and wave attenuation; a moderate and seasonal wave climate and sediments composed predominantly of medium to coarse marine biogenic carbonate sands. It also describes the regional distribution, together with the occurrence of wave energy, beach sediments, bar systems and dynamics, rip currents, human disturbance and the influence of geological inheritance and marine biota.

Assessing the maximum limit of SAR-OSL dating using quartz of different grain sizes

Abstract SAR-OSL dating studies of Romanian, Serbian and Chinese loess using fine and coarse quartz have previously resulted in a series of controversial issues. We extend here the investigations using fine (4–11 μm) and different coarse quartz (>63 μm) grains extracted from aeolianites from a site on Eivissa Island (southwestern Mediterranean). Aeolianites were chosen since they contain quartz from a different geological context and have significantly lower environmental dose rates. The dose response curves of the OSL signals for fine and coarse quartz are similar to those for loess and are also represented by the sum of two saturating exponential functions. For doses up to ~200 Gy, the dose response curves of fine and coarse grains from aeolianites can be superimposed and the ages obtained for the different grain sizes are in agreement up to ~250 ka, increasing our confidence in the accuracy of the ages obtained for samples with such doses, irrespective of the magnitude of the environmental dose rate. Particularly for the fine quartz fraction, a mismatch between the SAR dose response curve and the dose response curve obtained when doses are added to the natural is reported, indicating that the application of the SAR protocol in the high dose range is problematic. This dose dependent deviation is much less pronounced for coarse grains. Thus, it seems reasonable to infer that the dose response curves for the coarse grains, although saturating earlier can be regarded as more reliable for equivalent dose calculation than those for the fine grains.