[1] Enhancement of primary and export production following dust deposition pulses is well established for High Nutrient Low Chlorophyll regions, but the effect of atmospheric dust on the biogeochemistry of oligotrophic gyre regions remains unclear.Here we report atmospheric dust concentrations measured on Gran Canaria, Canary Islands, concomitantly with upper water biogeochemistry at the oligotrophic time series station ESTOC (European Station for Time series in the Ocean, Canary Islands) during a 2-year period from winter 1997 to 1999. ESTOC is located in the eastern subtropical Atlantic gyre about 100 km north of Gran Canaria and 500 km west of the Sahara, and receives aeolian dust episodically mainly in winter and summer. We found a close correlation of the magnitude of atmospheric dust concentration in winter with the magnitude of downward particle flux at ESTOC, mainly due to a relative increase in lithogenic matter and carbonate sedimentation. Higher aerosol concentration was not accompanied by higher primary or export production, however, indicating that phytoplankton production remained unaffected by atmospheric nitrogen supply on a seasonal or yearly timescale. However, by estimating bioavailable iron input and the need of the phytoplankton population, we found that the highly episodic dust pulses might exert a feast and famine effect on the phytoplankton. Despite the high lithogenic matter input, carbonate, mainly stemming from coccolithophorids, exceeded in importance the role of lithogenic matter as ballasting agent of sinking organic matter.

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Little is known about cetacean communities around La Palma Island. Therefore, and in order to determine the presence and distribution of the cetacean species on its west coast, daily censuses were carried out from November 2003 to April 2005. The platform used was a whale watching vessel certified by the Canary Government. Data collected included time, position, species identity, group size and, in some cases, the presence of calves and/or any other outstanding parameter. During the study period, 570 sightings were made, with a mean sighting success of 1.7 sightings per day, showing a high cetacean presence in the area. Thirteen species and one genus (Globicephala spp.) were positively matched, three of them included in the Mysticeti suborder and the other ten in the Odontoceti one. The four most sighted species, in decreasing order, correspond to Tursiops truncatus, Steno bredanensis, Globicephala spp. and Stenella frontalis. Diversity of sighted species shows a moderate peak during spring time, which is in agreement with the presence of occasional species. Most sightings were located off the central west coast of the island, exceeding 1.5 nautical miles. This is particularly outstanding in relation to Franja Marina de Fuencaliente SCI, where 90% of all sightings were located outside its boundaries. High cetacean presence and diversity off the west coast of La Palma Island seem to be connected with oceanographic and ecological features. Results gained provide, for this region, baseline data on cetacean populations and a useful tool in conservation plans.

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Marine microplastics (MPs) are exposed to environmental factors, which produce aging, weathering, surface cracking, yellowing, fragmentation and degradation, thereby changing the structure and behavior of the plastic. This degradation also has an influence on the adsorption of persistent organic pollutants over the microplastic surface, leading to increased concentration with aging. The degradation state affects the microplastic color over time; this is called yellowing, which can be quantified using the Yellowness Index (YI). Weathering and surface cracking is also related with the microplastic yellowing, which can be identified by Fourier transform infrared spectroscopy (FTIR). In this study, the degradation state of marine microplastic polyethylene pellets with different aging stages is evaluated and quantified with YI determination and the analysis of FTIR spectrums. A color palette, which relates to the microplastic color and YI, was developed to obtain a visual percentage of this index. The relation with the adsorption rate of persistent organic pollutant over the microplastic surface was also determined.

Por medio de un diseño de muestreo jerárquico se estudió la estructura poblacional y los patrones espaciales de variabilidad horizontal (diferencias entre las islas, las localidades dentro de las islas y los sitios dentro de localidades) y vertical (diferencias entre bandas de la zona intermareal) de los moluscos gasterópodos Osilinus atrata y O. sauciatus a lo largo del intermareal rocoso de las Islas Canarias. Se observaron diferencias en los patrones espaciales de distribución, abundancia y tamaño para ambas especies. Osilinus atrata fue más abundante que O. sauciatus en todo el Archipiélago Canario. Su abundancia varió entre las islas, presentando una distribución heterogénea entre las bandas intermareales de una isla a otra, si bien fue más frecuente en las bandas intermedia y superior. Osilinus sauciatus sólo se encontró en las islas orientales y no exhibió diferencias significativas entre las bandas, a pesar de que 91.35% de los individuos aparecieron en la banda superior y el resto en la banda intermedia. Osilinus sauciatus mostró una talla mayor que las de O. atrata. A su vez, ambas especies presentaron en general las mayores tallas medias en la banda superior.

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A modification of the method for the determination of aluminium by adsorptive cathodic stripping voltammetry of its 1,2-dihydroxyanthraquinone-3-sulfonic acid (DASA) complex is described. Rapid determination is achieved by using staircase modulation and high potential scan speeds (20 V s-1). Square wave modulation was found inefficient above 2 V s-1 because the potential pulse is distorted by the ohmic drop. The staircase modulation is also distorted, but the determination is not disturbed and high faradaic currents are obtained. The method was not sensitive to the turbulence of the solution during the scan, as a short scan time is required (several ms) and very high currents (FA) are obtained from the reduction of the DASA-A1 complex. Interference from oxygen was also overcome as DASA-A1 to oxygen current ratios are increased and background subtraction is feasible. The natural calcium concentration of sea-water enhances the DASA-A1 peak height; calcium should therefore be added to fresh water to enhance the determination. The method is proposed in particular for the determination of A1 on board oceanographic vessels. There is no need to purge samples, noise due to vibrations of motions of the ship during scanning is avoided, and the sensitivity is enhanced. The total analysis time can be decreased to 8-12 min per sample by using an adsorption time of 40 s. The technique has been tested s u c d u l l y for the on-board determination of Al in sea-water. Results obtained for seawater samples irradiated by ultraviolet tight were similar to those obtained using an existing fiuorimetric method.