Estudio de una comunidad planctónica nerítica en el Mar de Alborán. I. Ciclo de los factores ambientales y fitoplancton: N.º 339

• Jaime Rodríguez ^[1]
  1. [1] Universidad de Málaga

     Universidad de Málaga

     Málaga, España

     
• Localización: Boletín. Instituto Español de Oceanografía, ISSN 0074-0195, Tomo 7, Parte 1, 1982, págs. 97-114
• Idioma: español
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• Resumen

  • As a part of the study of the annual cycle of a neritic plankton community in the Alboran Sea, we show here the results about the environmental factors phytoplancton. Very important in the study of the temporal dynamics of the planktonic community is the alternance between the 2nd and 4th quadrant winds, these favouring deep water upwelling principally in the months of november and february. The summer thermal stratification can reach differences of 8º C between the superficial and the deeper layers of the water column, surface temperatures varying between a minimum of 13º in february and a maximum of 26º in july. Sanilities have ranged from 36,2 ‰ in the surface and 37,9 in the deeper layer. TS diagrams show great variability as to the kind of water mas present in the area studied at different moments of the year. Regarding the nutrients, the values registered have been higher than the commonly admitted for western mediterranean basin, due to the richer quantities of mineral salts of the Alboran Sea and to continental influence in the studied area. While the nitrites show a period of maximum concentration from march to july, nitrates show a cycle of high winter values, a spring maximum, a summer exhaustion and autumn increase up to the high winter values. Phosphate develop a similar cycle the deep layer, while in the surface the variations is much more irregular due to the direc continental influence, The water mass studied are found to be well oxygenated, with values over 5,5 ml/l. The annual cycle show an increuse from winter to spring, a sligh decrase in summer, to newly rise in autumn. The oxygen concentrations are normally higher in the surface waters, excepting the cases where there was a strong thermal stratification, when a maximum value can be found in the subsuperficial layer, originated by combined physical and biological factors: atmospheric diffusion from the sea surface and a high photosyntetic production under the thermocline, this impeding the diffusion of the excess oxygen to the superficial layer. The mean chlorophyll a values have varied from 0,5 to 1,9 mg/m3. The annual cycle show three periods of greater abundance: february, april-may and september. The chlorophyll concentrations are normally higher with the deep, being greater the gradients when there are thermic stratification characters. The chlorophyll concentrations are normally higher with the deep, being greater the gradients when there are thermic stratification characters. The pigmentary quotient (D^430 / D^665) have normally varied between 3 to 6, with a temporal evolution opposed to that of chlorophyll a, showing the phytoplankton renewal.