Distribución del fitoplancton y su comportamiento en el afloramiento en las Islas Galápagos

Abstract

Los objetivos de este crucero han sido colectar información que permitirá comprender mejor la dinámica poblacional (cuali-cuantitativo) de las diferentes masas de aguas que afloran al este y al oeste de las Islas Galápagos y su interacción entre las islas, estos resultados permitirán dar una mejor apreciación sobre áreas de mayor fertilidad marina ( clorofila "a", contajes celulares), organismos indicadores del afloramiento y su posible asociación con áreas de riqueza ictiológica.

During the cruise COII99, that took place September the 20th until October the 8th of 1999, aboard the V/R ORION of the ecuadorian Navy, where collected samples for the estimate of chlorophyll were, as well as cells counts and indicators of the phytoplankton are analyzed in 20 oceanographic stations (89-92°W; 1°N-2°S). The average of chlorophyll "a" surface was of 0.250 mg/m³, the highest concentration was between 0.526- 0.529 mg/m³, westward of Isabela Island, associated with the upwelling of Cromwell;and other flow to the southeast of the Islands (90°W) associated with the Current of Humboldt, cue this match with the standards of these currents for the season, and they have an impact on the high biological productivity. The smallest concentrations were found in the north side of the Galapagos. 88 species were identified in water samples and 119 species in net samples. The diatoms were dominant, in low concentration Dinoflagelados, Tintínnidos, Cocolitofóridos, Cyanophytas, Microflagelados and Ciliados. pseudonitzschia delicatissima, Thalassiosira subtilis and Gymnodinium sp. they were species with greater cellular content in the sections 92°, 91°, 90° and 89°W, probably related to three different water masses ( equatorial subtropical surface, of Cromwell and Humboldt) that originated a greatdiversity of species in the insular ecosistem. The smaller biological productivity was registered northward of the study area, related to an increase in species of warm conditions Planktoniella sol, Rhizosolenia imbricata, Proboscia alata, Ceratium azoricum, C. tripos. C.trichoceros, C. fusus, C. teres, C. lunula, C.furca, C. vultur, C. pentagunum, Gonyaulax polyedra, Goniodoma polyedricum, Protoperidinium crassipes), indicating water masses with low content of chlorophyll "a" and nutrients.