We conducted a study from January 2002 to February 2008 on silicofl agellate fl uxes in Alfonso Basin at the entrance to the Gulf of California. Thirteen taxa were identifi ed in sediment trap samples, with Octactis pulchra as the dominant species. Total fl ux climatology reached a maximum value of 5 × 10 6 skeletons m -2 day -1 in December and then sharply decreased to a minimum value in February (2.3 × 10 3 skeletons m -2 day -1 ) concurrently with the climatological sea surface temperature (SST) minimum. Subsequently, there was a positive trend with a second relative maximum of 1.6 × 10 6 skeletons m -2 day -1 in September coincident with a maximum in climatological SST. During this period, there was a similar increase to 1.4 × 10 6 skeletons m -2 day -1 in May. Factor analysis identifi ed three patterns of variation: " subtropical oceanic, " " subarctic, " and " equatorial El Ni ñ o. " Factors had reasonable correlations with the Pacifi c decadal oscillation (PDO), North Pacifi c Gyre oscillation (NPGO), and El Ni ñ o Modoki indices (r = 0.53, 0.67, and 0.63, respectively). The fi rst and second modes were apparently linked to decadal climatic conditions correlated to PDO and NPGO, as suggested by the silicofl agellate species Dictyocha messanensis forma messanensis and the assemblage of D. epiodon and Distephanus speculum , respectively; the third mode was related to the presence of warm equatorial-oceanic waters identifi ed by D. messanensis forma spinosa , which defi nes El Ni ñ o infl uence. These results demonstrate the importance of the region where there is a confl uence of the low-frequency, high-latitude PDO, NPGO, and high-frequency El Ni ñ o signals.
Los silicoflagelados pueden ser utilizados como indicadores indirectos de las condiciones prevalecientes de la capa superficial del océano, cuando ya se han depositado en el sedimento. No obstante, es esencial identificar y documentar las especies que habitan el área. Esto incluye la documentación visual y descriptiva de su variabilidad morfológica, lo cual fue logrado a través de observaciones continuas de los silicoflagelados en sedimentación en Cuenca Alfonso, Bahía de La Paz desde enero de 2002 a diciembre de 2003. Se identificaron 13 taxones distribuidos en 4 géneros: Corbisema (1 especie), Dictyocha (10 especies y variedades), Octactis (1 especie) y Distephanus (1 especie). En verano y otoño de ambos años se presentaron el mayor número de taxones (10 y 11 respectivamente); Octactis pulchra fue la única especie observada en las 65 muestras examinadas. Algunos taxones como Dictyocha calida, D. fibula var. robusta, D. epiodon y O. pulchra presentaron variaciones en sus esqueletos; ello sugiere una respuesta del grupo a las diferentes condiciones oceanográficas, lo que hace patente la necesidad de documentar esta variabilidad. Settling silicoflagellates at the southwestern region of the Gulf of California Silicoflagellates can be used, after their sedimentation, as a proxy of prevailing ocean surface conditions, however it is essential to identify and document the species inhabiting the study area. This includes a visual and descriptive record of their morphological variability which was accomplished by continuously monitoring the settling silicoflagellates in the Alfonso Basin (Bahia de La Paz) from January 2002 to December 2003.Thirteen taxa distributed in 4 genera: Corbisema (1 species), Dictyocha (10 taxa), Octactis (1 species) and Distephanus (1 species) were identified. Highest number of taxa (10 and 11 respectively) was observed during the summer and autumn seasons of both years. Octactis pulchra was the only species observed in the 65 samples analyzed. Certain taxa such as Dictyocha calida, D. fibula var robusta, D. epiodon and O. pulchra showed variations in their skeletons which suggest a group response to varying oceanographic conditions, making it imperative to document this variability.
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