Abstract
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 11respectively) 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.
Highlights
Silicoflagellates can be used, after their sedimentation, as a proxy of prevailing ocean surface conditions, 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
Octactis pulchra was the only species observed in the 65 samples analyzed
Seasonal variation of silicoflagellates in phytoplankton and varved sediments in the Gulf of California
Summary
La Cuenca Alfonso se localiza en la porción suroccidental del Golfo de California entre los 24° 35’ N y 110° 36’ W, dentro de la Bahía de La Paz en la isobata de los 400 m (Cruz-Orozco et al, 1996). Por medio de una trampa de sedimentos (Technicap PPS3/3) que se mantuvo anclada a 360 m de profundidad (Fig. 1) se obtuvieron 65 muestras del material en hundimiento del periodo de enero de 2002 a diciembre de 2003. Estas muestras fueron tratadas utilizando el método de Hasle y Fryxell (1970), para eliminar carbonatos y materia orgánica. Localización del sitio de anclaje de la trampa de sedimentos (punto negro) en Cuenca Alfonso, Golfo de California. Se obtuvieron imágenes de cada especie y sus variaciones morfológicas con un microscopio Zeiss con contraste de fases y una cámara digital CCD Pro-Series, utilizando el software Image-Pro Express. D. calida, D. californica, Dictyocha messanensis f. messanensis, Dictyocha messanensis f. spinosa fueron constantes durante los dos años de muestreo
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