HR: 11:25h
AN: OS32A-05    [Abstracts]
TI: Coccolithophore Dynamics In Alfonso Basin: Seasonal Variation And Species Composition
AU: * Cortés, M Y
EM: mycortes@uabcs.mx
AF: Depto. Geología Marina, Univ. Autónoma de Baja California Sur, Apdo. Postal 19-B, La Paz, BCS 23080, Mexico
AU: Urcádiz-Cázares, F J
AF: Depto. Geología Marina, Univ. Autónoma de Baja California Sur, Apdo. Postal 19-B, La Paz, BCS 23080, Mexico
AU: Silverberg, N
AF: Centro Interdisciplinaria de Ciencias Marinas (CICIMAR-IPN), Av. Instituto Politécnico Nacional s/n, La Paz, BCS 23096, Mexico
AU: Aguirre-Bahena, F
AF: Centro Interdisciplinaria de Ciencias Marinas (CICIMAR-IPN), Av. Instituto Politécnico Nacional s/n, La Paz, BCS 23096, Mexico
AU: Bollmann, J
AF: Geology Department, University of Toronto, 22 Russell Street, Toronto, ON M5S 3B1, Canada
AB: The production of organic and inorganic carbon by coccolithophores is considered to play a significant role in the global carbon cycle. Therefore, detailed knowledge of their vertical flux is needed. Here we present a time-series record of coccolithophore standing stock and vertical coccolith flux from Alfonso Basin, southwest coast of the Gulf of California. This location is of particular interest as it is very sensitive to changes in environmental conditions and these may be preserved in laminated underlying sediments. Coccolithophore standing stock and assemblage composition were obtained from plankton samples taken at 3- month intervals during 2002-2003. Furthermore, coccolith flux and species composition were determined in samples from a time-series sediment trap (sampling intervals 7-14 days) deployed at 350 m depth from January 2002 to October 2003. The coccolithophore standing stock and coccolith flux varied considerably between sampling periods but, in general, a seasonal pattern was apparent, with low fluxes in spring-summer and maximal values in autumn- winter. During 2002, fluxes ranged from 0.02x10⁸ coccoliths m^-2 d^-1 in summer to 64.7x10⁸ coccoliths m^-2 d^-1 in autumn. Values increased considerably during 2003: registering 52.4 x10⁸ coccoliths m^-2 d^-1 in spring to the highest (128.8x10⁸ coccoliths m^-2 d^-1) in late summer/autumn. The latter are related to hurricanes that occurred during the sampling period. In total 47 taxa were identified but only three species, Gephyrocapsa oceanica (43.6%), Emiliania huxleyi (28%) and Florisphera profunda (15.7%), constituted 88 percent of the total coccolith flux. This corresponds to the species composition observed in the water column. G. oceanica was always present and its flux pattern followed that of the total flux. The flux of E. huxleyi remained almost constant during the observed time period whereas F. profunda showed peak fluxes in autumn. Although the cosmopolitan species E. huxleyi has been considered the most important coccolithophore species on a global scale, G. oceanica is the most abundant species in Alfonso Basin and perhaps other marginal seas.
DE: 0410 Biodiversity
DE: 0460 Marine systems (4800)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 4855 Phytoplankton
DE: 4858 Population dynamics and ecology
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly