8th International Nannoplankton Association Conference


[Abstracts] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Y] [Z]

David U. Hernández-Becerril, Ernesto Bravo-Sierra:
High contributions of coccolithophorids to the phytoplankton abundances in Baja California, Mexico, during El Niño 1997-1998

The phytoplankton from waters off Baja California, Mexico, are relatively well-known: the best studied groups are diatoms and 'armoured' dinoflagellates. However, there have been few attempts to study the contributions of the different groups and/or fractions of phytoplankton to the biomass and productivity. During a cruise from March to April, 1998 - considered the fall of the El Niño (1997-1998) event - samples were taken to collect the 'preservable' fraction of the phytoplankton from three depths at six points in three different zones off Baja California: 4l of water were filtered and preserved with a buffered (pH7.5-8) solution. The analysis of the filters, by light and electron microscopy, revealed assemblages with low diversity, dominated by coccolithophorids, mainly the species, Emiliania huxleyi. Coccolithophores are a rather poorly-known group in Baja California. The abundances of phytoplankton ranged between 5.4x103 and 1.2x105, with the coccolithophorids contributing upto a maximum of 93% to the total abundance, and reaching to a ratio of 21:1 with regard to diatoms, traditionally the most important group in the study area. Diatoms were dominated by small (<20µm), solitary and lanceolate/centric species. The main thermocline was at about 50-60m, except in a shallow station. Discussion is made on the methodology used, as well as on the effects of the oceanographic changes caused by El Niño on the phytoplankton community.


[Registration and Accomodation Form]
[First Circular and Pre-Registration]
[Second Circular]

 [Division of Micropalaeontology] [Department of Geosciences] [Bremen University]

 [INA Europe]  

Copyright © 2000, most recent revision July 24, 2000

Tania Hildebrand-Habel (