HR: 0800h
AN: OS11A-0189    [Abstracts]
TI: Distribution of Living Coccolithophores North of the Canary Islands: Vertical, Seasonal and Interannual Variations
AU: * Bollmann, J
EM: bollmann@geology.utoronto.ca
AF: Department of Geology, University of Toronto, 22 Russel Street, Toronto, ON M5S 3B1, Canada
AU: Cortes, M Y
EM: mycortes@uabcs.mx
AF: Departamento de Geologà­a Marina Universidad Autàłnoma de Baja California Sur, Carr. al Sur Km 5.5 Col. El Calandrio, La Paz, BCS 23080, Mexico
AB: Coccolithophores are unicellular gold-brown algae covered with small calcium carbonate plates and production and burial of these organisms play an important role in the global carbon cycle. In order to assess their role, cell density and taxonomic composition of living associations were analyzed along an East-West temperature and productivity gradient in the North Atlantic Eastern Boundary Current. Water samples were taken from 9 different water depth levels (0-200m) at three locations near the mooring stations LP1 (29°45.7N, 17° 57.3W), JGOFS Time-series Station ESTOC (29°10.0N, 15°30.0W) and EBC2 (28°42.5, 13°9.3W) during several seasonal cruises from September 1995 to July 1998. Samples were filtered onto Nucleopore® membranes in order to determine coccolithophore cell densities and taxonomic composition of the assemblages. In addition, in situ CTD and fluorometer measurements were done and samples for nutrient and oxygen content were collected from the same water depth levels at all stations. Maximum total coccolithophore cell densities usually occurred in the upper photic zone above the deep chlorophyll maximum that was generally located between 50m and 125m water depth. A strong gradient in total coccolithophore cell densities was found during winter between the open ocean location LP1 with 20'000-40'000 cells/l and the near-shore location EBC2 with a maximum of 160'000 cells/l. During summer, a much weaker gradient occurred with 25'000 cells/l at LP1 and ~80'000 cells/l at EBC2. During spring (April), the cell density gradient was reversed with low cell densities at the near-shore location. In contrast, the strongest gradient in sea surface temperature and salinity occurred during late summer (September) with 24°C and 37.1 at station LP1 and 20.2°C and 36.5 at station EBC2. The weakest gradient was found during winter (January) with 19.5°C and 36.8 at station LP1 and 19.1°C and 36.7 at station EBC2. Four coccolithophore species dominated almost all assemblages analyzed. The most abundant species living in the upper photic zone (0- 100m)was Gephyocapsa ericsonii followed by Emiliania huxelyi and Umbellosphaera tenuis. Florisphaera profunda was the most abundant species below the deep chlorophyll maximum.
DE: 0410 Biodiversity
DE: 0424 Biosignatures and proxies
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL (0460)
DE: 4815 Ecosystems, structure, dynamics, and modeling (0439)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting