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Export production depth of Emiliania huxleyi in the Gulf of Calfornia : an evaluation of the alkenone Ukʹ₃₇ paleosst-proxy

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Title: Export production depth of Emiliania huxleyi in the Gulf of Calfornia : an evaluation of the alkenone Ukʹ₃₇ paleosst-proxy
Authors: Pontius, Amanda S.
Keywords: Coccolithus huxleyi
Issue Date: 2007
Abstract: In the present study. alkenone unsaturation patterns (UK'37). alkenone-specific carbon isotopic variation (δK37:2). and seasonal alkenone concentration and production rate are determined throughout the upper water column (0-40 m) in the Gulf of California in order to better constrain the depth of alkenone export production and to identify factors that might cause calculated UK•37 temperatures to underestimate SST when SST>26°C. Field data were collected during one wintertime (January - February 2005) and two summertime (July 2004 & July-August 2005) cruises. Alkenone production rates were determined using an in situ 13C incubation method utilized in a related study in the subtropical oligotrophic North Pacific [Prahl at al., 2005; Popp at al., 2006a]. which was originally modified after that employed previously in the Sea of Japan [Hamanaka at al., 2000] and the Bering Sea [Shin et al., 2002]. Alkenone export production was determined to originate from a depth of ~20-30 m, which is well below the SML during the summer. Exported UK '37 did underestimate SST by up to -3°C, but this underestimate was not as large as expected based on the temperature gradient between the SML and the depth of export, and probably resulted from a concurrent physiological response to growth under light limiting conditions. As a result, SST estimates made by measuring UK' 37 fall within the ±3°C variability observed in the core-top calibrations of Muller at al. [1998] and Conte at al. [2006], indicating that subsurface alkenone growth could still lead to relatively accurate SST predictions (i.e. within ±3°C). Additionally, the efficiency of alkenone export production to sediment traps deployed at 100 m is determined to be ~20%. This alkenone export efficiency is the first measurement of this type to be reported in the literature and implies considerable loss of alkenones probably due to the effects of grazing.
Description: Thesis (M.S.)--University of Hawaii at Manoa, 2007.
Includes bibliographical references (leaves 46-50).
v, 50 leaves, bound 29 cm
URI/DOI: http://hdl.handle.net/10125/20787
Rights: All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections:M.S. - Oceanography



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