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The abundance of iron containing protein, heme b, during a natural spring bloom under ocean acidification conditions
EP24218
Poster Title: The abundance of iron containing protein, heme b, during a natural spring bloom under ocean acidification conditions
Submitted on 11 Jul 2016
Author(s): Jessica Bellworthy, Mario Esposito, Eric P. Achterberg, Martha Gledhill
Affiliations: University of Southampton, Ocean and Earth Science, National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK. Geomar Helmholtz Institute for Ocean Research, Wischhofstr. 1-3, 24148 Kiel, Germany
This poster was presented at Institute for Life Sciences: Life in a High Carbon World
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Poster Information
Abstract: Concentrations of heme b were determined in a mesocosm experiment situated in Gullmar Fjord off Sweden. The mesocosm experiment lasted for ca. one hundred days and was characterised by the growth of a primary nutrient replete and a secondary nutrient deplete phytoplankton bloom. Heme b varied between 40 ± 10 in the prebloom period up to a maximum of 700 ± 400 pmol L-1 just prior to the time of the primary chlorophyll a maximum. Thereafter, heme b concentrations decreased again to an average of 120 ± 60 pmol L-1. When normalised to total particulate carbon, heme b was most abundant during the initiation of the nutrient replete spring bloom, when ratios reached 52 ± 24 µmol mol-1; ten times higher than values observed both pre and post the primary bloom. Concentrations of heme b correlated with those of chlorophyll a. Nevertheless, differences were observed in the relative concentrations of the two parameters, with heme b concentrations increasing relative to chlorophyll a during the growth of the primary bloom, decreasing over the period of the secondary bloom and increasing again through the latter period of the experiment. Heme b abundance was therefore influenced by nutrient concentrations and also likely by changing community composition. In half of the mesocosms, pCO2 was elevated and maintained at ca.1000 µatm, however we observed no significant differences between heme b in plus or ambient pCO2 mesocosms, either in absolute terms, or relative to total particulate carbon and chlorophyll a. The results obtained in this study contribute to our understanding of the distribution of this significant component of the biogenic iron pool, and provide an iron replete coastal water end member that aids the interpretation of the distributions of heme b in more iron deplete open ocean waters. Summary: The first record of planktonic heme b evolution during a natural spring bloom and under CO2 induced ocean acidification. Part of the KOSMOS experiment in Gullmar Fjord, Sweden.References: Gledhill M., et al.,(2013) Global Biogeochemical Cycles. 27:1-11
Riebesell U., et al., (2013) Biogeosciences. 10:1835-1847
Shi D., et al., (2010) Science. 327:676-679
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