Distributions of particulate Hemebin the Atlantic and Southern Oceans—Implications for electron transport in phytoplankton

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Abstract
Concentrations of hemeb, the iron‐containing component ofb‐type hemoproteins, ranged from < 0.4 to 5.3 pM with an average of 1.18 ± 0.8 pM (± 1σ;n = 86) in the Iceland Basin (IB), from < 0.4 to 19.1 pM with an average of 2.24 ± 1.67 pM (n = 269) in the tropical northeast Atlantic (TNA) and from 0.6 to 21 pM with an average of 5.1 ± 4.8 pM (n = 34) in the Scotia Sea (SS). Hemebconcentrations were enhanced in the photic zone and decreased with depth. Hemebconcentrations correlated positively with chlorophylla(chla) in the TNA (r = 0.41,p < 0.01,n = 269). Hemebdid not correlate with chlain the IB or SS. In the IB and SS, stations with high‐chlorophyll and low‐nutrient (Fe and/or Si) concentrations exhibited low hemebconcentrations relative to particulate organic carbon (< 0.1 μmol mol−1), and high chla:hemebratios (> 500). High chla:hemebratios resulted from relative decreases in hemeb, suggesting proteins such as cytochrome b6f, the core complex of photosystem II, and eukaryotic nitrate reductase were depleted relative to proteins containing chlorophyll such as the eukaryotic light‐harvesting antenna. Relative variations in hemeb, particulate organic carbon, and chlacan thus be indicative of a physiological response of the phytoplankton community to the prevailing growth conditions, within the context of large‐scale changes in phytoplankton community composition.

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