Alkenone δD as an ecological indicator: A culture and field study of physiologically-controlled chemical and hydrogen-isotopic variation in C37 alkenones

Effects of alkalinity and salinity at low and high light intensity on hydrogen isotope fractionation of long-chain alkenones produced by <i>Emiliania huxleyi</i>

“…The fact that the strong α C 37 -salinity response is also identified in E. huxleyi grown at high light conditions is important for understanding the influence of light and depth effects (i.e., Wolhowe et al, 2015) on the α C 37 of alkenones preserved in the sedimentary record. suggested that at light intensities above 200 µmol photons m −2 s −1 , α C 37 responds differently to changes in light intensity than below, with a larger reported range in fractionation values at light intensities below 200 µmol photons m −2 s −1 .…”

Testing the D / H ratio of alkenones and palmitic acid as salinity proxies in the Amazon Plume

“…As this effect is insufficient to explain the large T residue , advection is likely not the main factor responsible for the absence of a correlation between δD C 37 and δD H 2 O . Although the deviation in δD C 37 cannot be tied to a single factor, low alkenone production associated with the low-salinity, suspension-rich Amazon waters is likely the most important factor (Wolhowe et al, 2015). Thus, the temperature and δD C 37 deviations are likely caused by similar effects (Fig.…”

“…Species preferring shelf environments have a higher α C 37 than species favouring open marine habitats (M'Boule et al, 2014). In some situations α C 37 has shown a small temperature dependency (Zhang and Sachs, 2007). Furthermore, α C 37 is also dependent on algal growth phase and rate (Schouten et al, 2006;Wolhowe et al, 2009;Chivall et al, 2014b).…”

“…Although there are numerous laboratory and palaeoclimate studies confirming the applicability of δD Lipid to reconstruct the past isotopic composition of water, there have been only few calibration studies in oceanic environments Sachs, 2011, 2009;Wolhowe et al, 2015). To fill this gap, we analysed δD C 37 and δD PA of suspended particle samples along the salinity gradient induced by the Amazon freshwater plume and tested their applicability as salinity proxies (Fig.…”

“…For a potential impact on δD C 37 , factors similar to those considered for the temperature deviations have to be scrutinized: synthesis by coastal haptophyte species (M'Boule et al, 2014), changes in growth rate and phase (Schouten et al, 2006;Wolhowe et al, 2009), overprint by advected material and variations in salinity (Schouten et al, 2006). Since temperature is more or less uniform over the entire study area, a temperature effect as reported by Zhang and Sachs (2007) is not expected to play a role.…”