Physiological responses of lipids in Emiliania huxleyi and Gephyrocapsa oceanica (Haptophyceae) to growth status and their implications for alkenone paleothermometry
نویسندگان
چکیده
The physiological responses of alkenone unsaturation indices to changes in growth status of E. huxleyi and G. oceanica strains isolated from a water sample of the NW Paci®c were examined using an isothermal batch culture system. In both E. huxleyi and G. oceanica the unsaturation index U37 K0 changed during the growth period, but the eects of this change were dierent. This suggests that genotypic variation rather than the adaptation of the strains to the geographical environment of the sampling location is a major factor in determining the physiological responses to U37 K. Changes of U37 K0 were associated with those of the unsaturation indices of C38 and C39 alkenones, the abundance ratios of lower to higher homologues of alkenones, the abundance ratios of saturated to polyunsaturated n-fatty acids, the abundance ratio of ethyl alkenoate to alkenones, and sterol contents. These associations might be attributable to the physiological response of lipids for maintaining their ̄uidity. The degree of unsaturation both in alkenones and nfatty acids increased at day 8, possibly due to nutrient depletion. The ethyl alkenoate/total alkenone and ethyl alkenoate/C37 alkenone ratios increased abruptly at day 8 in both strains. These ratios should be useful in clarifying the relationship between the marine environment and its corresponding growth phase of batch culture. E. huxleyi and G. oceanica can be eectively distinguished using the U37 K-U38Et K diagram. # 2000 Elsevier Science Ltd. All rights reserved.
منابع مشابه
Alkenone abundance and its relationship to the coccolithophore assemblage in Gulf of California surface waters
Profiles of alkenone concentration, the abundance of the calcified alkenone-producing species Emiliania huxleyi and Gephyrocapsa oceanica as well as nutrient and phytoplankton pigment concentrations were measured through the euphotic zone in surface waters of the Gulf of California during cruises in two different summers (2004, 2005) and one winter (2005). As determined using a biomarker and pi...
متن کاملThe effect of temperature, salinity and growth rate on the stable hydrogen isotopic composition of long chain alkenones produced by Emiliania huxleyi and Gephyrocapsa oceanica
Two haptophyte algae, Emiliania huxleyi and Gephyrocapsa oceanica, were cultured at different temperatures and salinities to investigate the impact of these factors on the hydrogen isotopic composition of long chain alkenones synthesized by these algae. Results showed that alkenones synthesized by G. oceanica were on average depleted in D by 30‰ compared to those of E. huxleyi when grown under ...
متن کاملInter- and intraspecific phenotypic plasticity of three phytoplankton species in response to ocean acidification
Phenotypic plasticity describes the phenotypic adjustment of the same genotype to different environmental conditions and is best described by a reaction norm. We focus on the effect of ocean acidification on inter- and intraspecific reaction norms of three globally important phytoplankton species (Emiliania huxleyi, Gephyrocapsa oceanica and Chaetoceros affinis). Despite significant differences...
متن کاملTemperature Modulates Coccolithophorid Sensitivity of Growth, Photosynthesis and Calcification to Increasing Seawater pCO2
Increasing atmospheric CO₂ concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed ...
متن کاملRecent Reticulate Evolution in the Ecologically Dominant Lineage of Coccolithophores
The coccolithophore family Noëlaerhabdaceae contains a number of taxa that are very abundant in modern oceans, including the cosmopolitan bloom-forming Emiliania huxleyi. Introgressive hybridization has been suggested to account for incongruences between nuclear, mitochondrial and plastidial phylogenies of morphospecies within this lineage, but the number of species cultured to date remains rat...
متن کامل