Evaluation of long chain 1,14-alkyl diols in marine sediments as indicators for upwelling and temperature
Introduction
Over the last few decades, an increasing number of lipids from marine environments have been identified and linked to their natural sources, and some are now being used as proxies for past climate conditions (e.g. Eglinton and Eglinton, 2008 and references therein). Long chain alkyl diols form one group with high biomarker potential. After their discovery in the Black Sea (De Leeuw et al., 1981), they were found in Quaternary sediments from low to high latitudes (Versteegh et al., 1997, Versteegh et al., 2000 and references therein). Cultured marine and freshwater eustigmatophyte algae produce series of long chain alkyl diols, consisting mainly of C28–C32 1,13- and 1,15-diols (Volkman et al., 1992, Volkman et al., 1999). In the environment, a recent study of lipids and 18S rRNA genes in a freshwater lake has shown that long chain alkyl diols are produced by eustigmatophytes in the surface water of the lake (Villanueva et al., 2014). However, the role of eustigmatophytes as a source of marine long chain alkyl diols remains unclear. Reports of eustigmatophyte algae in marine environments are sparse and the long chain alkyl diol composition of marine eustigmatophytes does not match those of marine sediments (Volkman et al., 1992, Versteegh et al., 1997, Rampen et al., 2012). Despite uncertainty concerning their sources, recent work has indicated a correlation between sea surface temperature (SST) and fractional abundances of C28 1,13-, C30 1,13- and C30 1,15-diols in marine sediments. Based on this, a new temperature proxy, i.e. the long chain diol index (LDI), which expresses the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols, was introduced (Rampen et al., 2012). A strong correlation (R value 0.984 and p value < 0.001) between the LDI and SST was observed.
Besides 1,13- and 1,15-diols, long chain 1,14-alkyl diols are commonly reported in marine sediments. Sinninghe Damsté et al. (2003) and Rampen et al. (2007) showed that cultivated Proboscia diatoms produced both saturated and mono-unsaturated C28 and C30 1,14-diols and, in addition, saturated C28, C30 and C32 1,14-diols were recently reported in the marine Dictyochophyte Apedinella radians (Rampen et al., 2011). Sediment trap studies confirmed Proboscia diatoms as being a likely source of long chain 1,14-alkyl diols, particularly in upwelling areas (Rampen et al., 2008), whereas the importance of Apedinella as a source of sedimentary long chain 1,14-alkyl diols remains uncertain (Rampen et al., 2011). These sources may be distinguished on the basis of the occurrence of certain diols: C32 1,14-diols may be useful as an indicator for Apedinella input, as they are produced by A. radians but were absent from the 8 cultures of Proboscia spp. analyzed to date. Mono-unsaturated long chain 1,14-alkyl diols may, on the other hand, indicate Proboscia as a source, as these lipids have been identified in Proboscia cultures but not in Apedinella.
We previously reported that the chain length distribution and degree of saturation of long chain 1,14-alkyl diols in Proboscia cultures are related to growth temperature, indicating the potential of these diols to be used as a tool for reconstructing SST (Rampen et al., 2009). Changes in the chain length and degree of unsaturation of lipids are known adaptation mechanisms for bacteria, yeast, fungi and algae to changing environmental conditions (e.g. Russell and Fukunaga, 1990, Suutari and Laakso, 1994) and the following two indices, the diol chain length index (DCI) and the diol saturation index (DSI), were used to quantify the chain length distribution and degree of saturation of long chain diols:
However, application of these indices using surface sediments from the eastern South Atlantic Ocean showed only a moderate correlation of DCI with annual mean SST, while no correlation was observed between DSI and SST (R values 0.72 and 0.55 and p values < 0.001 and 0.535, respectively; Rampen et al., 2009). It was suggested that factors other than temperature could also play a role, indicating that more data were required to validate the use of long chain 1,14-alkyl diols as a proxy for temperature.
Proboscia diatoms are often abundant in nutrient-rich environments like upwelling areas (Hernández-Becerril, 1995, Lange et al., 1998, Koning et al., 2001, Smith, 2001) and their lipids may therefore be useful as tracers for these conditions. Indeed, sediment trap studies showed that, in the Arabian Sea, long chain 1,14-alkyl diols were found almost exclusively under upwelling conditions (Rampen et al., 2007, Rampen et al., 2008), whereas such a relationship was not observed for long chain 1,15- and 1,13-diols. Following this, diol index 1 was introduced:
It has been used as a proxy for upwelling in the Arabian Sea (Rampen et al., 2008), the Benguela Upwelling System (Pancost et al., 2009), the Eastern Equatorial Pacific (Seki et al., 2012), offshore southeastern Australia (Lopes dos Santos et al., 2012) and the westernmost Mediterranean (Nieto-Moreno et al., 2013).
Proboscia diatoms are also abundant in Antarctic waters and lipid analysis confirmed the presence of C28 and C30 1,14-diols in a sediment core from the Western Bransfield Basin (Willmott et al., 2010). However, unlike the Arabian Sea, C30 1,15-diol concentrations are low, whereas C28 and C30 1,13-diols are more abundant in this area, and consequently Willmott et al. (2010) introduced the diol index 2 to reconstruct upwelling of nutrient rich Upper Circumpolar Deep Water in the Western Bransfield Basin:
How widely applicable these long chain alkyl diol indices are as tracers for upwelling and nutrient rich conditions is unknown. In a study of Pliocene sediments from the Benguela Upwelling System, Pancost et al. (2009) observed both periods in which trends in 1,14-diol abundances and diol index 1 were consistent with those of other productivity markers, and periods when they differed. Contreras et al. (2010) related the increasing abundance of the C28 1,14-diol in the Peruvian upwelling system during the last interglacial to enhanced stratification, the abundance being low during periods with presumed strengthened upwelling. In addition, several studies reported high Proboscia diatom abundance under stratified rather than upwelling conditions (e.g. Table 1). Hence, perhaps the diol indices should rather be used as indicators for Proboscia productivity, which can be linked to different environmental conditions depending on the region studied.
To constrain the applicability of long chain 1,14-alkyl diols as indicators for temperature, upwelling/nutrient availability and other climate conditions, we have analyzed the long chain alkyl diol distributions in a comprehensive set of marine surface sediments (209), previously studied for long chain 1,13- and 1,15-alkyl diols (Rampen et al., 2012), and compared various long chain 1,14-alkyl diol indices with environmental parameters of the overlaying surface water, such as temperature, salinity, nutrient concentration, stratification and mixed layer depth.
Section snippets
Methodology
The sediments were globally distributed, although mainly from the North and South Atlantic Oceans (Fig. 1 and Supplementary Material). Long chain alkyl diol fractions were obtained and analyzed as described by Rampen et al. (2012). Briefly, sediments were extracted using accelerated solvent extraction (ASE) using a DIONEX 200 instrument with a mixture of dichloromethane (DCM) and MeOH (9:1; v:v) at 100 °C and 7–8 × 106 Pa. For a selected set of samples, the extracts were saponified with 6% KOH,
Results and discussion
Surface sediment (generally 0–1 cm) was obtained at locations with water depth ranging from ca. 20 to ca. 6000 m and a large range in annual mean SST (−1.8 to 28.8 °C), annual mean salinity (6.8–37.0), nutrient concentration, chlorophyll content (0–280 μg/l) and mixed layer depth (0.1–65 m) (see Supplementary Table 2); 187 sediments of the set (89%) contained quantifiable (i.e. signal to noise ratio > 10) 1,13- and/or 1,15-alkyl diols, together with 1,14-alkyl diols, although unsaturated long chain
Conclusions
Although it was previously reported that the chain length distribution and degree of saturation of long chain 1,14-alkyl diols in Proboscia cultures are related to growth temperature (Rampen et al., 2009), our comprehensive study of marine core tops does not show a strong correlation between SST and chain length distribution or degree of saturation of long chain 1,14-alkyl diols in marine surface sediments, indicating that these compounds are not widely applicable as a temperature proxy. It
Acknowledgements
We thank four anonymous reviewers for constructive comments. N. Koç and D. Klitgaard Kristensen, and the participants and the crew of the SciencePub IPY-cruise in 2007 on the R/V Lance from the Norwegian Polar Institute are appreciated for help with the Svalbard surface sediment sampling. Barents Sea samples collected within the Norwegian governmental mapping program MAREANO (www.mareano.no) were provided by J. Knies at Geological Survey of Norway. We are also grateful to various people who
References (55)
- et al.
The occurrence and identification of C30, C31 and C32 alkan-1,15-diols and alkan-15-one-1-ols in Unit I and Unit II Black Sea sediments
Geochimica et Cosmochimica Acta
(1981) - et al.
Free, esterified and residual sterols in Black Sea Unit I sediments
Geochimica et Cosmochimica Acta
(1983) - et al.
Molecular proxies for paleoclimatology
Earth and Planetary Science Letters
(2008) - et al.
Distribution of phytoplankton in the southern Black Sea in summer 1996, spring and autumn 1998
Journal of Marine Systems
(2003) - et al.
Unusual diatoms linked to climatic events in the northeastern English Channel
Journal of Sea Research
(2007) - et al.
The influence of oxic degradation on the sedimentary biomarker record I: Evidence from Madeira Abyssal Plain turbidities
Geochimica et Cosmochimica Acta
(2002) - et al.
Inferring upwelling rates in the equatorial Atlantic using 7Be measurements in the upper ocean
Deep-Sea Research
(2011) - et al.
Selective preservation of upwelling-indicating diatoms in sediments off Somalia, NW Indian Ocean
Deep-Sea Research I
(2001) - et al.
Late Quaternary productivity changes from offshore Southeastern Australia: a biomarker approach
Palaeogeography, Palaeoclimatology, Palaeoecology
(2012) - et al.
Distribution of chlorophyll a and Gymnodinium catenatum associated with coastal upwelling plumes off central Portugal
Acta Oecologica-International Journal of Ecology
(2003)
Climate conditions in the westernmost Mediterranean over the last two millennia: an integrated biomarker approach
Organic Geochemistry
On the meridional extend and fronts of the Antarctic Circumpolar Current
Deep-Sea Research I
Organic geochemical changes in Pliocene sediments of ODP Site 1083 (Benguela Upwelling System)
Palaeogeography, Palaeoclimatology, Palaeoecology
Comparison of contemporary and fossil diatom assemblages from the western Antarctic Peninsula shelf
Marine Micropaleontology
Seasonal and spatial variation in the sources and fluxes of long chain diols and mid-chain hydroxy methyl alkanoates in the Arabian Sea
Organic Geochemistry
A 90 kyr upwelling record from the northwestern Indian Ocean using a novel long-chain diol index
Earth and Planetary Science Letters
Impact of temperature on long chain diol and mid-chain hydroxy methyl alkanoate composition in Proboscia diatoms: results from culture and field studies
Organic Geochemistry
Occurrence of long chain 1,14 diols in Apedinella radians
Organic Geochemistry
Long chain 1,13- and 1,15-diols as a potential proxy for palaeotemperature reconstruction
Geochimica et Cosmochimica Acta
A comparison of thermal adaptation of membrane-lipids in psychrophilic and thermophilic bacteria
FEMS Microbiology Reviews
A diatomaceous origin for long-chain diols and mid-chain hydroxy methyl alkanoates widely occurring in Quaternary marine sediments: indicators for high nutrient conditions
Geochimica et Cosmochimica Acta
Understanding the Arabian Sea: reflections on the 1994–1996 Arabian Sea Expedition
Deep-Sea Research II
Potential palaeoenvironmental information of C24 to C36 mid-chain diols, keto-ols and mid-chain hydroxy fatty acids; a critical review
Organic Geochemistry
Mid-chain diols and keto-ols in SE Atlantic sediments: a new tool for tracing past sea surface water masses?
Geochimica et Cosmochimica Acta
Potential biological sources of long chain alkyl diols in a lacustrine system
Organic Geochemistry
C30–C32 alkyl diols and unsaturated alcohols in microalgae of the class Eustigmatophyceae
Organic Geochemistry
Eustigmatophyte microalgae are potential sources of C29 sterols, C22–C28 n-alcohols and C28–C32 n-alkyl diols in freshwater environments
Organic Geochemistry
Cited by (47)
Sources and seasonality of long-chain diols in a temperate lake (Lake Geneva)
2021, Organic GeochemistryCitation Excerpt :Here, the LDI, which is used to reconstruct seawater temperature, based on the relative distribution of LCDs in marine sediments, does not show any correlation with lake water or air temperature in Lake Geneva (data not shown). Rampen et al. (2014b) showed that certain eustigmatophyte species (Nannochlorospis gaditana and Goniochloris sculpta) increase the relative abundance of C32:1 1,15-diol and decrease that of C32 1,15-diol at higher growth temperatures. However, in Lake Geneva we observe an opposite trend as the fractional abundance of the C32 1,15-diol was lower in August (Fig. 2), which was the warmest month (Fig. 2).
Global temperature calibration of the Long chain Diol Index in marine surface sediments
2020, Organic GeochemistryLong chain 1,14-diols as potential indicators for upper water stratification in the open South China Sea
2020, Ecological IndicatorsEvaluation of environmental proxies based on long chain alkyl diols in the East China Sea
2020, Organic GeochemistryCitation Excerpt :These occurrences suggest their similar fluvial sources. In fact, culture studies have shown that some known families, such as Monopsidaceae, Eustigmataceae, and Goniochloridaceae, in the class of Eustigmatophyceae may produce C28-32 1,13- and 1,15-diols (Volkman et al., 1992, 1999; Rampen et al., 2014a; Balzano et al., 2018). Alternatively, the opposite response to ambient temperature of C30 1,15-diol to C28 and C30 1,13-diols (Rampen et al., 2012) might be another reason for the negative loadings of C30 1,15-diol vs C28 and C30 1,13-diols in the PCA diagram.
- 1
Present address: Alfred-Wegener-Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany.