Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

These data are published in Table 2 of Sachs et al., 2018 (doi: 10.1029/2018PA003469)

Methods are as per "Southward Shift of the Pacific ITCZ During the Holocene" in Paleoceanography and Paleoclimatology, volume 33, pages 1383-1395 (Sachs et al. 2018).

Sediment core PTLN‐PC1 was collected September 2013 in sequential 1m sections using a 5cm‐diameter Colinvaux‐Vohnout Livingstone‐type rod‐operated piston corer (Geocore, Columbus, Ohio). Each section was sealed in the field and refrigerated at 4 °C until core splitting and subsampling.

Sample ages were linearly interpolated from calibrated 14C dates (see dataset "T Lake PC1 Chronology") using the Clam 2.2 (Blaauw, 2010) software package.

Sediment subsamples were transferred to combusted glass vials, frozen, then freeze dried. Lipids were extracted with 10% methanol in dichloromethane on an accelerated solvent extractor (ASE 200; Dionex) at 100°C and 1500 psi with three 5‐min static cycles. Lipid extracts were saponified using 2:1 1N KOH in methanol:water at 70°C overnight. Saponified extracts were acidified to pH ~1 with HCl, neutral lipids extracted from the water/methanol phase with hexane, and the hexane extracts washed with water. Lipid extracts were acetylated at 70°C for 30 min in a mixture of 20 μl acetic anhydride of known isotopic composition and 20 μl pyridine. Sterol acetates were then isolated via preparative high‐performance liquid chromatography as per the methods in Nelson and Sachs (2013, 2014). Extracts were taken up in 25 μl of 2:1 dichloromethane:methanol and the complete volume injected onto an Agilent 1100 high‐performance liquid chromatography system equipped with a Zorbax Eclipse XDB C18 column; after an initial elution of polar compounds in 5:95 methanol:acetonitrile, sterol acetates were eluted with an isocratic mobile phase of 5:10:85 methanol:ethyl acetate:acetonitrile. Aliquots (5%) of each sample were injected on an Agilent 6890N GC with flame ionization detector and PTV inlet, equipped with an Agilent VF‐17 ms column (60 m × 0.32 mm × 0.25 μm), in splitless mode at 300°C using helium carrier gas at 1.5 ml/min. The initial oven temperature was 110°C, followed by a ramp to 320°C at 5°C/min, and was then held for 20 min. Detector response was determined via an α‐cholestane internal standard. Dinosterol fluxes were calculated from the product of dinosterol concentration per gram dry weight of sediment, the linear sediment accumulation rate, and the dry bulk density of sediment. Uncertainty in dinosterol fluxes is conservatively assumed to be 25%.

Hydrogen isotopes of dinosterol were measured via a modification of the procedures outlined in Nelson and Sachs (2013). Gas chromatography was conducted using a Thermo Trace GC Ultra equipped with a GC‐TC interface. Samples were injected into the 330°C inlet in splitless mode, with a 1.1 ml/min helium carrier flow through a VF‐17 ms column (60 m × 0.25 mm × 0.25 μm). The oven temperature was held at 120°C for the 2‐min splitless time, increased to 260 °C at 20 °C/min, increased to 325°C at 1°C/min, and held for 10 min. The pyrolysis interface was operated at 1400°C, and the sample hydrogen admitted to a Thermo Delta V Plus isotope ratio mass spectrometer via open split.

Isotope measurements are given as δ²>H values relative to Vienna Standard Mean Ocean Water and calibrated via external isotope standards (Arndt Schimmelmann, Indiana University). Secondary corrections were determined based on time‐in‐sequence, retention time, and peak area, as necessary, on a sequence‐by‐sequence basis. Each sample analyzed at least three times. δ²H values were corrected for added acetate hydrogen (−124.4‰ ± 8.1) via mass balance. Uncertainty is given as the standard deviation of these replicate analyses and uncertainty in the value of the known acetate, propagated through the mass balance calculation.

BCO-DMO Processing: modified parameter names (changed "2H_dino" to "dino_2H" because column names cannot start with numbers)

This project will survey the taxonomic, genetic, and functional diversity of the organisms found in marine lakes, and investigate the processes that cause gains and losses in this biodiversity. Marine lakes formed as melting ice sheets raised sea level after the last glacial maximum and flooded hundreds of inland valleys around the world. Inoculated with marine life from the surrounding sea and then isolated to varying degrees for the next 6,000 to 15,000 years, these marine lakes provide multiple, independent examples of how environments and interactions between species can drive extinction and speciation. Researchers will survey the microbes, algae, invertebrates, and fishes present in 40 marine lakes in Palau and Papua, and study how diversity has changed over time by retrieving the remains of organisms preserved in sediments on the lake bottoms. The project will test whether the number of species, the diversity of functional roles played by organisms, and the genetic diversity within species increase and decrease in parallel; whether certain species can greatly curtail diversity by changing the environment; whether the size of a lake determines its biodiversity; and whether the processes that control diversity in marine organisms are similar to those that operate on land.

Because biodiversity underlies the ecosystem services on which society depends, society has a great interest in understanding the processes that generate and retain biodiversity in nature. This project will also help conserve areas of economic importance. Marine lakes in the study region are important for tourism, and researchers will work closely with governmental and non-governmental conservation and education groups and with diving and tourism businesses to raise awareness of the value and threats to marine lakes in Indonesia and Palau.

(adapted from the NSF Synopsis of Program)
Dimensions of Biodiversity is a program solicitation from the NSF Directorate for Biological Sciences. FY 2010 was year one of the program.  [MORE from NSF]

The NSF Dimensions of Biodiversity program seeks to characterize biodiversity on Earth by using integrative, innovative approaches to fill rapidly the most substantial gaps in our understanding. The program will take a broad view of biodiversity, and in its initial phase will focus on the integration of genetic, taxonomic, and functional dimensions of biodiversity. Project investigators are encouraged to integrate these three dimensions to understand the interactions and feedbacks among them. While this focus complements several core NSF programs, it differs by requiring that multiple dimensions of biodiversity be addressed simultaneously, to understand the roles of biodiversity in critical ecological and evolutionary processes.