14C dates from core PC1 collected from T Lake, Palau in September 2013

14C dates from core PC1 collected from T Lake, Palau in September 2013 using a Colinvaux ‐ Vohnout Livingstone ‐ type rod ‐ operated piston corer.


Acquisition Description
Sediment core PTLN-PC1 was collected September 2013 in sequential 1-m sections using a 5-cm-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.
Thirteen macrofossils were pulled from the core and were pretreated with an acid-base-acid procedure according to the protocol in Brock et al. (2010) to remove extraneous organic materials.Accelerator mass spectrometry 14C dating was performed by DirectAMS in Bothell, WA, United States.

Processing Description
The modern age control (youngest age, at depth = 81 cm) was converted from fraction modern to 14C years using the pMC.age() function in the Bacon age-modeling software package (Blaauw and Christen, 2011).This produced a 90.3% confidence interval for the calibrated age estimate of −0.04611 to −0.05081 ka BP, or CE 1996-2001 (plus a small chance (4.6%) of −0.00831 to −0.00808 ka BP, or CE 1958); this age is anomalously young and clearly an outlier based on comparison with a nearby universal core, prompting its removal.All other dates were calibrated using IntCal2013 (Reimer et al., 2013)

Description
The piston corer is a type of bottom sediment sampling device.A long, heavy tube is plunged into the seafloor to extract samples of mud sediment.A piston corer uses a "free fall" of the coring rig to achieve a greater initial force on impact than gravity coring.A sliding piston inside the core barrel reduces inside wall friction with the sediment and helps to evacuate displaced water from the top of the corer.A piston corer is capable of extracting core samples up to 90 feet in length.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.

Dataset
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.
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