Simultaneous determination of⁸⁷Sr/⁸⁶Sr and trace-element data in otoliths and other sclerochronological hard structures

Abstract

Chronological data from hard structures has been instrumental in reconstructing information about the past across numerous disciplines. Isotopic and trace elemental chronologies from the depositional layers of speleothems, corals, bivalve shells, fish otoliths and other structures are routinely used to reconstruct climate, growth, temperature, geological, archeological and migratory histories. Advances in instrumentation have revolutionized the use of these structures and publications detailing new chemical and isotopic methods in sclerochronology and speleothem chronology have steadily increased in number. This is particularly true of fish, in which detailed origin, life-history, and migration history can be reconstructed from their otoliths. Specifically, improvements in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have allowed increases temporal resolution, precision, and sample throughput. Many studies now combine multiple chemical and isotopic tracers, taking advantage of multivariate statistical methods and multiple tracep-element and isotope systems to glean further information from individual samples. This paper describes a novel laser ablation split-stream (LASS) method which allows simultaneous collection of 87 Sr/ 86 Sr and traceelemental data from chronological carbonate samples. The study tests the accuracy and precision of multiple laser spot sizes on a marine shell standard and fish otoliths using LASS and traditional single stream methods and compared to prior otolith data on the same samples. Our results indicate that LASS techniques can be used to provide accurate and precise data at useful laser spot sizes for otolith studies, while providing time and integration-matched data reduction using newly developed features for the Iolite data reduction platform.

Natal origin and migration pathways of Mekong catfish (Pangasius krempfi) using strontium isotopes and trace element concentrations in environmental water and otoliths

“…Strontium is known as the best proxy for ambient water salinity [ 20 , 27 ], the Sr/Ca is the ideal variable to estimate fish movements between marine, brackish and fresh waters [ 28 , 29 ], whereas it is not affected by water temperature [ 30 ]. When compared with water concentrations and age estimates, otolith strontium isotope ratios ( 87 Sr/ 86 Sr) can provide valuable information about the migration pathways of species that pass through different habitats [ 17 , 31 , 32 ]. More specifically, the strontium isotopic ratio ( 87 Sr/ 86 Sr) signatures in the water [ 33 ] and the otoliths provide evidence for the origin of individual migratory and non-migratory fish [ 34 – 39 ].…”

Sawfish, read in tooth and saw: Rostral teeth as endogenous chemical records of movement and life‐history in a critically endangered species

“…All data reduction was completed using a custom built data reduction scheme operating within the Iolite software package (Fisher et al, 2017; Hegg & Fisher, 2020). All plotting and analyses were completed in R statistical software (https://www.r-project.org).…”

Sawfish, Read in Tooth and Saw: rostral teeth as endogenous chemical records of movement and life-history in a critically endangered species

“…Analysis was conducted at the Radiogenic Isotope and Geochronology Laboratory (RIGL) at Washington State University. Strontium ratio and trace element data were collected simultaneously using a laser ablation split stream (LASS) methodology (Hegg & Fisher, 2020). Laser ablation was conducted using a Teledyne Analyte Excite 193nm ArF laser using a 35μm spot diameter, 10μm/sec rastering speed, operating at 20Hz, and with laser fluence of ∼4J/cm 2 .…”

“…Trace element concentrations were normalized to the NIST-610 glass standard, while 87 Sr/ 86 Sr was corrected for K and Rb interferences and normalized to a modern marine shell and a 87 Sr/ 86 Sr of 0.70918 for modern ocean water, as described by (Hegg & Fisher, 2020). Trace element analysis was calibrated using the NIST 610 standard as described in (Hegg & Fisher, 2020).…”

“…All data reduction was completed using a custom built data reduction reduction scheme (DRS) operating within the Iolite software package (Fisher et al, 2017; Hegg & Fisher, 2020). All plotting and analyses were completed in R statistical software (https://www.r-project.org).…”