Dataset: Mytilus Elemental Fingerprints
Deployment: MuLTI-2_Mussel_Sampling

We quantified larval fingerprints during spawning at each of the potential source populations to develop a reference map that will allow us to assign settled mussels to natal sites based on the elemental fingerprints of their larval shell. To develop a reference map of elemental signatures, we reared larvae in situ at each major mussel population (see sample locations data). After populations spawned in the field (based on our monitoring of gonad indices in each population) adult mussels from multiple sites were collected, spawned in the laboratory and the eggs fertilized. Within 24-48 hours (before shell formation begins) larvae were placed into small chambers and moored in situ at 3-5m depth. Because spawning varied among the populations, we staggered our deployment of larvae to coincide with our estimates of spawning times. After four weeks, larval mussels were removed from in situ chambers, shells were rinsed in deionized water, dried and prepared for ICPMS. Settlers were collected from settlement plates deployed at each population.

Elemental concentrations were determined from single spot ablation in larval shells (85% energy, 10 hz, 200 shots, 25 μm spot diameter) for both larvae and settlers. Elemental compositions were quantified by external calibration (USGS MACS-3) and internal standardization. We quantified elemental compositions from count per second (cps) measurements of 24Mg, 55Mn, 59Co, 88Sr, 138Ba, 139La, 208Pb and 46Ca using laser ablation inductively coupled mass spectrometry (213 Nd:YAG laser coupled with Elan DRC II ICPMS) at the University of Massachusetts, Boston (LA-ICPMS). Elemental abundances were calculated as analyte cps/ 43Ca cps. We performed a one-point calibration using gas blank and MACS-3, and ran MACS-1 as a check standard every ten samples. Analytical accuracy and precision based on repeated check standard analyses was 96 + 4.4% (mean + sd). Each sample was analyzed in triplicate and mean concentrations normalized to calcium are reported.

Location:
Gulf of Maine: Frenchmen Bay (44 28.239 N -68 15.927 W) to Machais Bay (44 39.350 N -67 21.320 W).