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  • TRACE ELEMENTS AND INTERSTRIAL DISTANCES AS ENVIRONMENTAL AND ANTHROPOGENIC PROXIES IN THE ANTARCTIC SCALLOP, ADAMUSSIUM COLBECKI
Title: TRACE ELEMENTS AND INTERSTRIAL DISTANCES AS ENVIRONMENTAL AND ANTHROPOGENIC PROXIES IN THE ANTARCTIC SCALLOP, ADAMUSSIUM COLBECKI
The Antarctic scallop Adamussium colbecki may be a crucial paleoenvironmental proxy for coastal Antarctica. For example, two highly seasonal environmental parameters, glacial melt and productivity, were linked to trace elemental concentrations in a previous bulk shell analysis and a transect spanning ~ 3 months of juvenile growth. However, neither study examined seasonal variation in trace elements or tied variation to distances between small ridges (striae) on valve surfaces, which may also vary seasonally. Striae and interstrial growth between them are expressed as alternating narrow and wide groups (presumably winter and summer growth, respectively). If tied to trace elemental concentrations, striae could provide high-resolution sclerochronological proxies for seawater conditions. Here, we evaluate whether trace elements archived in A. colbecki striae can be used as seasonal indicators of glacial influence and nutrients over A. colbecki ontogeny. We examined trace elements from an adult and juvenile A. colbecki (shell height, 80.2 mm and 17.1 mm, respectively) collected live by divers from ~ 12 m water depth in Explorers Cove, western McMurdo Sound (2008 and 2016, respectively). Trace elements linked to glacial melt (Mg/Ca, Mn/Ca, Fe/Ca, and Pb/ Ca), metabolism (Mg/Ca), and productivity (Ba/Ca) were sampled with an LA-ICP-MS on each stria along the central growth axis of lower (right) valves from umbo to growing margin. Distances between sampled striae were measured along the central margin (FIJI). Interstrial distances (ISDs) and trace elements were compared using wavelet coherence analysis (Wavelet- Comp 1.1) and cross-correlation. Coherence and correlations that exceeded 95% significance are reported here. Coherence identifies areas of covariance between ISD and trace elements over ontogeny; cross-correlation describes the direction (±) of correlation between 113 NAPC 2019 PROGRAM & ABSTRACTS ISDs and trace elements where coherence exists. We expected trace elements that increase with glacial melt (Fe, Mn, Pb), productivity (Ba), and altered metabolism (Mg) to be coherent and correlate positively with ISD (highest concentrations at wide summer striae) throughout ontogeny. Preliminary results mostly do not conform to predictions. Though correlation remains consistently positive or negative under strong coherence, most elements are only coherent with ISD for short strial sequences (~ 8 striae) and only during adult growth. Of the elements associated with glacial melt, only Mn correlates positively with ISD and may be a potential proxy for seasonality. Other indicators of glacial melt (Pb/Ca, Fe/Ca) and productivity (Ba/Ca) correlate negatively with ISD. Mg/Ca correlates positively with ISD, indicating seasonal effects on metabolism. Ontogenetic variation in coherence urges cautious use of ISDs as proxies, but Pb/Ca (anthropogenic in Antarctica) is coherent with ISD throughout ontogeny; further analysis might illuminate seasonal effects of human activities on Antarctic ecosystems.  more » « less
Award ID(s):
1745057
NSF-PAR ID:
10214678
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
PaleoBios
Volume:
36
Issue:
0
ISSN:
0031-0298
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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