Interpreting life-history traits, seasonal cycles, and coastal climate from an intertidal mussel species: Insights from 9000 years of synthesized stable isotope data

Abstract

Understanding past coastal variability is valuable for contextualizing modern changes in coastal settings, yet existing Holocene paleoceanographic records for the North American Pacific Coast commonly originate from offshore marine sediments and may not represent the dynamic coastal environment. A potential archive of eastern Pacific Coast environmental variability is the intertidal mussel species Mytilus californianus. Archaeologists have collected copious stable isotopic (delta O-18 and delta C-13) data from M. californianus shells to study human history at California's Channel Islands. When analyzed together, these isotopic data provide windows into 9000 years of Holocene isotopic variability and M. californianus life history. Here we synthesize over 6000 delta O-18 and delta C-13 data points from 13 published studies to investigate M. californianus shell isotopic variability across ontogenetic, geographic, seasonal, and millennial scales. Our analyses show that M. californianus may grow and record environmental information more irregularly than expected due to the competing influences of calcification, ontogeny, metabolism, and habitat. Stable isotope profiles with five or more subsamples per shell recorded environmental information ranging from seasonal to millennial scales, depending on the number of shells analyzed and the resolution of isotopic subsampling. Individual shell profiles contained seasonal cycles and an accurate inferred annual temperature range of similar to 5 degrees C, although ontogenetic growth reduction obscured seasonal signals as organisms aged. Collectively, the mussel shell record reflected millennial-scale climate variability and an overall 0.52 parts per thousand depletion in delta O-18(shell) from 8800 BP to the present. The archive also revealed local-scale oceanographic variability in the form of a warmer coastal mainland delta O-18(shell) signal (-0.32 parts per thousand) compared to a cooler offshore islands delta O-18(shell) signal (0.33 parts per thousand). While M. californianus is a promising coastal archive, we emphasize the need for high-resolution subsampling from multiple individuals to disentangle impacts of calcification, metabolism, ontogeny, and habitat and more accurately infer environmental and biological patterns recorded by an intertidal species.

Publisher

Public Library Science

Publication Date

5-22-2024

Publication Title

PLOS ONE

Department

Geology

Document Type

Article

DOI

https://dx.doi.org/10.1371/journal.pone.0302945

Keywords

Santa-Cruz Island, California current system, Within-site variation, Mytilus-californianus, Time-series, Southern California, Change impacts, Growth-rates, Holocene climate, Oxygen isotopes

Language

English

Format

text

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