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Low-resolution profiles of Mg/Ca, Sr/Ca and Ba/Ca ratios along the maximum growth line of the mussel shell sample. (a) Low-resolution profile of Mg/Ca ratios along the growth line. The horizontal red line and vertical green line show a threshold value and the date of the great tsunami, respectively. Ovals show the data higher than the threshold. (b) Low-resolution profile of Sr/Ca ratios along the growth line. (c) Low-resolution profile of Ba/Ca ratios along the growth line. The simplified scales of the higher insolation (HI), higher temperature (HT), and lower tide period (double-edged arrow) are shown above the profiles. The periods of HI, HT, and lower tide were certified based on the threshold values in Figure 7.
Source publication
We report here hourly variations of Mg/Ca, Sr/Ca, and Ba/Ca ratios in a Mediterranean mussel shell (Mytilus galloprovincialis) collected at the Otsuchi bay, on the Pacific coast of northeastern Japan. This bivalve was living in the intertidal zone, where such organisms are known to form a daily or bidaily growth line comprised of abundant organic m...
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Citations
... In our data, Ba/Ca are most variable during these periods of elevated Mg/Ca and Sr/Ca. Ba/ Ca has been suggested as a potential proxy for riverine influx (Elliot et al., 2009) and primary productivity in Tridacna (Arias-Ruiz et al., 2017;Elliot et al., 2009;Hori et al., 2015) and other molluscs (Fröhlich et al., 2022;Gillikin et al., 2008;Marali et al., 2017), and short-term Ba/ Ca peaks have been introduced as indicators for storm events in Tridacna (Komagoe et al., 2018), and tsunamis in other mussels (Sano et al., 2021). During the rainy season, increased precipitation induces more run-off which increases nutrient availability for primary productivity, while the cloudy conditions and thus reduced solar irradiation inhibit primary productivity. ...
Giant clams (Tridacna) are well-suited archives for studying past climates at (sub-)seasonal timescales, even in
‘deep-time’ due to their high preservation potential. They are fast growing (mm-cm/year), live several decades
and build large aragonitic shells with seasonal to daily growth increments. Here we present a multi-proxy record
of a late Miocene Tridacna that grew on the western margin of the Makassar Strait (Indonesia). By analysing daily
elemental cycle lengths using our recently developed Python script Daydacna, we build an internal age model,
which indicates that our record spans 20,916 ± 1220 days (2 SD), i.e. ~57 ± 3 years. Our temporally resolved
dataset of elemental ratios (El/Ca at sub-daily resolution) and stable oxygen and carbon isotopes (δ18O and δ13C
at seasonal to weekly resolution) was complemented by dual clumped isotope measurements, which reveal that
the shell grew in isotopic equilibrium with seawater. The corresponding Δ47 value yields a temperature of 27.9
± 2.4 ◦C (2 SE) from which we calculate a mean oxygen isotopic composition of late Miocene tropical seawater of
− 0.43 ± 0.50 ‰. In our multi-decadal high temporal resolution records, we found multi-annual, seasonal and
daily cycles as well as multi-day extreme weather events. We hypothesise that the multi-annual cycles (slightly
above three years) might reflect global climate phenomena like ENSO, with the more clearly preserved yearly
cycles indicating regional changes of water inflow into the reef, which together impact the local isotopic
composition of water, temperature and nutrient availability. In addition, our chronology indicates that twice a
year a rainy and cloudy season, presumably related to the passing of the ITCZ, affected light availability and
primary productivity in the reef, reflected in decreased shell growth rates. Finally, we find irregularly occurring
extreme weather events likely connected to heavy precipitation events that led to increased runoff, high
turbidity, and possibly reduced temperatures in the reef.
... Based on aquaria and in situ experiments, Richardson et al. (1980) and Richardson (1987Richardson ( , 1988Richardson ( , 1989 identified a cyclic deposition of microgrowth bands in the shell of Cerastoderma edule, Ruditapes philippinarum and M. edulis, that was independent of the surrounding tidal regime, suggesting the role of an innate response. This driver, now widely described in the literature, refers to biological clocks and suggests their role in controlling the rhythm of shell increment formation (Schöne 2008;Warter et al., 2018;Sano et al., 2021;Louis et al., 2022). Biological clocks are molecular feedback loops that are set and reset by environmental factors (i.e. ...
Biomineralisation of bivalve shells raises questions at the level of genes to the final calcified product. For the first time, gene expression has been studied in association with growth increment deposition in the mussel Mytilus galloprovincialis. A short-term experiment highlighted that biomineralisation genes exhibit a rhythm of expression consistent with the observed tidal increment formation. Long-term mark-recapture experiments were conducted in three Mediterranean environments and revealed that the mussel shells harbour complex incrementation regimes, consisting of daily, tidal and a mixed periodicity of 1.7 growth increment.d-1 formed. The latter is likely related to the local tidal regime, although the mussels were continuously submerged and exposed to a small tidal range. The pattern of growth increments shifted from mixed to daily in Mediterranean lagoon, and to tidal at sea, probably linked to biological clocks. Based on our results and the literature, a hypothetical model for mussel shell increment formation in various habitats is proposed.
... The evaluation of the temporal interval of the analyzed cycles is crucial for successfully applying Daydacna. Other bivalves, for example, mussels, have shown semi-diurnal elemental cycles caused by semi-diurnal tidal influence (e.g., Sano et al., 2021). To analyze such samples using Daydacna, the expected time interval per cycle would need to be adapted. ...
... Ba/Ca in Tridacna has been proposed as an indicator of primary productivity (Arias-Ruiz et al., 2017;Elliot et al., 2009;Hori et al., 2015) and other mollusks (e.g., Fröhlich et al., 2022;Gillikin et al., 2008;Marali et al., 2017). Short and intense Ba/Ca peaks have also been connected to storm events in Tridacna (Komagoe et al., 2018) and Tsunamis in mussels (Sano et al., 2021). A higher variability during low growth (Figure 7) might indicate an increased storm activity during the rainy season, additionally impacting turbidity and nutrient availability through influx and resuspension and thus introducing higher variability in primary productivity. ...
Plain Language Summary
Shells of giant clams exhibit growth bands, similar to tree rings, which form in both seasonal (visible by eye) and daily (resolvable by microscope) increments. However, the optical visibility of daily bands in fossil giant clam shells can be poor. Fortunately, growth bands are often accompanied by changes in the chemical composition of the shell. The incorporation of trace elements into the shell depends on environmental factors (like temperature and light) and biological controls, which are both characterized by cyclic daily variation. With our Python script Daydacna, we present a tool that enables daily resolution scale changes in growth rate to be evaluated using daily geochemical cycle lengths, that is, how much the shell has grown each day. Daydacna then creates an internal age model and converts the respective element compositions from being expressed over distance to being expressed over time. This information enables an unambiguous estimate of growth rate to be compared to elemental compositions, enabling (e.g.) potential (co)dependencies of these parameters to be identified. Time‐resolved data also allow to determine the timing of seasonal environmental changes, affecting the shell composition, with higher confidence and thus form an important basis for research on the seasonal aspects of the (paleo)climate.