Coherent tracer correlations in deep-sea corals and implications for biomineralization mechanisms underlying vital effects

Correlative geochemical imaging of Desmophyllum dianthus reveals biomineralisation strategy as a key coral vital effect

“…5 ). Consistent with several previous studies 16 , 20 , a simple closed system Rayleigh-type fractionation model for the incorporation of elements into the skeletal aragonite (see Materials and Methods) can broadly replicate the arrays seen in the fibrous aragonite data, suggesting Rayleigh fractionation has an important role to play in causing compositional variation within the fibrous components of coral skeletons. Rayleigh models do not replicate the COC data as well, suggesting such fractionation has less of a role in the compositional variation within the COC components; a conclusion that aligns with previous work 16 .…”

“…4 ). For instance, we see elevated Li/Ca and Mg/Ca in the COCs compared to surrounding fasciculi 13 , 15 – 20 (see Supplementary Figure S2 for a comparison to data from Chen et al 20 ). In contrast to Shirai et al 24 and Gagnon et al 16 , but similar to others 21 – 23 , we see Sr/Ca is elevated in the COC, while B/Ca, U/Ca, and δ 11 B are lower compared to the fasciculi, consistent with numerous studies 25 – 27 , 29 , 39 but not Stewart et al 19 .…”

“…Previous studies have documented a suite of geochemical differences between these structural elements. For instance, elevated Li/Ca and Mg/Ca in the COCs compared to surrounding fasciculi (the fibrous crystals) has been documented previously in both deep-sea and tropical coral species, including D. dianthus , Lophelia pertusa , Porites clavus , and Porites lobata 13 , 15 – 20 ; elevated Ba/Ca has also been reported in the COCs of some tropical corals compared to the fasciculi 15 ; Sr/Ca is typically, but not always, enriched in COCs 16 , 19 , 21 – 24 ; whilst B/Ca, U/Ca, δ 13 C, and δ 11 B, are typically lower within the COCs compared to the fasciculi 19 , 20 , 25 – 29 . Adkins et al 28 also documented an additional δ 18 O depletion in COCs compared to the δ 13 C-δ 18 O trends defined by the fibres, although subsequent studies seem to have failed to replicate this finding 20 .…”

“…Obtaining geochemical information isolating just a single component has proven very difficult in previous studies (e.g. by micro-milling powders 19 , 20 ), but by combining this with established approaches using the boron-based tracers of calcifying fluid composition (pH and [CO 3 2− ] 40 ; Materials and Methods), we provide novel insights into the mechanisms of biomineralisation in the skeleton of the stony deep-sea coral Desmophyllum dianthus .

Figure 1 D. dianthus DY081-914DD: ( a ) removal of septa from specimen for both bulk solution geochemistry (Stewart et al .

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A Perspective on Probing Coral Resilience to Climate and Environmental Changes Using Stable Isotopes of Bio‐Utilized Metal Elements

“…Lastly, but certainly not least, it is imperative to frame our understanding of metal stable isotopes fractionation in various parts of the coral within the context of coral biomineralization models. Such models are invaluable for interpreting the composition and distribution of trace elements in coral skeletons (Chen et al., 2023; Marchitto et al., 2018). Therefore, we can draw on these models and explore metal stable isotopes fractionation in the coral biomineralization process by developing new models.…”