Structural and Elemental Analysis of the Freshwater, Low-Mg Calcite Coralline Alga Pneophyllum cetinaensis

Ragazzola, Federica; Kolzenburg, Regina; Zekonyte, Jurgita; Teichert, Sebastian; Jiang, Chulin; Žuljević, Ante; Caragnano, Annalisa; Falace, Annalisa

doi:10.3390/plants9091089

Cited by 7 publications

(3 citation statements)

References 62 publications

(80 reference statements)

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“…This trend is puzzling because a higher Mg/Ca ratio in oysters would increase solubility (Bischoff, Mackenzie & Bishop, 1987), exacerbating dissolution in low-salinity waters with low Ω CaCO3 . As previously suggested for high-magnesium coralline algae (Ragazzola et al ., 2020), a higher substitution rate of Mg 2+ for Ca 2+ might be a consequence of a general lack of Ca 2+ (Thomsen et al ., 2018). In our oysters, this trend appears to be compensated by increased deposition of protein-enriched, inter-crystalline OM (Fig.…”

Section: Discussionsupporting

confidence: 79%

Biomineralization and biomechanical trade-offs under heterogeneous environments in the eastern oysterCrassostrea virginica

Telesca,

Linsley,

Witek

et al. 2023

Preprint

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Accurate biological models are critical to reliably predict vulnerability of marine organisms and ecosystems to rapid environmental changes. Current predictions on the biological impacts of climate change and human-caused disturbances primarily stem from controlled experiments but lack assessments of the mechanisms underlying biotic variations in natural systems. Such information is key to translating experimental models to natural populations, especially for habitat-forming, climate sensitive species with key ecological roles. This study aimed to characterize and quantify spatial patterns of shell biomineralization and biomechanical properties in a key reef-building oyster,Crassostrea virginica, collected from restored reefs along natural estuarine gradients in the Hudson River Estuary (NY, U.S.). We characterized patterns of oyster shell production (i.e., shape and thickness), structure (i.e., abundance of foliated and chalky calcite), mineralogy (i.e., crystal size and density), composition (i.e., organic matrix and Mg/Ca ratios), and mechanical performance (i.e., elastic modulus and hardness) at the macro and micro scale. Our results demonstrate a strong protective capacity ofC. virginicafor compensatory adjustments in shell biomineralization and biomechanics to maintain shell production and protective functions as a response to biotic and abiotic stressors. We reveal salinity as a key predictor of oyster shell structure, mechanical integrity, and resistance to dissolution, and describe the functional role of chalky calcite in shaping shell mechanical performance. Compensatory adjustments along salinity gradients indicate that oysters produce shells withi) high mechanical resistance but increased vulnerability to dissolution under marine conditions, andii) lower structural integrity but higher protection from dissolution under brackish conditions. Our work illustrates that biomineralization and biomechanical adjustments may act as compensatory mechanisms in eastern oysters to maintain overall performance under heterogeneous estuarine environments, and could represent a cornerstone for calcifying organisms to acclimate and maintain their ecological functions in a rapidly changing climate.

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Section: Discussionsupporting

confidence: 79%

Biomineralization and biomechanical trade-offs under heterogeneous environments in the eastern oysterCrassostrea virginica

Telesca,

Linsley,

Witek

et al. 2023

Preprint

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“…One of the possible explanations for the survival of coralline algae is that their biomineralogical control is limited to polymorph specification and would be ineffectual in the regulation of skeletal Mg incorporation 51 . In this sense, in past geological eras, such as the Cretaceous and Paleogene, the Mg/Ca ratio of the oceans favors the precitation of low Mg calcite 29 , 52 , which are more stable to dissolution. In a parallel to present day, other fundamental aspect we should take into account is the speed of progression of these changes.…”

Section: Discussionmentioning

confidence: 99%

Global assessment of coralline algae mineralogy points to high vulnerability of Southwestern Atlantic reefs and rhodolith beds to ocean acidification

Carvalho

Rocha

Karez

et al. 2022

Sci Rep

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Coralline algae constitute one of the main groups of highly vulnerable calcified benthic organisms to ocean acidification. Although damaging effects of seawater acidification on the coralline algae skeleton have been widely demonstrated, the susceptibility to dissolution varies according to the Mg2+ in the calcite lattice. Even though the Southwest Atlantic Ocean exhibits the world’s largest rhodolith beds, which occupies 20,902 km2, there is no information regarding the coralline algae species mineralogy in this area. Here, we provide mineralogical data of twenty-four coralline algae species, examine the similarity in taxonomic groups, spatial occurrence and the vulnerability of these algae to seawater acidification. Mineralogy revealed that coralline algae skeletons were mainly composed of high-Mg calcite (> 70%) with minor presence of aragonite (< 30%) and dolomite (< 3%). There were no similarities between the skeletal mineralogy of taxonomic groups and sampling regions. Remarkably, the mean Mg-substitution of encrusting coralline algae from the Brazilian Shelf was 46.3% higher than global average. Because of the higher mean Mg-substitution in calcite compared with worldwide coralline algae, these algae from Southwest Atlantic Ocean would be highly susceptible to dissolution caused by the expected near-future ocean acidification and will compromise CaCO3 net production across the Brazilian Shelf.

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“…Following this principle, Mg/Ca ratios in CCAs have been used for temperature reconstruction in long living and subfossil marine species [6,7]. It has been estimated that the Mg content in CCA varies between 7.7 to 28.8 MgCO 3 (mol%) [8] depending on the region they live in [9,10]. Due to the higher solubility of high-Mg calcite, the calcified thallus of CCA is more vulnerable to ocean acidification especially in cold water environments such as polar regions where the water naturally has a lower saturation state, and higher solubility of CO 2.…”

Section: Introductionmentioning

confidence: 99%

Structural and Geochemical Assessment of the Coralline Alga Tethysphytum antarcticum from Terra Nova Bay, Ross Sea, Antarctica

et al. 2023

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Crustose coralline algae (CCA) occur from the tropics to the poles in photic benthic environments. Here, we report on some of the world’s southernmost and coldest CCA sites in Terra Nova, Ross Sea, Antarctica at 74°41′ S. The recently described red alga Tethysphytum antarticum is investigated for its skeletal architecture, its mineralogical and geochemical composition, as well as for its taxonomic classification. A phylogenetic analysis based on molecular genetics and the sequencing of the photosystem II protein D1 (psbA) gave a perfect match with T. antarcticum. Histological sections and micro-CT-scans provide new diagnostic details for the conceptacles (the reproductive organs of the alga). X-ray diffractometry and electron-microprobe measurements yielded a clear high-Mg calcite (~8 mol%) composition of the skeletal parts. Detailed back-scattered electron imaging of polished petrographic thin sections revealed a two-layered thallus (vegetative plant tissue), comprising an organic-rich irregularly calcified basal layer with rectangular cells, overlain by the main thallus. Elemental maps show relatively increased sulphur in the basal layer, clearly tied to organic cell walls. MgCO3 and SrCO3 were targeted with semiquantitative elemental mappings and in an ontogenetic quantitative spot transect. Compared with temperature (−1.95 °C to +1.08 °C), the MgCO3 (mol%) reflects this world’s coldest CCA site temperature with the lowest MgCO3 content of 7.9 ± 1.6 mol%. The along transect variability, however, shows with ~6 mol% a larger MgCO3 variability than expected for the 3 °C intra-annual temperature amplitude in Terra Nova Bay. This implies that in low amplitude settings the biomineralisation control on Mg/Ca ratios can outcompete its temperature sensitivity. Mark-recapture studies, next to the environmental logger station La Zecca are suggested, to perform a detailed growth rate and biomineralisation quantification.

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Structural and Elemental Analysis of the Freshwater, Low-Mg Calcite Coralline Alga Pneophyllum cetinaensis

Cited by 7 publications

References 62 publications

Biomineralization and biomechanical trade-offs under heterogeneous environments in the eastern oysterCrassostrea virginica

Biomineralization and biomechanical trade-offs under heterogeneous environments in the eastern oysterCrassostrea virginica

Global assessment of coralline algae mineralogy points to high vulnerability of Southwestern Atlantic reefs and rhodolith beds to ocean acidification

Structural and Geochemical Assessment of the Coralline Alga Tethysphytum antarcticum from Terra Nova Bay, Ross Sea, Antarctica

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