Mapping of recent brachiopod microstructure: A tool for environmental studies

Area of Science:

• Paleontology
• Geochemistry
• Marine Biology

Background:

• Brachiopod shells serve as valuable archives for reconstructing past environments.
• Shell microstructure and geochemistry are sensitive to climate and environmental changes.
• Understanding these relationships is key to accurate paleoenvironmental reconstructions.

Purpose of the Study:

• To develop a model correlating brachiopod shell microstructural patterns with environmental conditions.
• To investigate the morphology and size of secondary layer fibers in extant brachiopod taxa.
• To assess the influence of environmental factors on shell microstructure.

Main Methods:

• Microstructural analysis using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Electron Backscatter Diffraction (EBSD).
• Examination of shell samples from six extant brachiopod species across diverse environmental settings.
• Comparative analysis of fiber morphology and size in relation to age and environmental parameters.

Main Results:

• No significant difference in fiber morphology between ventral and dorsal valves.
• An ontogenetic trend was observed: fibers become larger, wider, and flatter with increasing age.
• A relationship was identified between fiber characteristics and environmental conditions (temperature, carbonate saturation state) in two species of the same genus.

Conclusions:

• The fibrous layer's morphostructure and organic content vary with age, impacting its suitability for geochemical analyses.
• Brachiopod shell microstructure, particularly fiber size and shape, is linked to ambient seawater temperature and calcite saturation state.
• This study provides a model for using brachiopod shell microstructure in paleoenvironmental reconstructions.