Biomineralization and biomechanical trade-offs under heterogeneous environments in the eastern oyster Crassostrea virginica.

This article focuses on how the eastern oyster, *Crassostrea virginica*, adjusts shell biomineralization and biomechanical properties across natural estuarine salinity gradients in the Hudson River Estuary (New York, USA). The study demonstrates that salinity is a key environmental driver influencing oyster shell thickness, microstructure, organic matrix composition, and mechanical performance, with oysters producing thicker, mechanically stronger shells with more chalky calcite under higher salinity and thinner, more brittle shells with higher chemical protection under lower salinity. These macro- and microscale shell trait variations reflect compensatory mechanisms balancing physical protection against predation and chemical resistance to dissolution, enabling oysters to maintain ecological functions amid heterogeneous and changing estuarine conditions. The findings highlight the importance of natural environmental complexity in shaping biomineralization responses and suggest that such plasticity may be critical for calcifying organisms’ resilience to climate-driven estuarine changes.