188-3 Investigating the response of Glycymeris septentrionalis (Bivalvia) and Terebratalia transversa (Brachiopoda) to euxinia: implications for mass extinctions

Session: Linking Biodiversity Loss to Environmental Stressors Through Integrated Approaches (Posters)

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In the wake of the end-Permian mass extinction, bivalves replaced articulate brachiopods as the dominant filter-feeders of the benthic marine realm, despite morphological and ecological similarities. Several theories have been raised to explain the extinction’s selectivity, including competition, ocean acidity, CO₂ poisoning, and reproductive potential. The spread of sulfidic water masses (euxinia) has been proposed several times as a general kill mechanism but its physiological selectivity has not been investigated. Laboratory survival studies of a bivalve (Glycymeris septentrionalis) and an articulate brachiopod (Terebratalia transversa) sourced locally from Friday Harbor, San Juan Island, WA, were carried out in controlled anoxic and euxinic environments at 13.7, 16, and 22 °C. Bivalves generally outperformed brachiopods in all scenarios, and by a greater margin in euxinia. The alignment between physiological tolerance in experimental settings and survival patterns in the paleontological record indicates that euxinia may have played a role in end-Permian extinction severity and selectivity, serving as an additional stressor in already warm, oxygen-depleted oceans.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6244

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