Invertebrate fossil correlation to climate trends in sediment core MD02-2504 from Santa Barbara Basin in the past 24 kyr

Miranda Stripe

Abstract

In the Southern California Bight, the upper reaches of minimally oxygenated waters rest at a depth of ~500 m. In such environments, invertebrate communities are adapted to low-oxygen levels and can exist due to annual oxygen replenishment events. Throughout the past 24 ka, oxygenation of this area fluctuated, with higher oxygenation occurring during glacial and stadial periods and hypoxic environments manifesting in interglacial and interstadial phases. To identify patterns between community structure and oxygen levels, I quantified invertebrate assemblages in Core MD02-2504 (481 m; Santa Barbara Basin, California, 34.23°N, 119.86°W) between 0.18-24.38 ka. These assemblages included ostracods, molluscs, and echinoderms. Molluscs were also identified to their lowest taxonomic groupings, where Lucinoma aequizonata and Astyris permodesta were the most abundant species within the core. Ostracod and mollusc densities increased with cooler, more oxygenated periods (e.g. the Last Glacial Maximum) and decreased in warmer, hypoxic intervals (e.g. the Bølling Allerød).

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