Data from: Ecological and environmental stability in offshore Southern California Marine Basins through the Holocene

In the face of ongoing marine deoxygenation, understanding timescales and
drivers of past oxygenation change is of critical importance. Marine
sediment cores from tiered silled basins provide a natural laboratory to
constrain timing and implications of oxygenation changes across multiple
depths. Here, we reconstruct oxygenation and environmental change over
time using benthic foraminiferal assemblages from sediment cores from
three basins across the Southern California Borderlands: Tanner Basin
(EW9504-09PC, 1194 m water depth), San Nicolas Basin (EW9504-08PC, 1442
m), and San Clemente Basin (EW9504-05PC ,1818 m). We utilize indicator
taxa, community ecology, and an oxygenation transfer function to
reconstruct past oxygenation, and directly compare reconstructed dissolved
oxygen to modern measured dissolved oxygen. We generate new, higher
resolution carbon and oxygen isotope records from planktic (Globigerina
bulloides) and benthic foraminifera (Cibicides mckannai) from Tanner
Basin. Geochemical and assemblage data indicate limited ecological and
environmental change though time in each basin across the intervals
studied. Early to mid-Holocene (11.0-4.7 ka) oxygenation below 1400 m (San
Clemente and San Nicolas Basins) was relatively stable and reduced
relative to modern. San Nicolas Basin experienced a multi-centennial
oxygenation episode from 4.7-4.3 ka and oxygenation increased in Tanner
Basin gradually from 1.7-0.8 ka. Yet across all three depths and time
intervals studied, dissolved oxygen is consistently within a range of
intermediate hypoxia (0.5-2.0 ml L-1 O2). Variance in reconstructed
dissolved oxygen was similar to decadal variance in modern dissolved
oxygen and reduced relative to Holocene-scale changes in shallower basins.