A 2,000-year-long record of reproduction in Santa Barbara Basin benthic foraminifera

This dataset accompanies a submission to Proceedings of the Royal Society B entitled "A nineteenth and twentieth century reproductive regime shift in benthic foraminifera from the Santa Barbara Basin, California." The dataset includes measurements of individual reproductive life history traits for 20,293 individuals. Specifically, these are reproductive mode (megalospheric or microspheric, via the the size of the proloculus, or first chamber) and accumulation rate (a time- and area-normalized test count). Paper Abstract: Long-term records that span the past several centuries and capture within-population variation are critical for distinguishing ephemeral ecosystem changes from regime shifts. Using a ~2 kyr record of reproductive life history from the central Santa Barbara Basin, we examined population trends in reproductive mode and accumulation rate (i.e., reproductive output) across four species in the biserial benthic foraminiferan genus Bolivina. Bolivina populations were consistently dominated by asexually-produced individuals until the mid-nineteenth century, after which they exhibit an increase in variance and decrease in mean proportion of asexualy-produced individuals. At the same time, they rundergo an order-of-magnitude decline in accumulation rate. The magnitude and persistence of these changes suggests that the nineteenth and twentieth century represent a life history regime shift. Compounding effects of anthropogenic impacts and long-term trends in the California Current system (such as heightened deoxygenation and altered sedimentation regimes) may have pushed Santa Barbara Basin towards increased investment in sexual reproduction.