Differential drivers of benthic foraminiferal and molluscan community composition from a multivariate record of early Miocene environmental change Academic Article uri icon

abstract

  • Climate changes are multivariate in nature, and disentangling the proximal drivers of biotic responses to paleoclimate events requires time series of multiple environmental proxies. We reconstruct a multivariate time series of local environmental change for the early Miocene Newport Member of the Astoria Formation (20.2618 Ma), using proxies for temperature (18O), productivity (13C), organic carbon flux (13C), oxygenation (15N), and sedimentary grain size (% mud). Our data suggest increases in productivity and declines in oxygenation on the Oregon shelf during this interval of global warming. We evaluate the association of individual environmental factors, and combinations of factors, with changes in faunal composition observed in benthic foraminiferal and molluscan communities collected from the exact same sediments as the environmental data. The 15N values are the most parsimonious correlates with major changes in foraminiferal composition, whereas molluscan composition is most closely related to 13C values, suggesting that different components of the environment are influencing each group. When the proxies that have the best supported relationships with the faunal gradients are removed from the analyses to simulate the absence of those proxy data, significant relationships between the faunal gradients and the remaining environmental proxies can still be found. This suggests that environmental drivers can be incorrectly attributed to faunal changes when key proxy data are missing. Paleoecological studies of biotic response that test multiple environmental drivers for multiple taxonomic groups are powerful tools for identifying the ecological consequences of past warming events and the regional drivers of ecological changes.

published proceedings

  • PALEOBIOLOGY

altmetric score

  • 1.1

author list (cited authors)

  • Belanger, C. L., & Garcia, M. V.

citation count

  • 9

complete list of authors

  • Belanger, Christina L||Garcia, Marites Villarosa

publication date

  • January 2014