Data from: Differential drivers of benthic foraminiferal and molluscan community composition from a multivariate record of Early Miocene environmental change

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 (20.26–18 Ma), using proxies for temperature (δ18O), productivity (δ13C), organic carbon flux (Δδ13C), oxygenation (δ15N), 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 δ15N values are the most parsimonious correlates with major changes in foraminiferal composition, whereas molluscan composition is most closely related to δ13C 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.SupplementalTable1Supplemental Table 1. Proportional abundances of foraminifera from 58 samples from Newport Member of the Astoria Formation with sample age, DCA site scores used in this paper, and MDS, NMDS and CA site scores for comparison. NMDS analyses were done with three axes and at a stress of 10.28. * denotes which foraminiferal samples were selected to more directly compare to the molluscan data.SupplementalTable2Supplemental Table 2. Proportional abundances of molluscs from 18 samples from the Newport Member of the Astoria Formation with sample age, DCA site scores used in this paper, and PCO, NMDS, and CA site scores for comparison. NMDS analyses were done with two axes and at a stress of 8.57.SupplementalTable3Supplemental Table 3. Foraminifera species identified in the Newport Member of the Astoria Formation with life habit information and DCA species scores. Life habit assignments are based on modern congenerics and are from Murray (1991, 2006).SupplementalTable4Supplemental Table 4. Molluscan species identified in the Newport Member of the Astoria Formation with life habit information and DCA species scores. Trophic group assignment made following Todd (2001). Taxonomy follows Moore (1963). Modern water depth distributions are given where possible and follow Keen (1937).SupplementalTable5Supplemental Table 5. Environmental proxy data from 36 samples where all proxies were available, PCA site scores used to examine environmental gradients this paper, and NMDS ordination scores based on the Euclidian distances among sites from proxy data for comparison. * denotes environmental data associated with foraminiferal samples that were selected to more directly compare to the molluscan data.SupplementalTable6Supplemental Table 6. Nitrogen isotope values measured from bulk sediment