Marine heat waves are forecasted to increase in frequency and intensity under future climate scenarios, but little is known about the impact of these events on the one of the most commonly used proxies of ocean temperature - foraminiferal assemblages. This research explores the planktic foraminifera community along the Newport Hydrographic Line, a long-term monitoring transect (44.6*N) in the northeast Pacific (NEP). Foraminifera in samples from fall (August-October) research cruises between 2010- present were identified and counted to assess foraminiferal abundances and community composition. During this timeframe, two marine heatwaves (MHWs) impacted the region, most notably the ‘Warm Blob’ from 2014-2016 (Bond et al., 2015). Foraminifera assemblages are known to correlate with sea surface temperature and other hydrographic conditions (Kucera et al., 2007), but have not been studied in the context of NEP MHWs.
In 2014-2016, results demonstrate that the foraminifera assemblage shifted from the typical polar, subpolar, and transitional species typically seen during colder years to warmer water subtropical and tropical species. Colder water species returned after the MHW dissipated in 2016. During a second MHW in 2019, which was of similar magnitude but shorter duration, the community shifted again from a cold to warm water assemblage but did not include tropical species. These results suggest that the planktic foraminifera might be useful as ecosystem indicators of transient environmental change and could also provide insight into the paleorecord of warm water events in NEP sediments.
Funding Statement (additional comments about funding)
This research and my education were funded by the National Science Foundation Graduate Research Fellowship, the OSU Provost Fellowship, Dawn Wright through the Lydia Dept. Dog Memorial Endowment, and Caron and Larry Ogg who generously supported me as an ARCS Scholar