MOCNESS plankton tows, sediment traps and sedimentary material are used to determine
the linkage between bio-physical forcing and foraminiferal response over a range of time
scales from the event scale to the glacial interglacial cycle. The annually averaged planktic
foraminiferal fauna of the modem California Current is a diverse community composed of
individuals from subarctic, transitional, and subtropical foraminiferal assemblages. This
community is more diverse, but less abundant in total standing stock and shell flux than the
subarctic community of the Gulf of Alaska. The use of plankton tow and isotopic data
allow us to partition the foraminiferal community into shallow dwelling euphotic zone
species and deep dwelling sub-thermocline species. On both the event and seasonal time
scales, heterotrophic species were most abundant in cold, biomass rich coastal waters. In
contrast, species which harbored endosymbionts were more abundant in oligotrophic
waters with higher ambient light levels. During the Last Glacial Maximum (LGM), the
diverse modern fauna was replaced with a low diversity, high flux, heterotrophic
community similar to that of the modern Gulf of Alaska. Modern analog temperature
estimates suggest the California Current was roughly 3��C cooler during the LGM than
today. Coupled with oxygen isotopic results from G. bulloides, the surface thermal
structure implies an equatorward flowing glacial California Current at these sites. The
Polar Front thus remained north of these locations during the LGM. Comparison of glacial
G. bulloides carbon isotopes and shell accumulation rates with organic carbon flux
estimates implies the glacial California Current was (1) higher in nutrient content, (2) lower
in plankton biomass, and (3) lower in export carbon flux than its modem counterpart. This
description suggests that during the LGM the plankton community of the California Current
was very similar to the modern plankton community of the Gulf of Alaska. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/23528 |
| Date | 02 May 1995 |
| Creators | Ortiz, Joseph D. |
| Contributors | Mix, Alan C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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