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Monterey Bay Studies

Monterey Bay Studies


Monterey Bay National Marine Sanctuary Project, 1999

Early 20th Century Record of Microscopic Organisms (Foraminifers) in Monterey Bay, California

by Mary McGann


In 1930-31, E. Wayne Galliher of Stanford University collected bottom samples from Monterey Bay, California in order to describe the nature and geographic distribution of the sediments in the region. Recently, archived assemblage slides of the microscopic organisms (benthic and planktic foraminifers) obtained from these sediment samples were located and the benthic species analyzed for faunal composition. Although no information is available regarding the method by which the foraminifers were extracted from his samples, it appears that they were picked in relative proportion to their total occurrence in the samples. If true, their abundances can be compared to those of foraminifers from sediment samples recovered by the USGS from the shelf of Monterey Bay over 60 years later (1995 and 1997). The foraminifers of Galliher's 1930s samples fall into five groups, or biofacies: nearshore, mid-shelf, outer shelf, and two from the southern portion of the shelf from Fort Ord to Pt. Pinos. All of the assemblages are dominated by specimens with calcareous shells. In contrast, five out of seven of the foraminiferal assemblages from the late 1990s samples are dominated by arenaceous shells composed of sand and mineral grains. It is possible that these arenaceous specimens were not included in the 1930s data set simply because they were not picked or because they were not even recognized as foraminifers. Considering this omission, it is surprising that the geographic distribution of the seven biofacies defined by the 1990s data is in general agreement with that of the 1930s, although it is somewhat more complex.

This abstract is from Monterey Bay National Marine Sanctuary Symposium, Sanctuary Currents '99, Climate Change and the Sanctuary, Poster Session, 1999.

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