Historical and modern distributions of benthic foraminifers on the continental shelf of Monterey Bay, California

Historical (early 1930s) and modern samples provide a detailed account of the spatial distribution of benthic foraminifers on the continental shelf of Monterey Bay, California. Ten species among a total of 110 present dominated the 110 samples investigated in the historical study. A cluster analysis of the foraminiferal abundances in the historical study identified five assemblages: Inner Shelf, Middle Shelf, Outer Shelf, Southeastern Shelf and Southwestern Shelf. Specimens with calcareous tests were most prevalent in all the assemblages. A cluster analysis of the modern foraminiferal frequencies from 95 samples also defined five assemblages: Inner Shelf, Middle Shelf, Middle/Outer Shelf Arenaceous, Outer Shelf, and Southern Shelf. Although arenaceous taxa dominate much of the modern fauna, the spatial distribution of the modern assemblages is similar to that of the historical record when presumably unrecognized taxa are eliminated from the data. Both the historical and, to a greater degree, the modern foraminiferal assemblages exhibit a strong correlation with the sediment grain size distribution.