Spatiotemporal variability of benthic and planktonic foraminifera off the coast of San Diego
Foraminifera are abundant in the marine environment and useful indicators of past and future climate change. However, there is no recent work on variation in fossil foraminiferal communities between 100-300m depth on the shelves of the California Continental Borderland, or measurable changes in fora...
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| Format: | Text |
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Digital USD
2022
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| Online Access: | https://digital.sandiego.edu/osp-researchweek/2021/ccurc/6 https://digital.sandiego.edu/cgi/viewcontent.cgi?article=1297&context=osp-researchweek |
| Summary: | Foraminifera are abundant in the marine environment and useful indicators of past and future climate change. However, there is no recent work on variation in fossil foraminiferal communities between 100-300m depth on the shelves of the California Continental Borderland, or measurable changes in foraminiferal communities over time or cyclical events. The goal of my research was to characterize fossil foraminiferal assemblages on shelves off San Diego to examine variability with water depth and dissolved oxygen over an 11-year time series. Samples were collected using a multicorer from three sites at 100-300 m depth on annual research cruises from 2001-2011. Planktonic and benthic foraminifera were extracted by sieving the upper 1 cm from each sample. Foraminifera were picked and mounted on slides for community analysis. At least 300 specimens from each sample were examined under a microscope and percent abundance of species was calculated. The most abundant planktonic foraminifera were Globigerinoides and Orbulina, and the most abundant benthic foraminifera were Cassidulina, Globo-cassidulina, Bolivina, Bulimina, and Cibicidoides. All foraminifera genera were observed at all stations, but at the shallowest station, Bolivina was most abundant, while Globo-cassidulina was most abundant at the deepest station. No temporal change was seen in the planktonic foraminifera community. In the benthic foraminifera community, spatial variability was consistent from 2001-2008, but relative abundance of Cassidulinain deeper stations increased in 2010. We observed a direct correlation between percent Bulimina and bottom dissolved oxygen. There was no change in community composition through time, likely due to sediment mixing. |
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