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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 57 (1973)

Issue: 4. (April)

First Page: 784

Last Page: 784

Title: Food Supply--Limiting Factor of Foraminiferal Populations: ABSTRACT

Author(s): Alfred M. Hirsch, David Govoni

Article Type: Meeting abstract


The standing crop of benthonic Foraminifera declines during the fall and increases during the early spring in Great Bay, New Jersey. Population sizes correlate with seasonal variations in phytoplankton and particulate organic carbon abundances, but do not correlate with changes in temperature or salinity or with differences in substrate textures.

Foraminiferal populations at 7 stations were repeatedly examined from the head to the mouth of the bay. The substrate ranged from a silty clay to a shelly, gravelly sand. Maximum salinity-temperature range within the bay on any sampling day never exceeded 8 ^pmil or 2°C, although salinities and temperatures varied from a maximum of 31 ^pmil and 26°C in late summer to a minimum of 10 ^pmil and 0°C in mid-winter, respectively.

The foraminiferal fauna is a typical midlatitude estuarine assemblage. The dominant species differ among stations and appear to be controlled by substrate texture and salinity; however, the standing crop at all stations exhibits a consistent seasonal variation. The live percentage of the total foraminiferal population decreases by more than 30% in the fall and winter and increases more than 10% in late winter-early spring. The decrease coincides with a decrease in chlorophyll a, but not with any marked change in temperature or salinity. In early March the increase coincides with an increase in chlorophyll a or particulate organic carbon, although temperatures in the bay are 5-6°C and salinities are depressed by runoff. The dominant zooplankton, copepods and nauplius larvae, as de ermined by others, exhibit a similar seasonal pattern.

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