Paper No. 0
Presentation Time: 1:45 PM
THE INFLUENCE OF PRIMARY PRODUCTIVITY AND SEASONALITY OF PRODUCTIVITY ON DEEP-SEA BENTHIC FORAMINIFERA
CORLISS, Bruce H.1, SUN, X.
1, BROWN, Christopher W.
2, MCCORKLE, Daniel C.
3, SHOWERS, William J.
4 and HIGDON, David M.
5, (1)Earth and Ocean Sciences, Duke Univ, Durham, NC 27708-0229, (2)NOAA, Camp Springs, MD 20746, (3)Dept. of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 27712, (4)Dept. of Marine, Earth and Atmospheric Sciences, N.C. State Univ, Raleigh, NC 27695, (5)Institute of Statistics and Decision Sciences, Duke Univ, Durham, NC 27708, bruce.corliss@duke.edu
The effect of spatial and temporal variability of primary productivity on the
d13 C of North Atlantic deep-sea benthic foraminifera has been investigated in two related studies. The first study is based on living (Rose Bengal stained) specimens of
Hoeglundina elegans collected over a one-year interval at a 3010m site south of Nantucket Island. Carbon isotopic data taken over a 10-month interval (March, May, July, October, 1996, January, 1997) were compared with an 11.5-month time-series of organic carbon from a sediment trap to assess the effect of variation of organic carbon flux. The
d13 C data show a 0.3 lower mean value following an organic carbon maximum resulting from a spring phytoplankton bloom. This change is suggested to be due to the presence of a phytodetritus layer on the seafloor and the subsequent depletion of
d13 C in the porewaters within the phytodetritus.
In a related study, the d13 C of Holocene benthic foraminifera from 45 core tops from 0-62oN in the Atlantic were studied and compared with satellite-derived primary productivity and seasonality. The d13 C of Epistominella exigua show a ~ 1 decrease over 60 degrees of latitude, with the data correlating with overlying primary productivity, organic carbon flux, and seasonality. This significant depletion of d13 C of E. exigua is attributed to the seasonal presence of phytodetritus over a large portion of the North Atlantic. No relationships were found between the d13 C of Planulina wuellerstorfi and primary productivity, organic carbon flux, or seasonality. These observations demonstrate that (i) variation in the spatial and temporal pattern of organic carbon affects the d13 C of certain deep-sea taxa, (ii) carbon isotopic data of E. exigua may be potentially useful in reconstructing organic carbon flux and primary productivity, and (iii) the d13 C of P. wuellerstorfiin the North Atlantic is unaffected by organic carbon flux and reflects the d13 C of the bottom waters.
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