Gulf of Maine carbon budgets have not included estimates of calcification r
ates and the flux of calcite to the sediments, processes which are thought
to rival organic production in terms of carbon ultimately buried in the sed
iments. Measurements of inorganic (calcification) and organic (photosynthet
ic) carbon production were made in March, June, and November of 1996 throug
hout the Gulf of Maine and Georges Bank. Photosynthetic rates ranged from 1
.3-182 mg C m(-3) d(-1), and calcification rates from 0-9.3 mg C m(-3) d(-1
), for all depths and locations sampled. June calcite production integrated
over the euphotic zone (based on 17 profiles of 6 depths) averaged 5% of t
otal carbon production, or 26 mg C m(-2) d(-1). Calcite (inorganic C) produ
ction in June was > 10% of total C production over deeper areas such as Wil
kinson Basin, the Northeast Channel, and the shelf break. This ratio was lo
west (1.3%) in tidally mixed, high-nutrient regions near Cape Sable and the
Bay of Fundy, where diatoms were abundant and euphotic zone nitrate concen
trations exceeded 2.2 mu M. The turnover time of calcite particles in the w
ater column, estimated from calcite production rates and suspended calcite
concentrations, averaged 11.8 days in June and nearly 200 days in November,
when calcite standing-stocks were high and calcification rates relatively
low. Advective loss of calcite from the Gulf before settling is likely with
long turnover times. Yearly carbon production for the Gulf of Maine was es
timated at 182 g m(-2) organic C and 3.7 g m(-2) inorganic C, in the absenc
e of an E. huxleyi bloom. If 1% of the organic carbon produced were buried
in sediments, and 50% of the inorganic carbon, the result would be an appro
ximately equal amount of each deposited in Gulf sediments. Inorganic carbon
production by coccolithophores may therefore be an important contributor t
o Gulf and slope sediments, even during the non-bloom conditions studied he
re. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.