Comparative laboratory and field studies on calcification and carbon fixation in foraminiferal-algal associations

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Abstract
Ca incorporation and photosynthetic C fixation was examined in 3 spp. of benthic foraminifera that harbor symbiotic microalgae. In all 3 spp., Archaias angulatus, Sorites marginalis and Cyclorbiculina compressa, light enhancement of calcification was observed and light rates were .apprx. 2-3 times dark rates. For A. angulatus and S. marginalis, light-enhanced calcification could be demonstrated in 4 h incubations. Rates for field incubated specimens of these 2 organisms were comparable to laboratory determined rates. In laboratory studies of both A. angulatus and S. marginalis, photosynthetic C fixation and calcification were proportional to light intensity from 0-200 .mu.Einsteins m-2 sec-1 and saturated at higher light intensities. Similar light saturation levels were obtained for field incubated specimens of both species. Nearly 3-fold higher rates of weight specific Ca incorporation and 2-fold higher rates of Ca incorporation were obtained with S. marginalis as compared to A. angulatus. In all 3 spp. examined, algal symbionts appear to be an improtant source of organic C as well as stimulating carbonate production.
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