Primary Production and Calcification by the Soritid Foraminifer Archais angulatus (Fichtel & Moll)*

SYNOPSIS. Symbiosis between Chlamydomonas hedleyi (Lee, Crockett, Hagen & Stone) and Archais angulatus (Fichtel & Moll) was examined during laboratory studies of primary production and light-enhanced calcification. Photosynthesis and calcification are directly proportional to light intensity in the range of 0–200 μEinsteins m^-2 sec^-1. Calcification in the light is directly proportional to photosynthesis and proceeds at rates that are 2–3 times that observed in the dark. The herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), in concentrations of 1–100 μM, completely inhibits photosynthesis and light-enhanced calcification. Calcification of the foraminiferan test is therefore due to the photosynthetic activity of the symbiote. Calcification rates for foraminifers incubated in the dark or with DCMU are not significantly different from the calcification rates obtained for dead foraminifers. Rates of calcification obtained with ⁴⁵Ca are twice that obtained with ¹⁴C.