Sequence of Morphological and Cytoplasmic Changes during Gametogenesis in the Planktonic Foraminifer Globigerinoides sacculifer (Brady)

The fate of nitrogen in the Orbulina universa foraminifera‐symbiont system determined by nitrogen isotope analyses of shell‐bound organic matter

“…1) were measured by conventional isotope ratio mass spectrometry (IRMS) except for the ␦ 15 N values of the endosymbionts. Direct isotope analysis of these dinoflagellate algae is not possible because the symbionts are digested or discarded by the foraminifera prior to gametogenesis (reproduction) (Bé et al 1983). However, these values can be estimated via mass balance relationships where the ␦ 15 N value of the symbionts is related to the amount and isotopic composition of the inorganic nutrients incorporated by the endosymbionts.…”

Nitrogen isotopic composition of planktonic foraminifera from the modern ocean and recent sediments

“…In scleractinian corals, the d 15 N of dinoflagellate symbionts is often lower than that of the host tissue, as expected if the symbionts consume the ammonium generated from the metabolism of the coral host (HoeghGuldberg et al 2004;Swart et al 2005). If the same dynamic applies to symbiont-bearing foraminifera, the foraminifera biomass d 15 N from the net tows would be lowered by the inclusion of the symbiont biomass, whereas the shell-bound N may derive from the host foraminifera tissue, with its slightly higher d 15 N. It has been observed for some foraminifera species (e.g., G. sacculifer) that most of the symbionts are digested prior to final calcification and gamete release (Bé et al 1983). Thus, the foraminifera (plus symbiont) biomass d 15 N measured from a net tow might be more similar to the ''final'' FB-d 15 N found in the sediments than to the shell-bound d 15 N from a shallow net tow.…”

Timing and mechanism for intratest Mg/Ca variability in a living planktic foraminifer

“…All specimens were maintained under sufficiently high light levels (>300 μmol photons m −2 s −1 , PAR) to maximize symbiont photosynthetic rates (Rink et al, 1998;Spero and Parker, 1985). Each foraminifer was fed a one-day-old Artemia nauplius every third day until gametogenesis (Bé et al, 1983), which typically occurred 6-10 days after collection.…”