Publication Date:
2020-07-27
Description:
The planktonic foraminifer Globigerinoides sacculifer (Brady) was cultured under
two different light intensities and in continuous darkness. High light intensity (HLI =
4oo-soo einsteins/m2/s) resulted in a longer lifespan, a greater number of chambers
formed, and a larger final shell size compared with individuals cultured under low
light intensity (LLI = 20-50 einsteins/m2/s) or in continuous darkness. Shell growth
rates were unaffected by increasing light intensity, but gametogenesis was delayed.
Continuous darkness induced a rapid onset of gametogenesis in organisms with shell
lengths larger than 250 m. Feeding frequency had a greater effect on growth and
reproduction than light intensity under conditions of LLI and HLI, but continuous
darkness had an overriding effect on growth and reproduction owing to the rapid onset
of gametogenesis which terminated the life of the mother cell. Our previous data
indicated that the longevity of G. sacculifer was dependent on feeding frequency, and
that G. sacculifer cultured under LLI had a lifespan of approximately 2-4 weeks.
Present results suggest that the lifespan can vary from a minimum of 8 days for
organisms fed daily in continuous darkness to a maximum of 54 days for organisms
fed once every 7 days and maintained in HLI. It is concluded that individual G. sacculifer
attain a shell size greater than 6oo ,urn only if they maintain their position in the euphotic
zone. Prolonged existence below the euphotic zone would result in premature death or
gametogenesis following stunted shell growth.
Type:
Article
,
PeerReviewed
Format:
text