RECOVERY OF THE PHOTOSYMBIOTIC FORAMINIFERA AMPHISTEGINA GIBBOSA FOLLOWING LONG-TERM APHOTIC INCUBATION

The larger benthic foraminifera Amphistegina gibbosa maintains an obligate symbiotic relationship with diatom symbionts. The photosynthate produced by the symbionts is necessary for the foraminifer to grow and reproduce. In this experiment, two populations of Am. gibbosa were maintained in aphotic conditions for 7 and 12 months respectively. Upon removal from these incubations and a return to sufficient light for photosynthesis, the foraminifers showed recovery of vital activity in a number of days, as well as recovery of color, indicating recovery of the internal symbiont population. These observations demonstrate that both the foraminifer and its symbiont population are capable of surviving extended periods with no sunlight. Such survival can help explain how these obligate mixotrophs, currently found in tropical and semitropical waters, could have thrived at higher latitudes during warmer times in Earth history, despite seasonally reduced light and possibly extended periods of darkness. It could also play a role in their ability to expand their range as waters continue to warm in the near future.