A note on the laboratory culture of the benthic foraminifer Cornuloculina balkwilli (MacFadyen)

Genetic studies of the Foraminifera provide valuable insights into marine speciation and biogeography, yet the discovery of vitally needed new genetic markers for this important group is being severely limited by an extreme lack of genetic data. The establishment of a laboratory culture from a single, asexually reproducing foraminifer, will be essential to provide enough pooled genetic material from these unicellular organisms, to facilitate full genome sequencing and genetic marker discovery, using next-generation sequencing techniques.

The aim of this study was to develop a simple and inexpensive method of culturing benthic foraminifera, via asexual reproduction, in a controlled laboratory environment. Individual specimens of the benthic foraminfer Cornuloculina balkwilli (MacFadyen) were placed in 7 cm plastic beakers, containing 50 ml natural seawater, filtered to 0.2 μm, and kept at 23°C, with a 12-hour light/dark cycle, and fed weekly on a mixed algal diet of Dunaliella tertiolecta and Phaeodactylum tricornutum. Asexually derived cultures were successfully established from 4 specimens of Cornuloculina balkwilli, originally added to the culture vessels as immature specimens. Many thousands of individuals were present after 6 months.

The method presented here demonstrates that only basic laboratory equipment is required to establish and maintain a thriving culture of the benthic foraminfer, C. balkwilli, from a single asexually reproducing specimen, providing an excellent source of genetic material for use in next generation sequencing. The method is easily reproducible and will greatly aid in the discovery of critically needed new genetic markers in the Foraminifera. It also highlights C. balkwilli as a good candidate species for use in the field of environmental micropaleontology.