DISPERSAL AND THE GROWTH OF ALLOCHTHONOUS BENTHIC FORAMINIFERA IN SHELF TO BATHYAL SETTINGS, WESTERN NORTH ATLANTIC

Dispersal largely controls the distribution of benthic foraminifera yet only a handful of studies have focused on it. Understanding dispersal is important to comprehend the ability for benthic foraminifera to respond to and recover from short and long-term events and it allows for assemblages to change over time. The purpose of this study is to assess foraminiferal dispersal off the northeast coast of the United States. To do this, foraminiferal propagule banks were collected from four sites, ranging from 70 – 2200 m, south of Cape Cod, MA. These propagule banks were incubated at non-ambient temperatures and foraminifera were allowed to grow. The resulting assemblages were compared to each other and to the assemblages found in situ at each of the sites. Results show that propagules of allochthonous taxa were present at all depths and grew from all of the collecting sites. Brizalina lowmani and Rosalina cf. R. floridana were able to grow from every site but were not found in any of the in situ assemblages. These species were the most prolific of the allochthonous taxa and likely originated from near shore, far south of the study area. The experimentally grown assemblages varied most based on the temperature at which they were grown rather than the site from which they originated. Opportunists such as Bathysiphon filiformis, Leptohalysis scottii, Prolixoplecta parvula, Textularia earlandi, and Brizalina lowmani grew in samples from 70-m to 740-m water depth at nearly all experimental temperatures. The results of this study suggest that foraminiferal dispersal varies among species with regard to horizontal distance and mode of life. Supported by NSF OCE-0850505 to STG and OCE-0850494 to JMB.