Dormancy in the Foraminifera: A Review

The Foraminifera are a diverse class of protists whose ubiquity in marine environments, small shells, and ease of collection have made them critical tools in bioindicator, bioassay, paleo-environmcntal, and paleoceanographic research. Despite the plethora of applications and accompanying literature on foraminifers, many aspects of their biology and ecology remain unexplored. One of these aspects is dormancy, a life-history strategy involving suspension of active life, arrested development, and reduced or suspended metabolic activity, mediated either by internal physiological factors (known as diapause) or exogenous factors (known as quiescence). Dormancy is a widespread adaptation, playing a role in the life cycles of a huge variety of organisms. Yet, despite anecdotal and circumstantial evidence, very little research has directly addressed this aspect of foraminiferal biology. The relatively recent discovery of cryptobiotic propagules has revealed a fundamental role for dormancy in the life cycles of foraminifers, most prominently for dispersal. Moreover, culture studies with environmental applications have shown that post-propagule quiescence (i.e., in juveniles, sub-adults and adults) may be a common response to environmental stressors, allowing rapid recovery of populations following disturbance or otherwise unfavorable conditions. A review of publications on foraminiferal biology revealed that observations indicating the potential for dormancy have been recorded for at least six decades, and that this potential is well represented throughout the class in a variety of forms, suggesting that dormancy may be a basic adaptation in the Foraminifera. If dormancy is as widespread as the literature suggests, its role in structuring foraminiferal assemblages and determining global distributions in the geological past, present, and future is fundamental. Further research into the mechanisms of dormancy will expand understanding of its role in foraminiferal life cycles, and provide new perspectives in the many fields that utilize and apply foraminiferal data