Sediment Interactions of Foraminifera: Implications for Food Degradation and Bioturbation Processes

Abstract

Despite their small size, foraminifera often reach high standing stocks and play a significant role in structuring the top layers of the sediment. However, the behavioral and ecological interactions of foraminifera with the surrounding sediments have been rarely investigated. In order to study these poorly known aspects of foraminiferal ecology, living foraminifera from bathyal and shallower water depths were successfully maintained in microcosms and their relationship with the sediment was investigated. Sediment-interactions of foraminifera take part mainly as a result of 1) locomotion, 2) deposit feeding with ingestion and egestion within different sediment layers, thus causing constant bioturbation, and 3) the use of particles for the formation of cysts for feeding, reproduction, chamber building or protection. Movement by foraminifera results in the ventilation of the sea floor as demonstrated by the active and passive transport of luminescent particles. From the experiment conducted, a high mixing rate (Db ഠ 0.2 cm 2 /day) for the foraminiferal assemblage was calculated. Thus, benthic foraminifera contribute significantly to the bioturbation of surface sediments. These observations are discussed in relation to microhabitats and the fate of organic matter at and below the sediment-water interface.

Distinguishing relative specialist and generalist species in the fossil record

“…This led Gross (2002) to suggest that the infaunal/epifaunal dichotomy of foraminiferal microhabitats must be re-examined and Murray (2006) to write that 'the distinction between infaunal and epifaunal [foraminifera] is to some extent arbitrary'. Thus, it cannot at present be suggested whether specialist behaviour favours infaunal or epifaunal species.…”

Deep-Sea Benthic Foraminifera

“…3b), are an important source of environmental heterogeneity in the deep sea, providing habitats and attachment substrates for rich assemblages of other foraminifera and metazoans (Levin and Thomas, 1988;Hughes and Gooday, 2004). Mobile infaunal species bioturbate the sediment as they move through it (Gross, 2002). Conversely, it has been suggested that the pseudopodial systems of foraminifera may help to bind together and stabilize deep-sea sediments (Nyholm, 1957), although this has not yet been clearly demonstrated.…”

Insights into foraminiferal influences on microfabrics of microbialites at Highborne Cay, Bahamas

“…Thecate forms, rather than agglutinated or carbonate-secreting forms, likely were the earliest evolving foraminiferal group (16). Thecate foraminifera, which are quite common in the deep sea and shallow Antarctic waters (17)(18)(19), are capable of bioturbating sediments (20).…”