[B-PT01] Biomineralization and Geochemistry of Proxies

[BPT01-02] Seascape ecological view as a new insight of benthic foraminiferal community

*Hiroshi Kitazato¹ (1.Tokyo University of Marine Science and Technology (TUMSAT))

Keywords:Seascape ecology, microhabitat, benthic foraminifers, biodiversity, biomineralization

Foraminifers secrete various chemicals for chamber walls. They are calcium carbonates such as calcite, aragonite, Mg-calcite, organic compounds for agglutinated chambers and/or organic cemented test walls. Foraminiferal test walls basically form according to genetic information. However, same test group is tended to gather at specific microenvironments. For instance, turf shaped algal microhabitat such as coralline algae at rocky shore is composed of both frond and thallus parts as microhabitat. Frond part is open space where fresh seawater moves inbetween one frond and to the other. Elphidium crispum, Pararotalia nipponica and Patellina corrugate and other calcareous foraminifers dwell at frondal surface. In contrast, thallus part is muddy and high concentration of organic matters. The thallus part shows less oxygenated than frondal part as the space is close. Microbial cascades are developed at thallus part. Minor elements such as Mg or Sr are relatively high in sediment. Soft-shelled forms such as Allogromia, gromiid, agglutinated forms and miliolids groups with high magnesian calcite tests flourish at the thallus part. Most of foraminifers dwelled at muddy environments are mobile mode of life.
Microhabitat segregation and microenvironmental differences may cause similar biomineralization of benthic foraminiferal tests. I would like to stress that micro-seascape should be important to characterize benthic foraminiferal communities.