Growth and habitat of some recent miliolid foraminifera: Palaeoecological implications

The miliolid foraminifera in reef flats of Akajima Island (Japan) are represented by the species of Marginopora, Amphisorus and Sorites. The species of Marginopora and Amphisorus settle freely on macrophytes and coral rubbles, while those of Sorites are permanently fixed to the blades of macroalgae and seagrass. This difference in the microhabitats of the three genera appears to be determined by the mechanism of attachment by the pseudopodia and the rates of growth and calcification. It is argued that thin tests of miliolids in fossil assemblage do not necessarily indicate a low-energy environment. Predominance of irregular tests of discoidal miliolids can be a supportive evidence of high-energy environments.