An Entzia-dominated marsh-type agglutinated foraminiferal assemblage from a salt marsh in Tubli Bay, Bahrain

Abstract

A salt-marsh assemblage of agglutinated foraminifera was recovered from a salt marsh on the east side of Tubli Bay in eastern Bahrain. This locality is one of the last remaining patches of salt marsh on the east coast of Tubli Bay. The salt marsh is covered by a single marsh plant species, Arthrocnemum macrostachyum. Samples were collected from beneath the Arthrocnemum canopy in two transects beginning at the maximum landward extent of halophytic plants in the high marsh and extending to a tidal channel at the seaward side of the low marsh. A distinct elevation-related zonation in foraminifera is observed from the high marsh to the low marsh. The trochamminids Entzia macrescens and Trochammina inflata are characteristic of the high marsh, whereas Ammonia, Elphidium, Peneroplis and smaller miliolids become common in the middle part of the marsh transect. The tidal channel at the lower limit of the marsh contains an assemblage dominated by Ammonia, Elphidium, adult specimens of Peneroplis, and smaller miliolids, with Clavulina and Agglutinella as the only agglutinated taxa. Living specimens of Entzia and Trochammina were observed during the winter 2019–2020 sampling season, whereas samples collected in Autumn 2019 contained only dead specimens. One new species, ?Sigmoilina canisdementis sp. nov., is described herein. This is the first report of a live Entzia-dominated salt marsh assemblage in the Arabian Gulf region.