Ec. Glenn-sullivan et I. Evans, The effects of time-averaging and taphonomy on the identification of reefal sub-environments using larger foraminifera: Apo Reef, Mindoro, Philippines, PALAIOS, 16(4), 2001, pp. 399-408
At Apo Reef Mindoro, a small, isolated, moderate-energy platform reef in th
e central Philippines, foraminifera comprise a significant portion (c.40%)
of the sediment. This study examines four assemlages of foraminifera: live
foraminifera; dead, unabraded foraminifera; abraded and fragmented foramini
fera; and the three data sets combined into a total assemblage in order to
determine their relative usefulness in identifying reefal sub-environments.
The time averaged assemblages, the product of taphonomic processes, prove
to be much more effective in delineating reefal physiographic sub-environme
nts than do the live assemblages. The abundance of live foraminifera, excep
t for minute sediment-attached rotaliines, is strongly controlled by the di
stribution of algal turf and filamentous algal mat. Filamentous algae, with
abundant live delicate species, occur in both high- and low-energy reef zo
nes. The time-averaged assemblages are characterized by robust calcarinids
in the shallow seaward zones; by free-living miliolids and small rotaliines
in the leeward zones; and by planktonics and large thin rotaliines in the
fore reef This enhanced fidelity of the time-averaged assemblages in relati
on to physiographic zones reflects a combination of the ecological distribu
tion of robust, abrasion-resistant species, the selective destruction of sm
all, delicate tests in higher-energy zones, and the failure of storms and o
ther mechanisms to homogenize the reefal sands.