Comparison is made between the distribution patterns of live and total foraminiferal assemblages using either a variety of cluster analyses techniques or a direct intuitive analysis. The former give quick, valid results; the latter brings out nuances of distribution not obvious in routine statistical analysis. The methods are complementary.

Contrasting physio-geomorphologic environments exist in the reef, on either side of the Ras Iwa Tine promontory. Trigon diagrams of the three foraminiferal suborders confirm the assessment of an open-marine foraminiferal environment. The miliolids dominate immediately north of the promontory, but decrease northward. Their abundance is inversely related to that of the rotalines, which dominate both the biocoenose and thanatocoenose of the southern sector. Thanatocoenoses have a high diversity in the lagoon channel and a low diversity in berm and reef-entrance regions, whereas the biocoenose has the highest diversity on the outer platform and the lowest in the channel. Total abundances and standing crops as directly related to gross environmental parameters are very variable in space. >

Two hundred and six species have been identified (104 of them living) in marked contrast to the 465+ species and varieties identified by Heron-Allen and Earland farther south at Kerimba. Relative percentage occurrences, abundances, and rank occurrence delimit distinct species associations. The genera Spiroloculina, Heterostegina, Ammonia, and Bolivina are common in the north, but are locally restricted. Similarly, Planorbulina, Epistomarioides, and Miliolinella characterize the south. Live and total assemblages reflect the prevailing biophysical and edophic environments.

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