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Title: Foraminiferal distribution and ecology in the fringing reef complex of the coast near Mombassa, Kenya
Author: Pereira, C. P. G.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1979
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The Kenyan fringing-reef studied between Mombasa harbour in the south and Mtwapa creek in the north is divisible into three intercalating physiogeographical zones: the inner reef-platform zone, the channel-lagoon zone and the outer reef-platform zone. Each of these zones is characterised by a distinctive, sediment and phytobenthic distribution pattern, hydrodynamic regime and topography. The reef is also divided latitudinally into two sectors; the northern sector, which is protected at low tide (especially during Spring tides) from the oceanic swell and the southern sector, which is exposed directly to the swell at its southern entrance. The northern and southern sectors of the channel lagoon are hydrodynamically separated by turbulent shear zones at Ras Iwa Tine which separates them. Some 206 foraminiferal species and varieties have been identified (104 of them found living (stained)), and their distribution in the coastal sediments has been compared to their world wide geographical and geological occurrences. Two new genera and a number of apparently new and endemic foraminiferal species have been described (however, new specific names have not been proposed). Foraminiferal distribution patterns and taxonomic associations have been determined using both a variety of cluster analysis techniques and a direct intuitive analysis. The former give quick, valid results; the latter brings out nuances of distribution not obvious in routine statistical analyses. The two methods are complementary. The miliolids dominate the biocoenose immediately north of the promontory, but increase northward, losing their dominance; the milioline proportion is inversely related to that of the rotalines, which dominate the thanatocoenose of the southern sector. Thanatocoenoses have a high diversity in the channel-lagoon, a variable one (high-low) on the inner and outer-platform and a low diversity in the berm and at the reef entrances. In contrast, biocoenoses have a high diversity on the outer-platform and a low one in the channel. Total abundances and Standing Crops are directly related to gross environmental parameters (e.g., sediment characteristics, floral distributions) but are very variable in space. Comparisons made between the distribution patterns of live and total foraminiferal assemblages indicate predominantly shoreward thanatocoenetic dispersion pathways for most species. The sedimentological and paleoecological implications are also discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available