Multivariate statistical study with a factor analysis of foraminiferal fauna from the Chilka Lake, India

Abstract

Foraminiferal fauna from the surface sediments of the Chilka Lake along the east coast of India has been studied as regards distribution of its assemblages. From Q-mode factor analysis of the data, eight significant factor groups for species have been noted explaining > 89% of the variance. Among the species recorded, 16 species during post-monsoon season (November) and 34 species during pre-monsoon season (May) form the differential factor groups providing maximum information for the distribution of the fauna. Fifteen stations are also grouped by R-mode analysis with five and four significant factor groups contributing about 85% and 79% of the variance in November and May respectively. Furthermore, the first two factor groups constitute stations mostly of the inner lagoon and they form the differential factor groups for both the seasons. The faunal assemblages obtained from the cross plot of the factor loadings of the first two factors for these seasons show that the outer channel (Assemblages I and II) is quite distinct from that of the inner lagoon (Assemblage III) of the lake and thus testifying to the presence of two biofacies: facies 1 (inner lagoon facies) dominated by Miliammina fusca, while facies 2 (outer channel facies) by Ammonia beccani (Linne). It is obvious from the factor score distributions of stations against latitude (N) and species with respect to average absolute abundance that the species observed are from a continuously varying population least affected by insidious environmental changes in the study area.