Intertidal Macro-algal Diversity and Zonation Patterns of the Eastern and Western coasts of Ghana

Abstract

Based on abundance and distribution of species along the intertidal continuum from the sublittoral to the supralittoral, rocky shores have been divided into zones globally. Rocky shore zonation has been assumed to follow broad regional and latitudinal patterns with no attention being paid to smaller scale patterns. The aim of this study is to find out if the global 3-zone division is applicable to Ghanaian shores based on multivariate analysis. Macroalgae which constitute the most visible and accessible species in the rocky intertidal were employed as the taxonomic units. The study focused on two similar rocky intertidal areas, 230 km apart, at Takoradi and Prampram, both in Ghana. A total of 36 species of macroalgae, comprising 9 Chlorophyta, 10 Phaeophyta, and 17 Rhodophyta were identified as present at the two locations. A multivariate analyses of the abundance and location of macroalgae in relationship to their level in the intertidal zone detected zonation differences in the macroalgal community structure between the western and eastern locations at Takoradi and Prampram respectively. It is observed that it is not necessary to characterize macroalgal zonation patterns based at species level but simply grouping the in major taxa such as Chlorophyta, Phaeophyta and Rhodophyta is sufficient to characterize zonation patterns satisfactorily. Multivariate analysis is a better tool in assessing vertical zonation, as it produced sub zonations or micro zonations in 5 zone method, for both sites than species occurrence. The universal zonation method might not be applicable to all shores as evidenced in this work.