![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
SUMMARY
The distribution of marine species on a rocky shore at Umdoni Park was analysed objectively by a computer technique using Normal Association Analysis (NAA) and Principal Components Analysis (PCA). Five communities were defined and the major gradient along the two principal components axes was correlated with that sector of the shore which received wave surge every day irrespective of the state of the tide.
This analysis is compared favourably with Eyre & Stephenson's (1938) zonation scheme for rocky shores of Natal. Based on physical characters Umdoni Park has a three-zone shore of which the midlittoral Ralfsia expansa community represents that sector in which many marine species have reached the upper limits of their physiological tolerance.