Ecology, Environment and Conservation Paper

CORRELATION AND MULTIPLE REGRESSIONS OF THE ENVIRON- MENTAL CONDITIONS AND ITS EFFECT ON THE ABUNDANCE OF BOTTOM DWELLING MACROBRACHIUM MACROBRACH ION AND MACROBRACHIUM VOLLENHOVENII IN THE BRACKISH WATER ZONE OF THE BENIN RIVER, SOUTHERN NIGERIA

Edokpayi and Clement Aghatise

Abstract

The Pearson simple correlation of 12 physical and chemical characteristics from a 24 months investigation of five stations along a 5 km stretch of Benin River, southern Nigeria was evaluated. The effect of these environmental factors on the abundance of Macrobrachium macrobrachion and Macrobrachium vollenhovenii during this period was also discussed. There was variability in the number of significant correlations at each station in the two years. Also, no similarity among the stations in terms of interactions of factors was observed. Only the correlation of conductivity to pH and salinity and that of water level to transparency was found to be common to both years in each station. Conductivity, dissolved oxygen, calcium and nitrate-nitrogen were significantly (P < 0.05 - 0.001) influenced by the other environmental factors as reflected by the multiple regression analysis.The abundance of M macrobrachion and M vol/enhovenii was significantly influenced by environmental conditions only in stations 1,11 and V. The interactions of the physical and chemical conditions and its influence on the abundance of M rnacrobrachion and M vollenhoyenii suggest that each station despite of their proximity may be unique and controlled by a set of local conditions.