Er. Akpan et Jo. Offem, COMPARISON OF CHLOROPHYLL-A AND CAROTENOIDS AS PREDICTORS OF PHYTOPLANKTON BIOMASS IN THE CROSS RIVER SYSTEM OF NIGERIA, Indian journal of marine sciences, 22(1), 1993, pp. 59-62
Spectrophotometric determinations of chl a and carotenoids were carrie
d out in Cross River system of south eastern Nigeria during 1 annual c
ycle (March 1988 - March 1989). Both pigments displayed significant se
asonal variations. Correlation coefficients (r) for linear relationshi
ps between phytoplankton cell density and chl a on the one hand and be
tween cell density and carotenoids on the other, were highly significa
nt. However, a comparison of coefficients of determination (r2) for bo
th linear correlations, revealed that 85% of the variance in chl a con
centrations can be explained by variations in total phytoplankton cell
density while cell density can only account tor 47% of variance in th
e concentration of carotenoids. A comparison of confidence intervals f
or coefficients of regression also showed that chl a would be a better
predictor of phytoplankton standing crop in the river system. The dif
ferences in prediction capabilities of both pigments were attributed t
o seasonal changes in phytoplankton species composition which can have
significant effects on carotenoids.