Distribution and Seasonal Variation of Nutrient Salts and Chlorophyll-a in Surface Seawater Along Alexandria Costal Zone Area

Abstract

The aim of the present study is to investigate the hydrographic characteristics, nutrient salts and chlorophyll-a (Chl-a) along Alexandria Costal Zone Area. The study revealed that the pH values lie slightly in the alkaline side, with a range of 7.53 to 8.12, salinity showed a slightly variation, it ranged from 35.34 to 38.28 PSU, the values of dissolved oxygen were fluctuated between 4.77 and 11.13 mgl-1. The annual average of nutrients (μM) was as follow: (7.97 ± 1.72), (0.66 ± 0.14), (2.18 ± 0.73), (0.37± 0.09) and (12.42 ± 4.04) for nitrate, nitrite, ammonium, reactive phosphate and silicate, respectively. Relatively high levels of Chl-a concentrations was recorded during the period of study ranged from 0.38 to 6.96µgl-1 and a positive correlation was found between Chl-a and both NO3, NH4, PO4 and SiO4 (r= 0.383, 0.303, 0.213 and 0.341, respectively). Very high values of N/P ratio were recorded during the study period, this consideration showed that Phosphorus was limiting factor in the study area.