Analysis of the relationship between phytoplankton biomass and the euphotic layer off Kuwait, Arabian Gulf

The Kuwait Bay is a shallow tidally well-mixed sub-tropical environment in the Arabian Gulf; and is characterized by excessive evaporation, little fre shwater input, and several anthropogenic disturbances attendant with oil ex plorations. From the Gulf we examined 219 Secchi disc readings and profiles of temperature, salinity, chlorophyll a, and nutrients. Features of intere st are: a) existence of marked differences in the magnitude of phytoplankto n biomass between the nearshore (3.8 - 113.4 mg chl a m(-2)) and offshore s tations (4.5 - 57.9 mg chl a m(-2), b) lower algal biomass (18.5 to 27.3 mg chl a m(-2)) at 3 inshore stations located off an industrial belt compared to offshore waters (>42 mg chl a m(-2)), c) absence of pronounced seasonal phytoplankton growth and d) small increases in biomass sometime during Mar ch -May, August and October - December. An analysis of the relationship bet ween scaled critical depth, integrated chlorophyll a and nutrients support the hypothesis that phytoplankton biomass in Kuwait waters, in general, was not restrained by physical environment. The correlation coefficient (Spear man Rank) for the sign trend test between scaled critical depth (Z'(cr) and integrated chlorophyll a was not significant at 10 stations suggesting dep endence of phytoplankton abundance an factor(s) other than light. Only at a n offshore station (#18) this correlation was negative and significant. Lig ht profiles yielded 83-275 W m(-2) near the bottom suggesting availability of sufficient light for algal growth in these well-mixed sub-tropical shall ow waters.