Environmental characterization of a semiarid hyper saline system based on dissolved trace metal-macronutrient synergy: A multivariate spatio-temporal approach

Highlights: • Trace metals analyzed for the first time using clean analytical techniques from the NW Arabian Gulf. • Multivariate analyses revealed marked spatial and seasonal disparity in water quality. • Compared to other macronutrients, demand for phosphate-P is high in Kuwait waters. • Nature of micronutrient limitation depends on light availability and nitrogenous nutrients. • Different methods used to evaluate supply-demand state for nutrients yielded similar results. - Abstract: Trace metals and macronutrients play key roles in marine biogeochemical processes. Despite their higher availability, no reliable information is available on their ecological role in the hypersaline waters of NW Arabian Gulf. The present study identifies their synergistic effect on environmental characteristics and autotrophic biomass in the shallow coastal and offshore waters, off Kuwait on a seasonal basis. Surface water samples collected along four predefined transects were analyzed for physico-chemical and biological variables during summer (n = 27) and winter (n = 27) seasons. Multivariate analyses revealed clear spatial and seasonal trends, and identified the best suit of environmental variables responsible for the seasonal variability in phytoplankton biomass. Using statistically derived supply to demand ratios, carbon-trace metal stoichiometry, and bioavailability of trace metals, we propose possible growth regulating factors for phytoplankton on a seasonal basis in the NW Arabian Gulf, off Kuwait. This is the first report on trace metals from the entire Arabian Gulf, using clean techniques and multivariate statistical approach.