Oceanologia (Jun 2006)
Relationships between water temperature, nutrients and dissolved oxygen in the northern Gulf of Aqaba, Red Sea
Abstract
Five years (1998, 2000-2003) of summer records of temperature,nutrients and dissolved oxygen concentrations in the upper 400 mof the water column of the northern Gulf of Aqaba were employedto produce a simple statistical model of the relationship betweentemperature versus nitrate, phosphate, silicate and dissolvedoxygen concentrations. Temperature profiles in the upper 400 mduring summer revealed a clear thermocline in the upper 200 m.This was reflected in nutrient and oxygen concentrations asnitrate, phosphate, and silicate increased from the surface todeep water while dissolved oxygen decreased. The best fit relationshipbetween temperature versus nitrate and phosphate was inverselinear and the best fit correlation between temperature versussilicate and dissolved oxygen was fractional. The observed nutrientconcentrations were shaped by a combination of the hydrodynamicsand biological factors. Deep winter mixing and high nutrientconcentrations dominate during winter. Shortly after the waterstratifies in spring, the nutrients are drawn down by phytoplanktonduring the spring bloom and remain low throughout the rest ofthe year. The regression equations presented here will be usefulin estimating nutrient concentrations from temperature recordsas long as the annual natural cycle is the main driver of nutrientconcentrations and external inputs are insignificant. Deviationsfrom these relationships in the future could provide insightinto modifications in the nutrient concentrations probably resultingfrom new nutrient sources, such as anthropogenic inputs.
