Environmental quality of the Jordanian coastal waters of the Gulf of Aqaba, Red Sea

Abstract

Abstract Records of long term (14 months) fine temporal resolution (weekly) monitoring of the ambient water temperature, dissolved oxygen concentration and percent saturation, the inorganic nutrients ammonia, nitrate, nitrite, phosphate and silicate and chlorophyll a concentrations were generated to assess sea water quality within the Jordanian coast of the Gulf of Aqaba. Surface water (1 m) samples were collected from four coastal stations, contrasting in their natural benthic habitats and adjacent human activities. Offshore surface water was also concurrently sampled at two locations. The offshore stations were reference sites. Modifications in the coastal water quality were assessed as the difference between the magnitude of a specific parameter recorded at a coastal station and the concurrently recorded value of the parameter at the reference offshore station, relative to the annual mean value at the reference offshore station. A sandy beach–sea grass bed habitat was found to have significantly positive modifications in chlorophyll a concentration, mainly during the spring–early summer period. A semi-enclosed harbour within the Port of Aqaba was found to be acutely modified with respect to all measured parameters. A coral reef exhibited positive modifications of nitrogen and dissolved oxgen concentrations and percent oxygen saturation during summer. An industrial site had consistently positive modifications in phosphate concentration, but not in nitrogen or chlorophyll a concentrations. In addition to these site specific modifications, ammonia and silicate concentrations were positively modified at all the coastal stations. Natural and anthropomorphic factors that shape the coastal water characteristics and result in the specific modifications are discussed.