ENVIRONMENTAL-CONDITIONS OF THE WATER COLUMN IN HAIFA-BAY, ISRAEL, DURING SEPTEMBER OCTOBER 1993

During September 1993, the water in Haifa Bay, Israel, turned brown an d turbid, and a phytoplankton bloom was observed. Preliminary examinat ion of the seawater showed very high concentrations of o-phosphate, ni trate and dissolved oxygen, and high pH values. In order to investigat e this unusual occurrence and determine the environmental conditions t hat allowed for its development, the chemical and physical characteris tics of the water column were measured, one during the unusual bloom i n September and one during October 1993, after the bay appeared to hav e returned to normal. The distribution of nutrients and chlorophyll-a at the surface corresponded closely to that of the salinity and temper ature, with high concentrations in the region close to the Kishon estu ary, decreasing northward and westward. It was possible to determine t hat the Kishon river was the main source of the nutrients to the bay, originating from the effluents discharged into the river by a sewage t reatment plant and nearby industries. During September, the input of n utrients from the Kishon to the bay was twice as in October, and this, together with favorable hydrographic conditions, most probably caused the unusual extensive phytoplankton bloom.