Subject to approval of the Council, the City Manager shall appoint and may remove all department directors. The department director shall be the head of his respective department and shall have direct supervision over all personnel within his department. Subject to such general rules and regulations or contractual obligations, as may be established by the Council and the City Manager, the department director shall appoint and may remove employees within his department, and he shall assign the duties and responsibilities of all personnel under his jurisdiction. Department directors shall be appointed solely on the basis of executive and administrative qualifications with special emphasis upon the specialized training and background necessary for the proper functioning and administration of each particular department. The Council shall establish salaries of the officers of the city by ordinance.