The legislative power of the City, except as limited by this Charter, and such additional powers as may be expressly granted by this Charter, shall be vested in a Council of seven members elected at large. The terms of the members of the Council shall begin the first day of January next following their election, and they shall serve for a term of four years or until their successors are chosen and qualified, except that the three members elected at the first election by the lowest votes shall serve for two years only.