The salary of members of Council shall be five hundred dollars per year, except that the salary of the Mayor shall be seven hundred fifty dollars per year, provided the Council may change the salaries of members of Council and the Mayor by ordinance adopted by a vote of not less than five members of the Council. Any ordinance changing the salary of members of Council or the Mayor shall be adopted at least ninety days prior to the next ensuing election at which members of the Council are to be elected, and shall be effective on the first day of December following such election. The compensation of all other officers and employees of the Municipality may be increased or decreased at any time by ordinance.