There shall be such advisory agencies and councils as established herein as well as such advisory boards and committees as are otherwise constituted and empowered by the Charter or this chapter, or by the Mayor and Council, or by the Mayor, or by the Council, as they may deem suitable and necessary. Such additional advisory boards and Committees may be appointed from time to time by any of the above appointing agencies to investigate, advise and recommend to the appointing agency for a specific purpose, and their creation may be provided for by a motion if such a body is formed for a temporary purpose. Any advisory board or committee so created shall be considered temporary if by the motion creating it its term is limited to no more than one calendar year.