(1) The powers of a district shall be vested in and exercised by a board of commissioners consisting of five (5) members to be appointed by the board of supervisors from a list of at least fifteen (15) candidates submitted by the supervisor in whose district the shoreline and beach preservation district is located. If the shoreline and beach preservation district is located in more than one (1) supervisors district, the supervisors in whose districts the shoreline and beach preservation district is located shall submit a list of at least fifteen (15) candidates mutually agreed upon by such supervisors. The members of the board of commissioners shall be landowners or residents of the district and shall be at least twenty-five (25) years of age and of sound and disposing mind and judgement. Upon their initial appointment, one (1) of the commissioners shall be appointed for a term of one (1) year; one (1) for a term of two (2) years; one (1) for a term of thr ee (3) years; one (1) for a term of four (4) years; and one (1) for a term of five (5) years. After expiration of the initial appointments, each commissioner shall be appointed and shall hold office for a term of five (5) years. Any vacancy occurring on the board of commissioners shall be filled by the board of supervisors at any regular meeting of the board of supervisors in the same manner as original appointments are made. The board of supervisors may fill all unexpired terms of any commissioner. Notwithstanding the appointive authority granted in this section to the board of supervisors, its legal and actual responsibilities, authority and function, subsequent to the creation of a district, shall be specifically limited to the appointive function and responsibilities outlined in Sections 49-28-21, 49-28-27 and 49-28-29. The operation, management, abolition or dissolution of a district, and all other matters in connection therewith, shall be vested solely and only in the board of commissioners to the specific exclusion of the board of supervisors, and the abolition, dissolution or termination of a district shall be accomplished only by unanimous resolution of the board of commissioners.