All eligible officers and employees of the Jekyll Island--State Park Authority shall be subject to a merit system of personnel administration as promulgated by that authority and under which all such officers and employees shall be selected on a basis of merit, fitness, and efficiency. All such officers and employees, except as otherwise provided in this Code section, are authorized to become members of the retirement system, provided that such membership shall become effective no earlier than April 1, 1958; provided, further, that any officer or employee of the authority who is already a member of the retirement system shall be entitled to credit for his total service with the authority. All specially classified maintenance and food service employees of the authority hired on or after July 1, 1987, and paid on an hourly basis shall not be members of the retirement system and shall not be included under the health insurance plan for state employees as provided for in Article 1 of Chapter 18 of Title 45. There shall be paid from the funds appropriated for the operation of the Jekyll Island--State Park Authority all contributions required by this chapter. All such payments shall be in addition to the regular compensation allowed to such officers and employees.