The General Assembly may annually appropriate from the Illinois Habitat Fund an amount equal to the annual investment income earned by the Trust Fund, any portion of the investment income earned in preceding years which was not transferred, and any additional amounts deposited into the Illinois Habitat Fund including the interest earned on the deposits, to the Department for the purposes set forth in Section 15. Upon request of the Director, the Comptroller and State Treasurer shall transfer amounts not to exceed the actual investment income earned from the Trust Fund to the Illinois Habitat Fund from time to time as needed for expenditures from the Illinois Habitat Fund in accordance with appropriations.