State analysts agreed Thursday to lower the expected rate of return on Florida’s $144 billion pension fund, while warning that it may be the first in a series of annual downward adjustments. The shift from a 7.65 percent rate of return to 7.6 percent may seem slight, but it has implications for the $82 billion state budget, which likely will be tight in the coming year. A lower expected return on investments means lawmakers will have to increase the state contribution to the pension fund, reducing the overall amount of money the Legislature will have for other needs, ranging from public schools to health-care programs.