Great photo!
The big tutrtle is a broadshell (Chelodina expansa)
Going clockwise from top right is an eastern long neck (Chelodina longiccolis),
Macquarie shortneck (Emydura macquaria), Macleays (Emydura macquaria dharra),
Mary River turtle (Elusor macrurus) and a saw shelled turtle (Elseya latisternum)