Are you sure you have it right?
Although european's wandered in and around the coast in the 17th century there are no recordings of anything being introduced at that time that I can find. Perhaps you mean 1770 when cookey arrived? In which case it could have been anything from Europeans to Scurvey or smallpox. Sheep and other such things mentioned above came much later (Merino shep in 1797).
It is unlikely that the 1707 Act of Union would impact on OZ as it didn't come into british colonial territory until early 19th C.
If this is a quiz, does it have a theme?