It would be negatively impacted because a foreign species would start to take over a native species’ role in the ecosystem and may also directly (if it’s a predator) or indirectly lead to the decline of other species. So as some species may start to decline and eventually become extinct in that particular ecosystem, the biodiversity level would lessen cuz there’s less types of plants and animals. Less plants and animals could lead to the ecosystem to eventually collapse and it would be literally a mass extinction.