Part A: Invasive species displace native species in their habitat hence reducing biodiversity that is necessary for a balanced ecosystem. This is because invasive species do not have a natural predator in their new environment and hence their growth is unchecked. They, therefore, take up much of the nutrients and other biotic factors utilized by the other species.
Part B; To deal with invasive species, one can introduce a predator of the invasive species into the environment. Another is the influencing a limiting factor (usually an abiotic factor) that affects the invasive species specifically. These will check the unregulated growth of invasive species and preserve the ecosystem’s biodiversity.