How can invasive species alter an ecosystems food web?

Invasive species can either replace an organism from the ecosystem food web or replace it.  

Explanation:

Invasive species are non-native species which can be animals, plants, micro-organisms, fish, etc. they are very much threatening to the native species and ecosystem food web.Invasive species are spread by humans mostly, it happens unintentionally when people travel and all. Even climate change could be a reason for its spread.So, it becomes threatening to native species because when you introduce it into a new ecosystem, it does not have a predator or control. It grows aggressively and takes over the resources for the native species.

Lacking something of the ozone layer