From the paragraph, tell me what is a dredger

Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing dams, dikes, and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but a few situations the excavation is undertaken by a specialist floating plant, known as a dredger.

Dredging is carried out in many different locations and for many different purposes, but the main objectives are usually to recover material of value or use, or to create a greater depth of water. Dredges have been classified as suction or mechanical. Dredging systems can either be shore-based, brought to a location based on barges, or built into purpose built vessels.

Dredging has significant environmental impacts: it can disturb marine sediments, leading to both short- and long-term water pollution, destroy important seabed ecosystems, and can release legacy human-sourced toxins captured in the sediment. These environmental impacts can significantly hurt marine wildlife populations, contaminate sources of drinking water and interrupt economic activities such as fishing.

A dredger is a specialist floating plant used to do excavation of material from a water environment. This process is called dredging.