The Industrial Revolution brought about the decline of the populations of many fish. Many factories used the Hudson's waters as a dumping location for waste products like heavy metals. The water was subsequently returned to the river. Due to the change in temperature, many fish were killed. However, not many species have become extinct.
Plankton is a term used to categorize any small creature in the river.
Phytoplankton are the microscopic producers of the river's ecosystem. They use sunlight and produce carbohydrates via photosynthesis to feed animals. Zooplankton, the small animals of the river, eat phytoplankton. Today, many plant species can be found in the valley. Such plants include oaks, hickories, tulips, and maples.