Giant salvinia, a floating fern from southern Brazil, is currently one of the most dangerous invasive aquatic plants in Texas. It damages aquatic ecosystems by outgrowing and replacing native plants that provide food and habitat for native animals and waterfowl. Additionally, it blocks out sunlight and decreases oxygen concentrations to the detriment of fish and other aquatic animals. When plant masses die, decomposition lowers dissolved oxygen still further. Giant salvinia infestations often expand very rapidly. It can double in size in about a week under the right circumstances.