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An estimated 186 non-native aquatic species could have been spread to new areas by Hurricane Ian’s floodwaters, according to a recently released USGS online map.

Storm surge and flooding caused by hurricanes and other storms can carry non-native plants and animals to new locations. Once established, they can be difficult to eradicate and can damage infrastructure and harm native ecosystems.

To help resource managers prepare for possible introduction of new non-native species, the USGS Nonindigenous Aquatic Species (NAS) team creates a Flood and Storm Tracker (FaST) map after large storms or flooding events to demonstrate the number and extent of non-native species’ possible spread.

The FaST maps are created by combining information from USGS streamgages, such as water levels, flow, and storm surge heights, with records of known non-native species from the NAS database. The NAS database tracks the distribution of non-native aquatic plants and animals across the U.S. The maps provide resource managers an early warning, helping them prepare for the removal of possible invasive plants and animals before they spread further.

A preliminary map is created within days of the storm’s initial impact. The NAS team then revises the map once flooding data becomes available. The final map is created approximately one year after the storm.

Hurricane Ian made landfall in southwest Florida in September 2022 as a Category 4 storm, making it the strongest storm to hit Florida since Hurricane Michael in 2018.