The Nonindigenous Aquatic Species Flood and Storm Tracker (FaST)

Science Center Objects

Storm-related flooding can lead to the potential spread of nonindigenous (or non-native) aquatic species into waterways they have not been seen in before. The USGS Nonindigenous Aquatic Species program has developed an innovative mapping tool to help natural resource managers with post-storm nonindigenous aquatic species detection and assessment efforts. 

Initial NAS FaST map of potential spread of coqui frog (Eleutherodactylus coqui) from flooding associated with Hurricane Lane.

Initial Nonindigenous Aquatic Species (NAS) Flood and Storm Tracker (FaST) map of potential spread of coqui frog (Eleutherodactylus coqui) from flooding associated with Hurricane Lane.

(Public domain.)

The Science Issue and Relevance: Storm surge and flooding events can assist the expansion and distribution of nonindigenous aquatic species through the connection of adjacent watersheds, backflow of water upstream of impoundments, increased downstream flow, and/or creation of freshwater bridges along coastal regions. The Nonindigenous Aquatic Species (NAS) program’s Flood and Storm Tracker (FaST) maps were developed to help natural resource managers with post-storm nonindigenous aquatic species detection and assessment efforts. The FaST maps were developed to be easily accessible, informative, and provide the most up-to-date information to resource managers about potential new invasions and act as an additional tool for early detection and rapid response (EDRR) systems. These maps provide natural resource managers with information on which species may have invaded and where to look. Once a species is introduced, the best chance of eradication or containment is as an emerging population.

Revised NAS FaST map of potential spread of giant applesnail (Pomacea maculate) from flooding associated with Hurricane Harvey.

Revised Nonindigenous Aquatic Species (NAS) Flood and Storm Tracker (FaST) map of potential spread of giant applesnail (Pomacea maculate) from flooding associated with Hurricane Harvey.

(Public domain.)

Methodology for Addressing the Issue: The USGS NAS FaST maps are developed in three steps: initial map, revised map, and final review. The initial FaST maps are created within two to three days of an event to quickly identify flooded 8-digit hydrologic unit codes (HUC8), or drainages, based on USGS Water Science Centers stream gages or storm tide sensors with water heights at or above flood stage. This map integrates potentially flooded drainages with known locations of established or possibly established introduced aquatic species. All drainages surrounding known locations of introduced species are included as possible areas of invasion until actual hydrologic connections have been determined, which occurs when the maps are revised. The initial NAS FaST map identifies both the established species within a drainage and the species that have potential for new introductions (defined as established species in adjacent drainages) due to flooding impacts. Users can select a species from a dropdown menu or select a drainage from the map to learn more about specific nonindigenous aquatic species.

The refined NAS FaST map is created once flood data become available, approximately two to six months after the event. This enhancement provides information only on the locations with flooding conditions that could breach drainage divides. We incorporate information on the relative flood height using the best available data from the USGS Water Science Centers including stream gages, storm surge gages, inundation maps (when available), and identified high water marks along with National Oceanic and Atmospheric Administration modeled storm surge. This information is combined with information on the elevation of the hydrologic units at the HUC8s boundaries (drainage divides) identified from digital elevation models. The flood elevation data are mapped with drainage divide elevations to determine if the flooding conditions were of sufficient height to breach the boundary. These "connection points" are identified along the hydrologic units' boundaries.

Revised NAS FaST map of potential spread of nonindigenous aquatic species in the Kissimmee drainage, FL, from flooding associate

Revised Nonindigenous Aquatic Species (NAS) Flood and Storm Tracker (FaST) map of potential spread of nonindigenous aquatic species in the Kissimmee drainage, FL, from flooding associated with Hurricane Irma.

(Public domain.)

The final review of the FaST map occurs about 18 to 24 months after the flooding event and involves reviewing which new NAS species sighting records could be attributed to the flooding event. All new NAS sightings that occur in the designated flood areas post-storm are reviewed to see if that species could have invaded due to transport from drainage connects from flooding of coastal storm surge or inland flooding.

Future Steps: Maps will be created for all future hurricanes and flooding events that have sufficient flooding conditions to connect numerous drainages. The NAS program plans to back-cast previous flooding events including 2016 Baton Rouge, Louisiana floods, 2016 Hurricane Matthew, and the 2015 North American storm complex in North and South Carolina. These back-casted FaST maps will provide evidence to validate assumptions of species moved between drainages as predicted.