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Pathways and places associated with nonindigenous aquatic species introductions in the Laurentian Great Lakes
Citation:
O'Malia, E., L. Johnson, AND J. Hoffman. Pathways and places associated with nonindigenous aquatic species introductions in the Laurentian Great Lakes. HYDROBIOLOGIA. Springer, New York, NY, 817(1):23-40, (2018).
Impact/Purpose:
To allow for a timely and cost-effective management response, early detection of aquatic invasive species should occur when the species is relatively rare and not yet widespread. However, surveillance for rare species is costly and time-intensive. Knowing where invasive species are likely to be introduced can improve surveillance efficiency. We examined how proxies for three major introduction pathways (commercial shipping, recreational boating, animals in trade) are associated with detections of select nonindigenous aquatic species (NAS) across the Great Lakes. We found that the best predictor of detecting NAS is city size, highlighting the important role of cities in terms of introduction and surveillance. We also found subtle shifts in the data suggesting aquarium species are a growing concern relative to NAS introduced by the other two pathways.
Description:
To evaluate what types of places historically have been susceptible to NAS introduction and establishment within the Great Lakes, we developed and evaluated geospatial metrics of three prominent anthropogenic introduction pathways: commercial maritime traffic, recreational maritime traffic, and live release from urban areas. Logistic and linear regression analyses were conducted between species presence/detections and introduction pathway intensity (i.e., number of vessel trips received by a port) for 23 NAS over a five-decade period (1970 2013) to explain the apparent spatial and temporal patterns of historical aquatic invasions. The probability of NAS detections increased with increasing city size, commercial maritime trips, and marina size for all NAS, decades, and pathway combinations. City population size was the best model factor and potential proxy of NAS presence, even for NAS introduced through ballast water discharge. Through time, city population size was an increasingly significant predictor of the presence of organisms in trade, signaling a change in both the types of organisms introduced and kinds of places where introductions are occurring. Nonetheless, city population size, total commercial maritime trips, and marina size may be reasonable proxies for propagule pressure given the significant relationships between these specific pathway metrics and NAS detections.
