Boats, Pathways, and Aquatic Biological Invasions: Estimating Dispersal Potential with Gravity Models

Biological invaders can have dramatic effects on the environment and the economy. To most effectively manage these invaders, we should consider entire pathways, because multiple species are dispersed through the same vectors. In this paper, we use production-constrained gravity models to describe movement of recreational boaters between lakes – potentially the most important pathway of overland dispersal for many aquatic organisms. These models are advantageous because they require relatively easily acquired data, hence are relatively easy to build. We compare linear and non-linear gravity models and show that, despite their simplicity, they are able to capture important characteristics of the recreational boater pathway. To assess our model, we compared observed data based on creel surveys and mailed surveys of recreation boaters to the model output. Specifically, we evaluate four metrics of pathway characteristics: boater traffic to individual lakes, distances traveled to reach these lakes, Great Lakes usage and movement from the Great Lakes to inland waters. These factors will influence the propagule pressure (hence the probability of establishment of invasive populations) and the rate of spread across a landscape. The Great Lakes are of particular importance because they are a major entry point of non-indigenous species from other continents, hence will act as the origin for further spread across states. The non-linear model had the best fit between model output and empirical observations with r2 =0.80, r2 =0.35, r2 =0.57, and r2 =0.36 for the four metrics, respectively. For the distances traveled to individual lakes, r2 improved from 0.35 to 0.76 after removal of an outlier. Our results suggest that we were able to capture distances traveled to most but not all lakes. Thus, we demonstrate that production-constrained gravity models will be generally useful for modeling invasion pathways between non-contiguous locations.

[1]  Anthony Ricciardi,et al.  Overland dispersal of aquatic invasive species: a risk assessment of transient recreational boating. , 2001 .

[2]  D. Pimentel,et al.  Environmental and Economic Costs of Nonindigenous Species in the United States , 2000 .

[3]  P. Hebert,et al.  Ecological and Genetic Studies on Dreissena polymorpha (Pallas): a New Mollusc in the Great Lakes , 1989 .

[4]  R. B. Jackson,et al.  Global biodiversity scenarios for the year 2100. , 2000, Science.

[5]  H. MacIsaac,et al.  Modeling ships' ballast water as invasion threats to the Great Lakes , 2002 .

[6]  D. Padilla,et al.  ESTIMATING THE PROBABILITY OF LONG-DISTANCE OVERLAND DISPERSAL OF INVADING AQUATIC SPECIES , 1999 .

[7]  Phil A. Graniero,et al.  BACKCASTING AND FORECASTING BIOLOGICAL INVASIONS OF INLAND LAKES , 2004 .

[8]  R. Lockwood.  Sportshing Angler Surveys on Michigan Inland Waters, 1993-99 , 2000 .

[9]  A. Green,et al.  Passive internal transport of aquatic organisms by waterfowl in Doñana, south-west Spain , 2003 .

[10]  Richard C. Stedman,et al.  Distribution of Recreational Boating across Lakes: Do Landscape Variables Affect Recreational Use? , 2000 .

[11]  Clifford E. Kraft,et al.  PREDICTION OF LONG‐DISTANCE DISPERSAL USING GRAVITY MODELS: ZEBRA MUSSEL INVASION OF INLAND LAKES , 2001 .

[12]  Kevin S. Cummings,et al.  A Transportation Model Assessment of the Risk to Native Mussel Communities from Zebra Mussel Spread , 1998 .

[13]  R. Hilborn,et al.  The Ecological Detective: Confronting Models with Data , 1997 .

[14]  L. Penaloza.  Boating pressure on Wisconsin's lakes and rivers: results of the 1989-1990 Wisconsin Recreational Boating Study, Phase 1. , 1991 .

[15]  D. Padilla,et al.  Models to Predict Potential Occurrence and Density of the Zebra Mussel, Dreissena polymorpha , 1992 .

[16]  Osvaldo E. Sala,et al.  Global biodiversity in a changing environment : scenarios for the 21st century , 2002 .

[17]  C. Kolar,et al.  Progress in invasion biology: predicting invaders. , 2001, Trends in ecology & evolution.

[18]  J. Geller,et al.  Ecological Roulette: The Global Transport of Nonindigenous Marine Organisms , 1993, Science.

[19]  C. Kraft,et al.  Regional differences in rates and patterns of North American inland lake invasions by zebra mussels (Dreissena polymorpha) , 2000 .