Zebra mussel invasion of Texas lakes: estimating dispersal potential via boats

Invasive zebra mussels (Dreissena polymorpha) pose both a significant economic and environmental threat to aquatic systems yet there are currently no effective methods for achieving large-scale eradication. As a result, predicting and preventing their spread play a critical role in management efforts. Zebra mussels were first found in Texas in 2009 and, as of November 2019, have invaded 39 lakes across five river basins. Prior state-specific risk-assessments have been solely based on habitat suitability and have not considered dispersal potential. We developed a water body specific, constrained gravity model incorporating habitat suitability and dispersal potential to predict potential future invasion patterns. We examined the relative importance of habitat suitability, lake attractiveness, the relative risk of different boater types, and the impact of boater compliance with recommended prevention measures. Differences in lake attractiveness resulted in different boater dispersal patterns but the impact on projected lake invasions were reduced by variation in habitat suitability. The model projected zebra mussels to be mainly limited by habitat conditions in east Texas and by dispersal in west Texas. Most lakes in central Texas were projected to become invaded in the near future unless boater compliance with preventive management was high.