Mapping waterhyacinth drift and dispersal in the Sacramento–San Joaquin Delta using GPS trackers
John Miskella and John Madsen
Waterhyacinth [Eichhornia crassipes (Mart.) Solms)] is a perennial free-floating aquatic plant species native to the Amazon region of South America. It has become invasive around the world, including in the Sacramento–San Joaquin Delta in central California. From June 2016 to February 2018, a study was conducted to determine the extent that wind, tidal movement, and mass flow drove the dispersal of waterhyacinth mats in the Delta. Global positioning system (GPS) trackers were deployed to track the movement of waterhyacinth mats, recording the location, speed, and direction of movement at 15-s intervals. The relationship between mat size and distance traveled was analyzed using linear regression and did not show correlation (R2 = 0.0462, P = 0.0738). The movement of each waterhyacinth mat containing a GPS tracker was compared to the wind and water movement during the period the tracker was deployed. The direction of water movement, influenced by both mass flow and tides, aligned more closely with the direction of waterhyacinth mats, with a mean difference of 0.31 radians (rad) (17.75°), than the wind direction did, with a mean difference of 1.31 rad (75.34°). The pattern of plant mat movement observed using the GPS trackers presents a difficult management situation, with the waterhyacinth mats moving back and forth with tidal movement.
- John J. Miskella, Biological Research Technician, USDA–ARS ISPHRU, Department of Plant Sciences, University of California, Davis (firstname.lastname@example.org)
- John D. Madsen, Research Biologist, USDA–ARS ISPHRU, Department of Plant Sciences, University of California, Davis (email@example.com)