The Effects of Hydrilla Infestation on Selected Wintering Waterfowl: Santee Copper Lake System, South Carolina

Hydrilla is an exotic aquatic weed that was introduced into Florida in the 1950\u27s. Since that time it has spread rapidly from lake to lake throughout the southeast and beyond. The Santee Cooper lake system in eastern South Carolina was infested with the weed in the early 1980\u27s. Since that time lake managers have sought ways to eliminate the aquatic plant and have succeeded to a great extent through the use of sterile grass carp as a biological control agent. This paper, however, contains evidence to support the view that hydrilla is actually a beneficial habitat for many species on and in the lake. In addition to the perceived positive impact on certain sportfish populations, especially largemouth bass, hydrilla is also a prime habitat for many species of waterfowl that winter on the lake. While traditional wintering species such as Wigeon and Gadwalls have taken advantage of this new source of nutrition and increased greatly in total numbers, Ringneck ducks have multiplied in total numbers during the years of infestation to levels never before seen on this lake. In addition, many species of waterfowl from the diving duck sub group such as Canvasback, Redhead, Scaup, Shoveler, and Bufflehead have been observed on the lake in greater numbers than any time in the recent past. The newfound success in eliminating the hydrilla from the lake, however, did reduce available hydrilla beds drastically over the 1996 - 97 winter migration year, with the existence of the weed in any substantial amounts in question for next year. If the aquatic plant is effectively eliminated from the lake system in coming years, the impact on waterfowl populations will be substantial