Ecological Approaches for
Biological Control of the
Aquatic Weed Eurasian Watermilfoil:
Resource and Interference
Competition, Exotic and
Endemic Herbivores and Pathogens
Sallie P. Sheldon
The accidental or intentional introduction of exotic plants into aquatic systems, as into terrestrial systems, has resulted in the rapid expansion of populations of exotic species and a reduction in abundance and species richness of native aquatic macrophytes (e.g., Aiken et al. 1979; Carpenter 1980; Arlington and Mitchell 1986; Room 1990). Such changes in the aquatic macrophyte community affect both littoral communities and human uses of the waters. Communities of native aquatic macrophytes significantly influence lakewide processes such as rates of sedimentation and succession, thermal structure, and dissolved oxygen concentration ( Carpenter and Lodge 1986). Mixed native macrophyte beds support a diverse community of invertebrates ( Campbell and Clark 1983; Cyr and Downing 1988; Miller et al. 1992; Morrow et al. 1992). Invertebrates use aquatic macrophytes as structure: some eat the epiphytes that grow on leaf surfaces ( Bronmark 1989), and some feed on the plants directly ( Lodge and Lorman 1987; Lodge 1991; Newman 1991). Finally, aquatic macrophyte communities are important to fish both for supporting invertebrate prey and for refuge ( Crowder and Cooper 1982; Stein and Savino 1982; Nichols and Shaw 1986).
In contrast, the extensive, nearly monospecific stands of introduced macrophyres often support a low diversity of aquatic plants (e.g., Nichols and Shaw 1986; Madsen et al. 1991) and fewer macroinvertebrates ( Keast 1984). From an
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Publication information: Book title: Ecological Interactions and Biological Control. Contributors: David A. Andow - Editor, David W. Ragsdale - Editor, Robert F. Nyvall - Editor. Publisher: Westview Press. Place of publication: Boulder, CO. Publication year: 1997. Page number: 53.