A Review and Secondary Analysis of Competition-Related Impacts of Nonindigenous Aquatic Plants in the Laurentian Great Lakes

Abstract

The Laurentian Great Lakes of North America are home to thousands of native fishes, invertebrates, plants, and other species that not only provide recreational and economic value to the region but also hold an important ecological value. However, there are also 55 nonindigenous species of aquatic plants that may be competing with native species and affecting this value. Here, we use a key regional database-the Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS)-to describe the introduction of nonindigenous aquatic plants in the Great Lakes region and to examine patterns relating to their capacity to compete with native plants species. Specifically, we used an existing catalog of environmental impact assessments to qualitatively evaluate the potential for each nonindigenous plant species to outcompete native plant species for available resources. Despite an invasion record spanning nearly two centuries (1837-2020), a great deal remains unknown about the impact of competition by these species. Nonetheless, our synthesis of existing documentation reveals that many of these nonindigenous species have notable impacts on the native plant communities of the region in general and on species of concern in particular. Furthermore, we provide a thorough summary of the diverse adaptations that may contribute to giving these nonindigenous plants a competitive advantage. Adaptations that have been previously found to aid successful invasions were common in 98% of the nonindigenous aquatic plant species in the database.

Keywords: Great Lakes; aquatic; competition; nonindigenous species.

Figure 1

Cumulative introduction of nonindigenous plants to the Great Lakes basin by vector of introduction. Note the Hybrid vector represents recombination of a nonindigenous captive species introduced intentionally as a garden plant with a native plant, probably via cross-pollination.

Figure 2

Distribution of aquatic nonindigenous plants in the Great Lakes basin by sub-watershed.

Figure 3

Nonindigenous aquatic plants by impact category—limited to impact attributed to competition with native plant species (n = 55). (Re-analysis of the impact assessments which appear in [29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44].

Figure 4

Adaptations identified as assisting in competition (n = 55; however, species can have multiple adaptations). Species scoring “unknown” or “low impact” typically also have adaptations noted and are included in this analysis.