Biota of Lakes and Reservoirs - Hydro-Environmental Analysis: Freshwater Environments - page 438

• Develop and carry out environmentally sound control methods to prevent, monitor, and

control unintentional introductions of nonindigenous species

• Understand and minimize the economic and ecological impacts of nonindigenous aquatic

nuisance species that become established

• Establish a program of research and technology development and assistance to states in the

management and removal of zebra mussels

There are a large number of invasive species in the United States and in other countries around
the world (some of which originated in the United States and are invasive elsewhere). The following
section provides an introduction to a few of these invasive species.

15.4.1 I nVaSIVe p LantS
A variety of plants, including many macrophytes, are native to speciic regions of the United States
and can be problematic with excessive growth. However, a number of the really problematic spe-
cies causing aquatic weed problems are introduced or invasive species. Examples of submerged
invasive species include the watermilfoil and the curly-leaf pondweed that cause some of the worst
problems in Florida (LakeWatch 2007) and other states. Other examples include those illustrated
in Figure 15.25 and Table 15.5. As indicated, many of these species were introduced as either orna-
mental through the aquarium trade or ship ballast waters. These plants can grow rapidly to the water
surface and form dense canopies.

Brazilian waterweed

Caulerpa, Mediterranean Clone

Alligatorweed

Purple loosestrife

Hydrilla

Eurasian watermilfoil

Water spinach

Water hyacinth

Water lettuce

FIGURE 15.25 Selected invasive macrophytes. (From USDA National Invasive Species Information
Center, NISIC.)