Introductions and Survival of Nonindigensou Species in the Marine Environment

Nonindigenous Euryhaline Plants

International shipping is probably responsible for the release of three species of nonindigenous plants in Florida (Schardt and Schmitz 1990). Although the original sites of the introductions may have been in marine or estuarine ecosystems, most problems by these plants are now in freshwater ecosystems. The introduced nonindigenous plants are:

Waterlettuce (Pistia stratiotes L.). Waterlettuce was first reported by J. W. Bratrum in 1765 (Bartram 1942), and many people now think the plant is native to Florida. There is, however, considerable evidence that the species was introduced by sailing ships from South America early during the colonization of North America. Waterlettuce is now a nuisance species worldwide.

Alligatorweed (Alternanthera philoxeroides; Mart. Griseb.). This plant seemingly entered the United States before 1987 as an accidental release from the ballast of sailing ships in Mobile, Alabama (Zeiger 1967). However, Schardt and Schmitz (1990) reported an unsubstantiated report that alligatorweed was present in Florida in 1890 (Weldon 1960). Alligatorweed is a problem species in this country and elsewhere.

Salvinia (Salvinia minima Baker). This plant was first collected in Florida during 1928 in the St. Johns River (Long and Lakela 1976). There have been two theories on its pathway of introduction; it was introduced in discharge of spore-contaminated ship ballast at the Port of Jacksonville or discarded as unwanted aquarium plants (Schmitz et al. 1991). It is now a problem species in Florida.