Procambarus clarkii

P. clarkii is known to outcompete native crayfish and rapidly take over habitat where it invades.; \"P. clarkii is also known to compete with native crayfish in Japan (Kawai & Kobayashi, 2005).”

P. clarkii is known to compete with, prey on, and reduce populations of a wide variety of aquatic species including amphibians, mollusks, macroinvertebrates, and fish.

P. clarkii has contributed to the dramatic decline of the European native crayfish in the Astacidae family through its transmission of the crayfish plague (Aphanomyces astaci) and direct competition.

“Intense herbivory by P. clarkii often causes the reduction of macrophyte mass and biodiversity and has been recorded in the Lake Chozas, Spain (Rodríguez et al, 2003); Lake Naivasha, Kenya (Smart et al, 2002); Lake Massaciuccoli, Italy (Gherardi et al, 1999); Lake Doccia, Italy (Gherardi & Acquistapace, 2007); Mediterranean wetlands (Geiger et al, 2005); and the Iberian peninsula (Rodríguez et al, 2003 in Cruz & Rebelo, 2007). Affected species include Nymphoides peltata, Potamopeton crispus, Ultricularia australis, Potamogeton spp. (Gherardi & Acquistapace, 2007; Gherardi et al, 1999).”

Another effect of the feeding, as well as burrowing, behavior of P. clarkii is altered water quality, increased bioturbation, and increased nutrient release from sediment (Angeler et al, 2001).

“P. clarkii is known to compete with, prey on, and reduce populations of a wide variety of aquatic species including amphibians, mollusks, macroinvertebrates, and fish. Competitive pressure and predation on native amphibians have been recorded from the Iberian Peninsula (Cruz & Rebelo, 2005), Sweden (Nystrom et al, 2002 in Ilheu et al, 2007), Europe (Gherardi, 2006). More specific reports include effects on Rana sp., Bufo bufo, and Triturus vulgaris in Italy (Gherardi et al, 2001; Renai & Gherardi, 2004 in Ilheu, 2007) and the Natterjack Toad (Bufo calamita in Donana Natural Park, Spain (Cruz et al, [2006]), and the California newt, Taricha torosa, in California (Gamradt & Kats, 1996 in Nystrom, 1999). Predation and competition pressure on mollusks include native snails in Doccia Lake, Italy (Gherardi & Acquistapace, 2007) and in the Iberian Peninsula (Cruz & Rebelo, 2007).

P. clarkii is known to compete with, prey on, and reduce populations of a wide variety of aquatic species including amphibians, mollusks, macroinvertebrates, and fish.

P. clarkii has contributed to the dramatic decline of the European native crayfish in the Astacidae family through its transmission of the crayfish plague (Aphanomyces astaci)

“Intense herbivory by P. clarkii often causes the reduction of macrophyte mass and biodiversity [...]\"; Dramatic reduction of aquatic vegetation results in many indirect effects as it serves habitat for invertebrates, amphibians, and fry; as a substrate for epiphytic algae; source of refuge for prey, and a primary food source for birds and other species (Nystrom, 1999; France, 1996 in Nystrom, 1999; Steinman, 1996 in Nystrom, 1999). For example, the introduction on P. clarkii to Lake Chozas, Spain caused a reduction of macrophyte plant coverage by 99% which in turn caused a 71% loss in macroinvertebrate genera, 83% reduction in amphibian species, a 75 loss in duck species, and a 52% reduction in waterfowl (Rodriguez et al, 2005).