Interactions between the Japanese abalone Haliotis discus hannai (Ino 1953) and Chilean species: Consumption, competition, and predation

The Japanese abalone, Haliotis discus hannai (Ino, 1953) is produced in Land-based culture on the coast of Chile. The high costs involved in such culture systems generated the interest to evaluate the possibility to culture the abalone confined to cages in the sea. Introduction of this species into the natural environment may pose risks to local flora and fauna, particularly the establishment of populations arising from escaped specimens or larval settlement. Laboratory experiments were carried out to evaluate interactions between this abalone and local species in order to determine rates of consumption of local algae by these molluscs, competition with other organisms occupying the same feeding niche, and predation on the abalone by some local carnivores. The experiments demonstrated consumption of all offered algae by the abalone, particularly Rhodymenia howeana at rates of 1.3% to 5% of their body weight per day. In competition with other species of herbivores it was observed that with some there was a decline in consumption rate both by the abalone and the competitors when they were together, suggesting occurrence of competitive interference. The abalone readily attracted and were consumed by a variety of predators, particularly Meyenaster gelatinosus and Cancer setosus. It was concluded that if H. discus hannai escapes from the cages or produces larvae which settle on rocky reefs, this species might become established as an additional component of the natural communities. However, due to competitive interactions, predation pressure, and an opportunistic fishery, the development of substantial populations, let alone population explosions, with serious negative environmental impacts is improbable.