Food chain dynamics of abalone in a polyculture system

The food chain dynamics of three species of commercially important abalone — the red abalone (Haliotis rufescens), the green (H. fulgens) and the Japanese (H. discus) — were measured to determine their relative success in the multispecies aquaculture system at Woods Hole Oceanographic Institution. The abalone were fed sea lettuce (Ulva lactuca) used in the polyculture system to remove nutrients regenerated by the bivalves.This polyculture system was operated on a moderate-sized scale during the summer of 1973. Growth and feeding rates of the abalone were measured during a 112-day period and net growth efficiency was calculated (net production/food ingested). All three species grew during the experiment but H. rufescens had the lowest efficiency of 10.2%, and H. fulgens had the highest efficiency of 22.7%. These differences might be due to the temperature regime (16–23°C) during the experiment. H. rufescens is typically found in colder waters whereas H. fulgens is common in warmer Southern California waters. The results suggest the feasibility of the browsing role of abalone in polyculture systems.