MACRO-ALGAL DIGESTION SURVIVAL IN 2 COMMERCIAL SPECIES OF ABALONE (HALIOTIS-LAEVIGATA DONOVAN AND HALIOTIS-RUBRA LEACH)

The survival of ingested macro-algae in two commercially fished specie s of abalone (Haliotis laevigata Donovan and Haliotis rubra Leach) was examined through a culture study of faecal matter that was dissected out of wild taken specimens. A similar study was made of faecal matter obtained from captive animals that were fed on solo diets of common d rift algae. Results indicated a number of brown, red and green macro-a lgae could pass through the digestive tract of both species with some degree of cellular integrity and pigmentation (although not necessaril y alive). Despite this variety, none of the fragments collected from t he faecal matter of wild taken abalone grew in culture. A large number of fine filamentous and micro-algae, presumably derived from the epip hytic communities on the macro-algae consumed by the abalone, were fou nd to grow in culture having survived digestion. Cultures from faecal matter of abalone fed on solo diets showed two species, Caulerpa brown ii (C. Agardh) Endlicher and Ulva australis Areschoug, were capable of surviving digestion; both algae are less preferred by abalone than ot her food species. Highly preferred algae are digested too efficiently to survive and the less preferred algae are either not consumed or oth erwise eaten in such small quantities that survival cannot be determin ed.