Settlement, growth and survival of donkey's ear abalone Haliotis asinina (Linne) in response to diatom diets and attachment substrate

The effect of feeding four diatom diets (Amphora sp., Navicula ramosissima, Amphora sp. + N. ramosissima, and mixed diatoms) and two attachment substrates (PP+CCA: polyvinyl plates with crustose coralline algae; PP-CCA: polyvinyl plates without crustose coralline algae) were determined for seed production of abalone, Haliois asinina. On day 5, significantly higher number of larvae settled on PP+CCA fed with mixed diatoms followed by Amphora sp., N. ramosissima, Amphora sp. + N. ramosissima, and abalone larvae reared on PP-CCA fied with N. ramosissima only. Fewer larvae settled on PP-CCA fed with Amphora + N. ramosissima, Amphora sp. and mixed diatoms. The size of abalone juveniles from PP-CCA was significantly bigger compared with juveniles measured from PP+CCA. However, the number of juveniles harvested from tanks provided with PP+CCA was higher compared with tanks with PP-CCA. This study has shown that crustose coralline algae favored the settlement of H. asinina larvae and inoculation of diatom slurry is necessary to provide sufficient food for the growing larvae