Author(s):

Emmanuel C. Capinpin Jr

Abstract: The settlement of abalone Haliotis asinina larvae on 5 species of locally isolated diatom strains (Navicula mollis, Stauroneis sp., N. ramosissima, Pleurosigma sp., and Cocconeis sp.) were examined in the laboratory. Attachment and metamorphosis of H. asinina were 2 distinctly different responses. Attachment was observed as the larval foot becomes firmly attached to the surface of the substratum. In the experiment, high attachment on all treatments, including control, was observed at 6 h after start of the experiment (about 45 h after fertilization) at 26.5-27.5 °C. Larvae were observed to detach and swim off the substratum for over 3 d after beginning of the experiment. The metamorphosis was non-reversible and could occur in larvae at 4.6 d after fertilization. All the diatom films stimulated attachment behavior but only a few induced low levels of normal metamorphosis over several days. Completion of metamorphosis as evidenced by shell growth was observed at low levels (4-16%) 5 days after experiment began (6 d after fertilization) only on Cocconeis sp., N. mollis, and Pleurosigma sp.

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