Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Factors affecting the food value of diatom strains for post-larval abalone Haliotis iris.

Abstract

Growth and survival of post-larval abalone, H. iris (mean initial shell length 570 µm), fed on 8 strains (7 species) of benthic diatom were examined. Post-larvae showed active feeding behaviour on all diatom strains. Two strains (Achnanthes longipes-1 and Nitzschia sp.) produced significantly faster growth (34-35 µm shell length daily) than the remaining 6 strains (11-17 µm daily). The 2 strains which resulted in rapid growth were efficiently digested by post-larvae, with 93-94% of live cells ruptured during passage through the gut. Two of the remaining strains could not be ingested during the growth experiment because the cells were too large (A. longipes-2) or too strongly attached (Cocconeis pseudomarginata). As for the remaining strains (Navicula britannica, Navicula ramosissima, Navicula sp. and Nitzschia ovalis) most cells passed through the gut alive. Survival rate was highest when fed on the 2 rapid-growth strains, and survival was positively correlated with growth rate (r = 0.73, P<0.05) and digestion efficiency (r = 0.80, P<0.05) of diatoms. The digestion efficiency of diatom strains appears to be an important factor determining their dietary value. Digestion efficiency can be influenced by diatom morphology, attachment strength, frustule strength and post-larval age/size. It is suggested that the isolation and use of digestible strains may improve hatchery culture of abalone.