A Growth Assessment of Juvenile Abalone Haliotis laevigata Fed Enriched Macroalgae Ulva rigida

The experiment was conducted to assess the growth of juvenile greenlip abalone Haliotis laevigata fed a range of Ulva rigida diets with different nitrogen contents and an artificial pelleted diet. The minimal nutrient concentration resulting in significant enrichment of U. rigida was 2.25 mg N l−1. The maximum nitrogen content obtained by U. rigida in this study was 6.099%, which resulted from an inorganic nutrient concentration of 7 mg N l−1. However, no further significant increase in enrichment occurred from nutrient concentrations of 10 and 15 mg N l−1. Abalone specific growth rate in shell length (SGRL) and wet weight (SGRW) and foot muscle yield were significantly higher for abalone fed the artificial diet compared to those fed any U. rigida diet. Abalone fed U. rigida enriched in less than 15 mg N l−1 had similar growth rates compared to abalone fed unenriched U. rigida. Abalone fed the artificial diet contributed a higher percentage of weight gain into the valuable foot muscle. The foot muscle moisture content of abalone fed the artificial diet was significantly lower than that of abalone fed any U. rigida diet. The conclusions reached by this study should assist Australian abalone producers in assessing the potential benefits of using U. rigida as an effluent biofilter and subsequent food source for the commercially important juvenile greenlip abalone.