The nutritional value of Palmaria mollis cultured under different light intensities and water exchange rates for juvenile red abalone Haliotis rufescens

A growth experiment with juvenile red abalone was conducted to determine whether the nutritional quality of red macroalga dulse (Palmaria mollis) was dependent on dulse culture conditions. Dulse culture conditions differed by seawater volume exchange rate (1, 6, or 35 d(-1)) and supplemental illumination (0 or 24 h d(-1)), creating a variety of dulse morphologies, biochemical compositions, and palatabilities for red abalone. The results of this study agreed with those of previous studies, showing dulse to be of high nutritional quality for abalone, with a relatively high protein content when compared with other macroalgae. Specific growth rates (SGR) of abalone fed on all dulse diets were higher than those of abalone fed on kelp ( Nereocystis luetkeana). In general, abalone grew faster on dulse cultured with supplemental illumination. Protein content of dulse (10.85-18.22% dry wt.), however, was directly dependent on seawater volume exchange per day, with highest protein levels observed in dulse cultured with 35 volume exchanges d(-1). We suggest that other variables apart from biochemical composition, such as epiphytic diatoms and morphological differences, contributed to the higher growth rates of abalone fed on light-supplemented diets. (C) 2000 Elsevier Science B.V. All rights reserved.