Introduction Directory UMM :Data Elmu:jurnal:A:Aquaculture:Vol185.Issue1-2.May2000:

Ž . Aquaculture 185 2000 121–136 www.elsevier.nlrlocateraqua-online The nutritional value of Palmaria mollis cultured under different light intensities and water exchange rates for juvenile red abalone Haliotis rufescens Gunther Rosen, Chris J. Langdon , Ford Evans Hatfield Marine Science Center and Department of Fisheries and Wildlife, Oregon State UniÕersity, Newport, OR 97365, USA Accepted 21 October 1999 Abstract A growth experiment with juvenile red abalone was conducted to determine whether the Ž . nutritional quality of red macroalga dulse Palmaria mollis was dependent on dulse culture Ž y1 . conditions. Dulse culture conditions differed by seawater volume exchange rate 1, 6, or 35 d Ž y1 . and supplemental illumination 0 or 24 h d , 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 Ž . Ž 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. Ž . 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 y1 . 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. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Haliotis; Dulse; Co-culture; Polyculture; Growth; Feeding rate; Protein; Diet; Macroalga

1. Introduction

Culture of red abalone in the United States has traditionally been based on abalone fed a diet of Macrocystis spp. or Nereocystis luetkeana harvested from coastal kelp Corresponding author. Tel.: q1-541-867-0231; fax: q1-541-867-0105. Ž . E-mail address: chris.langdonhmsc.orst.edu C.J. Langdon . 0044-8486r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 0 4 4 - 8 4 8 6 9 9 0 0 3 4 3 - 9 Ž . beds Hahn, 1989 . The absence of a reliable supply of these seaweeds outside of Ž . California Norman-Boudreau, 1988 , as well as the economic and environmental Ž . considerations in harvesting large quantities of kelp Mercer et al., 1993 , have prevented the expansion of abalone farming to other coastal areas. Co-culture of the red seaweed, Palmaria mollis, and red abalone, at Oregon State University, Hatfield Marine Ž . Science Center HMSC , has shown promise as an efficient method for abalone culture. This land-based approach will allow abalone aquaculture to be widely practiced in the Pacific Northwest. By growing the two commercially important species together, seawater-pumping costs can be reduced due to the seaweed’s ability to remove toxic ammonia excreted by abalone. In addition, dulse provides a nutritious food source for abalone. P. mollis has been shown to be a fast-growing and effective species for removal of Ž . ammonia, nitrate, and phosphate from aquaculture effluents Levin, 1991 . The alga also Ž . has been shown to support juvenile abalone shell length SL growth rates as high as 3.9 y1 Ž . mm month Evans, unpublished data . In a study of 56 species of marine algae occurring off the coast of Japan, a similar algal species, P. palmata, resulted in the Ž . highest monthly weight gain 51 of body weight , or an SL increase of 2.97 mm y1 Ž . month , when fed to H. discus hannaii Uki et al., 1986 . P. palmata is considered to be a well-balanced feed for abalone, with protein, lipid, and carbohydrate levels of 15, Ž . 3–5, and 20–30, respectively Mercer et al., 1993 . The primary diet of red abalone in northern California waters consists of N. Ž . luetkeana, a brown macroalga commonly known as bull kelp Hahn, 1989 . When given Ž . a choice, red abalone prefer brown seaweed to red Tenore, 1976 . Like most marine algae, bull kelp is relatively poor in nutritional value and has a high moisture content Ž . Britz, 1996 . Its abundance in the red abalone’s natural habitat and the soft texture of its Ž fronds, however, may explain why it is a preferred diet of abalone McShane et al., . 1994 . Bull kelp also tends to possess low concentrations of polyphenolic compounds, which have been shown to deter grazing, making it particularly attractive to herbivores Ž . Ž . Winter and Estes, 1992 . Ebert and Houk 1989 reported a high feeding rate of 16.8 of mean body weight d y1 for red abalone fed this alga, but only a modest SL increase of 1.6 mm month y1 . Ž . Evans and Langdon in press investigated the effect of different dulse–abalone co-culture conditions on growth rate and maximum stocking density of red abalone. Ž y1 . Ž Seawater volume exchange rate 1, 6, or 35 d and light exposure 0 or 24 h y1 . supplemental illumination d resulted in different dulse growth rates and morpholo- gies, creating potential changes in food quality for abalone. It is conceivable that Ž . experimental culture conditions reported by Evans and Langdon in press resulted in dulse that differed in nutritional value for abalone because protein content of macroalgae Ž . is often affected by both light intensity Lapointe and Tenore, 1981 and seawater flow Ž . rate Subander et al., 1993 . Dulse morphology and texture may also affect its food quality because abalone have been shown to have preference for soft macroalgal thalli Ž . Winter and Estes, 1992; McShane et al., 1994; Stepto and Cook, 1996 . Ž The objective of this study was to determine the effects of culture conditions 1, 6, or y1 y1 . 35 volume exchanges d ; 0 or 24 h supplemental illumination d on the nutritional value of dulse for juvenile red abalone. This growth study differs from that of Evans and Ž . Langdon in press in that abalone were fed on the different algal types separately from the co-culture system; therefore, culture conditions for dulse did not have a direct influence on abalone growth. A diet of wild-harvested bull kelp, N. luetkeana, was used as a control diet.

2. Materials and methods