Potential for Concentrated Microalgae as Replacement Diets for Juvenile Green-Lipped Mussels, Perna canaliculus

Abstract

The nursery culture of bivalves typically relies on the feeding of costly live microalgae, while the use of natural sources of phytoplankton for feed is uncertain due to their variable quality and abundance. Replacement diets have been applied in bivalve nursery culture to replace live microalgae with varying success. This study investigated the potential use of two concentrated microalgal diets at a range of levels of substitution with live microalgae. Shellfish Diet 1800® (called SD) and LPB™ Frozen Shellfish Diet® (called LPB) were fed to juvenile green-lipped mussels (Perna canaliculus) at five levels of substitution for live microalgae (i.e., 0, 25, 50, 75, and 100%) for 27 days. The mortality of mussels fed with 100% LPB replacement was significantly higher than the mortality of mussels fed at the lower levels of replacement, i.e., 0 and 25%. The overall final size of spat tended to decrease with the increasing level replacement of live microalgae. Proximate analysis (i.e., crude ash-free dry weight, crude protein, crude lipid, and carbohydrate) showed that only the proportion of carbohydrate content of spat was influenced by feeding treatments, with the mean total carbohydrate content of mussels tending to decrease with increasing levels of replacement of live microalgae. The results indicate that both concentrated microalgal feeds (SD and LPB) are effective at replacing live microalgae by up to 50% without compromising the survival and nutritional profile (AFDW, protein, lipid, and carbohydrate content) of juvenile green-lipped mussels and are therefore a useful resource for improving the efficiency of production.

Nutritional condition of wild and hatchery‐reared, green‐lipped mussel (Perna canaliculus) spat used for aquaculture

“…The total quantity of each biochemical component was also similar to what has been measured previously in Greenshell ™ spat (i.e., protein content between ∼300 and 800 mg g −1 of AFDW, lipid content between ∼10 and 100 mg g −1 of tissue mass and carbohydrate content between ∼10 and 30 mg g −1 of tissue mass), although in the case of both lipid and carbohydrates, some spat samples in this study reached considerably higher levels (i.e., lipid content reaching ∼400 mg g −1 of tissue mass and carbohydrate content reaching ∼80 mg g −1 of tissue mass) (Supono et al., 2023). Combined, these results provide a baseline for future assessments of spat nutritional condition and demonstrate that there may be considerable scope to improve the nutritional condition of spat prior to seeding out onto mussel farms, particularly in the case of those that are nutritionally compromised, that is, at the lower end of values measured in this study.…”

Partial Substitution of Fresh Microalgae with Baker’s Yeast (Saccharomyces cerevisiae) Enhances the Growth of Juvenile Ostrea edulis and Ruditapes decussatus

“…Microalgae production is the main limiting factor impeding the industrial growth of the bivalve aquaculture industry since it corresponds to 30-50% hatchery production's operating costs [1,2]. Diets aiming to substitute live microalgae have been implemented in the early stages of shellfish culture, with varying outcomes [3][4][5]. Yeast cells possess the capability for mass production, are highly stable in water, have an appropriate size for consumption, and high levels and quality of protein.…”