Microencapsulated diets to improve growth and survivorship in juvenile European flat oysters (Ostrea edulis)

Abstract

Sustainable expansion of aquaculture is critical to global food security, and bivalve shellfish aquaculture represents a sustainable method to provide people with affordable nutritious food. Oysters represent 54% of the global bivalve market by value, with propagation of juveniles within hatcheries critical to allow the industry to grow. Growth and survival of juvenile oysters in hatchery systems is constrained by suboptimal feed. The live algal feed currently used is expensive, of variable quality, contamination prone, and the high level of skill and equipment required limits where hatcheries can be located. We demonstrate how a novel microencapsulated diet can increase the growth and survivorship of Ostrea edulis (European flat oyster) juveniles in both the laboratory and hatchery setting. The microcapsules are easily produced in large quantities, stable for long term storage, and can be customised to have exceptionally high levels of nutrients key for oyster growth. O. edulis larvae fed a combined diet of microcapsules and algae for 8 days had a 46% greater increase in maximum size, 171% greater increase in minimum size, and 5% higher survival than larvae fed algae alone. O. edulis spat of 4 mm fed the combined diet for 7 weeks also had significantly greater survivorship (16% greater in hatchery, 58% greater in laboratory) and growth comparable (hatchery) or better (laboratory experiments) than algae alone. Further tailoring of the nutritional composition of microcapsules to specific bivalve species or growth stages could allow microcapsules to replace a greater proportion of or even completely replace algal diets. There is potential for these diets to revolutionise bivalve shellfish farming globally.

Microencapsulated algal feeds as a sustainable replacement diet for broodstock in commercial bivalve aquaculture

“…In Europe twice the number of antimicrobial substances were sold for animal versus human use in 2014 15 . Non-live diets are more sterile, and hence since the 1990s the bivalve aquaculture industry has been seeking non-live alternative feeds to reduce antibiotic needs 6 , 7 , 11 , 16 . FAO and EU sustainable aquaculture policies identify urgent and immediate needs to reduce land, energy, and antibiotic use in aquaculture 15 , 17 – 19 .…”

“…For bivalve nutrition Schizochytrium has advantages, with levels of key nutrients such as docosahexaenoic acid (DHA) exceeding 20% dry-weight; greater than twice the abundance of DHA in hatchery-grown algae 22 , 23 . Novel microcapsules are an ideal vehicle for delivering sustainable Schizochytrium -based diets to bivalve broodstock 6 , 8 , 11 , 24 . Mass production is simple and cost-effective 8 , 24 , and the microcapsules dry and shelf-stable thus circumventing conventional feed wastage costs 16 .…”

“…We also note that a 100% replacement of live algae will require further tailoring of the microcapsule formulation for increased protein content. Data sources and figure methodology: Supplementary Data S1 8 , 11 – 14 , 20 , 24 , 27 – 30 . …”

Vitamin Bullets. Microencapsulated Feeds to Fortify Shellfish and Tackle Human Nutrient Deficiencies

“…Novel microencapsulated feeds developed through recent chemical engineering innovations can provide a delivery vehicle for micronutrients to bivalves (24). It has already been demonstrated that this form of microcapsules are digestible by bivalves and can improve bivalve growth and sexual maturation [ (25,26); Willer and Aldridge, in review]. Mass production is simple and cost-effective (24,26), and the dry microcapsules have shelf lives in excess of one year in any sealed dry container (e.g., mylar bags) thus circumventing conventional feed wastage costs (27).…”

Growth performance and feeding utilization of alternative feed for adult horseshoe crabs Carcinoscorpius rotundicauda kept in captivity

“…The development of aquafeed has long been practiced in many economically important animals such as mud crabs (Holme, Zeng, & Southgate, ; Mirera & Mtile, ), lobsters (Liliyanti, Ali, & Faturrahman, ; Solanki et al, ), shrimps (Kureshy & Davis, ) and many bivalves such as mussels (Willer & Aldridge, ) and oysters (Willer & Aldridge, ). The animals were cultured in mass and to meet the market demands.…”