Ingestion and digestion of live microalgae and microalgae concentrates by sandfish, Holothuria scabra, larvae

Use of micro-algae concentrates for hatchery culture of sandfish, Holothuria scabra

“…Thus, Isochrysis 1800® was fed at a rate of 10,000 cells mL −1 on day 2, 11,000 cells mL −1 on day 3, 12,000 cells mL −1 on day 4, 13,000 cells mL −1 on day 5, and so on (Table 1). Because the microalgae used in this study vary considerably in cell size (Duy et al, 2015), and rations administered on an equal cell density basis would differ considerably in the mass or volume of micro-algae available to larvae across treatments, diets were presented to larvae on an equal dry weight basis (Knauer, 2011). The dry weight of each daily Isochrysis 1800® ration was calculated and all other micro-algae diets were administered at cell densities that provided the same dry weight (Table 1).…”

“…Three of the most digestible products identified in previous research (Duy et al, 2015) were used: (1) mono-cultured Isochrysis sp. (Haptophyceae) (Isochrysis 1800®); (2) mono-cultured Pavlova sp.…”

“…The daily ration was divided into three equal proportions fed three times a day with at least 4 h between feeds to ensure ingestion and digestion by larvae (Duy et al, 2015) and minimise the possibility of overfeeding (Morgan, 2001). Larvae were fed from day 2 to day 22 (Table 1).…”

“…In addition to appropriate characteristics for ingestion and subsequent digestion, suitable foods for sea cucumber larvae must have appropriate nutritional compositions (Duy et al, 2015). Determining relationships between dietary nutrient compositions and larval growth, development and survival is essential for optimising larval feeding protocols and deducing the nutritional requirements of larvae which, in the case of sandfish and holothurians more generally, are poorly known.…”

“…Commercially available micro-algae concentrates were recently reported to be well ingested and digested by different ages of sandfish auriculariae (Duy et al, 2015), and are thought to have potential as replacements for live micro-algae during hatchery culture of this species (Hair et al, 2011;Duy et al, 2015). Hair et al (2011) reported successful larval culture of sandfish larvae when the majority of live micro-algae was replaced with concentrated micro-algae, while Zacarías-Soto et al (2013) more recently reported successful larval culture of Isostichopus badionotus using micro-algae concentrates alone.…”