Feeding, selection, digestion and absorption of the organic matter from mussel waste by juveniles of the deposit-feeding sea cucumber, Australostichopus mollis

An understanding of the feeding and digestive capabilities of juvenile sea cucumbers is an important step for their aquaculture development. The feeding behaviour, food selectivity, digestion and absorption of total organic matter (TOM) were determined for juveniles (35–40 g wet weight) of the Australasian brown sea cucumber, Australostichopus mollis, kept in circular plastic tanks (9 l; 6 replicate tanks per feed treatment). Sea cucumbers were fed with feeds containing different levels of TOM (1, 4, 12 and 20%) prepared from sand mixed with the biodeposits of aquacultured green-lipped mussel, Perna canaliculus. No significant diurnal patterns in digestion were detected in all feed treatments. As the TOM level in the feed increased, the selection of organic particles decreased and most importantly overall nutrient absorption increased, which is likely to lead to improved growth rates. However, absorption efficiency declined as organic matter content of the feed increased. This study suggests that palatable-artificial diets rich in organic matter can be used to increase nutrient uptake and potentially facilitate increased stocking densities of sea cucumbers under controlled conditions.