Consumption and remediation of European Seabass (Dicentrarchus labrax) waste by the sea cucumber Holothuria forskali

Abstract

Integrated multi-trophic aquaculture (IMTA) systems combining finfish and sea cucumbers remain largely untested. Integrating a deposit-feeding species into existing aquaculture units prerequires survival of the deposit feeder, waste diet consumption and bioremediation effect of feeding activity. The sea cucumber, Holothuria forskali, was fed waste from cultured European Seabass, Dicentrarchus labrax, to determine palatability and impact of grazing by H. forskali. Sea cucumbers readily consumed waste diet at amounts suitable to process biodeposition beneath commercial sea-based D. labrax farms. Grazing by H. forskali significantly reduced total nitrogen content of D. labrax waste in short-term controlled feeding experiments (unpaired t test, p < 0.05) and suppressed total carbon content of D. labrax waste in long-term controlled feeding experiments (unpaired t test, p < 0.05). Survival, palatability and nutrient reduction results support investigation of H. forskali inclusion in IMTA systems focussed on bioremediation of finfish waste if limitations in understanding of growth potential, biology and life history are addressed.