Seagrass debris as potential food source to enhance Holothuria arguinensis' growth in aquaculture

Holothuria arguinensis aquaculture started to be developed in 2014, being the first sea cucumber species from Europe. However, some aspects of its aquaculture biotechnology, such diets, need to be assessed. This work aimed to evaluate seagrass debris of Zostera noltii and Cymodocea nodosa as food source for broodstock maintenance in tanks, during breeding periods. The given feed rations per tank were calculated as the 30% of the total sea cucumber biomass in each tank and reviewed each week. Then, feed rations of seagrass and sediment were calculated from this value, according to the following percentages: 40% sediment, 15% Z. noltii, 40% Z. noltii, 15% C. nodosa and 40% C. nodosa. H. arguinensis growth, feeding rate and nutritional value were assessed under these diets. H. arguinensis fed with 40% of Z. noltii showed the highest growth (specific growth rate = 0.09 +/- 0.06%/day, absolute growth rate = 0.11 +/- 0.07 g/day) increasing their final weight in 5.86 +/- 3.57% in 57 days. However, the individuals fed with C. nodosa showed a negative growth. H. arguinensis showed a reduction in its feeding rate as the organic matter content in the diets increased. H. arguinensis did not show any important change on proximate composition, protein, lipid, mineral contents and fatty acids profile among the feeding groups, or in comparison with the individuals collected from wild habitat. Therefore, H. arguinensis could be fed with Z. noltii debris during tanks maintenance along breeding period, ensuring its growth and maintaining its nutritional profile.