Introduction
The interest of Holothurians as deposit feeders has been demonstrated in different studies and their environmental value, through their mitigation ability, was highlighted within different IMTA systems (Hannah et al., 2013; Kang et al., 2003; Zhou, 2006) indicating that sea cucumbers can optimise the net use of wastes (Reid et al., 2013).
Given the existing research, the current studies investigated the potential for the integrated culture of the sea cucumber Holothuria. sanctori and Neostichopus grammatus with the abalone Haliotis tuberculata and Haliotis midae in order to develop an integrated Land Based IMTA production of these species.
Materials and methods
Experimental specimens
Young individuals of H. sanctori and N. grammatus were collected at a depth of 0-10 m, by scuba diving, and maintained and acclimated in experimental installations, placing them under abalone (H. tuberculata and H. midae) baskets (in which abalone were fed macroalgae and/or compound feed). After their acclimation, they were then respectively allocated to experimental IMTA units.
Adult abalone of H. tuberculata and H. midae were obtained from research and commercial facilities both at the University of Las Palmas de Gran Canaria and Wild Coast Abalone.
IMTA experimental set up
Experimental IMTA systems were designed to provide two levels compartments; one for the fed abalone and the other for sea cucumbers located below the abalone compartment. The abalone were placed in perforated baskets to allow water exchange and release of abalone wastes to reach the sea cucumbers located below.
Experimental parameters
Weight Gain (WG), and Specific Growth Rate (SGR) as well as ingestion rate, faecal production rate and water quality were analysed.
Results
The results obtained demonstrated the influence of abalone feed employed in the growth potential of the sea cucumbers and the impact on the ingestion rate. They also highlighted the potential to coculture abalone and sea cucumbers, the sea cucumber bioremediation capacity and growth under abalone as well as macroalgae production.
Discussion
The results obtained confirmed the potential to produce sea cucumbers in co-culture with abalone species as demonstrated by previous research. They highlighted the variation of sea cucumber growth potential as a function of the nature of abalone feed employed and the differences in ingestion and growth parameters according size, density and species. Moreover, the studies highlighted the potential to develop IMTA systems including only low trophic species and allowing the integration of macroalgae production in the systems. These results are of interest for the future development of low trophic species IMTA systems and the future successful integrated production of the sea cucumber species.
References
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Acknowledgements
This research is supported by the EU H2020 research and innovation program within the collaborative project “AQUAVITAE– New species, processes and products contributing to increased production and improved sustainability in emerging low trophic, and existing low and high trophic aquaculture value chains in the Atlantic” (https://aquavitaeproject.eu/) under Grant Agreement No. 818173.