Introduction
The sustainable extraction and production of food and biomass from the oceans is a priority with increasing attention and awareness. In line with this global interest, aquaculture-related activities in Flanders (Belgium) have been growing over the last two decades . Both industry and government are investing substantially in local aquaculture initiatives. However, they all face one common problem: the lack of starting material (bivalve spat, shrimp postlarvae and seaweed spores) in sufficient quantity and in desired quality, emphasizing their dependence on import or wild-catch. Within this project, we adapted hatchery and nursery concepts for molluscs , crustaceans and macroalgae to local (temperate) conditions, incorporated local North Sea species , and expanded our biological and technological knowledge on hatchery and nursery techniques with a strong emphasis on synergies and integration between the three species groups , in terms of infrastructure, rearing techniques and management .
The final goal was to design an integrated approach of a multispecies hatchery and nursery platform and knowledge center, and promote the development of aquaculture in Flanders, Belgium. The results were achieved by a team of academic and private partner s with expertise in sustainable aquaculture (BlueGent) , hatchery techniques and live feed (UGent-ARC), seaweed (UGent-Phycology), ecological risk assessment (UGent-GhEnToxLab), microalgae culture (Proviron), shrimp broodstock management and disease testing (Imaqua bvba), bivalve culture (Aquacultuur Oostende) , food retailing (Colruyt Group), seaweed cultivation and advanced aquaculture textiles (SIOEN) and offshore solutions (DEME Group).
Approach
For each species group (macroalgae, molluscs and crustaceans), w e started by collecting the baseline information and setting up the experimental infrastructure and biological material. We then investigated specific innovations (strain selection, RAS application, alternative feeds, disease control, …). Synergies in facilities and rearing techniques were identified and integrated concepts validated. Based on the experimental data, these synergies were then quantified and the gain in economic and ecological sustainability was valued through an integrated assessment tool. The final result is a first conceptual blueprint for a modular, integrated hatchery and nursery pilot, that forms the basis for a production unit for starting material , service center for experimental validation and knowledge hub for stakeholders.
Main results
A collection of local strains of five commercial seaweeds was built to serve as reliable source for the production of spores. The life cycle of the red seaweeds Palmaria palmata and Porphyra umbilicalis was further unravelled . Strains of Ulva sp. were selected , and the genomic diversity of favourable traits characterized, which resulted in an HD SNP map. Biodegradable cultivation substrates and binders for macroalgae spores were also investigated.
A functional RAS was designed and successfully implemented for the nursery cultivation of two oyster species (Crassostrea gigas and Ostrea edulis), observing a growth rate close to that of commercial hatcheries. A model on the associated mineral consumption reveals that the addition of Ca and CO3 is vital for culturing bivalves in a closed system. The microbial community profile associated with the mono - and multispecies setup was characterized. The first floating upwelling system (FLUPSY) in Belgium was successfully built and tested in the Spuikom , Ostend. The life-cycle and technical requirements for h ard-to-culture microalgae species such as Isochryis galbana and Skeletonema marinoi were documented and the first steps towards the upscaled cultivation of these species was undertaken.
The life cycle control of feed requirements for both the tropical Litopenaeus vannamei and the indigenous cold-water Palaemon prawn has been optimized. Shrimp larvae were successfully reared in a closed recirculating system, with a survival equal to that in batch systems. Freeze-dried microalgae proved a valuable alternative to liv e microalgae for the cultivation of early larval stages of L. vannamei , with some treatments reaching up to 70% survival. This further reduces the dependence on and the investments in a local microalgae culture . The micr obial community profile in systems fed with either of microalgae feed forms was characterized. New disease testing tools for shrimp were developed.
T he synergies between monospecies cultures were identified to establish experimental multispecies setups that provided insight into the nutrient flow between the system compartments and cultured organisms . Multiple proof-of-concepts on different combinations of resource recycling and species co-culture (integrated multitrophic a quaculture; IMTA) were investigated. An environmental impact and economic feasibility assessment w ere done for the most relevant scenarios. W ith the collected knowledge from all mono- an multispecies assessments, a first conceptual blueprint for a modular multispecies hatchery and nursery pilot was developed.
Acknowledgements
The BlueMarine³.Com project is funded by the Flemish government through Flanders Innovation and Entrepreneurship (VLAIO) and is facilitated by the Blue Cluster program. We also wish to thank the many colleagues, PhD, master and internship students that contributed to successfully complete all the aspects of this project.