Line of action:

Status:

Execution date:

General:

Evaluate and develop, at an industrial level, strategies based on multitrophic crops that reduce nitrogen and phosphorus content and, in addition, valorize effluents from land-based aquaculture facilities.

Specific:

1. Determination of the macroalgae that can be found in the farming facilities themselves or on the surrounding coast for use as a biofilter and to feed abalone.

2. Reduction of the amount of N and P in the effluents of turbot (Scophthalmus maximus) culture tanks through the use of macroalgae biofilters.

3. Use of the algal biomass generated to feed abalone (Haliotis tuberculata).

4. Dissemination of the data obtained to promote the development and use of this type of technology in the aquaculture industry.

A1- Determination of macroalgae present in the facilities and in the sea

1.1 On-site and offshore sampling design

1.2. Algae sampling

1.3. Determination of sampled species

1.4. Selection of the most suitable species to move on to the cultivation phase

1.5. Analysis of the results and determination of critical points in the implementation of this action

A2- Selection of macroalgae to be cultivated

2.1. Design and assembly of the culture units for the species to be tested

2.2. Cultivation of macroalgae at laboratory level

2.3. Analysis of the algae’s ability to assimilate nutrients from the environment (N and P)

2.4. Selection of the most suitable species or species to move on to the pilot cultivation phase.

2.5 Analysis of the results and determination of the critical points in the implementation of this action.

A3- Fish culture (Scophthalmus maximus)

3.1 Design and assembly of pilot cultivation units

3.2. Fish culture and control of tank biomass, amount of feed supplied and water parameters (temperature, salinity, pH and O2)

3.3. Analysis of N and P levels in the tributaries and effluents of the culture tanks

3.4. Analysis of the results and in particular of the levels of P and N generated by the fish as a function of the temperature and biomass of the culture tanks.

A4- Macroalgae cultivation

4.1. Design and assembly of pilot cultivation units

4.2. Algae culture, biomass control of culture units and removal of algal biomass to feed H. tuberculata. Measurement of culture water parameters (temperature, salinity, pH, O2 and lighting)

4.3. Analysis of N and P levels in the tributaries and effluents of the cultivation units

4.4. Analysis of the results, determination of critical points of the process and evaluation of the sustainable production capacity to feed Haliotis tuberculata.

A5- Growing abalone

5.1 Design and assembly of pilot culture units

5.2. Culture of H. tuberculata and control of water parameters (temperature, salinity, pH and O2), as well as tank biomass, mortalities and amount of macroalgae supplied.

5.3. Analysis of results, identification of critical points in the process and evaluation of production capacity

A6- Analysis of the data obtained.

6.1. Analysis of the data obtained and identification of the critical points of the farm, as well as the new challenges that arise for the development and implementation of this technology in the Spanish aquaculture industry.

A7- Dissemination of the data obtained

7.1. Making available to the general public the information and conclusions obtained on the CETGA website.

7.2. Presentation of the project’s conclusions to representatives of the different aquaculture companies and people interested in the subject at dissemination days.

The project allowed the study and development of pilot-scale methodologies to cultivate macroalgae (Ulva rigida) that reduce the levels of nitrogen and phosphorus in effluents from land-based aquaculture farms, constituting an interesting technology to optimize the use of resources and reduce the impact of turbot cultivation on the environment. This represents a great opportunity, if we take into account that in Spain 271 marine farms located in the Natura 2000 Network have been identified, some of which produce turbot and sole in their facilities on land.

In the case of the abalone, it has been seen that it is a delicate species and that it requires more research from the point of view of its zootechnics before taking the step for industrial exploitation. However, in the feeding tests, a greater growth potential of the abalone could be observed, when grown together with rigid Ulva in a tank nourished with the effluents of the turbot culture, compared to feed feed and rigid Ulva with filtered water, confirming the potential of multitrophic cultures and the need for further research to avoid the high mortality rates of abalone presented in this project.

On the other hand, it was identified that the main problem for the implementation of land-based integrated multitrophic culture technologies is the legislative framework and the complex procedures for the cultivation of a new species of animal or algae.

In this way, this project will allow other aquaculture companies to evaluate this technology and adapt it to their needs to improve the sustainability of their crops, reduce the impact on the environment and generate new production opportunities that allow diversifying the aquaculture sector in Spain.

The project included various actions to disseminate the project, both digitally – websites and social networks – and offline – press releases. Likewise, technical meetings, dissemination days and meetings with companies in the sector were held for the transfer of knowledge and results.