The aquaculture sector continues to grow rapidly across the globe but its environmental impacts are growing as well. Considering the risks carried by classical aquaculture systems, it is necessary to develop responsible aquaculture. This is achievable by reducing the needs for water and nutrients as well as limiting waste and effluents. To this end, a shift to integrated agri aquaculture systems is a prerequisite.
Aquaponics has proven to be an effective means of recirculating aquaculture and horticulture with a decreased environmental impact. The advantages it presents earned it a growing interest worldwide as environmentally friendly expedient to achieving a larger resource productive growth.
In this context, a preliminary study of the feasibility of the introduction of aquaponic systems in continental fish farms was conducted. Thus an aquaponic system was installed. Effluents from the Silver carp (Hypophthalmichthys molitrix) tank are redirected to plants (lettuce, pepper, mint), instead of being discharged into the environment. Fish waste is transformed by bacteria into nutrients that can be absorbed by plants. Purified water is then returned to the fish tank. Every week, the height of each plant was measured in centimeters. Dissolved Oxygen, pH, water temperature, NO3-, NO2- and NH3 were also measured. The growth of fish was determined by measuring body weight and total length. Also, for each sampling, Feed Conversion Ratio (FCR) and Specific Growth Rate were calculated. Variation in the measurements was expressed as the mean ± S.E.
The preliminary results are encouraging. Fish and plant growth rates were remarkable: no pathological abnormality was observed in fish. The mean growth of Silver carp had significantly improved during days of the experiment at (α ≤ 0,05). Comparing the average initial length (15,12 ± 1,50cm) and the average initial weight (60,68±19,15g), to the final experiment results, the average final length was 18,25 ± 1,89cm, and the average weight was 85,06±20,10g. Plants grew fast with no pesticide nor fertilizer input (The height was between 2,11 cm and 4,05 cm). Furthermore, the water quality was very good (water temperature (19-22°C), PH (6-7,3).
This study showed that the application of the aquaponic system has significant influence at nitrogen reduction (NO2- (12,6%), NH3 (19,04%) and NO3- (15,1%). In light of these results, recommendations were issued aiming to nurture the development of aquaponics in Morocco in the future.
Keywords— Environment, Continental fish farms, Aquaponic systems, Morocco