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 a gri 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, C ontinental fish farms , Aquaponic systems , Morocco