The Nitrate and Nitrite Levels From Both Spinach and Stellate Sturgeon Meat in an Aquaponic Integrated System

Abstract

Introduction. Integrated aquaponic systems represent a viable solution for the continuing upward trend of humanity demands, as long as the balance between productivity and final products quality and biosecurity is found. Aims . To identify the quality, in terms of nitrite and nitrate concentrations, of both spinach and stellate sturgeon meat, obtained under different culture densities (spinach) and feeding regimes (stellate sturgeon), in an integrated aquaponic system. Materials and Methods. The experiment on spinach was made in triplicate, by using 3 stocking densities: (V1 - 59crops/m 2 , V2 - 48crops/m 2 and V3 - 39crops/m 2 ). A 9 media grow bed hydroponic modules (LECA) and a 4 fish rearing units RAS were integrated, forming the integrated aquaponic experimental system. Fish were divided in 4 groups and were fed with 41% brute protein feed, at the following rations: F1 - 2,21%; F2 - 1,85%; F3 - 1,64% and F4 - 1,28% of total biomass. Chemical analyses concerning nitrite and nitrate levels were made on 5 samples, by using Griess method - STAS 9065:2002. Results: A statistical significant difference (p<0.05) was recorded between V1 and V3, in terms of both nitrates and nitrites concentrations. Also, higher nitrite and nitrate concentrations were observed on spinach grown under aquaponic conditions, comparing with spinach derived from field culture. Differences between F1 and F3, F4 nitrite and nitrate concentrations we observed to be significant (p<0.05). Conclusions. Considering the nitrite and nitrate concentrations, spinach grown in aquaponic conditions, as presented above, at densities of 59crops/m 2 and 48crops/m 2 , is marketable. Also, the level of fish meat nitrites and nitrates, from all 4 experimental variants, did not exceed the safety limits for human consumption.