Utilization of desalinated brackish water residues for cultivation of the marine fish species,Dicentrarchus labrax, Sparus aurata, and Sciaenops ocellatus
Al-Qutob, Mutaz A.
Qubaja, Ra'fat A.
Nashashibi, Tharwat S.
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The utilization of brackish water residues from desalination units for fish mariculture in Palestine could represent an environmental friendly alternative of disposing brine water which could have an adverse effect on wild life. In this study, three juvenile marine fish species (Gilt-head bream S. aurata, European sea bass D. labrax, and red drum S. ocellatus) with average weights of 0.7-4.9 g, were acclimated and reared in brine brackish water residues collected from Jericho desalination units with salinities of 6.5 ‰ and 11 ‰ diluted sea water as control for 3-7 months. Fish were fed 56 % rich protein diet. Brine brackish water contained high levels of Cl-1 (3369 mgL-1), Na+1(3735 mgL-1), K+1(300 mgL-1), SO4 -2 (716 mgL-1) with the divalent ions Mg+2 (57.3 mgL-1) and Ca+2 (276 mgL-1).The experimental well showed more than the maximum allowable concentration of Cr (14.49 μgL-1), Ag (5.3 μgL-1) and Mn (27.88 μgL-1) for water quality of fisheries use. The sea bass with an average weight of 0.76 g (at a salinity of 6.5 ‰) showed an acceptable growth performance parameters and reached a percentage weight gain (% WG) of 6345.23 % and a survival rate of 77.5 % compared to control groups at 11 ‰ that reached at the same time a % WG of 6543.78 % and a survival rate of 82 % after 30 weeks. The red drum juveniles reached a % WG of 2661.6 % and 2673.92 % after 15 weeks at 6.5 ‰ and 11 ‰ respectively while sea bream reached a % WG of 241.63 % and 772.44 % after 15 weeks at 6.5 ‰ and 11 ‰ respectively. Survival rate was only 5 % at both salinities for the two species. In a further study sea bass fingerlings with an average weight of 20.5 g were reared in brackish water of 6.5 ‰ salinity for 7 weeks and were fed superior fish meal with fish oil. They received diets of 2.1 %, 3.0 %, and 4.0 % of body weight. Sea bass fingerlings which received diets of 2.1 %, had the highest FCE (0.82) and PER (1.46) with the lowest FCR (1.22). These results confirm that the most suitable fish for cultivation utilizing brackish water from Jericho desalination units with salinity of 6.5 ‰ is sea bass D. labrax, while the other two species need some modification to acclimatize to this water. Furthermore, the best food % for optimum growth of sea bass at this salinity is 2.1 % after 7 weeks. Brackish water from Jericho desalination units are suitable for cultivation of these species, but may need some modification as adding salts to fish diet or water and reducing toxicity of some high trace metals present by a suitable method.