Browsing by Author "Neori, Amir"

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    Effect of water aeration and nutrient load level on biomass yield, N uptake and protein content of the seaweed Ulva lactuca cultured in seawater tanks
    (Springer, 2008) Msuya, Flower E.; Neori, Amir
    The effects of 16 different combinations of nutrient load and agitation on yield, nutrient uptake and proximate chemical composition of the seaweed Ulva lactuca cultured in tanks were evaluated. Intensive fishpond outflow passed through seaweed tanks at four nutrient loading levels and four water agitation combinations of water exchange, bottom aeration and frequently changing water levels (an accelerated tide regime). Specific results from these outdoor experiments were examined further under controlled conditions in laboratory experiments. Agitation treatments affected the performance of U. lactuca only under TAN (NH3 þ NHþ 4 ) load levels below 4 g N m−2 day−1; biofiltration of TAN was the parameter most affected. Biomass yields at each of the four nutrient loading levels were not significantly different between the agitation treatments. Protein content increased significantly with increasing nutrient loading. The agitation treatments had a slight effect on seaweed protein content only at the lowest nutrient loading levels. There were no significant differences in dissolved oxygen concentration, pH, and temperature among the agitation treatments at all nutrient loading levels. Under laboratory conditions, growth rates, protein content, and photosynthetic and biomass yield of the seaweed were affected by water velocity under low nutrient concentrations. It is concluded that the effect of air agitation under the conditions of these experiments was not directly related to photosynthesis, excess dissolved oxygen, or carbon limitation, but to the diffusion of macro nutrients from the water to the seaweed. Therefore, once nutrient concentrations are high enough (above about 4 μM of TAN with the other nutrients in their corresponding proportions), aeration per se is not essential for effective growth and biofiltration by seaweeds.
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    A novel three-stage seaweed (Ulva lactuca) biofilter design for integrated mariculture
    (Kluwer Academic Publishers, 2003) Neori, Amir; Msuya, Flower E.; Shauli, Lilach; Schuenhoff, Andreas; Kopel, Fidi; Shpigel, Muki
    Seaweed biofilters have proven their usefulness in the treatment of fishpond effluents. However, their performance poses a dilemma: TAN (Total Ammonia N) uptake rate – and with it seaweed yield and protein content – is inversely proportional to TAN uptake efficiency. The ideal for a seaweed biofilter performance would be a high uptake rate together with high uptake efficiency. The novel three-stage seaweed biofilter design described here has solved this dilemma. The design used the finding that the performance of seaweed ponds depended on the flux of TAN through them, and that therefore effluents with reduced TAN concentration could provide the seaweed with a high TAN flux if the water flow increased proportionally. Effluents from a seabream fishpond were passed through a series of three successively smaller (25, 12.5 and 6.25 m2, respectively) air-agitated Ulva lactuca ponds. The diminished inflow TAN concentrations to the second and third ponds of the biofilter system were compensated for by the increased water exchange rates, inversely proportional to their sizes. The biofilter performance was evaluated under several TAN loads. TAN was efficiently removed (85–90%), at a high areal rate (up to 2.9 g N m−2 d−1) while producing high protein U. lactuca (up to 44% dw) in all three stages, although with mediocre yields (up to 189 g fresh m−2 d−1). Performance of each seaweed biofilter pond correlated not with TAN concentration, but with areal TAN loads. The novel three-stage design provides significant functional and economic improvements in seaweed biofiltration of intensive fishpond water.
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    The performance of spray-irrigated Ulva lactuca (Ulvophyceae, Chlorophyta) as a crop and as a biofilter of fishpond effluents
    (Phycological Society of America, 2010) Msuya, Flower E.; Neori, Amir
    The seaweed Ulva lactuca L. was spray cultured by mariculture effluents in a mattress-like layer, held in air on slanted boards by plastic netting. Air-agitated seaweed suspension tanks were the reference. Growth rate, yield, and ammonia-N removal rate were 11.8% Æ d)1, 171 g fresh weight (fwt) Æ m)2 Æ d)1, and 5 g N Æ m)2 Æ d)1, respectively, by the spray-cultured U. lactuca, and 16.9% Æ d)1, 283 g fwt Æ m)2 Æ d)1, and 7 g N Æ m)2 Æ d)1, respectively, by the tank U. lactuca. Biomass protein content was similar in both treatments. Dissolved oxygen in the fishpond effluent water was raised by >3 mg Æ L)1 and pH by up to half a unit, upon passage through both culture systems. The data suggest that spray-irrigation culture of U. lactuca in this simple green-mattress-like system supplies the seaweed all it needs to grow and biofilter at rates close to those in standard air-agitated tank culture.
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    A semi-recirculating, integrated system for the culture of fish and seaweed
    (Elsevier, 2003) Schuenhoff, Andreas; Shpigel, Muki; Lupatsch, Ingrid; Ashkenazi, Arik; Msuya, Flower E.; Neori, Amir
    Biofiltration allows for environmentally sustainable mariculture. An intensive, biofiltered recirculating integrated system producing fish and seaweed on a semi-commercial scale was evaluated with respect to production and to nutrient and heat budgets. The system consisted of abalone (Haliotis discus hannai) and sea urchin (Paracentrotus lividus) tanks, an intensive fishpond (Sparus aurata), and a three-stage Ulva lactuca biofilter, which cleaned and recirculated 50% of the effluent back to the fishpond. To preserve water heat, the shellfish and fishpond units were both covered with greenhouses; the biofilter unit was covered with a greenhouse only during winter. Seaweed yield was variable and averaged 94 and 117 g m 2 day 1 (fresh weight) in periods with and without greenhouse cover, respectively. Protein content of U. lactuca averaged above 34% of dry weight. The biofiltration of only 50% of the water through the seaweed biofilter reduced the export of dissolved nutrients to the environment by nearly 30%. Peak ammonia excretion by the morning-fed fish coincided with maximum seaweed light-dependent ammonia uptake and concentrations of ammonia in the fishpond remained within nontoxic limits. Also, daytime photosynthesis of U. lactuca (uptake of CO2) met fish respiration (production of CO2), thus balancing fishpond pH levels within safe limits regarding ammonia toxicity. Daytime oxygen demand by the fish was partially met by the photosynthetically generated oxygen. Before covering the biofilter with a greenhouse, it lost much heat, reducing the temperature in the fishpond. Following the greenhouse covering of the biofilter, heat loss ceased and consequently the fishpond temperature was raised. Recirculation through the biofilter improved system sustainability; it reduced water use, lowered negative environmental impact, and maintained stable and safe water quality conditions in the fishpond.
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    Ulva reticulata and Gracilaria crassa: Macroalgae That Can Biofilter Effluent from Tidal Fishponds in Tanzania
    (Western Indian Ocean Marine Science Association, 2002) Msuya, Flower E.; Neori, Amir
    Macroalgae (seaweed) can be cultured effectively for the production of useful algal biomass and removal of nutrients from fishpond effluents. A land-based, tide/gravity-driven flow-through, fish-macroalgae integrated system was studied at Makoba Bay, Zanzibar, Tanzania, during May–October, 2000. Rectangular cages made of 1-inch mesh netting were constructed in channels that received the outflows of the fishponds. Four species of macroalgae were planted in the cages and compared for their usefulness as biofilters. Gracilaria crassa and Ulva reticulata grew at average rates of 1.5 and 1.2 %, respectively. Both species removed nitrogen as seaweed protein at rates of up to 0.4 g N/m2/d. The algal biomass produced was of good quality with protein dry weight contents of 13% for G. crassa and 26 % for U. reticulata. The biofilters also raised the pH values of the fishpond effluents and oxygenated the water. In contrast to Ulva and Gracilaria, species of Eucheuma and Chaetomorpha performed poorly in the fishpond effluents.