Abstract
Growth, production and biofiltration rates of seaweed, Ulvalactuca were investigated at two stocking densities (3kg and 6kgm(-2)) and two effluent flow rates (5.4 and 10.8m(3)day(-1)) to optimize an integrated mariculture system at Saudi Red Sea coast. effluents from fish-rearing tank, stocked with 200kg fish (Oreochromisspilurus), fed to six seaweed tanks via sedimentation tank. Fish growth (weight gain 1.75g fish day(-1)), net production (NP, 10.16kgm(-3)) and survival (94.24%) were within acceptable limits. Ulva showed significantly higher (F=62.62, d.f. 3, 35; P<0.0001) specific growth rates at lower density compared with higher density and under high flow versus low flow (SGR=5.78% vs. 2.55% at lower flow and 10.60% vs. 6.26% at higher flow). Biomass yield of Ulva at low- and high-stocking densities (111.11 and 83.2g wet wt m(-2)day(-1), respectively) at low flow and (267.44 and 244.19g wet wt m(-2)day(-1), respectively) at high flow show that high flow rate and lower density favoured growth. Removal rates of total ammonia nitrogen (TAN) (0.26-0.31gm(-2)day(-1)) and phosphate phosphorus (0.32-0.41gm(-2)day(-1)) by U.lactuca were not significantly different (F=1.9, d.f. 3, 59; P=0.1394 for TAN and F=0.29, d.f. 3, 59; P=0.8324 for phosphates) at both the flow rates and stocking densities. Results show that the effluent flow rate has significant impact over the performance of the seaweed than stocking density.