Bioremediation potential, growth and biomass yield of the green seaweed, Ulva lactuca in an integrated marine aquaculture system at the Red Sea coast of Saudi Arabia at different stocking densities and effluent flow rates

Abstract

Growth, production and biofiltration rates of seaweed, Ulva lactuca were investigated at two stocking densities (3 kg and 6 kg m À2 ) and two effluent flow rates (5.4 and 10.8 m 3 day À1 ) to optimize an integrated mariculture system at Saudi Red Sea coast. effluents from fish-rearing tank, stocked with 200 kg fish (Oreochromis spilurus), fed to six seaweed tanks via sedimentation tank. Fish growth (weight gain 1.75 g fish day À1 ), net production (NP, 10.16 kg m À3 ) 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 lowand high-stocking densities (111.11 and 83.2 g wet wt m À2 day À1 , respectively) at low flow and (267.44 and 244.19 g wet wt m À2 day À1 , respectively) at high flow show that high flow rate and lower density favoured growth. Removal rates of total ammonia nitrogen (TAN) (0.26-0.31 g m À2 day À1 ) and phosphate phosphorus (0.32-0.41 g m À2 day À1 ) 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.

Reproductive sterility increases the capacity to exploit the green seaweed Ulva rigida for commercial applications

“…The green seaweed Ulva is an increasingly important food (Ortiz et al, 2006), feed (Ahmed et al, 2015;Cyrus et al, 2015), and biofuel feedstock (Bruhn et al, 2011), as well playing a role in the delivery of crucial wastewater and CO2 remediation services (Chung et al, 2011;Al-Hafedh et al, 2015). Interest in Ulva as a source of bioproducts and bioprocesses has driven concomitant efforts to optimize Ulva cultivation (Hiraoka & Oka, 2008;Bolton et al, 2009;Carl et al, 2016).…”

An Ocean Acidification Acclimatised Green Tide Alga Is Robust to Changes of Seawater Carbon Chemistry but Vulnerable to Light Stress

“…Ulva , a cosmopolitan genus which is common in tide-pools, has been gaining significant interest due to its potential value in animal feed [20,21], human food [22,23], biofuel [24,25] as well as the delivery of crucial ecosystem services such as wastewater bioremediation [26,27] and CO 2 removal [28,29]. Meanwhile, Ulva is the only genus contributing to reported green tide events [30,31].…”

Biofiltering efficiency and productive performance of macroalgae with potential for integrated multi-trophic Aquaculture (IMTA)

“…In addition, IMTA uses various industrial applications for algae (NEORI, 2008;BIXLER and PORSE, 2010) and these are recognized as a high-quality food and have traditionally been used as food and feed (FLEURENCE, 1999;FAO, 2014), especially in Asian countries (KUMAR et al, 2008). Many algae species have a suitable chemical composition for use as an ingredient in aquaculture with the potential for large-scale production (AL HAFEDH et al, 2014), without being antinutritional (PEREIRA et al, 2012).…”