Culture of the seaweed Ulva ohnoi integrated in a Solea senegalensis recirculating system: influence of light and biomass stocking density on macroalgae productivity

Abstract

A growth model was developed to optimize the management of multi-trophic aquaculture systems by analyzing the influence of light and biomass stocking density (SD in the productivity of Ulva ohnoi fed with the effluents from Solea senegalensis culture tanks.Experimental growth rates and productivity were determined in three flat bottom algae tanks with different incident photon irradiances ( ) (163, 280 and 886 µmol m -2 s -1 ), photoperiod 12:12h and with stocking densities ranging from 82 to 340 gdw m -2 . The distribution of photon irradiance in the algae tanks was estimated as a function of the and SD.The results obtained showed that, the algae exposed to the highest (886 µmol m -2 s -1 ) and below 170gdw m -2 experimented a strong decrease in their growth rate, together with morphological changes.The model proposed to estimate the specific growth rate ( ), on the basis of and , assumed that photosynthetic activity is dependent on the local photon flux density and, therefore, spatially distributed in the tank. The non-linear regression used to estimate the growth kinetic parameters showed a standard deviation of the distance between measured and fitted data values equal to 0.011 d -1 .In terms of biomass productivity per unit area ( ) the model shows, for each level, a trend to increase with SD, achieving a maximum , where SD can be considered optimal, and decreasing for higher SD values. The optimal SD and the maximum achievable can be also determined as a function of .

CULTIVATION OF THE SEAWEED <i>Ulva</i> spp. WITH EFFLUENT FROM A SHRIMP BIOFLOC REARING SYSTEM: DIFFERENT SPECIES AND STOCKING DENSITY

“…The concentrations of TAN, nitrite, nitrate, and orthophosphate were also within the range found in other studies (Khoi and Fotedar, 2011;Ge et al, 2018). Alkalinity remained above 100 mg L -1 , which is recommended to improve the availability of inorganic carbon for algae (Oca et al, 2019).…”

Desempenho de curto prazo de Ulva fasciata produzida em diferentes densidades em Aquicultura multitrófica integrada

“…A razão mais provável desse resultado é a maior disponibilidade de espaço nos tanques e, consequentemente, de luz no cultivo com menores densidades, que resultam em uma menor competição enfrentada pelas algas para a obtenção desse fator chave para seu pleno crescimento. Os tanques de cultivo utilizados para a produção da Ulva fasciata possuem paredes opacas, que implicam em uma incidência de luz somente na superfície da água, logo, menores densidades usufruem de uma maior dispersão superficial enquanto maiores densidades são prejudicadas pelo próprio sombreamento, como também observado por Oca et al (2019) em seu experimento.…”

Digestibility and gastrointestinal transit of Ulva fasciata seaweed meal in tilapia (Oreochromis niloticus) juveniles: basis for the inclusion of a sustainable ingredient in aquafeeds

“…In this sense, IMTA has the potential to produce algae strains rich in proteins and with low chemical heterogeneity, as environmental conditions can be more controlled in closed aquaculture systems than in the open sea. However, optimal parameters have yet to be determined in cultivation, such as stocking density, nutrient availability, water flow and light intensity, as these parameters can determine algae growth and chemical composition (Diamahesa et al, 2017;Oca et al, 2019;Shpigel et al, 2019).…”