# Valuable Nutri from _Ulva rigida_: Modulation by Seasonal and Cultivation Factors
## 3 Results and Discussion
### Fat and Fatty Acid Profile  
The fat content and fatty acid profile of the green macroalgae cultivated in IMTA under distinct conditions were evaluated throughout the four seasons, specifically in samples collected in August, November, February and May (Figure 3). The fat content varied between 0.23 \(\pm\) 0.05% DW and 1.31 \(\pm\) 0.15% DW throughout the entire experiment. These values are close to those of the range reported in the literature for wild _U. rigida_ collected in different sites of the world (0.37\(-\)1.63% DW) [17; 19; 45]; however, they are inferior either to those reported for IMTA grown specimens also cultivated by ALGAplus (1.7 to 3.4% DW) [28] or _Ulva_ spp. cultivated in a land-based system (2.6 to 3.5% DW) [31]. Most probably, differences are due to the distinct extraction methodologies and/or solvents applied in the two studies. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Mineral**}} & \multirow{2}{*}{**Condition**} & \multicolumn{6}{c}{**Months**} \\ \cline{3-10}  & & **August** & **September** & **October** & **2016** & **2016** & **2017** & **2017** & **2017** & **2017** \\ \hline \multirow{4}{*}{Iron} & L\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 81.1 \({}^{\text{a}}\) & 82.1 & 81.3 \({}^{\text{a}}\) & 59.1 & 81.1 \({}^{\text{a}}\) & 96.0 \({}^{\text{a}}\) & 101.7 \({}^{\text{a}}\) & 82.0 \\  & H\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 67.5 & 77.8 & 51.7 & 103.6 & 72.9 & 96.7 \({}^{\text{a}}\) & 85.0 & 130.0 \({}^{\text{a}}\) \\  & L\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 43.5 & 51.8 \({}^{\text{a}}\) & 35.7 & 80.2 & 66.0 \({}^{\text{a}}\) & 136.7 & 86.0 \({}^{\text{a}}\) & 90.8 \\  & H\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 67.6 & 70.3 & 51.7 & 62.3 \({}^{\text{a}}\) & 86.3 & 100.0 & 123.3 & 170.0 \\ \hline \multirow{4}{*}{Manganese} & L\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 10.4 & 10.5 & 9.5 & 11.4 & 6.7 \({}^{\text{a}}\) & 3.4 \({}^{\text{a}}\) & 4.1 & 4.2 \\  & H\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 9.2 & 7.5 \({}^{\text{a}}\) & 10.3 & 9.9 \({}^{\text{a}}\) & 10.3 & 2.7 & 5.9 & 8.4 \\  & L\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 6.4 \({}^{\text{a}}\) & 6.8 & 6.5 & 7.6 \({}^{\text{a}}\) & 8.3 & 6.7 & 7.3 & 5.0 \\  & H\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 5.9 & 4.8 \({}^{\text{a}}\) & 5.0 & 7.1 \({}^{\text{a}}\) & 9.6 & 5.5 \({}^{\text{a}}\) & 11.0 & 11.5 \\ \hline \multirow{4}{*}{Copper} & L\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 2.7 & 2.7 \({}^{\text{a}}\) & 3.0 & 2.5 & 2.6 & 1.9 & 1.1 & 1.2 \\  & H\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 2.9 & 2.7 & 2.8 & 2.5 & 2.5 & 1.9 & 1.2 & 1.6 \\  & L\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 2.1 & 2.3 & 2.7 & 2.8 & 2.6 & 2.1 & 1.1 & 1.4 \\  & H\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 2.3 & 3.2 \({}^{\text{a}}\) & 3.1 & 2.8 & 3.0 & 2.2 & 1.6 & 2.0 \\ \hline \multirow{4}{*}{Zinc} & L\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 1.6 & 1.2 & 1.6 & 1.6 & 1.5 & 1.5 & 0.8 & 0.9 \\  & H\({}_{\text{Fr}}\)/L\({}_{\text{Sd}}\) & 1.5 & 1.5 & 1.4 & 1.5 & 1.1 \({}^{\text{a}}\) & 1.7 & 1.0 & 1.0 \({}^{\text{a}}\) \\  & L\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 1.0 & 1.2 & 1.5 & 1.7 & 1.9 & 1.8 & 1.0 & 1.1 \\  & H\({}_{\text{Fr}}\)/H\({}_{\text{Sd}}\) & 1.1 & 0.8 & 1.6 & 1.6 & 1.7 & 1.9 & 1.5 & 1.7 \\ \hline \end{tabular} Values are expressed as mean of three replicates from different cultivation tanks analysed in triplicate; coefficient of variation. (CV) \(<\) 30% with exception of those marked as \({}^{\text{a}}\), for which CV was between 35 and 70%.  
\end{table} 
Table 1: Seasonal variation of trace minerals (mg/100 g dry weight) in _Ulva rigida_ produced by IMTA under different conditions of flow rate, high (H\({}_{\text{Fr}}\)) and low (L\({}_{\text{Fr}}\)); and of stocking density, high (H\({}_{\text{Sd}}\)) and low (L\({}_{\text{Sd}}\)). Lipid contents were shown to vary seasonally, reaching the maximum and minimum values in winter and summer, respectively.