## 4 Discussion
acicularis_ revealed a high moisture content across all treatments, ranging from 68.79% to 73.65%, but with no significant differences found between samples. According to [PERSON] et al. [69], seaweeds tend to retain a high water content when grown under optimal culture conditions. The cultivation conditions were generally suitable for seaweed growth, as indicated by the consistent moisture levels. However, the NB medium showed the lowest moisture content, suggesting that it was the worst culture media to grow this seaweed. In contrast to moisture, significant differences in ash content were observed, ranging from 7.28% fw (27.01% dw), for the VSE cultivated biomass, to 9.08% fw (30.80% dw), for the wild biomass. These values are within the expected values for Gigartinales (16.55%) [70] and for the red seaweed _Gracilaria_ spp. (19% to 25%) [71; 72]. Algae ash content varies between locations and cultivation sites due to differences in key factors such as salinity, temperature, and nutrient availability [73]. Therefore, the lower ash content of cultivated seaweeds compared to the wild may be attributed to optimized nutrient solutions that might limit certain minerals, reducing mineral uptake and, thus, the ash content [37; 74]. The organic matter content showed significant differences between treatments, with seaweeds cultivated with NB exhibiting the highest concentration after 7 days. Conversely, seaweeds grown with PES and red LED light showed the lowest concentrations of organic matter. Cultivated seaweeds often have higher ash content and moisture levels due to controlled nutrient availability and environmental conditions, which can lead to a lower percentage of organic matter and dry weight when compared to wild specimens [74]. Red algae are rich in the pink pigment phycoerythrin, which absorbs light over a wide blue-green light spectral range, roughly 460-570 nm, including spectral regions which are not available for other photosynthetic pigments [75]. Also, red seaweeds exhibit rapid phycobilin acclimatory responses to changes in light, enhancing light harvesting [76]. Thus, the use of LED lights plays a crucial role in optimizing the growth of red seaweeds by influencing their photosynthetic efficiency and pigment production. Different light intensities and wavelengths can be used as a tool to enhance the concentration of valuable compounds in seaweed aquaculture, such as photosynthetic pigments. Our results show that white LED light delivered the best growth, providing a broad spectrum (a narrow peak at 450 nm and a wide peak between 550 and 620 nm) which supports balanced growth and enhances the overall biomass production of seaweeds [77]. Red LED light also showed significantly higher growth and yield. Red LED light (narrow peak at \(\sim\)655 nm), although less effective for some species, can significantly boost the production of phycoerythrin, thereby enhancing the red colouration of the seaweed. As to blue LED light (narrow peak at \(\sim\)455 nm), although it has been reported that it is particularly effective in promoting the synthesis of chlorophyll and other photosynthetic pigments [78], it did not prove to be adequate for the growth of _C. acicularis_. Hence, while beneficial for certain species, blue LED light may not provide the optimal spectrum for this species, leading to reduced photosynthetic efficiency [79]. However, studies have shown that the combination of these LED lights can lead to improved growth rates and higher concentrations of valuable bioactive compounds in red seaweeds, making them a promising tool for sustainable aquaculture practises [60; 80; 81; 82; 83; 84; 85]. The different chemical compositions of the biomasses are denoted by the colour of the biomass, as analyzed through CIE Lab components. The increasing \(\Delta\)E values indicate that there was a noticeable colour difference over time compared to the initial state. The increase in the biomass grown with PES showed the highest variation, easily visible to the naked eye [86].