## 4 Discussion
polyschides_ aligns with previous studies showing high photosynthetic capacity in kelp and pseudo-kelp species, particularly under optimal environmental conditions [97]. Similarly, chlorophyll _c_--an accessory group of pigments involved in light harvesting--was more abundant in _S. polyschides_ (965.62 \(\pm\) 127.39 \(\upmu\)g\(\cdot\)g\({}^{-1}\) fw) compared to _L. ochroleuca_ (681.34 \(\pm\) 159.54 \(\upmu\)g\(\cdot\)g\({}^{-1}\) fw). Chlorophyll \(c\) facilitates efficient light absorption in the blue region of the spectrum, especially under low light or subtidal conditions, and its levels may reflect adaptive strategies to environmental light gradients. Variations in chlorophyll \(c\) concentrations could be due to several factors, including the specific methods used for extraction and quantification, and should be confirmed, in the future, by HPLC. Indeed, according to [PERSON] et al. [98], the extraction of photosynthetic pigments is influenced by a combination of abiotic and biotic factors [36; 99], the type of solvent used, the state of the sample (fresh or dry) and the stage of the algae's life cycle. Regarding fucoxanthin, fresh _S. polyschides_ again demonstrated higher levels (695.48 \(\pm\) 22.51 \(\upmu\)g\(\cdot\)g\({}^{-1}\) fw) than fresh _L. ochroleuca_ (439.93 \(\pm\) 30.32 \(\upmu\)g\(\cdot\)g\({}^{-1}\) fw). This supports its potential as a valuable source of bioactive compounds for nutraceutical and pharmaceutical applications [51]. Besides, the maceration process also resulted in the release of more pigments. As to the results obtained for photosynthetic pigments in the dried samples, the lower values recorded may be related to the drying process, which can degrade chlorophylls [77]. This comparison highlights the pigment degradation or transformation post-harvest, which is consistent with the known thermal and oxidative sensitivity of these compounds. Across all pigments, concentrations in the dried samples were markedly lower. For instance, the highest fucoxanthin content was found in the residual pulp (157.53 \(\pm\) 2.72 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw), which is noteworthy given that this material is typically regarded as a byproduct. Its unexpectedly high fucoxanthin content may result from residual pigment retention in fibrous fractions or partial concentration during drying. _M. pyrifera_ exhibited the lowest fucoxanthin content (56.71 \(\pm\) 1.38 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw), likely due to species-specific differences in pigment biosynthesis. Meanwhile, chlorophyll \(a\) remained the highest in the dry biomass of _L. ochroleuca_ (26.59 \(\pm\) 1.93 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw), and intermediate values were recorded in _S. polyschides_ (22.18 \(\pm\) 2.47 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw) and the residual pulp (16.63 \(\pm\) 2.33 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw). This suggests that while chlorophyll \(a\) is susceptible to degradation, some fraction is retained even in waste material, offering opportunities for valorisation. The pattern for chlorophyll \(c\) was similar, with _L. ochroleuca_ and _S. polyschides_ again showing the highest values (2.95 \(\pm\) 0.09 and 2.66 \(\pm\) 0.03 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw, respectively). Notably, the residual pulp retained very low levels (0.15 \(\pm\) 0.08 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dw), indicating greater susceptibility of chlorophyll \(c\) to degradation or leaching during processing. [PERSON] et al. [100] studied the photosynthetic pigments of _S. polyschides_ and _L. ochroleuca_, among other algae. Despite recording differences between parts of the thalli and the harvesting site, these authors recorded a range of fucoxanthin and chlorophyll \(a\) values like ours. However, our chlorophyll \(c\) concentrations were always lower than those in the aforementioned study. These findings highlight the biotechnological potential of _S. polyschides_ and _L. ochroleuca_ as primary sources of chlorophylls and fucoxanthin.