# Solving Nuisance Cyanobacteria Eutrophication Through Biotechnology
## 5 Discussion
Biomass sedimentation in the lagoon establishes anoxic conditions that could, combined with the high concentration of organic matter, induce methane and/or H\({}_{2}\) production (Figures 5 and 6). This decomposition process may deplete oxygen (establishment of anoxic conditions), and in turn may lead to fish kills and in a range of other effects reducing biodiversity [10]. In order to overcome this negative impact of eutrophication, we propose the removal of the algae from the lagoon before the onset of sedimentation and transferring them to simple, closed reactors for H\({}_{2}\) and biofuel production according to the simplified scheme of Figure 7.  
Indeed, the total carbohydrate content estimated in this study (Figure 4) in water and in algal biomass was relatively high and in the same range of other published works [23]. Another promising downstream pathway from algal biomass is the lipid extraction for biodiesel. The technology of turning algae lipids to biodiesel is, in principle, relatively easy, but the algal biomass should contain high quantities of fatty acids, something that does not happen in this particular case of our paradigm. As far as the fatty acid composition of _Limnorapalis_ biomass is concerned, it showed high levels of saturated fatty acids (51.5 \(\pm\) 3.9% of the total), whereas the levels of mono-unsaturated and poly-unsaturated fatty acids (PUFA) were 48.5 (\(\pm\)2.6%) of the total (Figure 3). Similar results were also obtained [54; 55]. Moreover, in agreement with other studies [54; 56] the palmitic acid (PA-C16:0) has been documented as the most prevalent fatty acid of cyanobacteria biomass. The presence of eicosapentaenoic (C20:5\(\omega\)-3), EPA 3.5 \(\pm\) 0.9%, and docosahexaenoicenoic (C22:6\(\omega\)-3), DHA 1.7 \(\pm\) 0.3%, polyunsaturated fatty acids (PUFAs) in the particular algal biomass is worth mentioning. Although the major sources of both acids EPA and DHA, on a worldwide basis, are still marine fish, microalgae and cyanobacteria, exhibiting competitive advantages as sources of PUFAs because fish have typically lower contents (on a mass basis), are subject to seasonal variations in fatty acid profile, and may be significantly contaminated with heavy metals owing to pollution throughout the food chain [57; 58]. Besides confirming the appropriateness of some cyanobacteria for wide use as feed in the aquaculture  
Figure 7: Simplified model based on the separation of eutrophication into two distinct steps (before and after the algal sedimentation), and transferring the second step process to a bioreactor, we can protect the water quality and biodiversity of the lagoons and keep the socioeconomic impact on fish production and community positive. In addition, the environmental impacts will find a sustainable solution through a “smart” biotechnological application that leads to high yield production of hydrogen and biofuels. industry, they have been used for functional food formulation aimed at therapeutically enhanced and nutritional features [59]. Additionally, biomass rest could be excellent organic fertilizer, mainly because of their N\({}_{2}\) fixation procedure [60]. Since harmful algal blooms also have a wide range of detrimental impacts through the production of toxins, care should also be undertaken in the case of the Lafri lagoon. The toxicity of species of genus _Linnnoraplis_, between others the synthesis of the liver toxin microcystin seems to depend on the strain and environmental triggers [33; 61], and therefore the evaluation of biomass for toxins has to be determined [62]. In general, the potential applications of nuisance microalgae blooms is still largely unconsidered and unexplored [63]. In conclusion, by separating the natural process of eutrophication into two distinct steps (before and after the algal sedimentation), and transferring the second step process to a bioreactor, we can protect the water quality and biodiversity of the lagoons and keep the socioeconomic impact on fish production and community positive.