# Emerging Trends in Sustainable Biological Resources and Bioeconomy for Food Production
## 4 Blue Bioeconomy Resources
### Algal-Derived Resources  
Algae are emerging as a promising alternative protein source due to their high nutritional value, rapid growth rate, and minimal environmental footprint. Both microalgae (such as Spirulina and Chlorella) and macroalgae (seaweeds) contain significant amounts of protein, essential amino acids, vitamins, and antioxidants. Unlike traditional crops, algae can be cultivated on non-arable land using saline or wastewater, making them highly sustainable. Their versatility in food applications--from supplements to meat alternatives--positions algae as a key player in the future of sustainable nutrition. Marine algae, encompassing both microalgae and macroalgae, represent a heterogeneous group of photosynthetic organisms that are not taxonomically unified but are functionally critical to aquatic ecosystems and the global carbon cycle. These organisms reduce atmospheric CO2 through oxygenic photosynthesis--predominantly via chlorophyll a--contributing to nearly 50% of global photosynthetic activity [52]. From a biotechnological perspective, both groups of algae offer distinct advantages and limitations that are critical to valorization pathways in the blue economy. Microalgae are characterized by high growth rates, metabolic plasticity (autotrophic, mixotrophic, or heterotrophic modes), and the ability to be cultivated under controlled conditions (e.g., photobioreactors), making them ideal for large-scale industrial use. They are widely exploited for the production of high-value compounds such as proteins, lipids, carotenoids, polyunsaturated fatty acids, and antioxidants, with applications in nutraceuticals, pharmaceuticals, cosmetics, aquaculture, and wastewater treatment [53]. Meanwhile, macroalgae play a key ecological role in coastal ecosystem stability, primary productivity, and habitat provision. They are traditionally used in food, agriculture, and hydrocolloids (e.g., agar, alginates, carrageenan) and are gaining momentum for biofuel, bioplastic, and bioactive compound production. However, macroalgal biomass--especially in the form of marine macroalgal waste (MMW) from blooms like Sargassum--can also pose environmental risks, including GHG emissions and disease vector proliferation. The valorization of algal biomass, particularly from waste streams, supports a circular bieconomy by converting low-value or problematic residues into valuable bioproducts, though technical and economic challenges remain in optimizing scalability, biomass consistency, and extraction efficiency. Thus, understanding the physiological, ecological, and biotechnological differences between micro- and macroalgae is essential for leveraging their full potential in sustainable marine resource exploitation [54]. Algal proteins derived from microalgae such as _Spirulina_, _Chlorella_, and _Nannochloropsis_ have attracted increasing attention as sustainable and nutritious alternatives to traditional animal-based proteins. These microalgal proteins are rich in essential amino acids, such as leucine, lysine, and phenylalanine, alongside valuable micronutrients like vitamins and minerals, making them suitable for human nutrition, pharmaceutical applications, and industrial formulations. Notably, species like Spirulina platensis and Chlorella vulgaris contain approximately 51-58% protein by dry weight, with high concentrations of essential amino acids such as leucine, lysine, and phenylalanine [55]. Nannochloropsis species, including _N. oculata_ and _N. gaditana_, also demonstrate notable protein content, with values ranging from 35% to 71% of dry matter. These microalgae are particularly rich in glutamic acid and aspartic acid, contributing to their umami flavor profile [56; 57; 58]. Chlorella stands out not only for its high protein content but also for its versatility in cultivation, particularly in wastewater treatment systems, thus providing an environmentally responsible and economically viable approach to food security and sustainability [59].