## 1 Introduction  
Oceans are a unique source of natural resources, offering a wealth of biodiversity that has long inspired scientific exploration and innovation [1]. However, until the mid-20 th century, the challenge of reaching the depths of the oceans limited our understanding of many marine species. Advances in diving technology in the 1970s and 1980s allowed scientists to study previously unexplored marine organisms, including a wide range of algae and invertebrates. Today, the rapid growth in the human population, climate change, and environmental degradation emphasize the urgent need for the sustainable management of marine resources [2]. Among marine organisms, seaweeds have traditionally been harvested from the wild for a variety of uses, including food, animal feed, and soil enhancers [3; 4]. Seaweeds are renowned for their high nutritional value, with carbohydrate, protein, lipid, and ash contents ranging approximately from 31 to 68%, 9 to 47%, 0.1 to 9.8%, and 7 to 39%, respectively [5]. In recent decades, however, seaweeds have become a prominent source of bioactive compounds with applications in the food, medical, and biotechnological industries [5]. The intertidal environment, in which many seaweeds thrive, exposes these organisms to fluctuating conditions of humidity, temperature, salinity, sunlight, and water movement, which in turn influences their biochemical composition and structural adaptations [6; 7]. Among the diverse seaweed species, red algae (Rhodophyta) are particularly notable for their high-value polysaccharides, such as carrageenanans [8]. The compounds derived from red seaweeds such as _Chondrus crispus_, _Eucheuma_ spp., _Kapaphyccus_ spp., _Gigartina_ spp., _Chondracanthus acicularis_, and other Gigartinales possess thickening, gelling, and stabilizing properties, making them highly sought after in the pharmaceutical and cosmetic industries [9; 10; 11]. In addition, red seaweeds are a rich source of unique bioactive compounds, including phychotimes, mycosporine-like amino acids (MAAs), and various other secondary metabolites. Phychotimes, such as phycoerythrin and phycocyanin, are water-soluble pigments that act as accessory light-harvesting molecules, allowing red algae to absorb and utilize a broader spectrum of light. These pigments possess potent antioxidant and anti-inflammatory properties, making them valuable compounds in nutraceuticals and medical formulations, and their fluorescent properties enable their use as markers in biomedical imaging and diagnostics [12; 13; 14]. Mycosporine-like amino acids, which protect algae from ultraviolet (UV) radiation, are particularly promising as natural UV filters in sunscreens, providing a safe alternative to synthetic UV-blocking agents [15; 16; 17]. Carrageenanans are versatile polysaccharides with a wide range of applications in various industries, as they have unique properties such as biodegradability, biocompatibility and functional versatility and have been widely used in the food industry as gelling, thickening, and stabilizing agents [18; 19]. Additionally, red seaweeds are rich in other bioactive compounds including other polysaccharides, polyphenols, and fatty acids, exhibiting antimicrobial, antiviral, and antitumor activities. Together, these compounds not only contribute to the survival and resilience of red seaweeds in harsh marine environments but also provide a sustainable source of high-value bioactive molecules with applications in pharmaceuticals, cosme, and functional foods [12; 20]. The carrageenanan industry has expanded rapidly in recent years, with demand now far outstripping what can be sustainably supplied from wild seaweed stocks and growing at an annual rate of over 7.5%. This demand is increasingly being met by aquaculture, as wild harvesting becomes less viable [21]. With global seaweed production set to reach a record 37.8 million tons in 2022, the sustainable aquaculture of seaweed has emerged as an essential strategy to meet increasing demand while preserving natural habitats [22].