The intensification of aquaculture systems can lead to an increased incidence of diseases in farmed animals due to favorable conditions for pathogen growth and spread, resulting in reduced productivity and subsequent economic losses.
For a long time, antibiotics were the solution for protecting and treating these animals. However, their continuous use has raised serious food safety concerns, diminishing the natural immune response and increasing resistance to harmful bacterial strains.
In response to these challenges, natural functional additives, particularly substances derived from various marine organisms, have been introduced. These have proven to be effective as immunomodulators and antioxidants when applied to aquatic animals.
A team of scientists from Chiang Mai University, Gorgan University of Agricultural Sciences and Natural Resources, The Arctic University of Norway, Cairo University, the University of Messina, the Norwegian University of Science and Technology, among other organizations, published a scientific review on the sources, modes of action, and effects of marine-derived biomolecules on aquatic animals.
Marine-derived biomolecules
The marine environment is a rich source of natural products, including polysaccharides, oligosaccharides, peptides, vitamins, minerals, fatty acids, sterols, carotenoids, and phenolic compounds.
Bioactive molecules derived from algae, crustaceans, mollusks, fungi, and fish, such as astaxanthin, carotenoids, chitosan, fucoidan, lectins, and polyunsaturated fatty acids (PUFAs), are among the most commonly used additives in aquaculture. These substances have significant potential to enhance the health and resilience of aquatic organisms while increasing production.
Sources and mechanisms of action
Numerous marine organisms contain compounds with chemical and medicinal potential. In the marine environment, invertebrates serve as a rich source of substances used as functional compounds.
Historically, some materials derived from marine organisms have been used as food ingredients, including polysaccharides, commonly referred to as immunostimulants.
Polysaccharides
Red macroalgae contain sulfated polysaccharides that have been employed in the food and other industries as thickeners, gelling agents, stabilizers, and suspending agents. Additionally, carrageenans provide phospholipids to aquatic animals and enhance the physical characteristics of many animals. The effectiveness of carrageenan as a growth promoter has been demonstrated in common carp.
Furthermore, macroalgae serve as a source of bioactive compounds that can produce various secondary metabolites with antifungal, antibacterial, and antihelminthic activity. The study reports that the alkaloid caulerpin obtained from Caulerpa scalpelliformis has demonstrated antimicrobial effects against Vibrio anguillarum.
Carotenoids
Carotenoids are the most abundant lipid-soluble pigments. These pigments are primarily found in algae chloroplasts but can also be produced by fungi and bacteria.
These pigments have various effects due to their double structure, including camouflage, reproduction, photoprotection, consumer acceptance, and application in ornamental fish.
Polyunsaturated fatty acids
Polyunsaturated fatty acids, including EPA, DHA, and AHA, are essential fatty acids that perform multiple functions in most organisms.
“Some fatty acids serve as signaling molecules that directly modulate cellular processes and affect immunity in aquatic animals. An increase in arachidonic acid (ARA) in the diet results in increased prostaglandins, which enhance macrophage performance and white blood cell activity,” report the researchers.
Marine yeasts
Marine yeasts are a polyphyletic group of basidiomycete and ascomycete fungi that share the unique ability to grow as unicellular forms. Yeasts are primarily used in the food sector for alcohol and baked carbon dioxide production, brewing, and winemaking.
These organisms participate in the decomposition of plant substrates, oil biodegradation, parasitism, and nutrient recycling. Marine yeasts were first discovered in the Atlantic Ocean and are present in seawater, algae, and marine mammals.
Effects in aquaculture and beyond
The introduction of these marine-derived substances into aquaculture has significantly impacted the health and productivity of aquatic organisms. Benefits include enhanced immune response, increased disease resistance, and improved pigmentation, resulting in high-quality marine products.
In addition to aquaculture, marine-derived biomolecules have extended to other sectors, including nutraceuticals, pharmaceuticals, cosmetics, and agriculture. Their antioxidant properties and capacity to modulate the immune response have opened up a world of possibilities in the search for natural and sustainable solutions.
Conclusion
The use of marine-origin biomolecules in aquaculture represents a step toward sustainability in marine food production. These substances not only benefit aquatic animals but also contribute to food safety and the quality of end products.
As we continue to explore these natural sources of health and resilience, we are equipping the scientific community with essential knowledge to support sustainable aquaculture in the future.
The study was funded by Chiang Mai University and the Ministry of Agriculture of the Czech Republic: NAZV project.
Contact
Mahmoud A.O. Dawood
The Center for Applied Research on the Environment and Sustainability
The American University in Cairo
11835 Cairo, Egypt
Email: mahmoud.dawood@agr.kfs.edu.eg
Reference (open access)
Hien Van Doan, Parvathy Prakash, Seyed Hossein Hoseinifar, Einar Ringø, Ehab El-Haroun, Caterina Faggio, Rolf Erik Olsen, Hung Quang Tran, Vlastimil Stejskal, Hany M.R. Abdel-Latif, Mahmoud A.O. Dawood. 2023. Marine-derived products as functional feed additives in aquaculture: A review, Aquaculture Reports, Volume 31, 2023, 01679, ISSN 2352-5134, https://doi.org/10.1016/j.aqrep.2023.101679.
