Abstract

Swine wastewater is a major environmental concern due to its high concentrations of nutrients and organic matter, which can contribute to eutrophication and oxygen depletion in aquatic ecosystems. Traditional treat- ment approaches, such as microalgae-based systems, are limited by low nutrient removal efficiency and high freshwater demand. This study presents the first successful cultivation of the red seaweed Agardhiella subula- ta in diluted swine and aquaculture wastewater,demonstrating its strong potential as a sustainable bioremedi- ation tool for nutrient-rich effluents. Under salinity conditions of 27–34 ppt and ammonia concentrations up to 600 μM, A. subulata removed up to 93% of ammonium (NH ) and 68% of phosphate (PO³) within 24 hours. It also significantly improved water quality by raising dissolved oxygen levels. Moreover, the seaweed exhibited an exceptional carbon sequestration capacity, capturing approximately 52.5 t-CO ha¹ yr¹—five times greater than the average annual carbon uptake by global forests. These results highlight the feasibility of integrating A. subulata into aquaculture or coastal wastewater treatment systems as a nature-based solution to mitigate nu- trient pollution while enhancing ecosystem services. By reducing reliance on freshwater, lowering greenhouse gas emissions, and enabling nutrient recycling, A. subulata cultivation offers a dual benefit for sustainable aquaculture and environmental protection. Looking ahead, the incorporation of red seaweed bioremediation into circular aquaculture practices—especially near livestock farming zones—can play a key role in closing nu- trient loops, reducing pollution loads, and promoting blue carbon strategies in coastal regions.

Abstract

The continuous growth of aquaculture places a growing demand on alternative sources for fish oil (FO) and fishmeal (FM) in aquafeeds. Certain microorganisms provide a potential sustainable replacement for FO and FM due to their high content of omega-3 long-chain polyunsaturated fatty acids, which are essential for fish health. Salmon feeding trials were conducted to determine the effects of replacing FO and FM with oil and biomass from different microorganisms. The first trial replaced FO with a microbial oil (MO) derived from Schi- zochytrium. The second reduced FO and replaced FM with algal biomass (AB) derived from Pavlova.These diets provided a unique opportunity to determine how dietary DHA, EPA and phytosterols influence lipid me- tabolism and physiological pathways in salmonids. Growth was unaffected when microbial products replaced dietary fish oil and fishmeal; however, lipid profiles and gene expressionwere altered. With MO, linoleic acid and α-linolenic acid were present in low proportions, and DHA was present in very high proportions in the cellular membrane, especially in muscle tissue. In addition to cholesterol in muscle tissue, cholestanol, campesterol, stigmasterol, dinosterol and 24-methylpavlovol were detected in salmon. With AB, DHA was present in high proportions in tissues of all dietary treatments, especially in cellular membranes. Stable isotope data indicated a direct integration of EPA and DHA and not biosynthesis from its precursor ALA. Growth performance, lipid class composition, phospholipid fatty acid composition, and compound specific stable isotope analysis all sug- gest that salmon grown on microbial-based diets digested and utilized nutrients well, and directly incorporated critically important fatty acids into their tissues.

Abstract

The ongoing climate changes generally worsen the oxygen conditions in the sea due to increased temperature and eutrophication. In open sea cages stocked salmon and trout, low dissolved oxygen (DO) concentration can be a potential problem, especially in late summer and autumn at peak water temperature and high fish densi- ty. Over the last ten years, use of so-called lice skirts shielding salmon from sea lice attacks, has been widely applied. Unfortunately, deep lice skirts reduce the water exchange through the cages and reinforce the oxygen deficit problems. A minimum concentration of ca. 80% DO throughout the growth cycle is generally considered adequate to ensure good fish welfare and growth conditions.

There are two principle ways to improve the oxygen conditions in open or lice shielded cages: by direct injection of pure oxygen or by pumping of oxygen-rich deep water to the surface layer. Oxygenation, i.e. adding on-site produced oxygen or liquid oxygen by a diffuser network in salmon cages, has demonstrated reduced mortality and maintained feed appetite during warm periods with critical DO deficit. Pumping of water from 15-20 m depth using specially designed air-lifts run by large air bubbles is a promising method to improve the DO levels in the upper parts of salmonid cages.

Abstract

Tomatoes (Lycopersicon esculentum) are one of the most common agricultural produces in the world, with a global annual production that exceeds 180 million tons, as fresh and processed product. Industrial tomato processing generates a large amount of waste consisting of peels, seeds, residual pulp, stems and inedible parts (rotten, bruised and immature). These by-products can cause many problems if not properly managed and can contribute to environmental pollution when discarded in landfills. The current research was aimed to valorize peels and seeds from tomatoes to fortify different fresh foods using a new approach. Pasta and ham- burgers, made up of turkey and beef respectively, were optimized by means of a panel test evaluation, before and after cooking. Fiber content and antioxidant potential were also assessed for each food. To make a proper comparison among the developed fortified products, the sensory score recorded for the cooked food, the fiber content and the antioxidant potential, properly normalized, were used as quality parameters to calculate a Glob- al Quality Index (GQI). The GQI allowed quantifying advantages and limitations of adding seeds and peels from tomatoes to each food formulations. Recorded results are interesting, thus suggesting that the new calculated GQI represents a valid approach for comparing customized food developed in a more sustainable perspective.