Reuse and recycle: Integrating aquaculture and agricultural systems to increase production and reduce nutrient pollution

Climate change effects on aquaculture production and its sustainable management through climate-resilient adaptation strategies: a review

Aquaculture witnessed a remarkable growth as one of the fastest-expanding sector in the food production industry; however, it faces serious threat from the unavoidable impacts of climate change. Understanding this threat, the present review explores the consequences of climate change on aquaculture production and provides need based strategies for its sustainable management, with a particular emphasis on climate-resilient approaches. The study examines the multi-dimensional impacts of climate change on aquaculture which includes the shifts in water temperature, sea-level rise, ocean acidification, harmful algal blooms, extreme weather events, and alterations in ecological dynamics. The review subsequently investigates innovative scientific interventions and climate-resilient aquaculture strategies aimed at strengthening the adaptive capacity of aquaculture practices. Some widely established solutions include selective breeding, species diversification, incorporation of ecosystem-based management practices, and the implementation of sustainable and advanced aquaculture systems (aquaponics and recirculating aquaculture systems (RAS). These strategies work towards fortifying aquaculture systems against climate-induced disturbances, thereby mitigating risks and ensuring sustained production. This review provides a detailed insight to the ongoing discourse on climate-resilient aquaculture, emphasizing an immediate need for prudent measures to secure the future sustainability of fish food production sector.

Effects of organic fertilizers produced from fish pond sediment on growth performances and yield of Malabar and Amaranthus vegetables

The increasing intensification of aquaculture production requires the development of strategies to reduce its environmental impacts such as the pollution caused by the discharge of nutrient-rich sediments into local water bodies. This research was undertaken to investigate and evaluate the effect of using organic fertilizers produced from the pond sludge of freshwater snakehead fish (Channa striata) composted with organic amendments of peanut shells and coir fiber on growth performance indices and yields of Malabar spinach (Basella alba L.) and Amaranthus cruentus (Amaranthus L.) vegetables in the dry and wet seasons. An organic fertilizer quality experiment showed that the richest nutrient contents of the produced organic fertilizer were achieved when using 30% sludge mixed with 70% organic amendments (50% peanut shells + 50% coir fiber). This was selected and used for a vegetable cultivation experiment. For the reference treatment, only chemical fertilizer was applied, while in the other four treatments, 25, 50, 75, and 100% of the chemical fertilizer were substituted with the organic fertilizer. A 25–50% reduction in the chemical fertilizer application resulted in better growth performance indices and final yields than the other treatments, including the reference treatment, for both crops. The highest yields of Malabar spinach and Amaranthus cruentus vegetables were found in Treatment 3 (50% chemical fertilizer combined with 50% organic fertilizer), followed by Treatment 2 (25% organic fertilizer combined with 75% inorganic fertilizer) (P < 0.05). The results show that the reuse of sludge from snakehead fish ponds mixed with agricultural by-products as organic fertilizer for vegetables not only improves vegetable productivity but also reduces the costs of chemical fertilizer and decreases environmental pollution.

Aquaponics as a Promising Strategy to Mitigate Impacts of Climate Change on Rainbow Trout Culture

Simple Summary

Climate change and overexploitation of natural resources drive the need for innovative food production within a sustainability corridor. Aquaponics, combining the technology of recirculation aquaculture systems (RAS) and hydroponics in a closed-loop network, could contribute to addressing these problems. Aquaponic systems have lower freshwater demands than agriculture, greater land use efficiency, and decreased environmental impact combined with higher fish productivity. Rainbow trout is one of the major freshwater fish cultured worldwide, which, however, has not yet been commercially developed in aquaponics. Nevertheless, research conducted so far indicates that the trout species represents a good candidate for aquaponics.

Abstract

The impact of climate change on both terrestrial and aquatic ecosystems tends to become more progressively pronounced and devastating over the years. The sector of aquaculture is severely affected by natural abiotic factors, on account of climate change, that lead to various undesirable phenomena, including aquatic species mortalities and decreased productivity owing to oxidative and thermal stress of the reared organisms. Novel innovative technologies, such as aquaponics that are based on the co-cultivation of freshwater fish with plants in a sustainable manner under the context of controlled abiotic factors, represent a promising tool for mitigating the effect of climate change on reared fish. The rainbow trout (Oncorhynchus mykiss) constitutes one of the major freshwater-reared fish species, contributing to the national economies of numerous countries, and more specifically, to regional development, supporting mountainous areas of low productivity. However, it is highly vulnerable to climate change effects, mainly due to the concrete raceways, in which it is reared, that are constructed on the flow-through of rivers and are, therefore, dependent on water’s physical properties. The current review study evaluates the suitability, progress, and challenges of developing innovative and sustainable aquaponic systems to rear rainbow trout in combination with the cultivation of plants. Although not commercially developed to a great extent yet, research has shown that the rainbow trout is a valuable experimental model for aquaponics that may be also commercially exploited in the future. In particular, abiotic factors required in rainbow trout farming along, with the high protein proportion required in the ratios due to the strict carnivorous feeding behavior, result in high nitrate production that can be utilized by plants as a source of nitrogen in an aquaponic system. Intensive farming of rainbow trout in aquaponic systems can be controlled using digital monitoring of the system parameters, mitigating the obstacles originating from extreme temperature fluctuations.