Abstract

From the perspective of geoecology and Earth sciences, it is essential to examine the relationship between innovative feed technologies and the condition of aquatic environments. This study focuses on evaluating the effectiveness of biobased feed additives derived from locally available agricultural and plant waste—such as fermented soybean hulls, aloe vera fibers, and microalgae—as environmentally sustainable alternatives to traditional fishmeal. A 12-week experimental trial was conducted on tilapia (Oreochromis niloticus) to assess growth performance, feed conversion ratios, immunological parameters, and water quality. The results demonstrated significant improvements in weight gain and feed efficiency, reductions in nitrogen and phosphorus concentrations in water, and increased resistance of fish to pathogens. Geoecological analysis confirmed a reduction in anthropogenic pressure on aquatic ecosystems, aligning with the principles of sustainable natural resource management and environmental conservation. The findings highlight the potential of biobased feeds in supporting climate-neutral aquaculture systems, particularly beneficial for small- and medium-scale farms in developing regions. The proposed approach integrates scientific rigor with practical solutions, contributing to the broader framework of the circular bioeconomy and sustainable development.

Abstract

Global climate change has led to increasingly frequent and intense episodes of elevated sea surface temperatures. These temperature shifts are known to cause significant physiological stress in marine organisms, particularly through oxidative stress. Scallops, one of the most important aquaculture bivalves globally, are especially popular in East Asia, where species such as Chlamys farreri (Zhikong scallop) and Argopecten irradians (bay scallop) are widely farmed due to their favorable taste and high nutritional value. As global demand for seafood continues to rise, scallop aquaculture is also expanding. However, mass mortality events of bivalves during summer have become increasingly common in regions like South Korea, primarily due to abrupt and extreme changes in sea temperature. To address this issue, it is crucial to investigate molecular-level responses to thermal stress and to explore practical mitigation strategies in aquaculture settings. In this study, we focus on C. farreri and A. irradians, two scallop species cultured along the southern coast of Korea. Our research includes laboratory-scale experiments to analyze antioxidant system responses to temperature fluctuations and field-scale studies to assess how vertical distribution within the water column affects scallop resilience to high-temperature stress. Despite genetic similarities among scallop species, our findings aim to identify those with higher thermal tolerance—especially those less sensitive to sudden summer temperature changes. Furthermore, we seek to determine optimal aquaculture environments using vertical water column stratification as a tool to mitigate heat stress. Ultimately, our work provides foundational insights for developing more sustainable and resilient scallop farming practices in the face of climate-driven ocean warming.

Abstract

Global economic uncertainty has recently led to a 50-100% increase in fertilizer costs. Sustainable organic farming is an alternative for farmers, as it reduces input costs and also benefits the environment. This research has discovered the beneficial effects of seaweed extract (SWE) as a biostimulant and biochar as a soil conditioner for sustainable organic tea farming (Camellia sinensis). This project was aimed to (1) identify the optimal extraction parameters and the bioactive compounds for red and brown seaweed, and (2) investigating the effect of seaweed extracts (SWE), with/without biochar addition, on tea growth, physiology and soil fertility. The red (Kappaphycus alvarezii) and brown (Sargassum polycystum) seaweeds were prepared and extracted using the Response Surface Method. The LC-MS analysis profiled the bioactive compounds in each seaweed. The best SWE were selected for further experimentation. For the greenhouse experiment, six-month-old tea cuttings underwent 18 treatments with 5 replicates. Treatments included full and half-strength chemical fertilisers, 2% foliar-applied SWE (red, brown and commercial), and 3% soil-mixed biochar. We found the optimal extraction conditions varied: red seaweed (40 ^oC, 30 min) and brown seaweed (80 ^oC, 83 min), both at 40 mL g^-1 solvent ratio. Combining SWE with biochar under half-strength fertilization achieved comparable performance to full-strength fertilizer controls, as it enhanced tea growth, chlorophyll content, gas exchange capacity, nutrient uptake, and antioxidant activity (AOA) and also improved soil fertility and microbial diversity. We conclude the SWE with biochar combinations can reduce fertiliser consumption by 50%, and is useful for sustainable organic tea farming in future.

Abstract

Aquaponics combines aquaculture and hydroponics in a closed-loop system, offering a sustainable approach to food and water challenges. Despite its potential, limited comparative evidence exists on how nutrient dynamics, water quality, and fish–plant synergy vary across regions, constraining optimization and broader adoption. This qualitative meta-analysis investigates nutrient flows and plant–fish interactions in recirculating aquaponic systems (RAS) across Kenya, the United States, India, and the Netherlands, focusing on productivity and environmental performance. A systematic review of studies published between 2010 and 2024 yielded 23 empirical sources meeting strict inclusion criteria, including metrics on nutrient fluxes, water quality, productivity, and system inputs. Data were standardized across five themes: fish–plant pairings, nutrient conversion efficiency, water quality, productivity outputs, and environmental trade-offs. Findings reveal Kenya’s low-energy systems, often incorporating local innovations such as Azolla pinnata, produced competitive yields (up to 22.1 kg/m²/yr for tilapia–tomato) with moderate nitrogen-use efficiency (up to 81%). U.S. systems showed high commercial viability, using bluegill–basil and trout–Swiss chard pairings in controlled environments, but required higher energy inputs. India’s semi-automated systems favored native species but experienced higher waste output and moderate nutrient utilization. The Netherlands led in water and nutrient efficiency achieving as low as 30 L/kg yield and 150 g/kg waste through AI-managed precision systems, though energy demands were high (up to 3.7 kWh/kg yield). Overall, optimal RAS outcomes depend on localized adaptation, species compatibility, and appropriate technological integration. These insights inform efforts to improve aquaponic sustainability, scalability, and environmental performance worldwide