66 MARCH 2025 • WORLD AQUACULTURE • WWW.WAS.ORG further contamination of aquaculture facilities (Adofo et al. 2022; Al-Jammal and Juzsakova 2017). Rapid Response and efficient containment, clean-up and recovery methods are crucial for minimizing damages from oil pollution. Bioremediation involves the utilising microorganisms to degrade and metabolize oil pollutants. This environmentally friendly approach can be applied in both marine and aquaculture settings to enhance the natural degradation of oil and reduce its impact on fish and other organisms. Oil Spill Clean-up Techniques Physical methods Physical methods such as containment and recovery, shoreline clean-up, and burning are labour-intensive and time-consuming (Idris et al. 2013). Hence, several types of equipment are used for oil spill clean-ups including: • Booms: Floating barriers designed to contain or divert oil, preventing it from spreading or entering protected areas. • Skimmers: Devices used to remove oil from the water’s surface, including weirs, oleophilics, and suction skimmers. • Sorbents: Materials that absorb or adsorb oil, such as natural fibres (e.g., peat moss), synthetic polymers, and mineral-based products. • Vacuum Pumps and Oil Recovery Vessels: Used to suction oil directly from the surface or saturated areas. Although such machinery is suitable for large-scale spills, it can be ineffective in rough seas or for submerged oil due to limited accessibility, disposal requirements, oil viscosity and saturation capacity. Chemical Methods Chemical methods involve the application of substances to alter the properties of oil, making it easier to remove or disperse. These methods include the use of dispersants, surfactants and emulsifiers and are often used in conjunction with physical techniques. Dispersants include chemicals such as Corexit 9500 and Dasic Slickgone that reduces oil’s surface tension and break oil into smaller droplets, thus, preventing it from reaching shorelines and enhancing natural biodegradation (Adofo et al. 2022). Surface washing and cleaning agents are applied to hard surfaces to release oil. Solidifiers or emulsifiers react with oil to form a solid mass, making it easier to remove. Certain oxidizing agents like hydrogen peroxide or ozone are used to degrade oil by chemical oxidation and convert it into harmless by-products such as carbon dioxide and water. Although these techniques are effective for restoring contaminated areas, certain challenges such as risk of chemical residue, potential toxicity, secondary contamination, high cost, limited scalability and concerns about long-term environmental effects still persist. Biological Methods Biological methods leverage microorganisms and natural processes to degrade or remove oil from the environment. These eco-friendly approaches are highly cost-effective along with enhanced sustainability. But these are very slow processes, requiring significantly more time for getting effective results, and they have limited effectiveness in extreme conditions (Mapelli et al. 2017; Ogidi and Njoku 2017; Whitehead et al. 2012). Bioremediation involves enhancing natural biodegradation by utilizing natural oileating microbes to metabolize hydrocarbons. This technique includes either Bioaugmentation (adding oil-degrading microorganisms to the spill site) or Biostimulation (enhancing the activity of native microbes by adding nutrients and oxygen) (Wilkes et al. 2016; Varjani 2017). Phytoremediation utilizes plants and hydrophytes like salt marsh grasses and mangroves to stabilize contaminants, particularly in coastal oil spill scenarios (Yan et al. 2020). While visually restorative, this method is confined to specific habitats and is characterized by a slow recovery process. The application of enzymes to break down oil into simpler compounds involves high production costs and limited scalability. However, these enzymes have demonstrated significant potential in breaking down polymers, aromatic hydrocarbons, halogenated compounds, dyes, detergents, and agrochemical compounds (Bhandari et al. 2021). Natural attenuation relies on processes such as evaporation, photo-oxidation, and microbial degradation to gradually reduce oil contamination (Ward and Overton, 2020). However, after the first several days this approach is slow and unpredictable due to minimal human intervention. Combining techniques such as physical containment, chemical dispersants, bioremediation, and mechanical recovery have been successfully implemented for oil spill cleanup (Madhubashani et al. 2021). However, mechanical approaches often pose challenges due to their high cost of recovery over large areas and their limitation to thicker oil layers (Khalil et al. 2022). Restoration and Rehabilitation Efforts to restore and rehabilitate habitats affected by oil pollution are essential for supporting the recovery of fish populations. Stock enhancement programs, based on the release of hatchery-reared fish into affected areas, can help accelerate the recovery of fish populations that have been impacted by oil pollution, particularly in aquaculture settings. The development of standardized protocols, sharing of expertise, and collective efforts are essential to mitigate the effects of oil pollution on fisheries and aquaculture (Bhowmik et al. 2024). Conclusion Oil contamination seriously threatens the health and sustainability of both fisheries and aquaculture. The wide-ranging impacts, from direct mortality and habitat degradation to economic losses and contamination of aquaculture products, underscore the FIGURE 2. Algal mats and oiled algae. Source: Little et al. (2021).
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