64 MARCH 2025 • WORLD AQUACULTURE • WWW.WAS.ORG Basic Classification of Oil Spills Oil pollution in marine environments arises from several source points, including oil spills, operational discharges from ships, urban runoff, and atmospheric deposition. 1) Minor oil spills: These occur during berthing, bunkering, and other terminal vessel operations, as well as from accidental discharges of oily water mixtures from the bilges of machinery spaces. Minor oil spills, often resulting from seepage or dripping, are frequently overlooked but can be harmful to the local ecosystem and may accumulate in nearby water bodies (Kankara et al. 2016). 2) Major oil spills: These occur due to major ship collisions, groundings, fires or other forms of damage, or due to damage of undersea pipelines, drilling rigs, platforms etc. by natural or anthropogenic phenomenon. 3) Dishonourable discharges: Spills that are referred to as “dishonourable discharges” or “midnight dumpers” result from intentional dumping of waste oil and oily waters into the marine environment to save money or time. Effects of Oil Pollution Direct Mortality Oil spills can have an immediate impact, causing mortality due to direct exposure to toxic hydrocarbons. The ingestion of oilcontaminated water can lead to internal damage and disrupt vital physiological processes, causing death in various fish species. Oil slicks have direct physical effects on surface-dwelling animals. Oils are toxic to marine organisms due to the presence of polycyclic aromatic hydrocarbons (PAHs) with low molecular weight. These PAHs enters into the marine animals’ bodies through ingestion, gill ventilation and dermal contact. They then produce certain metabolites that can cause cellular damage, mortality and can even impair growth The threat posed by oil pollution to fisheries and aquaculture is significant, as it can cause widespread and devastating consequences for aquatic ecosystems. Heavy crude oils are intricate combinations of organic compounds and transmit supplementary contaminants, such as sulphur, nickel, iron etc. (Cederwall et al. 2020). Whether released accidentally or through chronic leaks, the introduction of petroleum hydrocarbons into marine environments has immediate and longterm impacts on aquatic organisms, aquatic habitats, and overall ecosystem health. Unfortunately, the annual average number of global oil spills per decade 1970-2023 is rising prominently due to increases in oil demand and sea trade. On an annual basis starting in 2020, there was an approximate average of 1.3 significant oil spills resulting from tanker incidents. In 2023, a single oil spill involving over 700 metric tons of leaked oil was documented. Every decade witnesses the spillage of millions of tons of oil into aquatic environments, with the potential to greatly affect aquatic habitats (Grosell and Pasparakis 2021). Aquatic environments are predominantly susceptible to oil spills because wind and currents can swiftly disperse oil across the water surface, expanding the contamination area and hindering control measures. While some components of the oil may break down and increase exposure and bioavailability, crude oil can reach the water column as tiny droplets. Additionally, heavy oils have the potential to sink in fresh water, layering the sediments and further damaging the environment, particularly for benthic organisms. Oil toxicity extends its influence across multiple biological systems, such as vision, cardiovascular performance, lipid metabolism, calcium homeostasis, nervous system functions, osmoregulation, pH equilibrium of internal fluids and stress responses. This comprehensive examination aims to explore the various effects of oil pollution on aquaculture while proposing potential strategies to mitigate these environmental challenges. Managing Marine Oil Pollution: Safeguarding Aquaculture Potluri Sai Kishore and Arun Konduri FIGURE 1. Natural processes that move oil in the marine environment after an oil spill. Source: Maung-Douglass et al. (2015). The threat posed by oil pollution to fisheries and aquaculture is significant, as it can cause widespread and devastating consequences for aquatic ecosystems. Heavy crude oils are intricate combinations of organic compounds and transmit supplementary contaminants, such as sulphur, nickel, iron etc.
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