Spatial and temporal distribution of floating tarballs and associated ecological pollution in the Eastern Arabian Sea

Recent observations in the eastern Arabian Sea reveal the persistent presence of surface-floating tarballs along India's west coast from May to December. These tarballs originate from oil seepage caused by accidental spills, shipping activities, shipwrecks, or natural seepage, and undergo weathering that results in a hardened outer layer with a semi-solid interior. Field sampling indicates that tarballs range in size from 0.1 to 4 cm and can be transported over long distances by seasonally reversing monsoonal winds and the West India Coastal Current. Chemical analysis identified eleven polycyclic aromatic hydrocarbons (PAHs) along with toxic heavy metals, including lead (Pb), chromium (Cr), and cadmium (Cd), highlighting their potential for bioaccumulation and ecological risk. The attachment of goose barnacles of varying sizes suggests prolonged residence time and transport pathways. The impact of oil spills extends beyond the immediate pollution, affecting marine biogeochemistry and ecosystem health. Beyond direct pollution, tarballs may act as vectors for the dispersal of non-indigenous species and pathogenic microorganisms such as Vibrio, posing additional ecological and public health concerns. This study emphasizes the importance of monitoring tarball distribution to better identify pollution sources and develop effective management strategies for protecting coastal ecosystems and supporting Sustainable Development Goal 14 (Life Below Water).