Every year, as pre-monsoon winds lash Mumbai’s coastline, dark sticky tarballs — a visible sign of a recurring seasonal oil spill — begin washing ashore from Juhu to Versova and Aksa to Girgaon, coating beaches, fragile mangroves and rocky shores in toxic petroleum residue. Marine ecologist Shaunak Modi warns that the oily sludge poses a threat to both marine biodiversity and human health.

According to Modi, the sticky black globs are not isolated incidents, but part of a seasonal oil spill affecting India’s west coast from April to September. He has raised concerns that while visible tarballs on beaches are cleared, those that land on rocky terrain take months to clear out, often leaching back into the ocean.