A one-year impingement monitoring was conducted at Madras Atomic Power Station (MAPS), Kalpakkam, southeastern coast of India and identified a total of 67 species of marine organisms in the cooling water system. Estimates of total annual impingement contributed about 1.47 × 106 individuals and 142.5 t of biomass. Jellyfish contributed about 6.8 × 105 individuals and 135.6 t of biomass. Crabs, shrimps and fish were the most vulnerable organisms contributing about 4.29 × 105 individuals, 1.39 × 105 individuals and 2.16 × 105 individuals respectively. Commercially important species namely Trichiurus lepturus, Sardinella longiceps and Portunus pelagicus were found to be impinged 1.88% and 0.29% by number and weight of the total biomass respectively. Out of ~ 327 fish species recorded at Kalpakkam, only about 9.4% of species were impinged at MAPS. Multispecies impingement at MAPS poses the problem of finding the best mitigation options for tropical conditions. © 2017 Elsevier Ltd