Post-flooding blooms of the non-indigenous freshwater jellyfish <i>Craspedacusta sowerbii</i> Lankester, 1880 in Kollam District of Kerala, India

Abstract Cnidarian jellyfish are common components of marine food webs, though a small number of species also thrive in freshwaters. Freshwater jellyfish (class Hydrozoa) are not uncommon in tropical and subtropical India. Several genera, each with few (&amp;lt;10) species, are represented. The non-indigenous Peach Blossom Jellyfish Craspedacusta sowerbii has, however, only been sighted thrice in India in the past; twice (2009 and 2016) in Kerala State, southwest India. We report on a mass occurrence of C. sowerbii in a small freshwater water body (Chirakkal pond, Karurkadavu village, Karunagapalli, Kollam District) following a major flood event in August 2018. We provide notes on environmental conditions present and the jellyfish bloom characteristics. This report establishes the presence of the invasive species in the water bodies of Kerala and its post-flooding, adding it to the 32 already reported aquatic alien species in the state. While the fate of the herein-reported C. sowerbii population explosion in Kerala State is not entirely known, we call for more regional awareness and research attention, including community involvement.