Jellyfish bloom of Craspedacusta in tilapia farms in Southern Brazil

MIRIAN N. PEREIRA; DESERTI, MARIA IRENE; JEFERSON A. DURÁN-FUENTES; MAXIMILIANO M. MARONNA; FLORIAN LÜSKOW; EVGENY A. PAKHOMOV; STAMPAR, SERGIO

Kerala

Simposio; 7 International Jellyfish Blooms Symposium; 2023

University of Kerala and ICAR - Central Marine Fisheries Research Institute

A rarity among cnidarian species due to its ability to inhabit freshwater environments, the jellyfish of the genus Craspedacusta has captured the attention of scientists and nature enthusiasts for its erratic appearance episodes. While its origin lies in Asia, Craspedacusta has found its way to various parts of the world, including South America. Its appearance is striking, boasting a translucent bell-shaped body adorned with tentacles that delicately extend into the water. Craspedacusta sowerbii was first documented in South America by Gliesh in 1930 from Porto Alegre, Rio Grande do Sul state, and it has been reported in sevenfive other states of Brazil, and throughout South America. However, many of these sporadic records do not have consistent data and thorough analyzes have not been carried out in South America. In April 2022, all tilapia specimens (Oreochromis niloticus) in a fish farm lake in the municipality of Ariranha do Ivaí, Paraná, Brazil, were completely exterminated (loss of approximately US$200,000) by the appearance of thousands of jellyfish. Two dozen specimens were collected and brought to the laboratory for morphological and molecular analyses (mtDNA COI). Thus, we identified the animals as Craspedacusta sowerbii, but the molecular data indicated a close relationship with specimens sequenced from lakes in Canada, with no molecular variation related to the focus material of this study. These results are interesting as they may indicate recent connections arising from secondary carryover, probably due to the transfer of substrates such as aquatic plants. These data encourage further studies to understand how such distant areas maintain some kind of human-based connectivity. Understanding this dynamic is very important for avoiding new invasions and possible financial losses.