“Microbial communities of farmed mussel Mytilus galloprovincialis and seawater in the estuary of Krka River in Croatia (7338)”

Microbial communities of farmed mussel Mytilus galloprovincialis and seawater in the estuary of Krka River in Croatia

Mytilus galloprovincialis, commonly known as the Mediterranean mussel, is significant shellfish species in Croatian marine aquaculture, with a total production of 926 tonnes live weight averaged across 2021, 2022 and 2023. The investigation of the mussel microbiome has gained significant attention due to its critical role in mussel physiology, health, and aquaculture productivity. Mussels serve not only as a food source but also as biofilters, efficiently removing particulate matter and potentially harmful microbes from the water, thus improving water quality and ecosystem health. In this study, the entire microbial community present in the tissues (gills and hepatopancreas) of farmed mussels, as well as in the marine water of the Krka River estuary was examined on a monthly scale during 2022 and 2023 using DNA metabarcoding. The analysis targeted the V4-V5 variable region of the 16S rRNA gene. Bioinformatic evaluation of the data revealed that Proteobacteria, Bacteroidota, and Firmicutes were the most abundant bacterial phyla in the mussel tissues, with notable seasonal variations. Among the 648 genera identified, 522 were found in gills, 516 in hepatopancreas, and 498 in seawater samples, with 331 genera common to all three sample types. Potentially pathogenic genera and coliforms such as Vibrio, Clostridium, and a group classified as Escherichia-Shigella were detected, albeit at very low abundances and exclusively in the hepatopancreas. Alpha diversity was highest in the seawater samples and lowest in the gills and hepatopancreas. The results provide insights into mussel host-microbe-environment interactions that can enhance aquaculture practices and support sustainable mussel farming. This research was supported by the Ministry of Agriculture of the Republic of Croatia through Operational Program for Maritime Affairs and Fisheries for the period 2014-2020 and the European Union through the European Fund for Maritime Affairs and Fisheries, under project INNODAGNJA.

1. TRUMBIĆ, ŽELJKA, University of Split, Department of Marine Studies, Croatia, Presenter
2. ĆURKO, TENA, University of Split, Croatia, Author
3. HRABAR, JERKO, Institute of Oceanography and Fisheries Split, Croatia, Author
4. BOGDANOV, LARISA, University of Split, Department of Marine Studies, Croatia, Author