engleski

Dynamics and diversity of Vibrio species in relation to oscillation of environmental parameters in Eastern Adriatic bivalve aquaculture

Bivalve aquaculture in Croatia is carried out in natural coastal and estuarine environments. Since the complete bivalve farming cycle is carried out in situ, these organisms are influenced by environmental changes. Moreover, tissues of bivalves are colonized by microorganisms via seawater filtration process. Among them, bacteria of the genus Vibrio are of particular concern, owing to their association to diseases of marine organisms and humans that may be exposed to infections through consumption of contaminated seafood. Therefore, our aim of study was to analyze how environmental parameters affect on abundance and diversity of Vibrio sp. species. Study was conducted on two locations known for traditional bivalve aquaculture - Lim Bay and Mali Ston Bay. We sampled seawater, sediment and tissue (hepatopancreas and gills) of two most important aquaculture bivalves in Croatia - European flat oyster, Ostrea edulis (Linneaus, 1758) and Mediterranean mussel, Mytilus galloprovincialis (Lamarck, 1819) bimonthly on both locations. We also determined physico-chemical parameters of seawater. Furthermore, culturable heterotrophic and total Vibrio bacteria in seawater, sediment and shellfish tissues were isolated on Marine agar and Vibrio selective TCBS medium on 22°C and 35°C. Additionally, we identified Vibrio clades with MALDI-TOF MS and species with MLSA (multilocus sequence alignment) method. Results show that both culturable heterotrophic and total Vibrio bacteria in seawater, sediment and bivalve tissues were higher in Lim Bay. Temperature was the most dominant environmental parameter that influenced the abundance and diversity of Vibrio species. Temperature related fluctuations showed that Vibrio species are more abundant on higher temperature. This trend is most visible in tissue samples, while for water and sediment it was observable only for species belonging to Harveyi clade. Our results raise questions on how further perturbation of environmental conditions related to global warming, may affect the susceptibility of farmed bivalves to colonization by Vibrio pathogens.

Vibrio ; bivalve ; aquaculture ; antibiotic resistance

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