Temporal and Spatial Survey on the Abundance of Amoebae and Bacteria in an Estuary and the Role of Environmental Parameters.

Free-living amoebae are phagotrophic protists that prey on bacteria. However, under certain conditions, some bacteria can resist phagocytosis and become pathogenic. Environmental parameters altered by climate change may impact amoebae and bacterial diversity, as well as their pathogenicity. In our study, we monitored amoebae and bacterial abundance both temporally, over 1 year, and spatially, along a river estuary, while also recording key environmental parameters. Naegleria was the most represented amoebae genus, present year-round from the river to the estuary. Similarly, Vibrio was the most dominant bacterial genus. Salinity, and to a lesser extent dissolved oxygen, influenced amoebae and bacterial abundance. In particular, the genera Naegleria, Paramoeba, Pseudomonas and Legionella were the most affected. In conclusion, this study highlights the impact of salinity on amoebae diversity, suggesting that this parameter, as a key factor in coastal environments, will impact both amoebae and the associated bacterial communities.