Scientists has made new progress in understanding the dynamics and determinants of amoeba community, occurrence and abundance in subtropical reservoirs and rivers.

Scientists from The Aquatic Ecohealth Group, together with Christopher Rensing and Regin Ronn at Institute of Urban Environment, Chinese Academy of Sciences, selected different habitat waters (including reservoirs and rivers) according to urban-to-rural gradient, extending from urban sites to more rural sites in a subtropical city.

Free-living amoebae are single-celled eukaryotic microorganisms, they are widely distributed both in natural and man-made aquatic ecosystems, and they play key roles in water purification and in biogeochemical cycling and fertility maintenance of aquatic and terrestrial ecosystems.

The composition of amoeba communities varies between seasons in drinking water treatment system, but mechanisms that mediate seasonal variation in community structure have not been well investigated. Similarly, most studies of amoeba communities have focused on a single type of habitat, while the variation in composition of free-living amoeba communities between habitats remains poorly understood.

During the research, a total of 108 surface water samples were collected on a seasonal basis from four reservoirs and two rivers in Xiamen city, subtropical China. They used high throughput sequencing and qPCR methods to explore the occurrence and abundance of free-living amoebae.

In total, 335 amoeba OTUs were detected, and only 32 OTUs were shared by reservoir and river habitats. The reservoirs and rivers harbored unique amoebae communities and exhibited distinct seasonal patterns in community composition.

Moreover, the temporal patterns of amoebae communities were significantly associated with water temperature, indicating that temperature is an important variable controlling the ecological dynamics of amoebae populations. However, further comparative analysis indicated that both environmental selection, and neutral processes, significantly contributed to amoeba community assembly.

The genera detected here include pathogenic species and species that can act as vectors for microbial pathogens, which can cause human infections.

Overall, the results of this study suggest that the free-living amoeba communities are more affected by habitat (river vs. reservoir) than by the season in these subtropical aquatic ecosystems.

The results also indicate that abiotic factors, in particular water temperature, play an important role in amoeba ecology. Both environmental selection and neutral processes play important roles in the community assembly, while the stochastic processes were more important for shaping the communities of free-living amoebae in reservoir than in river.

The study was published in Water Research entitled "Dynamics and determinants of amoeba community, occurrence and abundance in subtropical reservoirs and rivers".

This study was supported by the National Natural Science Foundation of China, the Xiamen Municipal Bureau of Science and Technology.