Bacterioneuston in Lake Baikal: Abundance, Spatial and Temporal Distribution.

Agnia Galachyants,Olga Belykh,Elena Sukhanova,Valentina Domysheva,Yulia Shtykova,Maria Sakirko,Ekaterina Zimens,Irina Tomberg,Vadim Blinov,Maria Suslova

doi:10.3390/ijerph15112587

Abstract

An aquatic surface microlayer covers more than 70% of the world’s surface. Our knowledge about the biology of the surface microlayer of Lake Baikal, the most ancient lake on Earth with a surface area of 31,500 km2, is still scarce. The total bacterial abundance, the number of cultured heterotrophic temporal bacteria, and the spatial distribution of bacteria in the surface microlayer and underlying waters of Lake Baikal were studied. For the first time, the chemical composition of the surface microlayer of Lake Baikal was determined. There were significant differences and a direct relationship between the total bacterial abundance in the surface microlayer and underlying waters of Lake Baikal, as well as between the number of cultured heterotrophic bacteria in studied water layers in the period of summer stratification. In the surface microlayer, the share of cultured heterotrophic bacteria was higher than in the underlying waters. The surface microlayer was characterized by enrichment with PO43−, total organic carbon and suspended particulate matter compared to underlying waters. A direct relationship was found between the number of bacteria in the surface microlayer and environmental factors, including temperature, total organic carbon and suspended particulate matter concentration.

Highlights

The aquatic surface microlayer (SML) is a physical boundary between the hydrosphere and the atmosphere
In the underlying waters (UW) (0–2 cm thick), the total bacterial abundance was in the range of 0.7–2.8 × 106 cells/mL [30], which is comparable to our data
We have identified significant differences and a direct relationship between the total bacterial abundance in the SML and UW, as well as between the number of cultured heterotrophic bacteria in these water layers during the summer season

Summary

Introduction

The aquatic surface microlayer (SML) is a physical boundary between the hydrosphere and the atmosphere. Thickness of the SML is several tens of micrometers; it differs significantly from the water column in physicochemical characteristics and contains high concentrations of organic compounds, such as lipids, proteins and polysaccharides [1]. The SML occupies approximately 71% of earth’s surface, covering all marine and fresh water bodies. Due to its unique physicochemical characteristics, the SML forms a distinct biotope inhabited with a specific microbial community called neuston. Bacteria inhabiting the SML, or bacterioneuston, are an important component of water ecosystems [3]. They play a considerable role in maintaining

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Discussion

Conclusion