Abstract
The aim of this paper was to determine the abundance and secondary production by bacteria inhabiting the surface microlayer and subsurface water in a specific water basin, i.e., polluted estuarine harbour channel. In a 3-year seasonal cycle, the total number of bacteria and their biomass were higher in the surface microlayer (SML) 7.57 × 108cells dm−3 and 15.86 µg C dm−3 than in the subsurface water (SSW) 4.25 × 108cells dm−3 and 9.11 µg C dm−3 of the studied channel. The opposite relationship was noted in the level of the secondary production (SML—37.16 μg C dm−3 h−1, SSW—60.26 μg C dm−3 h−1) in this water basin. According to the analysed microbiological parameters, the total number of bacteria and secondary production varied along the horizontal profile in the water of the studied channel. The total number of bacteria and their secondary production showed the seasonal variation as well.
Highlights
The surface microlayer (SML) is a boundary between the hydrosphere and atmosphere of a thickness varying from 10 to 250 μm, which chemical, physical, and biological properties differ from those of the subsurface water (SSW) (Chance et al 2018; Zäncker et al 2021)
The analysis of these data showed that the total number of bacteria in the studied water layers varied in different years from 0.18 to 14.72 cells × 108 dm−3 with the mean value of 5.91 cells × 108 dm−3, while their biomass changed from 2.86 to 29.44 μg C dm−3 with the mean value of 12.48 μg C dm−3
The bacterial secondary production (BP) estimated from the rate of thymidine incorporation in the bacterial DNA in the studied channel varied from 0.86 to 222.00 μg C dm−3 h−1 and the bacterial growth rate changed within the range 0.04–32.71 day−1
Summary
The surface microlayer (SML) is a boundary between the hydrosphere and atmosphere of a thickness varying from 10 to 250 μm, which chemical, physical, and biological properties differ from those of the subsurface water (SSW) (Chance et al 2018; Zäncker et al 2021). The surface microlayer is generally enriched in both dissolved and particulate organic matter by physical processes including diffusion, convection, advection, adhesion to rising bubble, upwelling of sub-surface water and particle deposition from air (Kurata et al 2016; Perliński et al 2017). The surface microlayer can be enriched up to102103 times in molecular and dissolved organic matter consisting mainly of proteins, carbohydrates, lipids, nucleic acids, chitin, pectin and cellulose The surface microlayer can be enriched up to102103 times in molecular and dissolved organic matter consisting mainly of proteins, carbohydrates, lipids, nucleic acids, chitin, pectin and cellulose (Perliński et al. Vol.:(0123456789)
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