Distribution and activity of bacteria in the headwaters of the Rhode River Estuary, Maryland, USA

Biology Department Whitman College 99362 Walla Walla WA USA; Marine Biological Laboratory Ecosystems Center 02543 Woods Hole MA USA
Microbial Ecology (Impact Factor: 3.28). 08/1984; 10(3):243-255. DOI: 10.1007/BF02010938

ABSTRACT A transect along the axis of the headwaters of a tidal estuary was sampled for microbial, nutrient, and physical parameters. Chlorophylla averaged 42g 1–1 and phytoplankton comprised an estimated 80% of the total microbial biomass as determined by adenosine triphosphate (ATP). Bacterial concentrations ranged from 0.3–53.9106 cells ml–1 and comprised about 4% of the total living microbial biomass. Bacterial production, determined by3H-methyl-thymidine incorporation was about 0.05–2.09 109 cells 1–1 h–1, with specific growth rates of 0.26–1.69 d–1. Most bacterial production was retained on 0.2m pore size filters, but passed through 1.0m filters. Significant positive correlations were found between all biomass measures and most nutrient measures with the exception of dissolved inorganic nitrogen nutrients where correlations were negative. Seasonal variability was evident in all parameters and variability among the stations was evident in most. The results suggest that bacterial production requires a significant carbon input, likely derived from autotrophic production, and that microbial trophic interactions are important.

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    ABSTRACT: The temporal variability of the abundance and the incorporation of 3H-thymidine and 14C-glucose by attached and free-living bacteria, as well as their relation with environmental factors, were analyzed in a coastal marine ecosystem during a year. Both communities were quantitatively very different. Attached bacteria represented only 6.8% of the total bacterial abundance, whereas free-living bacteria represented 93.2%. The environmental factors most closely linked to the abundance and activity of free-living bacteria were temperature and the concentration of dissolved nutrients. Moreover, the free-living community showed similar temporal variations in abundance and in activity, with lower values in the cold months (from October to May). The attached community did not present the same pattern of variation as the free-living one. The abundance of the attached bacteria was mainly correlated to the concentration of particulate material, whereas their activity was correlated to temperature. We did not find a significant correlation between the abundance and the activity of the attached community. On the other hand, the activity per cell of the two communities did not present a clear temporal variation. Attached bacteria were more active than free-living ones in the incorporation of radiolabeled substrates on a per cell basis (five times more in the case of glucose incorporation and twice as active in thymidine incorporation). However, both communities showed similar specific growth rates. The results suggest that the two aquatic bacterial communities must not be considered as being independent of each other. There appears to be a dynamic equilibrium between the two communities, regulated by the concentrations of particulate matter and nutrients and by other environmental factors.
    Microbial Ecology 12/1991; 23(1):27-39. · 3.28 Impact Factor
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    ABSTRACT: Vertical profiles of bacterial biomass (AODC method), production of biomass (Thymidine method) and total ETS (Electron Transport System) activity were recorded on 14 dates during the destratification process in the monomitic eutrophic Biétri Bay (Ebrié lagoon, Ivory Coast). Bacterial biomass and production were both very high, indicating the importance of heterotrophic processes in this system. Interpretation of ETS data suggests that bacteria or "bacteria-associated organisms" are responsible for most of the oxygen consumed in the water column. Integrated bacterial production of biomass represented ca 80% of carbon produced by primary producers, thus showing that autotrophic production does not meet heterotrophic requirements of bacteria. Destratification appears to be of less importance than suggested by the physical and chemical characteristics, resulting in decrease of bacterial biomass and production by a factor of 2 in the epilimnion. (D'après résumé d'auteur)
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    ABSTRACT: The growth characteristics of small (0.2-1.0μm) and large (1.0-3.0 (μm) free-living and attached bacteria were studied in Lake Constance by comparing the spatial and seasonal dynamics of their biomass turnover time (ratio of biomass/production). The biomass of small free-living bacteria usually turned over significantly faster than that of large free-living bacteria throughout the water column. The turnover of attached bacterial biomass was characterized by large fluctuations. Occasionally, in aphotic water layers, it was as long as that of large free-living bacteria, but when large amounts of decaying organic particles were present, it was shorter than that of small free-living cells. Biomass turnover times of free-living bacteria were in the same range as their generation times, which were estimated from the increase in bacterial abundance in 3μm prefiltered samples. The biomass turnover time of actively metabolizing bacteria was comparable to the generation time of actively metabolizing cells. These results indicate that the biomass turnover time is a useful indicator of the growth of different bacterial fractions, as it reflects their different amounts of participation in microbial processes of aquatic ecosystems.
    Microbial Ecology 03/1988; 15(2):151-63. · 3.28 Impact Factor

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