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Relative importance of biotic and abiotic factors affecting bacterial abundance in Lake Biwa: an empirical analysis

Relative importance of biotic and abiotic factors affecting bacterial abundance in Lake Biwa: an empirical analysis,10.1007/s102010170012,Limnology,Te

Relative importance of biotic and abiotic factors affecting bacterial abundance in Lake Biwa: an empirical analysis   (Citations: 12)
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To determine the relative importance of factors affecting bacterial abundance in Lake Biwa, correlation and multiple regression analyses were performed with relevant biotic and abiotic variables. Data used in the analyses were collected weekly from April 1997 to June 1998 at a pelagic site in the north basin. The bacterial abundance ranged from 1 to 7 × 106 cells ml−1, and its spatio-temporal pattern was virtually identical to that in previous studies conducted 12–15 years ago. In the surface layer (0–12.5 m), bacterial abundance was significantly correlated with water temperature and with protozoan and metazoan grazers, but not with chlorophyll a and nutrient concentrations. The results suggest that loss factors rather than growth factors are more important in determining bacterial abundance in this lake. However, grazing effects on bacterial abundance differed among zooplankton. Bacterial abundance correlated negatively with phagotrophic nanoflagellates (PNF) and Daphnia, but positively with Eodiaptomus. Thus, PNF and Daphnia act to reduce the bacterial abundance, while Eodiaptomus acts to stimulate. In contrast, these biotic factors did not explain changes in bacterial abundance in the middle (12.5–25 m) and deep (>25 m) layers. Instead, the bacterial abundance in the deep layer was highly correlated with vertical mixing regimes, suggesting that bacterial abundance was directly or indirectly affected by abiotic factors. These results indicate that bacterial abundance in Lake Biwa was regulated by different factors at different depths.
Journal: Limnology , vol. 2, no. 1, pp. 19-28, 2001
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    • ...Temperature is one factor that limits the bacterial growth rate (Morris and Lewis, 1992; Berger et al., 1995; Gurung and Urabe, 1999), abundance (Gurung et al., 2001), and production (White et al., 1991; Unanue et al., 1992; Kirchman and Rich, 1997; Yager and Deming, 1999), and this factor has been well investigated in marine and freshwater ecosystems, and in wastewater treatment systems (Henze et al., 1996; Lishman et al., 2000)...

    Takeshi Mikiet al. Effects of asynchronous fluctuations in DOC supply and bacterial growt...

    • ...Indeed, empirical analyses by Gurung et al. (2001) of bacterial plankton in Lake Biwa, Japan, suggest that differences in nutrient recycling efficiency between Daphnia and copepods cause a differential impact on bacterial abundance...
    • ...In this lake, Daphnia galeata, a cladoceran, made up the dominant macrozooplankton in spring to early summer, while Eodiaptomus japonicus, a calanoid copepod, dominated from summer to fall (Gurung et al. 2001; Yoshida et al. 2001)...
    • ...Among microzooplankton (ciliates, heliozoa, and rotifers), Kellicottia longispina was the most abundant, followed by Epistylis sp. and Askenatia sp. Bacterial and HNF abundance were 5.1× 10 6 and 0.9× 10 3 cells ml ‐1 , respectively, and within the typical range of Lake Biwa (Gurung et al. 2001)...
    • ...Bacterial and HNF abundances were within the typical range of Lake Biwa (Gurung et al. 2001)...
    • ...The result supports empirical analyses showing that the net effect of Daphnia on bacterial abundance is negative in Lake Biwa (Gurung et al. 2001)...
    • ...The result again coincides with both field (Gurung et al. 2001) and experimental results (Nagata et al. 1996) that show a positive relationship between Eodiaptomus and bacterial abundance in Lake Biwa...
    • ...Gurung et al. (2001) hypothesized that Eodiaptomus stimulate bacterial abundance not only by reducing bacterial grazers and but also by releasing limited nutrients...
    • ...Thus, the increased bacterial growth rate at the high macrozooplankton biomass in the control appears to have been caused by nutrient regeneration from Eodiaptomus, in agreement with the findings of Gurung et al. (2001)...

    Takehito Yoshidaet al. Contrasting effects of a cladoceran ( Daphnia galeata ) and a calanoid...

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