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
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DOI：
10.1007/s102010170012
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发表时间：
2001-04
期刊：
影响因子：
1.6
通讯作者：
T. Gurung;M. Kagami;T. Yoshida;J. Urabe
中科院分区：
文献类型：
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作者：
T. Gurung;M. Kagami;T. Yoshida;J. Urabe
为了确定影响琵琶湖细菌丰度的因素的相对重要性，对相关的生物和非生物变量进行了相关和多元回归分析。分析中使用的数据是从1997年4月至1998年6月在北部盆地的一个远洋地点每周收集的。细菌丰度范围为1~7×106个细胞/ml−-1，其时空格局与12~15年前的研究结果基本一致。在表层(0-12.5m)，细菌丰度与水温、原生动物和后生动物显著相关，与叶绿素和营养盐浓度无关。结果表明，在决定该湖细菌丰度时，损失因素比生长因素更重要。然而，放牧对不同浮游动物细菌丰度的影响是不同的。细菌丰度与吞食性纳米鞭毛虫和水蚤呈负相关，与原甲藻呈正相关。因此，PnF和Daphnia起到降低细菌丰度的作用，而Eodiaptomus起到刺激作用。相反，这些生物因素不能解释中层(12.5-25m)和深层(>；25m)细菌丰度的变化。相反，深层细菌丰度与垂直混合方式高度相关，表明细菌丰度直接或间接受到非生物因素的影响。这些结果表明，琵琶湖细菌丰度在不同深度受不同因素的影响。
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 × 106cells 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 chlorophyllaand 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) andDaphnia, but positively withEodiaptomus. Thus, PNF andDaphniaact to reduce the bacterial abundance, whileEodiaptomusacts 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.