Control of primary productivity and the significance of photosynthetic bacteria in a meromictic kettle lake. Mittlerer Buchensee, West-Germany
Control of primary productivity and the significance of photosynthetic bacteria in a meromictic kettle lake. Mittlerer Buchensee, West-Germany
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半聚壶湖初级生产力的控制和光合细菌的意义。
作者：
J. Overmann;M. Tilzer
1986 年，对一个小型（A0 = 11.8 · 103 m2，Zmax = 11.5 m）半聚壶湖（Mittlerer Buchensee）的浮游初级生产和控制因素进行了调查。年浮游植物生产力估计约为 120 gC·m−2·a−1 (1,42 tC·lake−1·a−1)。湖泊明显的热分层导致叶绿素浓度（Chla）垂直分布不规则，并且在较小程度上导致光合作用（Az）垂直分布不规则。在 0 至 6 m 的深度之间，发现了低 Chla 浓度 (< 7 mg·m−3) 和相对较高的背景光衰减（kw = 0,525 m−1，由于 gelbstoff 和 abioseston 导致的总衰减的 77%）。因此，藻类的光吸收率较低（平均值为 17.4%），并且不存在自遮光。由于 Chla 浓度的季节性变化较小，因此未观察到 Chla 与面积光合作用 (ΣA) 之间存在显着相关性。仅在初夏（六月至七月），生物量似乎会在更大范围内影响光合作用的垂直分布。在8 m 深度左右，适应弱光的藻类和光养细菌形成了致密的层。由于环境辐照度较低，这些生物体对总初级生产力的贡献很小。初级产量和入射辐照度彼此显着相关（r2 = 0.68）。尽管最大同化数（Popt）显示出明显的水温依赖性（Q10 = 2.31），但后者对面积光合作用的重要性次要。
During 1986 planktonic primary production and controlling factors were investigated in a small (A0 = 11.8 · 103 m2, Zmax = 11.5 m) meromictic kettle lake (Mittlerer Buchensee). Annual phytoplankton productivity was estimated to ca 120 gC · m−2 · a−1 (1,42 tC · lake−1 · a−1). The marked thermal stratification of the lake led to irregular vertical distributions of chlorophylla concentrations (Chla) and, to a minor extent, of photosynthesis (Az). Between the depths of 0 to 6 m low Chla concentrations (< 7 mg · m−3) and comparatively high background light attenuation (kw = 0,525 m−1, 77% of total attenuation due to gelbstoff and abioseston) was found. As a consequence, light absorption by algae was low (mean value 17,4%) and self-shading was absent.Because of the small seasonal variation of Chla concentrations, no significant correlation between Chla and areal photosynthesis (ΣA) was observed. Only in early summer (June–July) biomass appears to influence the vertical distribution of photosynthesis on a bigger scale. Around 8 m depth, low-light adapted algae and phototrophic bacteria formed dense layers. Due to low ambient irradiances, the contribution of these organisms to total primary productivity was small. Primary production and incident irradiance were significantly correlated with each other (r2 = 0.68). Although the maximum assimilation number (Popt) showed a clear dependence upon water temperature (Q10 = 2.31), the latter was of minor importance to areal photosynthesis.