Influences of Flow Regime on Development and Desiccation Response of Lotic Diatom Communities
Influences of Flow Regime on Development and Desiccation Response of Lotic Diatom Communities
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流态对流态硅藻群落发育和干燥响应的影响
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发表时间：
1987
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影响因子：
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通讯作者：
C. Peterson
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文献类型：
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作者：
C. Peterson
在米德湖以下的科罗拉多河中的庇护或直流栖息地中发育的硅藻群落受到短期干燥处理，以检验以下假设：栖息在平静（庇护）环境中的群落比来自更严格（直流）栖息地的群落对不可预测的干扰的抵抗力更低。直流社区表现出较低的细胞积累率和支持较低的生物量和硅藻密度比庇护社区，这表明电流剪切和流动的变化限制直流积累。在庇护生境中生长的硅藻群落对干燥胁迫的抵抗力低于来自更严格水流条件下的群落。生物量和细胞密度都减少了干燥的庇护基板，而相同的干燥频率在直流电要么没有影响，或造成增加的丰度参数，这取决于社会年龄。干燥在庇护环境中比在直流环境中引起更大的分类变化。保护环境中的低抗干燥性可能是由于水流缺乏营养更新和高密度群落对资源的竞争。灰分含量的时间变异性在两个流态中未受干扰的群落比干燥的群落更大，表明干燥群落的结合能力更强，并表明粘液产量随着干燥而增加。在直流群落中，硅藻的积累受到与快速流动相关的剪切力的抑制，干燥后的粘液产生可能增强了硅藻的移民成功，导致干燥群落的密度和多样性都更高。
Diatom communities developed in either sheltered or direct-current habitats in the Colorado River below Lake Mead were subjected to short-term desiccation to test the hypothesis that communities inhabiting placid (sheltered) environments are less resis- tant to unpredictable disturbance than are those from more rigorous (direct-current) hab- itats. Direct-current communities exhibited lower cell accumulation rates and supported lower biomass and diatom densities than sheltered communities, suggesting that current shear and flow variability limited accumulation in direct current. Diatom communities that developed in sheltered habitats were less resistant to desiccation stress than com- munities from more rigorous flow conditions. Both biomass and cell densities were reduced by desiccation on sheltered substrates, whereas the same desiccation frequency in direct current had either no effect or caused increases in abundance parameters, depending on community age. Desiccation caused greater taxonomic change in sheltered than in direct- current environments. Low resistance to desiccation in sheltered environments was prob- ably due to lack of nutrient renewal by current and to competition for resources in high- density communities. Temporal variability in ash content was greater in undisturbed than in desiccated communities in both flow regimes, indicating greater binding capacity of desiccated communities and suggesting that mucilage production increased with desicca- tion. In direct-current communities, where diatom accrual was suppressed by shear forces associated with fast flow, mucilage production after desiccation may have enhanced diatom immigration success, resulting in both higher densities and diversity in desiccated com- munities.