MODIFICATION OF BENTHIC INSECT COMMUNITIES IN POLLUTED STREAMS - COMBINED EFFECTS OF SEDIMENTATION AND NUTRIENT ENRICHMENT
MODIFICATION OF BENTHIC INSECT COMMUNITIES IN POLLUTED STREAMS - COMBINED EFFECTS OF SEDIMENTATION AND NUTRIENT ENRICHMENT
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DOI：
10.1007/bf00007232
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发表时间：
1982-01-01
期刊：
影响因子：
2.6
通讯作者：
LEMLY, AD
中科院分区：
文献类型：
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作者：
LEMLY, AD
在长达8个月的时间里，研究人员监测了美国南部阿巴拉契亚鳟鱼流的底栖昆虫群落对无机沉积和营养物富集的反应。点源污染物的进入建立了不同的污染区域，从而可以评估单独沉积和与营养物水平升高相关的影响。泥沙的输入导致底水界面床载显著增加，pH显著降低（P < 0.05）。从牲畜牧场吸收养分径流的区域显示出硝酸盐和磷酸盐水平升高，但现有数据表明这些浓度相当低。滤食性毛翅目、双翅目、掠食性翼翅目和部分蜉蝣目的物种丰富度、多样性和总生物量均显著降低。无机沉积是影响滤食性类群的主要因素，它通过破坏取食和填补间隙间接起作用。床载中与物质相关的化合物的分解可能会降低pH值，并消除对酸敏感的翼翅目和蜉蝣目。这种酸化过程可能对阿巴拉契亚溪流特别重要，因为该地区地表水的pH值在沉积之前是典型的酸性。颗粒在身体表面和呼吸结构上的积累，可能是蜡和粘液分泌或表面电特性的功能，似乎是无机沉积对溪流昆虫的主要直接影响。丝状细菌Sphaerotilus natans的生长也经常与在接受营养物添加的区域淤积的个体有关。细菌的分布表明，泥沙底物可能与铁化合物的存在有关，需要在稀营养液中定植。贻贝菌落的主要作用似乎是通过细菌细丝形成的网来增加颗粒积累。无机沉降和营养物添加协同作用，与单独暴露于一种污染物相比，消除的类群数量要多得多。
Responses of the benthic insect community of a southern Appalachian [USA] trout stream to inorganic sedimentation and nutrient enrichment were monitored over a period of 8 mo. Entry of pullutants from point sources established differentially polluted zones, allowing an assessment of impacts due to sedimentation alone and in association with elevated nutrient levels. Input of sediment resulted in a significant increase in bed load and decrease of pH at the substrate-water interface (P < 0.05). The zone receiving nutrient runoff from livestock pasture exhibited elevated levels of nitrate and phosphate, but available data indicated such concentrations to be quite low. Species richness, diversity and total biomass of filter feeding Trichoptera and Diptera, predaceous Plecoptera and certain Ephemeroptera were significantly reduced in the polluted zones. Inorganic sedimentation, operating indirectly through disruption of feeding and filling of interstitial spaces, was the primary factor affecting filter feeding taxa. Decomposition of compounds associated with materials in the bed load may depress pH and eliminate acid sensitive species of Plecoptera and Ephemeroptera. Such processes of acidification may be particularly important to Appalachian streams since the pH of regional surace waters is characteristically acidic prior to sedimentation. Accumulation of particles on body surfaces and respiratory structures, perhaps as a function of wax and mucous secretion or surface electrical properties, appears to be the major direct effect of inorganic sedimentation on stream insects. Growths of the filamentous bacterium Sphaerotilus natans were also frequently associated with silted individuals in the zone receiving nutrient addition. Distribution of the bacterium suggested that silted substrates, perhaps as related to the presence of Fe compounds, are required for colonization in dilute nutrient solutions. The primary effect of Sphaerotilus colonies appears to be augmentation of particle accumulation through net formation by bacterial filaments. Inorganic sedimentation and nutrient addition operate synergistically, eliminating a significantly greater number of taxa than exposure to one pollutant alone.