Blankson Emmanuel R, Deb Adhikary Nihar R, Klerks Paul L
Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.
Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.
Chemosphere. 2017 Jan;167:19-27. doi: 10.1016/j.chemosphere.2016.09.128. Epub 2016 Oct 2.
The present study investigated the effect of lead (Pb) on bioturbation by the oligochaete worm Lumbriculus variegatus, using freshwater microcosms. The experiment used lead at "0", 140, 700, and 3500 μg/g in sediment, and used two different laboratory populations of L. variegatus. A molecular genetic analysis and bioassays were conducted to determine if the two populations differed genetically and whether they differed in Pb-sensitivity. The bioturbation of L. variegatus was estimated using luminophores placed at the sediment-water interface at the beginning of the experiment. After the 14 d experiment the luminophore profiles in sediment were used to estimate the biodiffusion and bioadvection coefficients, using the diffusion-advection model. The results showed that the biodiffusion and bioadvection coefficients were generally negatively related to the Pb concentrations in the sediment. Lead at 700 and 3500 μg/g reduced both coefficients, while Pb at 140 μg/g did not. Luminophore profiles in the "0" and 140 μg/g treatments were indicative of a non-local transport, while a diffusive transport was observed at the higher Pb levels. The two laboratory populations of L. variegatus used in the experiment differed in their sensitivity to Pb when mortality was used as the endpoint, but they did not differ in sediment bioturbation or the Pb-sensitivity of this process. Moreover, the genetic analysis did not detect any genetic differences between the populations. This study demonstrated that elevated levels of Pb can impact ecosystem functioning by decreasing the bioturbation activity of benthic organisms such as L. variegatus.
本研究利用淡水微观生态系统，调查了铅（Pb）对寡毛纲蠕虫颤蚓（Lumbriculus variegatus）生物扰动的影响。实验中沉积物中铅的含量分别为“0”、140、700和3500微克/克，并使用了两个不同的颤蚓实验室种群。进行了分子遗传分析和生物测定，以确定这两个种群在基因上是否存在差异，以及它们对铅的敏感性是否不同。在实验开始时，通过放置在沉积物-水界面的发光体来估计颤蚓的生物扰动。在为期14天的实验结束后，利用扩散-平流模型，根据沉积物中发光体的分布情况来估计生物扩散系数和生物平流系数。结果表明，生物扩散系数和生物平流系数通常与沉积物中的铅浓度呈负相关。700和3500微克/克的铅降低了这两个系数，而140微克/克的铅则没有。“0”和140微克/克处理组的发光体分布表明存在非局部运输，而在较高铅含量水平下观察到的是扩散运输。当以死亡率作为终点时，实验中使用的两个颤蚓实验室种群对铅的敏感性不同，但它们在沉积物生物扰动或该过程对铅的敏感性方面没有差异。此外，遗传分析未检测到种群之间存在任何基因差异。这项研究表明铅含量升高会通过降低颤蚓等底栖生物的生物扰动活动来影响生态系统功能。
