Department of Earth & Environmental Science, K.C. Irving Environmental Science Center, Acadia University, Wolfville, Nova Scotia, Canada.
Environ Toxicol Chem. 2013 Aug;32(8):1888-95. doi: 10.1002/etc.2264.
The polychaete worm Nereis diversicolor engineers its environment by creating oxygenated burrows in anoxic intertidal sediments. The authors carried out a laboratory microcosm experiment to test the impact of polychaete burrowing and feeding activity on the lability and methylation of mercury in sediments from the Bay of Fundy, Canada. The concentration of labile inorganic mercury and methylmercury in burrow walls was elevated compared to worm-free sediments. Mucus secretions and organic detritus in worm burrows increased labile mercury concentrations. Worms decreased sulfide concentrations, which increased Hg bioavailability to sulfate-reducing bacteria and increased methylmercury concentrations in burrow linings. Because the walls of polychaete burrows have a greater interaction with organisms, and the overlying water, the concentrations of mercury and methylmercury they contain is more toxicologically relevant to the base of a coastal food web than bulk samples. The authors recommend that researchers examining Hg in marine environments account for sediment dwelling invertebrate activity to more fully assess mercury bioavailability.
沙蚕通过在缺氧潮间带沉积物中建造含氧的洞穴来改造其环境。作者进行了一项实验室微宇宙实验，以测试多毛类动物的挖掘和摄食活动对来自加拿大芬迪湾沉积物中汞的生物可利用性和甲基化的影响。与无蠕虫沉积物相比，洞穴壁中可利用的无机汞和甲基汞的浓度升高。蠕虫洞穴中的黏液分泌物和有机碎屑增加了可利用汞的浓度。蠕虫降低了硫化物的浓度，这增加了硫酸盐还原菌对汞的生物利用度，并增加了洞穴衬里中甲基汞的浓度。由于多毛类动物洞穴的墙壁与生物体和上覆水的相互作用更大，因此它们所含的汞和甲基汞的浓度与沿海食物网的基础相比，在毒理学上更具相关性。作者建议研究海洋环境中汞的研究人员考虑到沉积物栖居无脊椎动物的活动，以更全面地评估汞的生物可利用性。
