Shoults-Wilson W Aaron, Elsayed Norhan, Leckrone Kristen, Unrine Jason
Department of Biological Chemical and Physical Sciences, Roosevelt University, Chicago, Illinois, USA.
Environ Toxicol Chem. 2015 Feb;34(2):412-9. doi: 10.1002/etc.2825. Epub 2015 Jan 6.
The invasive zebra mussel (Dreissena polymorpha) has become an accepted biomonitor organism for trace elements, but it has yet to be studied along the Lake Michigan shoreline. Likewise, the relationships between tissue concentrations of elements, organism size, and sediment concentrations of elements have not been fully explained. The present study found that a variety of allometric variables such as length, dry tissue mass, shell mass, organism condition indices, and shell thickness index were useful in explaining intrasite variability in elemental concentrations. The flesh condition index (grams of tissue dry mass per gram of shell mass) explained variability at the most sites for most elements. Once allometric intrasite variability was taken into account, additional significant differences were found between sites, although the net effect was small. Significant positive relationships between sediment and tissue concentrations were found for Pb and Zn, with a significant negative relationship for Cd. It was also found that Cu and Zn concentrations in tissues increased significantly along the shoreline in the southeasterly direction, whereas Hg increased in a northwesterly direction. Opportunistic sampling found that zebra mussels accumulate significantly higher concentrations of nearly all elements analyzed compared to Asian clams (Corbicula fluminea) at the same site. The present study demonstrates the need to fully explain natural sources of variability before using biomonitors to explain spatial distributions of trace elements.
入侵性斑马贻贝（多形饰贝）已成为公认的痕量元素生物监测生物，但尚未在密歇根湖沿岸进行研究。同样，元素的组织浓度、生物大小和元素的沉积物浓度之间的关系也尚未得到充分解释。本研究发现，各种异速生长变量，如长度、干组织质量、壳质量、生物状况指数和壳厚度指数，有助于解释站点内元素浓度的变异性。肉质状况指数（每克壳质量的组织干质量克数）解释了大多数站点大多数元素的变异性。一旦考虑到站点内的异速生长变异性，站点之间还发现了其他显著差异，尽管净效应很小。铅和锌的沉积物浓度与组织浓度之间存在显著正相关，镉则存在显著负相关。还发现，组织中的铜和锌浓度沿东南方向的海岸线显著增加，而汞则沿西北方向增加。机会性采样发现，与同一地点的亚洲蛤蚌（河蚬）相比，斑马贻贝积累的几乎所有分析元素的浓度都显著更高。本研究表明，在使用生物监测器解释痕量元素的空间分布之前，需要充分解释变异性的自然来源。
