Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong, People's Republic of China.
Arch Environ Contam Toxicol. 2011 Oct;61(3):491-9. doi: 10.1007/s00244-010-9641-z. Epub 2011 Feb 3.
This is the first study to investigate the rate of mercury (Hg) biomagnification in the aquaculture pond ecosystem of the Pearl River Delta (PRD), China, by analyzing total mercury (THg) and methyl mercury (MeHg) concentrations in various species of fish at different trophic levels (TLs). Species representing a gradient of trophic positions in the aquaculture pond food chains were chosen for analyzing THg and MeHg concentrations. In this study, there were two kinds of the aquaculture pond food chains: (1) omnivorous (fish feeds, zooplankton, grass carp [Ctenopharyngodon idellus], and bighead carp [Aristichthys nobilis]) and (2) predatory (zooplankton, mud carp [Cirrhina molitorella], and mandarin fish [Siniperca kneri]). Bighead carp and mandarin fish had the highest MeHg and THg concentrations, i.e., an order of magnitude higher than other species, in their respective food chains. More than 90% of the THg concentrations detected in bighead carp, mandarin fish, and mud carp were in the methylated form. In this study, %MeHg increased with TLs and MeHg concentrations, reflecting that MeHg is the dominant chemical species of Hg accumulated in higher concentrations in biota, especially biota associated with higher TLs in the food chains. The trophic magnification factors were 2.32 and 2.60 for MeHg and 1.94 and 2.03 for THg in omnivorous and predatory food chains, respectively, in PRD. Hg concentrations in fish tissue correlated to Hg levels in the ambient environment, and sediment seemed to be the major source for Hg accumulated in fish. In addition, feeding habit also affected Hg accumulation in different fish species. Four significant linear relationships were obtained between log-THg and δ(15)N and between log-MeHg and δ(15)N. The slope of the regression equations, as biomagnification power, was smaller in magnitude compared with those reported for temperate and arctic marine and freshwater ecosystems, indicating that THg and MeHg biomagnifications were lower in this PRD subtropical aquaculture pond ecosystem. This was probably due to low Hg bioavailability at lower TLs as well as individual feeding behavior of fish.
这是首次研究通过分析珠江三角洲（PRD）水产养殖池塘生态系统中不同营养级（TL）鱼类体内总汞（THg）和甲基汞（MeHg）浓度，来调查汞（Hg）生物放大率。选择了代表水产养殖池塘食物链中营养位置梯度的物种来分析 THg 和 MeHg 浓度。在这项研究中，有两种水产养殖池塘食物链：（1）杂食性（鱼类饲料、浮游动物、草鱼[Ctenopharyngodon idellus]和鳙鱼[Aristichthys nobilis]）和（2）肉食性（浮游动物、 鲤鱼[Cirrhina molitorella]和鳜鱼[Siniperca kneri]）。在各自的食物链中，鳙鱼和鳜鱼的 MeHg 和 THg 浓度最高，即比其他物种高出一个数量级。在大头鱼、鳜鱼和鲤鱼中检测到的 THg 浓度超过 90%为甲基化形式。在本研究中，%MeHg 随 TL 增加而增加，且 MeHg 浓度增加，表明 MeHg 是 Hg 积累的主要化学物质，在生物体内浓度更高，特别是在食物链中与更高 TL 相关的生物体内浓度更高。在 PRD 中，杂食性和肉食性食物链中 MeHg 的营养放大因子分别为 2.32 和 2.60，THg 的营养放大因子分别为 1.94 和 2.03。鱼类组织中的 Hg 浓度与环境中的 Hg 水平相关，沉积物似乎是鱼类中 Hg 积累的主要来源。此外，摄食习性也影响不同鱼类对 Hg 的积累。在 log-THg 和 δ(15)N 之间以及在 log-MeHg 和 δ(15)N 之间获得了四个显著的线性关系。回归方程斜率（作为生物放大能力）的幅度小于温带和北极海洋和淡水生态系统中报道的值，这表明 THg 和 MeHg 的生物放大作用在这个 PRD 亚热带水产养殖池塘生态系统中较低。这可能是由于较低 TL 下 Hg 的生物利用度较低以及鱼类的个体摄食行为所致。
