Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 1220 Prospect Ave, No 285, Melbourne, FL 32901, USA.
Sci Total Environ. 2012 Jan 1;414:445-55. doi: 10.1016/j.scitotenv.2011.10.014. Epub 2011 Nov 21.
Stable-isotope ratios (δ(13)C and δ(15)N) and mercury in a model predator, and associated prey community assessments were used to make inferences regarding food web relationships and how these relationships are influenced by habitat variability and anthropogenic factors. Although interconnected, the three major basins of the Indian River Lagoon system on the Atlantic coast of Florida comprise noticeably different available habitat types with spatially distinct faunal communities and available prey for spotted seatrout, Cynoscion nebulosus, a model predatory fish species. Water quality, degree of urbanization, human population density, and levels of nitrogen enrichment clearly differ between these representative estuarine basins. The differences can influence feeding ecology and therefore result in different mercury concentrations and different stable-isotope signatures of spotted seatrout between basins. Mercury concentrations in spotted seatrout were greatest in Mosquito Lagoon (ML) and least in the Indian River Lagoon proper (IRL), although concentrations were low for all basins. Spotted seatrout from IRL were carbon-depleted and nitrogen-enriched compared with those from the other basins; this suggests either that the fish's primary source of carbon in IRL is an algae- or phytoplankton-based food web or that the pathway through the food web is shorter there. The δ(15)N values of IRL spotted seatrout were greater than those in the Banana River Lagoon or ML, suggesting slightly different trophic positioning of fish in these basins. The greater δ(15)N values in IRL spotted seatrout may also reflect the greater human population density and resultant anthropogenic inputs (e.g., observed higher total nitrogen levels) in IRL compared with the other more pristine basins examined. Understanding species' responses to broad-scale habitat heterogeneity in estuaries and knowing basin-specific differences in stable isotopes, mercury, prey communities, and comprehensive food web relationships will be useful in the future for long-term monitoring of impacts of anthropogenic disturbances and of recovery from restoration efforts.
稳定同位素比值（δ(13)C 和 δ(15)N）和汞在模型捕食者中的含量，以及相关的猎物群落评估用于推断食物网关系，以及这些关系如何受到栖息地变异性和人为因素的影响。尽管相互关联，但佛罗里达州大西洋沿岸的印度河泻湖系统的三个主要流域构成了明显不同的可用栖息地类型，具有空间上不同的动物群落和可供斑点石斑鱼（Cynoscion nebulosus）使用的可用猎物，斑点石斑鱼是一种模型捕食性鱼类。水质、城市化程度、人口密度和氮富集水平在这些具有代表性的河口流域之间明显不同。这些差异会影响摄食生态，从而导致不同流域斑点石斑鱼体内的汞浓度和稳定同位素特征不同。尽管所有流域的浓度都较低，但斑点石斑鱼体内的汞浓度在莫斯基托泻湖（ML）中最高，在印度河泻湖本身（IRL）中最低。与其他流域的鱼相比，IRL 的斑点石斑鱼的碳含量较低，氮含量较高；这表明，IRL 中鱼类的主要碳源是藻类或浮游植物为基础的食物网，或者食物网中的途径较短。IRL 斑点石斑鱼的 δ(15)N 值高于香蕉河泻湖或 ML，这表明这些流域中鱼类的营养位置略有不同。IRL 斑点石斑鱼的 δ(15)N 值较高，也可能反映了与其他更原始的流域相比，IRL 中较高的人口密度和由此产生的人为输入（例如，观察到的总氮水平较高）。了解物种对河口广泛栖息地异质性的反应，以及了解稳定同位素、汞、猎物群落和综合食物网关系的流域特异性差异，将有助于未来对人为干扰的长期监测以及从恢复努力中恢复的情况。
