School of Earth and Environmental Sciences, Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea.
Marine Ecosystem Research Center, Marine Environmental & Climate Research Division, Korea Institute of Ocean Science and Technology, Busan 49111, Republic of Korea.
Environ Int. 2019 Oct;131:104981. doi: 10.1016/j.envint.2019.104981. Epub 2019 Jul 11.
Stable isotope analysis was used to investigate the benthic food web dynamics in the Geum River estuary where continuous river flow has been blocked by a sea dike over the past 25 years. In order to address the dike effect(s) on distribution of food sources (i.e., organic matters and microphytobenthos) and their utilization by marine predators, a three years monitoring survey (total of 30 surveys) was seasonally conducted at four fixed locations at both inside of dike and outer tidal flats. All the collected biota (total of 19 species; >1100 individuals and microphytobenthos) and abiotic (n = 118) samples were analyzed for carbon (δC) and nitrogen (δN) stable isotopes. In particular, two dominant marine bivalves inhabiting outer reach of tidal flats, Mactra veneriformis and Cyclina sinensis, were targeted to identify their feeding strategies that being related to a year-round population growth. In general, the stable isotopic signatures of samples indicated dissimilarity in distribution of organic matters between inside and outside of dike, supporting geographical and/or trophic isolation. The taxa-dependent trophic levels are also evidenced in consistent manner, with two to three levels being positioned over the years. Meantime, their dietary contributions varied in time, i.e., seasonal chances in compositions of major food sources (microphytobenthos and particulate organic matters) were observed for two target bivalves. Such temporal variations could be further linked to selective feedings that evidenced by age(size)-dependent and/or tissue specific distributions. Altogether, the present study suggested seasonality, diet preference, and growth dependent food web dynamics in the Geum River estuary. Overall, the present study suggested that the stable isotopic technique could be a powerful tool for characterizing the long-term anthropogenic influences of a sea dike on marine food-web dynamics.
稳定同位素分析被用于研究过去 25 年来，由于海堤的阻隔导致基川河口的底栖食物网动态变化。为了研究堤坝对食物源（即有机物质和微型底栖生物）分布及其对海洋捕食者的利用的影响，我们在堤内和外潮滩的四个固定地点进行了为期三年（共 30 次调查）的季节性监测调查。共采集了 19 个物种（>1100 个个体和微型底栖生物）和 118 个非生物样本，用于分析碳（δC）和氮（δN）稳定同位素。特别是，我们选择了栖息在外潮滩远岸的两种优势海洋双壳类动物，文蛤和中国蛤蜊，以确定它们的觅食策略，这与全年的种群增长有关。总的来说，样本的稳定同位素特征表明，有机物质在堤内和堤外的分布存在差异，支持地理和/或营养隔离。多年来，以分类为基础的营养层次也以一致的方式得到证实，有两个到三个层次。同时，它们的食物贡献也随时间而变化，即两种目标双壳类动物的主要食物源（微型底栖生物和颗粒有机物质）组成的季节性变化。这种时间变化可能与选择性摄食有关，这可以通过年龄（大小）依赖性和/或组织特异性分布来证明。总的来说，本研究表明基川河口的食物网动态具有季节性、饮食偏好和生长依赖性。总的来说，本研究表明，稳定同位素技术可以成为描述海堤对海洋食物网动态的长期人为影响的有力工具。
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