The aim of this study was to assess the temporal variability in the trophic structure of a fish community and the trophic levels of dominant fish species off the eastern coast of Korea. We analyzed the community composition and the stable carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) for fish species in Hupo coastal waters over four seasons. Fish assemblages were mainly dominated by resident benthic and benthopelagic fish. In contrast, there were low numbers of pelagic fish, including migrating and occasional species, which varied significantly by season. The fish assemblages generally had relatively wide ranges of δ¹³C and δ¹⁵N (− 21.1 to − 16.3‰ and 10.0 to 14.2‰, respectively), reflecting a clear distinction between resident (mostly benthic or benthopelagic) vs migratory (mostly pelagic) fish. Resident species showed no seasonal differences in their isotopic signatures, whereas pelagic species showed temporal variability in δ¹³C and δ¹⁵N values. The isotopic niche of fish assemblages showed distinctly different patterns between spring–summer and winter–fall with the seasonal changes in the fish community. These patterns might be associated with seasonal variation in the fish community caused by seasonal changes in environmental conditions (e.g., hydrographic parameters and food availability). Our results can offer baseline information/trophic data for ecosystem models that can be used to evaluate the effects of climate on marine ecosystems.

中文翻译：

---

东日本海食物网结构和鱼类群落组成的季节性变化

这项研究的目的是评估一个鱼类群落的营养结构的时间变异性以及韩国东部沿海以外主要鱼类的营养水平。我们分析了社区组合物和稳定的碳和氮同位素比率（δ ¹³ C和δ ¹⁵在琥珀沿海水域鱼类物种N）超过四个季节。鱼群主要由底栖和底栖鱼类主导。相比之下，远洋鱼类的数量较少，包括迁徙鱼类和偶发鱼类，随季节变化很大。鱼组合通常具有相对宽的范围δ ¹³ C和δ ¹⁵N（分别为− 21.1至− 16.3‰和10.0至14.2‰），反映出居民（主要是底栖或底栖鱼类）与迁徙（主要是浮游鱼类）之间的明显区别。居民品种表现出他们的同位素特征没有季节差异，而中上层鱼类在δ显示时间变化¹³ C和δ ¹⁵N个值。随着鱼类群落的季节性变化，鱼类组合的同位素生态位在春夏至冬秋之间显示出明显不同的模式。这些模式可能与环境条件的季节性变化（例如，水文参数和食物供应量）引起的鱼类群落的季节性变化有关。我们的结果可以为生态系统模型提供基线信息/营养数据，可用于评估气候对海洋生态系统的影响。