ABSTRACT: The alternation of the classic and microbial food-webs in spring and winter, respectively, and the trespass towards higher trophic levels represented by fish early stages, are not well understood in Patagonia. These trophic routes were investigated in the inner Sea of Chiloe, an estuary of high ecological relevance in northern Patagonia. The isotopic values of δ¹³C and δ¹⁵N of ichthyoplankton and particulate organic matter were analyzed in late winter and spring 2017 to evaluate whether seasonal changes (e.g. in the composition of the freshwater discharge) were reflected in the isotopic signals of fish larvae. For this purpose, larvae of dominant fish species with contrasting feeding strategies were collected up to 100 m depth. The inshore zone of northern Patagonia was characterized by a dominance of marine carbon production, with increasing input of terrestrial organic matter during winter. δ¹³C values < -25 ‰ at the outermost estuary stations indicated the influence of allochthonous carbon exported from the inshore area in spring. The δ¹³C-larval signature of the species of the lightfish Maurolicus parvipinnis, the pipefish Leptonotus blainvilleanus, and the rockfish Sebastes oculatus followed the isotopic signature of the particulate organic matter in both seasons, at inshore and the exchange (outer) zone. Food partitioning was detected between species, with Merluccius spp. at the highest trophic position and L. blainvilleanus at the lowest. The fish larval community reached more diverse and higher δ¹⁵N values in winter, when larvae likely fed on prey items of higher trophic level, or instead when the food-web was partly sustained by microbial sources. Our results showed seasonal variations in δ¹³C values, suggesting differences in the source of organic carbon incorporated by the studied fish larvae. Moreover, trophic plasticity at larval stages may be an important characteristic of this type of estuarine environment.

中文翻译：

---

使用δ13C和δ15N同位素阐明巴塔哥尼亚北部最丰富的鱼幼虫的营养途径

摘要：巴塔哥尼亚对春季和冬季的经典食物网和微生物食物网的交替以及以鱼类早期阶段为代表的较高营养水平的侵入没有得到很好的理解。这些营养路径在Chiloe内海进行了调查，Chiloe是巴塔哥尼亚北部具有高度生态意义的河口。的δ同位素值¹³ C和δ ¹⁵在2017年冬末和春季末对鱼鳞浮游生物的N和颗粒状有机物进行了分析，以评估鱼类幼虫的同位素信号是否反映了季节性变化（例如淡水排放的组成）。为此，收集了具有对比的进食策略的优势鱼类的幼虫，直至100 m的深度。巴塔哥尼亚北部沿海地区的特征是海洋碳产量占主导地位，冬季期间陆上有机物的输入量增加。δ ¹³ C值<-25‰在最外河口站指示的弹簧从近海区域导出的异地碳的影响。该δ ¹³的lightfish物种的C-幼虫签名Maurolicus parvipinnis，在沿海和交换（外）区两个季节，the鱼Leptonotus blainvilleanus和石鱼Sebastes oculatus都遵循颗粒有机物的同位素特征。在Merluccius spp物种之间检测到食物分配。在最高的营养位置处和blainvilleanus在最低的营养处。鱼仔社区达到了更加多样化和更高的δ ¹⁵在冬季的N值，当幼虫可能饲喂高营养级的猎物，或改为当食物网的部分原因是微生物来源持续。我们的研究结果显示，δ季节性变化¹³C值，表明所研究的鱼幼虫掺入的有机碳来源不同。此外，幼体阶段的营养可塑性可能是这种河口环境的重要特征。