The quantification of niche diversity and niche overlap is useful for understanding the impacts of fisheries regulation and management. In this work, we evaluate isotopic niche size and overlap at the guild and species levels. Specifically, we analyzed guild‐ and species‐specific isotopic niche space and niche space overlap using the SIBER and nicheROVER packages, and we evaluated length‐specific and geographic contrasts in isotopes for fishes in the north‐central Gulf of Mexico. Stable carbon and nitrogen isotope values (δ¹³C and δ¹⁵N) of fish species were compared among four ecotype‐based fish guilds: estuarine, coastal migratory pelagic (CMP), reef, and large offshore pelagic (LOP). Significant differences in the mean stable isotope values were found among fish guilds. Estuarine guild species exhibited the highest δ¹³C variability, and Red Drum Sciaenops ocellatus were the most isotopically diverse. Variability of δ¹³C for CMP fish was comparable to that of some estuarine species, whereas reef and LOP fish were less variable. Fishes within the LOP guild had the largest δ¹⁵N range. Reef guild fishes had the smallest isotopic niche space and LOP guild species consistently had the largest, although no species in any guild occupied as large of an isotopic niche space as Red Drum. Distinct and well‐separated isotopic niches were also observed between most estuarine species and CMP species; however, high niche overlap was observed for species within the reef and LOP guilds. We found a positive relationship of δ¹⁵N and fish TL for Red Drum, Blackfin Tuna Thunnus atlanticus, and Yellowfin Tuna T. albacares, and we found that δ¹⁵N values for Red Drum and Red Snapper Lutjanus campechanus showed distinct isotope differences between geographic areas. This study provides data not only on how species within and without ecotypes interact but also on the variability of their interactions, all of which can inform ecosystem‐based fisheries management models.

中文翻译：

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墨西哥中北部海湾四个鱼类协会的稳定同位素生态位变异性和重叠

生态位多样性和生态位重叠的量化对于理解渔业监管和管理的影响是有用的。在这项工作中，我们评估行会和物种水平上的同位素生态位大小和重叠程度。具体来说，我们使用SIBER和nicheROVER软件包分析了行会和物种特定的同位素生态位空间和生态位空间重叠，并评估了墨西哥中北部海湾鱼类同位素的长度特定和地理对比。稳定碳和氮同位素值（δ ¹³ C和δ ¹⁵在四个基于生态型的鱼类行会中比较了N）种鱼类：河口，沿海迁徙中上层（CMP），珊瑚礁和大型近海中上层（LOP）。在鱼类行会中，平均稳定同位素值存在显着差异。河口公会品种表现出最高δ ¹³ C ^变性，红鱼美国红鱼是最同位素不同。δ变异¹³ ℃，CMP鱼媲美一些河口品种，而珊瑚礁和鱼类LOP不太变量。罗布泊公会内鱼类有最大δ ¹⁵N范围。礁公会鱼类的同位素生态位空间最小，而LOP公会物种始终具有最大的同位素位，尽管在任何公会中，没有一个物种像Red Drum那样占据同位素生态位空间那么大。在大多数河口物种和CMP物种之间也观察到了独特且分离的同位素生态位。但是，在珊瑚礁和LOP行会中的物种却观察到了很高的生态位重叠。我们发现δ存在正相关关系¹⁵ N和对红鱼，黑鳍金枪鱼鱼TL金枪鱼阿特兰提库斯，和黄鳍金枪鱼T.鳍金枪鱼，我们发现δ ¹⁵对红鱼和红鲷鱼的N值笛campechanus在地理区域之间显示出明显的同位素差异。这项研究不仅提供有关生态型内外物种之间如何相互作用的数据，而且还提供它们之间相互作用的可变性的数据，所有这些信息都可以为基于生态系统的渔业管理模式提供信息。