Two subspecies of bottlenose dolphins are observed, not simultaneously, in a narrow coastal area of the western South Atlantic Ocean. However, their trophic interaction is unknown. Such information can be explored using stable isotope composition in teeth, warranting time series data. We analyzed carbon and nitrogen isotopic values (δ¹³C and δ¹⁵N) of dentin growth layer groups in teeth of Tursiops truncatus truncatus and Tursiops truncatus gephyreus stranded along this area of potential co-occurrence in order to investigate the trophic, spatial and temporal dimensions of their isotopic niches. For each subspecies, we calculated isotopic niche width and the possible overlap in resource use between them. We modeled δ¹³C and δ¹⁵N according to age to verify ontogenetic variations in resources use. We also measured the ratio of individual variation by that of the population to estimate the degree of individual specialization within each subspecies. Mean isotopic values differed only for carbon values (δ¹³C_Ttg = − 12.7‰; δ¹³C_Ttt = − 14.3‰), and a small overlap in resource use between subspecies was observed. Individual specialization was evident in both subspecies suggesting temporal consistency in resource use and indicating they forage upon various preys. Although weaning age and feeding habit seem similar, subspecies diverge especially in habitat use, indicating they adapted for feeding in different environments. These results show a clear habitat partitioning between subspecies and only a small overlap on resource use within the area, reinforcing the hypothesis of a parapatric distribution with very occasional contacts in this region of the western South Atlantic Ocean.

在南大西洋西部的狭窄沿海地区，发现了两个宽吻海豚亚种，但并非同时出现。但是，它们之间的营养相互作用是未知的。可以使用牙齿中稳定的同位素组成来探索此类信息，从而保证时间序列数据。我们分析了碳和氮同位素值（δ ¹³ C和δ ¹⁵中的齿数N）牙本质生长层组的宽吻海豚截和宽吻海豚gephyreus沿着这个区域的潜在共同出现的在为了研究营养链的，空间和时间同位素壁ni的尺寸。对于每个亚种，我们计算了同位素的生态位宽度以及它们之间资源利用的可能重叠。我们模拟δ ¹³C和δ ¹⁵ n按年龄在资源使用来验证个体发育变化。我们还测量了个体变异与种群变异的比率，以估计每个亚种内个体专业化的程度。平均数同位素值仅相差为碳值（δ ¹³ C ^ _TTG  = - 12.7‰;δ ¹³ C ^ _TTT = − 14.3‰），并且观察到亚种之间资源使用的重叠很小。在两个亚种中，个体专长明显，表明资源利用的时间一致性，并表明它们在各种猎物上觅食。尽管断奶年龄和进食习惯似乎相似，但亚种尤其在栖息地使用方面存在差异，表明它们适合在不同环境中进食。这些结果表明，亚种之间的生境有明显的划分，并且该地区的资源利用只有很小的重叠，这增强了南大西洋西部该地区极少有接触的超自然分布的假说。