Denton Mathew J, Cherkiss Michael S, Mazzotti Frank J, Brandt Laura A, Godfrey Sidney T, Johnson Darren, Hart Kristen M
Wetland and Aquatic Research Center, U.S. Geological Survey, Gainesville, Florida, United States of America.
Wetland and Aquatic Research Center, U.S. Geological Survey, Davie, Florida, United States of America.
PLoS One. 2025 Jun 27;20(6):e0326148. doi: 10.1371/journal.pone.0326148. eCollection 2025.
Hydrologic alterations within the Everglades have degraded American alligator (Alligator mississippiensis) habitat, reduced prey base, and increased physiological stress. Alligator body condition declined across many management areas from 2000 through 2014, prompting us to investigate the relationship between their intraspecific isotopic niche dynamics and body condition. Alligators within the estuary had a larger niche driven by a wider range in stable carbon isotope ratios than those sampled in freshwater habitats. Spatially, model predictability was higher at the smaller scale, reflecting the variability in basal sources and biochemistry among capture sites. Male niches were often larger than those of females, driven by wider ranges of δ13C values, suggesting that they differ in their proportional use of habitats and or resources. However, the similar ranges of δ15N values indicated both sexes foraged within the same trophic level. Furthermore, while not significantly different, large alligators often had a larger niche with elevated δ15N values compared to medium-sized alligators. Although alligators utilize similar stable carbon and nitrogen isotope pools through time, there was considerable temporal variability. These temporal variations in alligators' isotopic niche were likely influenced by seasonal hydrologic fluctuations within each site, with their niches often being larger in the spring captures than the fall captures. Alligators' body condition estimates were correlated with intraspecific niche characteristics, including the mean centroid distance between sexes and the interaction between male and female niche size and overlap, within a site, capture period, and year. The variability in intraspecific niche dynamics, landscape heterogeneity, and dynamic hydrology are considerations for designing sustainable management strategies to conserve and enhance alligator populations within the Everglades landscape.
大沼泽地内的水文变化已经破坏了美国短吻鳄（密西西比鳄）的栖息地，减少了猎物基数，并增加了生理压力。从2000年到2014年，许多管理区域内短吻鳄的身体状况都有所下降，这促使我们去研究它们种内同位素生态位动态与身体状况之间的关系。河口内的短吻鳄具有更大的生态位，这是由稳定碳同位素比率的更广泛范围驱动的，比在淡水栖息地采样的短吻鳄更大。在空间上，较小尺度下模型的可预测性更高，这反映了捕获地点之间基础来源和生物化学的变异性。雄性生态位通常比雌性的大，这是由更广泛的δ13C值范围驱动的，表明它们在栖息地和/或资源的比例利用上存在差异。然而，δ15N值的相似范围表明两性在相同的营养级觅食。此外，虽然没有显著差异，但大型短吻鳄通常比中型短吻鳄具有更大的生态位，其δ15N值升高。尽管短吻鳄随时间利用相似的稳定碳和氮同位素库，但存在相当大的时间变异性。短吻鳄同位素生态位的这些时间变化可能受到每个地点季节性水文波动的影响，它们的生态位在春季捕获时通常比秋季捕获时更大。在一个地点、捕获时期和年份内，短吻鳄的身体状况估计与种内生态位特征相关，包括两性之间的平均质心距离以及雄性和雌性生态位大小与重叠之间的相互作用。种内生态位动态、景观异质性和动态水文的变异性是设计可持续管理策略以保护和增加大沼泽地景观内短吻鳄种群时需要考虑的因素。
