Chelotti Luiza de David, Gadig Otto Bismarck Fazzano
UNESP - Campus de Rio Claro, Rio Claro, Brazil.
Laboratório de Pesquisa em Elasmobrânquios, Instituto de Biociências, UNESP, Campus do Litoral Paulista, São Vicente, Brazil.
J Fish Biol. 2023 Jan;102(1):248-257. doi: 10.1111/jfb.15257. Epub 2022 Nov 7.
The present study compares the trophic ecology of two guitarfishes (Pseudobatos percellens and Pseudobatos horkelii) from the continental shelf of the São Paulo State, Brazil, caught by the bottom pair trawls between 2007 and 2009. These two sympatric species are under different threat categories, "Vulnerable" and "Critically Endangered," respectively, according to Brazilian agencies. Thus, any study considering trophic ecology parameters is pivotal in understanding the trophic ecology role of such species in the ecosystem. The authors analysed 500 stomachs of P. percellens and 108 of P. horkelii, quantifying with dietary indexes: numerical (%N), gravimetric (%W), frequency of occurrence (%FO) and the prey-specific index of relative importance (%PSIRI). For P. percellens and P. horkelii, 26 and 14 different prey items were found, respectively. Crustacea and Teleostei were the most important prey items for both species, indicating a specialist feeding behaviour due to their low niche amplitude. The results provide evidence related to ontogenetic dietary shift in P. percellens and individual-level diet specialization in both species. These two benthic-demersal elasmobranchs are important mesopredators (3,7 for P. percellens, and 3,5 for P. horkelii) in the study area, with high trophic-level values.
本研究比较了2007年至2009年间在巴西圣保罗州大陆架通过底拖网捕获的两种犁头鳐（细纹犁头鳐和霍氏犁头鳐）的营养生态学。根据巴西相关机构的划分，这两种同域分布的物种分别处于不同的受威胁类别，即“易危”和“极度濒危”。因此，任何考虑营养生态学参数的研究对于理解这些物种在生态系统中的营养生态学作用都至关重要。作者分析了500个细纹犁头鳐和108个霍氏犁头鳐的胃，并用饮食指标进行量化：数量占比（%N）、重量占比（%W）、出现频率（%FO）和猎物特定相对重要性指数（%PSIRI）。对于细纹犁头鳐和霍氏犁头鳐，分别发现了26种和14种不同的猎物。甲壳类动物和硬骨鱼类是这两个物种最重要的猎物，由于它们的生态位幅度较低，表明其具有特化的摄食行为。研究结果为细纹犁头鳐的个体发育饮食转变以及这两个物种的个体水平饮食特化提供了证据。这两种底栖 - 近底层软骨鱼类是研究区域重要的中型捕食者（细纹犁头鳐为3.7，霍氏犁头鳐为3.5），营养级值较高。
