Navia Andrés F, Mejía-Falla Paola A, Giraldo Alan
Fundación Colombiana para la Investigación y Conservación de los Tiburones y Rayas, SQUALUS, Carrera 64 A No 11A-53, Cali, Colombia.
BMC Ecol. 2007 Sep 18;7:8. doi: 10.1186/1472-6785-7-8.
Stomach contents of 131 specimens of five elasmobranch species (Mustelus lunulatus, Dasyatis longa, Rhinobatos leucorhynchus, Raja velezi and Zapteryx xyster) caught in the central fishing zone in the Pacific Ocean of Colombia were counted and weighed to describe feeding habits and dietary overlaps.
Twenty-one prey items belonging to four major groups (stomatopods, decapods, mollusks and fish) were identified. Decapod crustaceans were the most abundant prey found in stomachs. The mantis shrimp Squilla panamensis was the main prey item in the diet of M. lunulatus; tiger shrimp Trachypenaeus sp. was the main prey item in the diet of Rhinobatos leucorhynchus and Raja velezi, and Penaeidae shrimp were the main prey items in the diet of Z. xyster. Furthermore, fish were important in the diet of Raja velezi, Z. xyster and D. longa. The greatest diet breadth corresponded to Z. xyster whereas M. lunulatus was the most specialized predator. Finally, four significant diet overlaps between the five species were found, attributable mainly to Squillidae, Penaeidae and Fish.
Shrimps (Penaeidae and stomatopods) and benthic fishes were the most important food types in the diet of the elasmobranch species studied. Diet breadth and overlap were relatively low. Determination of food resource partitioning among the batoid species studied was not possible. However, we identified partitions in other niche axes (time of feeding activity and habitat utilization). It is possible to assume that diffuse competition could be exceeding the biunivocal competition among the studied species. Therefore, this assemblage would have a strong tendency to trophic guild formation.
对在哥伦比亚太平洋中部捕捞区捕获的5种软骨鱼类（月形鼬鲨、长魟、白吻犁头鳐、韦氏鳐和尖鼻鳐）的131个样本的胃内容物进行了计数和称重，以描述其摄食习性和食物重叠情况。
共识别出属于四大类（口足类、十足类、软体动物和鱼类）的21种猎物。十足目甲壳类动物是在胃中发现的最丰富的猎物。巴拿马螳螂虾是月形鼬鲨饮食中的主要猎物；虎虾属的虾是白吻犁头鳐和韦氏鳐饮食中的主要猎物，对虾科虾类是尖鼻鳐饮食中的主要猎物。此外，鱼类在韦氏鳐、尖鼻鳐和长魟的饮食中也很重要。食物种类最多的是尖鼻鳐，而月形鼬鲨是最具专一性的捕食者。最后，发现这五个物种之间有四个显著的食物重叠，主要归因于虾蛄科、对虾科和鱼类。
虾类（对虾科和口足类）和底栖鱼类是所研究的软骨鱼类饮食中最重要的食物类型。食物种类广度和重叠相对较低。在所研究的鳐形目物种之间无法确定食物资源分配情况。然而，我们在其他生态位轴（摄食活动时间和栖息地利用）上确定了分配情况。可以假设，扩散竞争可能超过了所研究物种之间的一对一竞争。因此，这个组合有很强的形成营养类群的趋势。
