Large sharks generally occupy the highest trophic levels and are important links in the structuring of trophic networks. However, the decline of these predators has been observed worldwide, with population reduction rates reaching over 90% for some species. Through these declines, it is believed that the effect of the loss of predators could result in the disturbances in ecosystems. Based on this, the present study aimed to test the role of elasmobranchs in a coastal ecosystem in southern Brazil. Also, we tested if the changes in fishing effort cause changes in trophic structure. For this, a trophodynamic model was performed, based on reliable data on biomass and species feeding in the region. The mass balance modeling software Ecopath with Ecosim (EwE) was used to assess the trophic position of sharks and rays, and to understand what their interactions are with other groups in the ecosystem. Among the parameters of the model, the Paraná coast showed to be an immature system, with high connectivity and medium complexity. The trophic levels of the coast varied from 1 to 4.4, with level > 4 composed of sharks, and rays belonging to the third trophic level. Sharks were strong impacted by fishing. According to changes in fishing effort simulations, we observed changes of intermediate levels due to the decline of large sharks. However, no cascade effects were observed from the simulations. The high diversity of the system, feeding overlap, and the redundancy between mesopredator and other teleosts can decrease the chances of a cascade effect occurring.

大鲨鱼一般占据最高的营养级，是构建营养网络的重要环节。然而，世界范围内已经观察到这些捕食者的减少，某些物种的种群减少率达到了 90% 以上。通过这些下降，据信捕食者丧失的影响可能导致生态系统受到干扰。基于此，本研究旨在测试 elasmobranchs 在巴西南部沿海生态系统中的作用。此外，我们测试了捕捞努力量的变化是否会导致营养结构的变化。为此，基于该地区生物量和物种饲养的可靠数据，建立了营养动力学模型。质量平衡建模软件 Ecopath with Ecosim (EwE) 用于评估鲨鱼和鳐鱼的营养位置，并了解他们与生态系统中其他群体的互动。在模型的参数中，巴拉那海岸是一个不成熟的系统，具有高连通性和中等复杂性。海岸的营养级从 1 到 4.4 不等，其中 > 4 级由鲨鱼组成，鳐鱼属于第三营养级。鲨鱼受到捕鱼的强烈影响。根据捕捞努力量模拟的变化，我们观察到由于大​​鲨鱼数量减少导致的中间水平变化。然而，从模拟中没有观察到级联效应。系统的高度多样性、进食重叠以及中掠食性动物和其他硬骨鱼类之间的冗余可以减少发生级联效应的机会。巴拉那海岸是一个不成熟的系统，具有高度连通性和中等复杂性。海岸的营养级从 1 到 4.4 不等，其中 > 4 级由鲨鱼组成，鳐鱼属于第三营养级。鲨鱼受到捕鱼的强烈影响。根据捕捞努力量模拟的变化，我们观察到由于大​​鲨鱼数量减少导致的中间水平变化。然而，从模拟中没有观察到级联效应。系统的高度多样性、进食重叠以及中掠食性动物和其他硬骨鱼类之间的冗余可以减少发生级联效应的机会。巴拉那海岸是一个不成熟的系统，具有高度连通性和中等复杂性。海岸的营养级从 1 到 4.4 不等，其中 > 4 级由鲨鱼组成，鳐鱼属于第三营养级。鲨鱼受到捕鱼的强烈影响。根据捕捞努力量模拟的变化，我们观察到由于大​​鲨鱼数量减少导致的中间水平变化。然而，从模拟中没有观察到级联效应。系统的高度多样性、进食重叠以及中掠食性动物和其他硬骨鱼类之间的冗余可以减少发生级联效应的机会。鲨鱼受到捕鱼的强烈影响。根据捕捞努力量模拟的变化，我们观察到由于大​​鲨鱼数量减少导致的中间水平变化。然而，从模拟中没有观察到级联效应。系统的高度多样性、进食重叠以及中掠食性动物和其他硬骨鱼类之间的冗余可以减少发生级联效应的机会。鲨鱼受到捕鱼的强烈影响。根据捕捞努力量模拟的变化，我们观察到由于大​​鲨鱼数量减少导致的中间水平变化。然而，从模拟中没有观察到级联效应。系统的高度多样性、进食重叠以及中掠食性动物和其他硬骨鱼类之间的冗余可以减少发生级联效应的机会。