Branco Paulo, Mascarenhas Ana Margarida, Duarte Gonçalo, Romão Filipe, Quaresma Ana, Amaral Susana Dias, Ferreira Maria Teresa, Pinheiro António N, Santos José Maria
Forest Research Centre, Associate Laboratory TERRA, School of Agriculture, University of Lisbon, 1349-017 Lisbon, Portugal.
Civil Engineering for Research and Innovation for Sustainability, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal.
Biology (Basel). 2023 Nov 15;12(11):1431. doi: 10.3390/biology12111431.
River artificial fragmentation is arguably the most imperilling threat for freshwater-dependent fish species. Fish need to be able to freely move along river networks as not only spawning grounds but also refuge and feeding areas may be spatially and temporally separated. This incapacity of free displacement may result in genetic depletion of some populations, density reduction and even community changes, which may in turn affect how meta-community balances are regulated, potentially resulting in functional resilience reduction and ecosystem processes' malfunction. Fishways are the most common and widely used method to improve connectivity for fish species. These structures allow fish to negotiate full barriers, thus reducing their connectivity impairment. Among all technical fishway types, vertical slot fishways (VSF) are considered to be the best solution, as they remain operational even with fluctuating water discharges and allow fish to negotiate each cross-wall at their desired depth. In the present study, we collected both published and original data on fish experiments within VSF, to address two questions, (1) What variables affect fish passage during experimental fishway studies? and (2) What is the best VSF configuration? We used Bayesian Generalized Mixed Models accounting for random effects of non-controlled factors, limiting inherent data dependencies, that may influence the model outcome. Results highlight that fish size, regardless of the species, is a good predictor of fishway negotiation success. Generally, multiple slot fishways with one orifice proved to be the best solution. Future work should be focused on small-sized fish to further improve the design of holistic fishways.
河流人工碎片化可以说是对依赖淡水的鱼类物种最具威胁的因素。鱼类需要能够在河网中自由移动，因为不仅产卵地，而且避难所和觅食区在空间和时间上可能是分开的。这种无法自由移动的情况可能导致一些种群的基因枯竭、密度降低甚至群落变化，进而可能影响元群落平衡的调节方式，有可能导致功能恢复力下降和生态系统过程失灵。鱼道是改善鱼类连通性最常见和使用最广泛的方法。这些结构使鱼类能够越过完全的障碍物，从而减少它们的连通性受损情况。在所有技术鱼道类型中，竖缝式鱼道（VSF）被认为是最佳解决方案，因为即使在水流流量波动的情况下它们仍能运行，并允许鱼类在其期望的深度越过每个横墙。在本研究中，我们收集了已发表的和关于竖缝式鱼道内鱼类实验的原始数据，以解决两个问题，（1）在实验性鱼道研究中哪些变量会影响鱼类通过？（2）最佳的竖缝式鱼道配置是什么？我们使用了贝叶斯广义混合模型，考虑了非受控因素的随机效应，限制了可能影响模型结果的内在数据依赖性。结果表明，无论物种如何，鱼的大小是鱼道通过成功的一个良好预测指标。一般来说，单孔多缝鱼道被证明是最佳解决方案。未来的工作应集中在小型鱼类上，以进一步改进整体鱼道的设计。
