Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
Division of Conservation Biology, Vegetation and Landscape Ecology, Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.
Glob Chang Biol. 2017 Nov;23(11):4970-4986. doi: 10.1111/gcb.13760. Epub 2017 Jun 9.
The future distribution of river fishes will be jointly affected by climate and land use changes forcing species to move in space. However, little is known whether fish species will be able to keep pace with predicted climate and land use-driven habitat shifts, in particular in fragmented river networks. In this study, we coupled species distribution models (stepwise boosted regression trees) of 17 fish species with species-specific models of their dispersal (fish dispersal model FIDIMO) in the European River Elbe catchment. We quantified (i) the extent and direction (up- vs. downstream) of predicted habitat shifts under coupled "moderate" and "severe" climate and land use change scenarios for 2050, and (ii) the dispersal abilities of fishes to track predicted habitat shifts while explicitly considering movement barriers (e.g., weirs, dams). Our results revealed median net losses of suitable habitats of 24 and 94 river kilometers per species for the moderate and severe future scenarios, respectively. Predicted habitat gains and losses and the direction of habitat shifts were highly variable among species. Habitat gains were negatively related to fish body size, i.e., suitable habitats were projected to expand for smaller-bodied fishes and to contract for larger-bodied fishes. Moreover, habitats of lowland fish species were predicted to shift downstream, whereas those of headwater species showed upstream shifts. The dispersal model indicated that suitable habitats are likely to shift faster than species might disperse. In particular, smaller-bodied fish (<200 mm) seem most vulnerable and least able to track future environmental change as their habitat shifted most and they are typically weaker dispersers. Furthermore, fishes and particularly larger-bodied species might substantially be restricted by movement barriers to respond to predicted climate and land use changes, while smaller-bodied species are rather restricted by their specific dispersal ability.
未来河流鱼类的分布将受到气候和土地利用变化的共同影响，迫使物种在空间中移动。然而，人们知之甚少的是，鱼类物种是否能够跟上预测的气候和土地利用驱动的栖息地变化，特别是在破碎的河流网络中。在这项研究中，我们将 17 种鱼类的物种分布模型（逐步增强回归树）与它们的扩散特异性模型（鱼类扩散模型 FIDIMO）相结合，应用于欧洲易北河集水区。我们量化了（i）在 2050 年“中度”和“严重”气候和土地利用变化情景下，预测的栖息地变化的程度和方向（向上-或向下游），以及（ii）鱼类在明确考虑到迁移障碍（例如，水坝，堰）的情况下，追踪预测的栖息地变化的扩散能力。我们的研究结果表明，在中度和严重的未来情景下，每种鱼类的适宜栖息地的净损失中位数分别为 24 和 94 公里。预测的栖息地增益和损失以及栖息地变化的方向在物种之间具有高度的可变性。栖息地增益与鱼类体型大小呈负相关，即较小体型的鱼类的适宜栖息地预计会扩大，而较大体型的鱼类的适宜栖息地则会缩小。此外，预测低地鱼类的栖息地将向下游转移，而上游鱼类的栖息地则会向上游转移。扩散模型表明，适宜的栖息地可能比物种的扩散速度更快地发生变化。特别是，体型较小的鱼类（<200mm）似乎最脆弱，最无法追踪未来的环境变化，因为它们的栖息地变化最大，而且它们通常是较弱的扩散者。此外，鱼类，特别是较大体型的物种，可能会受到迁移障碍的严重限制，无法应对预测的气候和土地利用变化，而较小体型的物种则受到其特定的扩散能力的限制。
