University of Idaho, Center for Ecohydraulics Research, 322 E. Front Street, suite 340, Boise, Idaho 83702.
Idaho Power | Resource Planning and Operations, 1221 W. Idaho St., Boise Idaho.
Sci Total Environ. 2021 Sep 15;787. doi: 10.1016/j.scitotenv.2021.147532. Epub 2021 May 6.
Current expectation is that projected climate change may have adverse effects on fish habitats and survival. The analysis leading to these concerns is typically done at large scale with limited possibility to quantify the local biological response and compare with previous conditions. Our research investigated the effects of recorded climate conditions on Chinook salmon () spawning and rearing habitats and growth responses to the local climate and compared those conditions to predicted responses to a climate change. The study site was a 7 km long reach of Bear Valley Creek, an important spawning stream for this US Endangered Species Act listed species, in the Pacific Northwest of United States. We used 2D numerical modeling supported by accurate, high-resolution survey data to calculate flow hydraulics at various discharges from base to bankfull flows. For past and future conditions, computed flow hydraulics were combined with habitat suitability indices (SI) to compute spawning and rearing habitat suitability. Information on habitat suitability along with fish density and stream water temperature informed a growth model to quantify the potential fish size, an index of survival rates and fitness. Our results indicate that yearly-averaged rearing habitat quality remains similar to historic, but the timing of high- and low-quality habitat periods shift within the calendar year. Future spawning habitat quality may be significantly reduced during the seasonal period to which Chinook have currently adapted their spawning behavior. The growth model indicates an increase in anticipated size of Chinook salmon for predicted future climate conditions due to water temperature increase. Consequently, future climate conditions may have a substantial negative impact on spawning and limited impact on rearing conditions due to flow reduction and thus quality and extent of available habitat. However, the expected warmer stream water temperatures may benefit rearing, because of increased fish size in these high elevation streams.
目前的预期是，预计的气候变化可能对鱼类栖息地和生存产生不利影响。导致这些担忧的分析通常是在大规模进行的，几乎不可能量化当地的生物反应，并将其与以前的条件进行比较。我们的研究调查了记录的气候条件对奇努克鲑（Oncorhynchus tshawytscha）产卵和育肥栖息地的影响，以及对当地气候的生长反应，并将这些条件与气候变化的预测反应进行了比较。研究地点是美国太平洋西北地区熊谷溪的一个 7 公里长的河段，这是该美国濒危物种法案列出的物种的一个重要产卵溪流。我们使用二维数值模型，辅以准确、高分辨率的调查数据，计算各种流量从基流量到满流量的水流动力学。对于过去和未来的条件，计算出的水流动力学与栖息地适宜性指数（SI）相结合，以计算产卵和育肥栖息地的适宜性。栖息地适宜性信息以及鱼类密度和溪流水温为生长模型提供了信息，以量化潜在的鱼类大小，这是存活率和适应能力的指标。我们的结果表明，每年平均育肥栖息地质量与历史相似，但高和低质量栖息地时期在日历年中的时间会发生变化。未来的产卵栖息地质量可能会在奇努克鲑目前适应其产卵行为的季节性期间显著降低。生长模型表明，由于水温升高，预测未来气候条件下的奇努克鲑预期尺寸会增加。因此，未来的气候条件可能会对产卵产生重大负面影响，并对育肥条件产生有限影响，这是由于流量减少以及因此可用栖息地的质量和范围减少所致。然而，预计的溪流水温升高可能会有利于育肥，因为这些高海拔溪流中的鱼类体型会增大。
