U.S. Geological Survey, Northern Rocky Mountain Science Center, 2327 University Way, Suite 2, Bozeman, MT 59715, USA.
U.S. Fish and Wildlife Service, Lahontan National Fish Hatchery Complex, 1340 Financial Blvd., Suite 161, Reno, NV 89502, USA.
Sci Total Environ. 2022 Aug 1;832:154614. doi: 10.1016/j.scitotenv.2022.154614. Epub 2022 Mar 28.
In arid ecosystems, available water is a critical, yet limited resource for human consumption, agricultural use, and ecosystem processes-highlighting the importance of developing management strategies to meet the needs of multiple users. Here, we evaluated how water availability influences stream thermal regimes and life-history expressions of Lahontan cutthroat trout (Oncorhynchus clarkii henshawi) in the arid Truckee River basin in the western United States. We integrated air temperature and stream discharge data to quantify how water availability drives stream temperature during annual spawning and rearing of Lahontan cutthroat trout. We then determined how in situ stream discharge and temperature affected adult spawning migrations, juvenile growth opportunities, and duration of suitable thermal conditions. Air temperatures had significant, large effects (+) on stream temperature across months; the effects of discharge varied across months, with significant effects (-) during May through August, suggesting increased discharge can help mitigate temperatures during seasonally warm months. Two models explained adult Lahontan cutthroat trout migration, and both models indicated that adult Lahontan cutthroat trout avoid migration when temperatures are warmer (~ > 12 °C) and discharge is higher (~ > 50 m*s). Juvenile size was best explained by a quadratic relationship with cumulative degree days (CDD; days>4 °C) as size increased with increasing CDDs but decreased at higher CDDs. We also found an interaction between CDDs and discharge explaining juvenile size: when CDDs were low, higher discharge was associated with larger size, but when CDDs were high, higher discharge was associated with smaller size. Stream temperatures also determined the duration of juvenile rearing, as all juvenile emigration ceased at temperatures >24.4 °C. Together, our results illustrated how stream discharge and temperature shape the life-history of Lahontan cutthroat trout at multiple stages and can inform management actions to offset warming temperatures and facilitate life-history diversity and population resilience.
在干旱生态系统中，可用水资源是人类消费、农业利用和生态系统过程的关键且有限资源-这凸显了制定管理策略以满足多用户需求的重要性。在这里，我们评估了可用水资源如何影响溪流热状况和拉洪坦大口黑鲈（Oncorhynchus clarkii henshawi）的生活史表现，该评估是在美国西部干旱的特拉基河流域进行的。我们整合了空气温度和溪流流量数据，以量化可用水量如何在拉洪坦大口黑鲈的年度产卵和育肥期间驱动溪流温度。然后，我们确定了现场溪流流量和温度如何影响成年产卵洄游、幼鱼生长机会和适宜热条件的持续时间。空气温度对整个月的溪流温度有显著的、大的影响（+）；流量的影响在整个月内变化，5 月至 8 月期间有显著的影响（-），表明增加流量有助于缓解季节性温暖月份的温度。两个模型解释了成年拉洪坦大口黑鲈的洄游，并且两个模型都表明，当温度较高（~ > 12°C）和流量较高（~ > 50 m*s）时，成年拉洪坦大口黑鲈会避免洄游。幼鱼大小与累积度日（CDD；>4°C 的天数）呈二次关系，随着 CDD 的增加而增加，但在更高的 CDD 时减少。我们还发现 CDD 和流量之间存在相互作用，解释了幼鱼的大小：当 CDD 较低时，较高的流量与较大的尺寸相关，但当 CDD 较高时，较高的流量与较小的尺寸相关。溪流温度还决定了幼鱼育肥的持续时间，因为当温度>24.4°C 时，所有幼鱼都停止洄游。总的来说，我们的结果说明了溪流流量和温度如何在多个阶段塑造拉洪坦大口黑鲈的生活史，并为缓解升温、促进生活史多样性和种群恢复力的管理措施提供信息。
