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Channel morphology, hyporheic exchange, and temperature gradients within Chinook salmon spawning habitat.

機譯：奇努克鮭魚產(chǎn)卵棲息地內(nèi)的通道形態(tài)，水交換和溫度梯度。

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Snake River fall Chinook salmon (Oncorhynchus tshawytscha ) populations in the Pacific northwestern United States (U.S.) have declined during the past 30 years, leading to their protection under the U.S. Endangered Species Act. Recovery activities and water management planning necessitate an understanding of the physical habitat characteristics affecting Snake River fall Chinook salmon spawning and incubation environments. The purpose of this research was to evaluate the relationships among channel morphology, river discharge, hydrologic exchange, and egg pocket water temperature in Snake River fall Chinook salmon spawning areas. The studies were completed at 15 fall Chinook salmon spawning sites distributed throughout 160 km of the Snake River in Hells Canyon, Idaho, U.S. The results indicate that 84% of fall Chinook salmon spawning areas are correlated with riffles (Chi-square=152.1, df=3, p0.001), with 63% of those areas located on the upstream side of riffle crests. Differences in head pressure between the river and riverbed were small, often within +/-2 cm. Measured temperature gradients in the riverbed indicated significant interactions between the surface and subsurface water. Neither hydraulic nor temperature gradients at most sites were significantly affected by either short- or long-term changes in discharge operations from Hells Canyon Dam. Only 2 out of 14 study sites exhibited acute flux reversals between the river and riverbed resulting from short-term, large magnitude changes in discharge. At all sites temperature increased with depth into the riverbed, including significant differences (p0.05) in mean water temperature of up to 3.8°C between the river and the riverbed among all the sites. During each of the three water years studied, river and riverbed temperatures varied significantly among all the study sites, among the study sites within each reach, and between sites located in the two reaches. Considerable variability in riverbed temperatures among the sites resulted in fall Chinook salmon emergence timing estimates that varied by as much as 55 days. By incorporating the knowledge of channel morphology, hydrologic exchange processes and incubation environment characteristics in fall Chinook salmon spawning habitat into recovery activities and water management planning, regional agencies will be better prepared to make science-based water management decisions within the Snake River basin.
機譯：在過去的30年中，美國西北太平洋地區(qū)（美國）的Snake River秋季奇努克鮭魚（Oncorhynchus tshawytscha）種群數(shù)量有所減少，因此受到《美國瀕危物種法》的保護?；謴?fù)活動和水管理計劃需要了解影響蛇河秋天奇努克鮭魚產(chǎn)卵和孵化環(huán)境的自然棲息地特征。這項研究的目的是評估蛇河秋天奇努克鮭魚產(chǎn)卵區(qū)河道形態(tài)，河流流量，水文交換和卵囊水溫之間的關(guān)系。研究在美國愛達荷州地獄峽谷的160公里的蛇河分布的15個秋季奇努克鮭魚產(chǎn)卵場完成。結(jié)果表明，秋季奇努克鮭魚產(chǎn)卵區(qū)與淺灘相關(guān)（卡方= 152.1，df = 3，p <0.001），其中63％的區(qū)域位于淺灘波峰的上游。河流和河床之間的頭部壓力差很小，通常在+/- 2 cm之內(nèi)。在河床中測得的溫度梯度表明地表水與地下水之間存在顯著的相互作用。大多數(shù)地點的水力梯度和溫度梯度都沒有受到地獄峽谷大壩排水操作的短期或長期變化的顯著影響。在14個研究地點中，只有2個顯示出由于流量的短期，大幅度變化而導(dǎo)致的河流和河床之間的急劇通量逆轉(zhuǎn)。在所有站點，溫度隨著向河床深度的增加而增加，其中所有站點之間的河流和河床之間的平均水溫高達3.8°C時存在顯著差異（p <0.05）。在所研究的三個水年中的每一年中，所有研究地點之間，每個河段內(nèi)的研究地點之間以及兩個河段內(nèi)的地點之間的河床和河床溫度均發(fā)生顯著變化。這些地點之間河床溫度的顯著變化導(dǎo)致奇努克鮭魚出現(xiàn)秋天的時間估計相差多達55天。通過將秋季奇努克鮭魚產(chǎn)卵棲息地的河道形態(tài)，水文交換過程和孵化環(huán)境特征知識納入恢復(fù)活動和水管理規(guī)劃中，區(qū)域機構(gòu)將更好地準備在蛇河流域內(nèi)做出基于科學(xué)的水管理決策。

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