一項(xiàng)新的研究報(bào)告說(shuō),，在36條北美河流中的食物鏈（即由進(jìn)食生物和被進(jìn)食生物所進(jìn)行的連續(xù)性的能量轉(zhuǎn)移）受到了能量和水流變化的影響,。
這些發(fā)現(xiàn)可能會(huì)影響河流中食物網(wǎng)的管理，因?yàn)楦珊岛蜌夂蜃兓A(yù)計(jì)會(huì)使河流變干加速并增加水流容積率的可變性,；從而危及一個(gè)已經(jīng)很脆弱的魚類和其它水生生物的食物供應(yīng),。 食物鏈的長(zhǎng)度是決定能量流動(dòng)、碳交換及營(yíng)養(yǎng)物循環(huán)的生態(tài)系統(tǒng)的一個(gè)重要的特征,。食物鏈長(zhǎng)度還對(duì)人類的健康非常重要,，它會(huì)影響我們所吃的動(dòng)物體內(nèi)污染物質(zhì)的生物積累量。 然而,，食物鏈的長(zhǎng)度會(huì)有很大的變化,，而生態(tài)學(xué)家一直在努力了解是什么造成了這些變化。John Sabo及其同事在此提出了不同因素（如生態(tài)系統(tǒng)的大小,、能量供應(yīng)及水流的容積率）的同時(shí)性效應(yīng)是如何進(jìn)行相互作用以影響食物鏈的長(zhǎng)度的,。
文章的作者觀察了來(lái)自整個(gè)美國(guó)的36個(gè)流域的數(shù)據(jù)后發(fā)現(xiàn)，這些流域中的食物鏈長(zhǎng)度會(huì)隨著生態(tài)系統(tǒng)的變大而增加,，隨著能量流的變化而縮短（這與過(guò)去在河流中的發(fā)現(xiàn)是一致的）,；但他們還顯示了在生態(tài)系統(tǒng)大小與水流的容積率之間的關(guān)系會(huì)對(duì)食物鏈的長(zhǎng)度造成很強(qiáng)的影響。 此外,，河流的變干會(huì)縮短食物鏈的長(zhǎng)度,，因?yàn)閿鄶嗬m(xù)續(xù)的河流在水流的速度上要比長(zhǎng)期持續(xù)性的河流或周期性河流有著高得多的變異性。（生物谷Bioon.com）
生物谷推薦英文摘要：
Science DOI: 10.1126/science.1196005
The Role of Discharge Variation in Scaling of Drainage Area and Food Chain Length in Rivers
John L. Sabo,1 Jacques. C. Finlay,2 Theodore Kennedy,3 David M. Post4
Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL remain unclear. Here, we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanism underlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.
1 Faculty of Ecology Evolution and Environmental Sciences, School of Life Sciences, Arizona State University. P.O. Box 874501, Tempe AZ 85287–4501, USA.
2 Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA.
3 U.S. Geological Survey, Southwest Biological Science Center, 2255 North Gemini Drive, Flagstaff, AZ 86001, USA.
4 Department of Ecology and Evolutionary Biology, Yale University. P.O. Box 208106, 165 Prospect Street, New Haven, CT 06520–8106 USA.
