Do Top-Down and Bottom-Up Controls Interact to Exclude N-Fixing Cyanobacteria From the Plankton of Estuaries?

作者：rwh2@cornell.edu（Robert W. Howarth），注日期： 1996年3月26日12：08 PM优先级：正常收件人：cdahm，nsf 2 CC：rmm3@cornell.edu，注释CC：compuserve.com，注释主题：DEB 9527405摘要- Hi Cliff - 这是我对你要的摘要的初步理解。 迈克·佩斯和我仍然 做预算 鲍勃 DEB-95-27405：“自上而下和自下而上的控件是否相互作用以排除 从河口的浮游生物中分离出固氮蓝藻" 富营养化和浮游植物的生产经常受到河口中氮和湖泊中磷的限制。 其中一个原因 显著的差异是固氮作用的差异。 在湖泊中， 氮的有效性低，固氮生物开花， 通过将分子氮固定到 生物可利用的形式。 在大多数河口，没有这样的反应发生。 这一提议检验了微量金属的低可用性 (Fe和钼）在河口相对于湖泊导致缓慢的增长率， 固氮生物，使这些生物容易受到 动物食用，从而防止固氮。 在 研究人员用装满海水的水箱进行了初步实验， 通过保持动物种群数量， 低 这是第一次常见的固氮生物 在北美任何地方的河口水域都能找到。 新 研究将建立在这些坦克研究，以更全面地测试 湖泊和河口之间的假想差异。

Author: rwh2@cornell.edu (Robert W. Howarth) at NOTE Date: 3/26/96 12:08 PM Priority: Normal TO: cdahm at nsf2 CC: rmm3@cornell.edu at NOTE CC: 73753.2331@compuserve.com at NOTE Subject: Abstract for DEB 9527405 ------------------------------- Message Contents ------------------------------- Hi Cliff -- Here is my stab at the abstract you requested. Mike Pace and I are still working on the budget. Bob DEB-95-27405: "Do top-down and bottom-up controls interact to exclude nitrogen-fixing cyanobacteria from the plankton of estuaries?" Eutrophication and phytoplankton production are frequently limited by nitrogen in estuaries and by phosphorus in lakes. One reason for this striking differences is a difference in nitrogen fixation. In lakes when nitrogen availability is low, nitrogen-fixing organisms bloom and help alleviate the nitrogen deficit by fixing molecular nitrogen into biologically available forms. In most estuaries, no such response occurs. This proposal tests the hypothesis that low availabilities of trace metals (Fe and Mo) in estuaries relative to lakes leads to slow growth rates of nitrogen-fixing organisms, leaving these organisms vulnerable to consumption by animals, and thereby preventing nitrogen fixation. In preliminary experiments with tanks full of seawater, the investigators successfully grew nitrogen fixing organisms by keeping animal populations low. This was the first time nitrogen-fixing organisms of the sort common to lakes were found in estuarine water anywhere in North America. The new research will build on these tank studies to more completely test the hypothesized difference between lakes and estuaries.