LTREB: Response of a Reservoir Ecosystem to Declining Subsidies of Nutrients and Detritus

LTREB：水库生态系统对养分和碎屑补贴减少的反应

• 批准号: 0235755
• 负责人: Michael Vanni
• 金额: $ 30万
• 依托单位: Miami University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-15 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235755&HistoricalAwards=false
• 关键词: LTREB; Response; Reservoir; Ecosystem; Declining

Intellectual Merit. The proposed LTREB research will use long-term data to test hypotheses about how reservoir ecosystems respond to reduced nutrient and detritus (sediment) subsidies. Nutrient and sediment subsidies to the study site, Acton Lake, are declining because of changes in agricultural practices in the lake's agricultural watershed. These include a marked increase in conservation tillage and a reduction in phosphorus fertilizers. These changes appear to bedriving decreases in concentrations and loads of phosphorus and suspended sediments in Acton Lake's inflow streams, based on an 8-year trend. In Acton Lake, concentrations of suspended inorganic sediment have declined, and biomass of phytoplankton has increased, over this period. We hypothesize that reductions in detritus input will induce a decline in the population density of an important detritivorous fish, the gizzard shad, leading to further changes in the ecosystem. In addition, we hypothesize that phytoplankton and zooplankton species composition will change such that taxa typical of high productivity (eutrophic) habitats will decline and those typical of mesotrophic conditions will increase. This research will be unique in that it will consist of a long-term study on interactive effects of multiple ecosystem subsidies: 1) nutrient subsidies from watersheds, 2) detritus subsidies from watersheds, and 3) nutrient subsidies via detritivorous fish. The proposed research is also unique because it integrates watersheds, streams, and a reservoir ecosystem. Although there are many studies of eutrophication and recovery in natural lakes, we know little about how reservoirs respond to reduced nutrient subsidies. Because nutrient and sediment exports are declining in many agricultural watersheds in the US and globally, this research will shed light on how these understudied ecosystems respond to a widespread and common influence.Broader Impacts. The proposed research will have several educational, environmental and societal impacts. Undergraduates will do summer research through a variety of programs including an REU Site Program. Primary school teachers will be recruited along with graduate students and postdocs, as well. Data will be shared and collaborations continued with state and federal agencies. This research will facilitate decision-making in regards to watershed management, alternative agricultural practices (hence socio-economic influences on farmers), water quality, and fisheries management.

知识价值。拟议的LTREB研究将使用长期数据来测试关于水库生态系统如何响应减少的营养和碎屑（沉积物）补贴的假设。由于阿克顿湖农业流域农业实践的变化，对研究地点阿克顿湖的营养和沉积物补贴正在减少。这些措施包括显著增加保护性耕作和减少磷肥的使用。根据8年的趋势，这些变化似乎导致了阿克顿湖流入河流中磷和悬浮沉积物的浓度和负荷的下降。在此期间，阿克顿湖悬浮无机沉积物的浓度有所下降，浮游植物的生物量有所增加。我们假设，碎屑输入的减少将导致一种重要的食腐鱼类沙棘鱼的种群密度下降，从而导致生态系统的进一步变化。此外，我们假设浮游植物和浮游动物的物种组成将发生变化，即典型的高生产力（富营养化）栖息地的分类群将减少，而典型的中营养化条件的分类群将增加。本研究的独特之处在于，它将包括对多种生态系统补贴的相互作用的长期研究：1)流域营养补贴，2)流域碎屑补贴，3)食腐鱼类营养补贴。这项拟议中的研究也是独一无二的，因为它整合了流域、溪流和水库生态系统。虽然有许多关于天然湖泊富营养化和恢复的研究，但我们对水库对营养补贴减少的反应知之甚少。由于美国和全球许多农业流域的养分和沉积物出口量正在下降，这项研究将阐明这些未被充分研究的生态系统如何应对广泛而共同的影响。更广泛的影响。拟议的研究将对教育、环境和社会产生若干影响。本科生将通过包括REU现场项目在内的各种项目进行夏季研究。招收小学教师、研究生和博士后。数据将共享，并继续与州和联邦机构合作。这项研究将促进流域管理、替代农业做法（因此对农民的社会经济影响）、水质和渔业管理方面的决策。