Dissertation Research: Periwinkle Grazing On and Control of Spartina Alterniflora.

许多水生群落受自上而下的控制，而大多数以维管植物为主的系统被认为受自下而上的力量控制。近50年来，盐沼生态学的主流范式一直是自下而上的力量，如养分供应，是沼泽草生产的主要决定因素。在这个提议中，我们表明，当捕食者不抑制东南沼泽中最常见的食草无脊椎动物——紫花滨螺（Littoraria irorata）的密度时，大西洋西部盐沼中优势植物的直立作物大量减少，基质完全剥落。然而，在这些结果被普遍接受之前，我们的观察结果表明，Littoraria广泛地以活的米草属植物为食，而目前的范式认为Littoraria是沼泽系统中最重要的营养物质，这两者之间的明显矛盾必须得到解决。为了做到这一点，我们提出了一个详细的研究计划，以获得对Littoraria - live spartina相互作用的机制理解。这项研究的结果可能会迫使我们重新评估我们目前对沼泽系统的理解，并为维管植物群落是否容易受到失控消费者效应的影响这一正在进行的辩论提供关键信息。

Project SummaryMany aquatic communities have been shown to be under top-down control, while most systemsdominated by vascular plants are assumed to be controlled by bottom-up forces. For nearly50 years, the prevailing paradigm in salt marsh ecology has been that bottom-up forces,such as nutrient availability, are the primary determinants of marshgrass production. Inthis proposal, we show that the standing crop of the dominant plant in western Atlanticsalt marshes is reduced wholesale and the substrate completely denuded when predators donot suppress densities of the most common grazing invertebrate in southeast marshes, theperiwinkle Littoraria irrorata. Before these results can be generally accepted, however,the apparent contradiction between our observations that Littoraria graze extensively onlive Spartina and the current paradigm which holds that Littoraria is the most importantdetritivore in the marsh system must be resolved. To do this, we present a detailedresearch plan to obtain a mechanistic understanding of the Littoraria - live Spartinainteraction. Results from this study will likely force us to reevaluate our currentunderstanding of marsh systems and add critical information to the ongoing debate as towhether or not vascular plant communities are susceptible to run-away consumer effects.