Collaborative Research: Response of Tropical Stream Ecosystem Structure and Function to Amphibian Extinctions

摘要。两栖动物代表了水生和陆地栖息地之间重要的能量纽带，特别是在多样性和丰度非常高的热带地区。蝌蚪以藻类和有机物质为食，当它们变成青蛙时，将能量和营养物质从水生栖息地转移到陆地栖息地，青蛙回到水中繁殖时，将能量和物质转移回来。然而，两栖动物的数量在世界范围内急剧下降，在过去的20年里，13个拉丁美洲国家的两栖动物数量大量减少。在大多数情况下，在给定的地点，超过75%的两栖动物消失了。这项研究将通过调查两栖动物的减少如何改变河流的生物多样性，河流中的能量流动，河流内和河边的食物网，以及河流和陆地栖息地之间的能量交换，来研究两栖动物减少对热带河流的影响。这将通过巴拿马高地溪流与天然两栖动物种群和附近两栖动物最近消失的溪流的溪流群落、食物网和能量流模式的密集比较来完成。初步研究表明，两栖动物的减少将对河流产生大规模的影响，包括群落结构的变化，藻类能源的重要性增加，有机物质下游运输的减少，以及从河流到陆地栖息地的能量转移的减少。更广泛的影响。这项研究的更广泛的含义是，研究结果将与影响许多地区的紧迫问题（即两栖动物的减少）相关。拟议的研究还将为来自拉丁美洲和美国的学生提供机会，研究一个重要的、大规模的环境问题，并将进一步促进3个相关机构和其他研究热带相关问题的科学家之间的合作。

Abstract. Amphibians represent an important energetic link between aquatic and terrestrial habitats, particularly in the tropics where diversity and abundance are very high. Tadpoles feed on algae and organic materials and transfer energy and nutrients from aquatic to terrestrial habitats when they emerge as frogs, and frogs transfer energy and materials back when they return to water to breed. However, amphibian populations have declined dramatically around the world, including massive losses in 13 Latin American countries in the last 20 years. Most declines involve disappearances of over 75% of amphibians at a given site. This research will examine the consequences of amphibian declines on tropical streams by investigating how losses alter stream biodiversity, energy flow in streams, in-stream and streamside food webs, and energy exchange between streams and terrestrial habitats. This will be accomplished through intensive comparisons of stream communities, food webs, and energy flow patterns in Panamanian highland streams with natural amphibian populations and nearby streams where amphibians have recently disappeared. Preliminary studies suggest that amphibian declines will have large-scale effects on streams, including changes in community structure, shifts to increased importance of algal energy sources, reduced downstream transport of organic materials, and reduced energy transfer from streams to terrestrial habitats. Broader impacts. The broader implications of this research are that findings will be relevant to an urgent problem (i.e. amphibian declines) influencing many regions. The proposed research will also provide opportunities for students from Latin America and the U.S. to work on an important, large-scale environmental issue and will further collaboration between the 3 institutions involved and other scientists researching related issues in the tropics.