Vaughn Caryn C, Spooner Daniel E, Galbraith Heather S
Oklahoma Biological Survey and Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
Ecology. 2007 Jul;88(7):1654-62. doi: 10.1890/06-0471.1.
We asked whether species richness or species identity contributed more to ecosystem function in a trait-based functional group, burrowing, filter-feeding bivalves (freshwater mussels: Unionidae), and whether their importance changed with environmental context and species composition. We conducted a manipulative experiment in a small river examining the effects of mussel assemblages varying from one to eight species on benthic algal standing crop across two sets of environmental conditions: extremely low discharge and high water temperature (summer); and moderate discharge and water temperature (fall). We found strong species identity effects within this guild, with one species (Actinonaias ligamentina) influencing accrual of benthic algae more than other species, but only under summer conditions. We suspect that this effect is due to a combination of the greater biomass of this species and its higher metabolic and excretion rates at warm summer temperatures, resulting in increased nitrogen subsidies to benthic algae. We also found that Actinonaias influenced the condition of other mussel species, likely through higher consumption, interference, or both. This study demonstrates that species within trait-based functional groups do not necessarily have the same effects on ecosystem properties, particularly under different environmental conditions.
我们探究了在一个基于性状的功能类群——穴居滤食性双壳类动物（淡水贻贝：蚌科）中，物种丰富度或物种身份对生态系统功能的贡献更大，以及它们的重要性是否会随环境背景和物种组成而变化。我们在一条小河中进行了一项操纵性实验，研究了在两组环境条件下，从一到八个物种不等的贻贝组合对底栖藻类现存生物量的影响：极低流量和高温（夏季）；以及中等流量和水温（秋季）。我们在这个类群中发现了强烈的物种身份效应，其中一个物种（韧带射带蚌）对底栖藻类积累的影响比其他物种更大，但仅在夏季条件下如此。我们怀疑这种效应是由于该物种更大的生物量以及在温暖夏季温度下更高的代谢和排泄率共同作用的结果，从而导致对底栖藻类的氮补贴增加。我们还发现韧带射带蚌影响了其他贻贝物种的状况，可能是通过更高的消耗量、干扰作用或两者兼而有之。这项研究表明，基于性状的功能类群中的物种对生态系统属性的影响不一定相同，特别是在不同的环境条件下。
