Spooner Daniel E, Vaughn Caryn C
Oklahoma Biological Survey and Department of Zoology, University of Oklahoma, 111 E. Chesapeake Street, Norman, OK, USA.
Oecologia. 2008 Nov;158(2):307-17. doi: 10.1007/s00442-008-1132-9. Epub 2008 Sep 16.
The sustained decline in habitat quality and community integrity highlights the importance of understanding how communities and environmental variation interactively contribute to ecosystem services. We performed a laboratory experiment manipulating effects of acclimation temperature (5, 15, 25, and 35 degrees C) on resource acquisition, assimilation and subsequent ecosystem services provided by eight freshwater mussel species. Our results suggest that although freshwater mussels are broadly categorized as filter feeders, there are distinct nested functional guilds (thermally tolerant and sensitive) associated with their thermal performance. At 35 degrees C, thermally tolerant species have increased resource assimilation and higher rates of contributed ecosystem services (nutrient excretion, benthic-pelagic coupling). Conversely, thermally sensitive species have decreased assimilation rates and display an array of functional responses including increased/decreased benthic-pelagic coupling and nutrient excretion. Although thermally sensitive species may be in poorer physiological condition at warmer temperatures, their physiological responses can have positive effects on ecosystem services. We extrapolated these results to real mussel beds varying in species composition to address how shifts in community composition coupled with climate change may shift their contributed ecological services. Comparative field data indicate that two co-existing, abundant species with opposing thermal performance (Actinonaias ligamentina, Amblema plicata) differentially dominate community biomass. Additionally, communities varying in the relative proportion of these species differentially influence the magnitude (benthic-pelagic coupling) and quality (N:P excretion) of ecosystem services. As species are increasingly threatened by climate change, greater emphasis should be placed on understanding the contribution of physiological stress to the integrity and functioning of ecosystems.
栖息地质量和群落完整性的持续下降凸显了理解群落与环境变化如何相互作用对生态系统服务产生影响的重要性。我们进行了一项实验室实验，操控驯化温度（5、15、25和35摄氏度）对8种淡水贻贝物种的资源获取、同化作用以及随后提供的生态系统服务的影响。我们的结果表明，尽管淡水贻贝被广泛归类为滤食性动物，但与其热性能相关存在明显的嵌套功能类群（耐热和敏感）。在35摄氏度时，耐热物种的资源同化增加，对生态系统服务的贡献速率更高（营养物排泄、底栖 - 水层耦合）。相反，热敏物种的同化速率下降，并表现出一系列功能响应，包括底栖 - 水层耦合和营养物排泄的增加/减少。尽管热敏物种在较高温度下生理状况可能较差，但其生理反应可能对生态系统服务产生积极影响。我们将这些结果外推到物种组成不同的实际贻贝床，以探讨群落组成的变化与气候变化相结合如何改变它们所贡献的生态服务。比较实地数据表明，两种共存且数量丰富、热性能相反的物种（韧带射线蚌、褶纹冠蚌）在群落生物量中占主导地位的情况不同。此外，这些物种相对比例不同的群落对生态系统服务的大小（底栖 - 水层耦合）和质量（氮：磷排泄）有不同影响。随着物种受到气候变化的威胁日益增加，应更加重视理解生理应激对生态系统完整性和功能的贡献。
