Lee Philip O, McLellan Sandra L, Graham Linda E, Young Erica B
Department of Biological Sciences, University of Wisconsin-Milwaukee, 3209 N. Maryland Ave., Milwaukee, WI 53201, USA.
The School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E. Greenfield Ave., Milwaukee, WI 53204, USA.
FEMS Microbiol Ecol. 2015 Jan;91(1):1-12. doi: 10.1093/femsec/fiu001. Epub 2014 Dec 5.
Dreissenid mussels have invaded the Laurentian Great Lakes causing dramatic changes to benthic-pelagic interactions. Despite research on food web impacts, there is limited data on mussel effects on benthic bacterial communities. This study examined effects of dreissenid mussels and benthic algae on sediment bacterial community composition and diversity. Triplicate experimental sediment plus lake water microcosms were used and either mussels, benthic algae or both were added. Changes in water nutrient chemistry and sediment bacterial communities were monitored using 16S rRNA amplicon sequencing, over 21 days. When mussels were present, nitrate and soluble reactive P increased significantly as the dominant N and P forms. Bacterial diversity increased in all microcosms, although bacterial community composition was distinct between treatment. Higher nitrate in mussel microcosms was accompanied by increases in nitrifying taxa (Nitrospira, Nitrosomonas), which are important in oxidizing mussel-excreted ammonium. Microcosms with algal additions showed increases in bacterial taxa capable of degrading algal cellulose, and Pelagibacter (SAR11) disappeared from all but control microcosms. This study suggests that bacterial communities in lake sediments respond to mussels and algae. Functional analysis of bacterial communities provides insights into changes in microbially mediated benthic nutrient transformations associated with invasive dreissenid mussels and benthic algae in lake ecosystems.
斑马贻贝已经入侵了五大湖，给底栖-水层相互作用带来了巨大变化。尽管对食物网的影响进行了研究，但关于贻贝对底栖细菌群落影响的数据有限。本研究考察了斑马贻贝和底栖藻类对沉积物细菌群落组成和多样性的影响。使用了一式三份的实验沉积物加湖水微宇宙，并添加了贻贝、底栖藻类或两者。使用16S rRNA扩增子测序在21天内监测了水营养化学和沉积物细菌群落的变化。当存在贻贝时，硝酸盐和可溶性活性磷作为主要的氮和磷形式显著增加。所有微宇宙中的细菌多样性都增加了，尽管不同处理之间细菌群落组成不同。贻贝微宇宙中较高的硝酸盐伴随着硝化类群（硝化螺菌属、亚硝化单胞菌属）的增加，这些类群在氧化贻贝排泄的铵方面很重要。添加藻类的微宇宙中能够降解藻类纤维素的细菌类群增加，除对照微宇宙外，Pelagibacter（SAR11）在所有微宇宙中都消失了。本研究表明，湖泊沉积物中的细菌群落对贻贝和藻类有反应。细菌群落的功能分析为与入侵的斑马贻贝和湖泊生态系统中的底栖藻类相关的微生物介导的底栖营养转化变化提供了见解。
