Denitrification and Nitrogen Fixation Dynamics in the Area Surrounding an Individual Ghost Shrimp (Neotrypaea californiensis) Burrow System
Denitrification and Nitrogen Fixation Dynamics in the Area Surrounding an Individual Ghost Shrimp (Neotrypaea californiensis) Burrow System
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DOI：
10.1128/aem.00114-12
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发表时间：
2012-06-01
影响因子：
4.4
通讯作者：
Ziebis, Wiebke
中科院分区：
文献类型：
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作者：
Bertics, Victoria J.;Sohm, Jill A.;Ziebis, Wiebke
生物扰动沉积物被认为是反硝化或固定氮(N)损失增加的区域；然而，最近的研究表明，并非所有的氮都可能从这些环境中流失，一些氮通过微生物二氮（N-2）固定返回到系统中。我们研究了潮间带泻湖（Catalina Harbor， CA）的反硝化和N-2固定，这是一个以新加利福尼亚海虾（thalassinidean shrimp, Neotrypaea californiensis）的生物扰动为特征的环境。实地研究结合了在狭窄水族箱（15 cm × 20 cm × 5 cm）中单个鬼虾洞穴系统周围反硝化和N-2固定的详细测量。这两种活动的同时测量是在1.5厘米网格内采集的样品上进行的，以二维方式说明它们的强度和分布。然后将这些发现与从泻湖收集的大块环境沉积物样本进行的速率测量进行比较。水族馆的结果表明，反硝化和N-2固定在洞穴周围呈斑块状分布，彼此之间、沉积物深度或与洞穴的距离没有明显的相关性。野外反硝化速率在生物扰动区平均低于非生物扰动区；然而，重复显示出非常高的变异性。反硝化现场结果与先前报道的同一泻湖N-2固定率的比较表明，在非生物扰动区域，深度整合（10 cm）反硝化率高于整合N2固定率（类似于9至50倍）。相反，在受生物扰动的沉积物中，根据年份和生物扰动强度的不同，通过反硝化作用损失的氮中有一部分（约6.2%）可能是通过N-2固定损失的。
Bioturbated sediments are thought of as areas of increased denitrification or fixed-nitrogen (N) loss; however, recent studies have suggested that not all N may be lost from these environments, with some N returning to the system via microbial dinitrogen (N-2) fixation. We investigated denitrification and N-2 fixation in an intertidal lagoon (Catalina Harbor, CA), an environment characterized by bioturbation by thalassinidean shrimp (Neotrypaea californiensis). Field studies were combined with detailed measurements of denitrification and N-2 fixation surrounding a single ghost shrimp burrow system in a narrow aquarium (15 cm by 20 cm by 5 cm). Simultaneous measurements of both activities were performed on samples taken within a 1.5-cm grid for a two-dimensional illustration of their intensity and distribution. These findings were then compared with rate measurements performed on bulk environmental sediment samples collected from the lagoon. Results for the aquarium indicated that both denitrification and N-2 fixation have a patchy distribution surrounding the burrow, with no clear correlation to each other, sediment depth, or distance from the burrow. Field denitrification rates were, on average, lower in a bioturbated region than in a seemingly nonbioturbated region; however, replicates showed very high variability. A comparison of denitrification field results with previously reported N-2 fixation rates from the same lagoon showed that in the nonbioturbated region, depth-integrated (10 cm) denitrification rates were higher than integrated N2 fixation rates (similar to 9 to 50 times). In contrast, in the bioturbated sediments, depending on the year and bioturbation intensity, some (similar to 6.2%) to all of the N lost via denitrification might be accounted for via N-2 fixation.