Utilization of Spartina- and Phragmites-derived dissolved organic matter by bacteria and ribbed mussels (Geukensia demissa) from Delaware Bay salt marshes
Utilization of Spartina- and Phragmites-derived dissolved organic matter by bacteria and ribbed mussels (Geukensia demissa) from Delaware Bay salt marshes
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DOI：
10.1007/s12237-008-9061-8
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发表时间：
2008-09-01
影响因子：
2.7
通讯作者：
Velinsky, David J.
中科院分区：
文献类型：
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作者：
Bushaw-Newton, Karen L.;Kreeger, Danielle A.;Velinsky, David J.
芦苇一直在入侵整个大西洋中部互花米草占主导地位的盐沼。虽然，芦苇具有较高的初级生产率，但不知道该物种是否以与米草相同的方式支持沼泽食物网的较低营养级。使用几个相关的光化学和生物测定，我们比较了植物初级生产的有机物质流的模式，通过一个关键的盐沼后生动物，肋贻贝（Geukensia demissa），使用细菌中间。溶解有机物（DOM）来自植物收集的特拉华州湾盐沼和生长在实验室中的C-14-CO2。细菌利用植物来源的DOM测量碳矿化显示，这两个物种提供生物可利用的DOM本地盐沼细菌。19天后，米草处理的总碳矿化（36%（CO2）-C-14 +/- 3 SE）高于芦苇处理（29% +/- 2 SE; Wilcoxon-Kruskal-沃利斯秩和检验，P < 0.01）。在初始测量期间，将DOM预暴露于自然阳光仅增强或降低DOM对浮游细菌的生物利用度（例如，7天或更短），但这些差异在孵育过程中不显著。C-14-DOM处理的C-14-标记浮游细菌（可能还有有机絮体）混合物被G.米草属和芦苇属处理之间的相似速率。此外，C-14同化效率的贻贝摄取的材料是高的植物来源，从74%到90%不等，植物来源之间没有显着差异。阳光照射并没有影响贻贝的浮游细菌DOM组合的营养价值。有许多可能的营养和栖息地之间的差异，米草属和芦苇占主导地位的沼泽，可能会影响G。demissa，但命运的维管植物溶解有机碳的DOM浮游细菌贻贝营养途径出现这些沼泽类型之间的可比性。
Phragmites australis has been invading Spartina-alterniflora-dominated salt marshes throughout the mid-Atlantic. Although, Phragmites has high rates of primary production, it is not known whether this species supports lower trophic levels of a marsh food web in the same manner as Spartina. Using several related photochemical and biological assays, we compared patterns of organic matter flow of plant primary production through a key salt marsh metazoan, the ribbed mussel (Geukensia demissa), using a bacterial intermediate. Dissolved organic matter (DOM) was derived from plants collected from a Delaware Bay salt marsh and grown in the laboratory with C-14-CO2. Bacterial utilization of plant-derived DOM measured as carbon mineralization revealed that both species provided bioavailable DOM to native salt marsh bacteria. Total carbon mineralization after 19 days was higher for Spartina treatments (36% (CO2)-C-14 +/- 3 SE) compared with Phragmites treatments (29% +/- 2 SE; Wilcoxon-Kruskal-Wallis rank sums test, P < 0.01). Pre-exposing DOM to natural sunlight only enhanced or decreased bioavailability of the DOM to the bacterioplankton during initial measurements (e.g., 7 days or less) but these differences were not significant over the course of the incubations. Mixtures of C-14-labeled bacterioplankton (and possibly organic flocs) from C-14-DOM treatments were cleared by G. demissa at similar rates between Spartina and Phragmites treatments. Moreover, C-14 assimilation efficiencies for material ingested by mussels were high for both plant sources ranging from 74% to 90% and not significantly different between plant sources. Sunlight exposure did not affect the nutritional value of the bacterioplankton DOM assemblage for mussels. There are many possible trophic and habitat differences between Spartina- and Phragmites-dominated marshes that could affect G. demissa but the fate of vascular plant dissolved organic carbon in the DOM to bacterioplankton to mussel trophic pathway appears comparable between these marsh types.