Pollen transport through distributaries and depositional patterns in coastal waters
Pollen transport through distributaries and depositional patterns in coastal waters
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DOI：
10.1016/s0031-0182(98)00205-3
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发表时间：
1999-06-01
影响因子：
3
通讯作者：
Campbell, ID
中科院分区：
文献类型：
--
作者：
Chmura, GL;Smirnov, A;Campbell, ID
在这项研究中，我们比较了密西西比河从密西西比河维克斯堡到路易斯安那州贝利查斯下游以及路易斯安那州摩根城的支流阿查法拉亚河河水中的季节性花粉和孢子组合。Vicksburg和Belie Chasse水域的花粉组合相似，但与Atchafalaya河的花粉组合明显不同。与流经鸟脚三角洲的蜿蜒的密西西比河主河道相比，在吻合的阿恰法拉亚河河道中，当地的花粉输入更为重要。河流花粉和孢子的组合也与密西西比河羽流附近路易斯安那大陆架的表层沉积物进行了比较。在这个地区，海洋花粉和孢子组合的主要来源似乎是密西西比河主茎的排放物，Atchafalaya的输入有限。因此，沉积在这些沿海水域的花粉提供了密西西比流域植被的记录，而不是当地沿海地区。大陆架上的花粉组合随距离河流源头的远近而变化，但不是系统的。这种模式可以用生物控制海水中的细颗粒沉积来解释，即……花粉在桡足动物粪便颗粒中的沉积。由于桡足类动物的放牧依赖于浮游植物的生产，来自河流羽流的花粉沉积将受到河口附近高浊度的限制。我们假设在浅海环境中，花粉优先沉积在相应的高浮游植物产量区域，这些区域具有浊度降低和养分有效性高的特征。(C) 1999 Elsevier Science B.V.版权所有
In this study we compare seasonal pollen and spore assemblages in river waters from the Mississippi River at Vicksburg, Mississippi to those downstream at Belie Chasse, Louisiana and in a distributary, the Atchafalaya River at Morgan City, Louisiana. Assemblages of pollen in waters at Vicksburg and Belie Chasse are similar to each other, but distinctively different from those in the Atchafalaya River. Local pollen inputs are more important in the anastomosing Atchafalaya River channel, as compared to the meandering main stem Mississippi channel which discharges through the bird-foot delta. Riverine pollen and spore assemblages are also compared to those of surface sediments from the Louisiana continental shelf in the vicinity of the Mississippi River plume. In this area the primary source of marine pollen and spore assemblages appears to be the discharge from the main stem Mississippi, with limited input from the Atchafalaya. Thus, pollen deposited in these coastal waters provides a record of vegetation in the Mississippi drainage basin, rather than local coastal areas. Pollen assemblages on the continental shelf vary with distance from the river source, but not in a systematic manner. The pattern is explained by biological controls on fine-particle deposition in marine waters, i.e.. deposition of pollen in copepod fecal pellets. As copepod grazing is dependent upon phytoplankton production, pollen deposition from the river plume will be limited by high turbidities proximal to the river mouth. We hypothesize that in neritic environments, pollen is preferentially deposited in areas corresponding to high phytoplankton production, which are characterized by reduced turbidity and high nutrient availability. (C) 1999 Elsevier Science B.V. All rights reserved.