Miller Andrew C, Payne Barry S
Environmental Laboratory, US Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199, USA.
J Environ Manage. 2004 Nov;73(2):147-54. doi: 10.1016/j.jenvman.2004.06.006.
In response to proposed dredging in a 122-km reach of the Big Sunflower River, Mississippi, we studied freshwater mussels (family: Unionidae) using qualitative, semi-quantitative, and quantitative (0.25 m(2) total substratum removal) methods in 1987, 1993, 1994, 2001, 2002, and 2003. Our objectives were to identify important mussel resources, to devise methods for minimizing dredging risks, and to identify habitat improvement features. Approximately 60% of the fauna was located on two high-density shoals characterized by extreme dominance of the commercially valuable threeridge (Amblema plicata). Shallow nearshore and main channel areas comprised approximately 10 and 88% of the aquatic habitat in the project area; however, these areas were of less importance for mussels and supported densities of approximately 5 and 0.5 individuals/m(2), respectively. Throughout the project area the mussel fauna exhibited little or no evidence of recent recruitment, dominance of relatively few species (either A. plicata, or the bank climber Plectomerus dombeyanus), and low species diversity (H') and evenness. No federally listed endangered or threatened mussels were found, although the pyramid pigtoe (Pleurobema pyramidatum), a species listed as endangered in Mississippi, was collected in and upstream of the project area. Two other state-listed species, Plethobasus cyphyus (sheepnose) and Quadrula cylindrica (rabbitsfoot), were only found on gravelly shoals upriver of the project area. Maintenance plans were redesigned to minimize environmental damage; a hydraulic cutterhead dredge will be used in most of the mainstem to reduce risk to nearshore habitats. High-density assemblages on four shoals will not be dredged and 150 and 100 m buffer zones will be left immediately up and downriver. Enhancements for aquatic biota will be created with gravel substratum and wing dams.
针对在密西西比州大向日葵河122公里河段进行疏浚的提议，我们于1987年、1993年、1994年、2001年、2002年和2003年采用定性、半定量和定量（去除总计0.25平方米的底层基质）方法对淡水贻贝（蚌科）进行了研究。我们的目标是确定重要的贻贝资源，设计将疏浚风险降至最低的方法，并确定栖息地改善特征。大约60%的动物群位于两个高密度浅滩上，其特点是具有商业价值的三脊蚌（Amblema plicata）占绝对优势。浅近岸和主河道区域分别约占项目区域水生栖息地的10%和88%；然而，这些区域对贻贝来说重要性较低，贻贝密度分别约为5只/平方米和0.5只/平方米。在整个项目区域，贻贝动物群几乎没有或没有近期补充的迹象，相对较少的物种（要么是三脊蚌，要么是岸栖的多瘤楔蚌Plectomerus dombeyanus）占主导地位，物种多样性（H'）和均匀度较低。虽然在项目区域内及其上游采集到了在密西西比州被列为濒危物种的金字塔猪鼻蚌（Pleurobema pyramidatum），但未发现联邦列出的濒危或受威胁贻贝。另外两种被该州列为物种的贻贝，即肥珠蚌（Plethobasus cyphyus，羊鼻蚌）和柱形丽蚌（Quadrula cylindrica，兔足蚌），仅在项目区域上游的砾石浅滩上被发现。重新设计了维护计划以尽量减少环境破坏；大部分主干河道将使用液压刀盘式挖泥船以降低对近岸栖息地的风险。四个浅滩上的高密度组合将不进行疏浚，并将在其上下游立即留出150米和100米的缓冲区。将用砾石底层基质和翼坝为水生生物群落创造改善条件。
