BURDICK DM, SHORT FT
Department of Natural Resources Jackson Estuarine Laboratory Center for Marine Biology University of New Hampshire Durham, New Hampshire 03824, USA
Environ Manage. 1999 Feb;23(2):231-240. doi: 10.1007/s002679900182.
/ The effects of docks on eelgrass beds were measured using plant population characteristics (shoot density, canopy height, and growth rates), light levels, and an assessment of eelgrass bed quality in Massachusetts estuaries. Eelgrass populations were impacted under and directly adjacent to docks, as shown by depressed shoot density and canopy structure. Severe impacts can cause fragmentation of eelgrass beds, thus contributing to large-scale declines in estuaries such as Waquoit Bay. Impacts were fewer under docks supported by piers than under floating docks, and taller piers resulted in fewer impacts. Based on this investigation, we conclude that docks should be greater than 3 m in height above the bottom in areas with tidal ranges less than 1 m to allow enough light to sustain eelgrass beds under the docks. In addition to dock height, orientation and width were also found to be important factors affecting eelgrass. Narrow docks with a north-south orientation can best ensure the long-term survival of eelgrass under and near the dock. KEY WORDS: Docks; Shade; Eelgrass beds; Zostera marina; Seagrass
通过植物种群特征（茎密度、冠层高度和生长速率）、光照水平以及对马萨诸塞州河口鳗草床质量的评估，来测定码头对鳗草床的影响。正如茎密度降低和冠层结构所显示的那样，鳗草种群在码头下方及紧邻码头的区域受到了影响。严重的影响会导致鳗草床破碎，从而致使像瓦夸特湾这样的河口大规模衰退。由桥墩支撑的码头下方的影响比浮码头下方的少，并且桥墩越高，影响越少。基于此项调查，我们得出结论，在潮差小于1米的区域，码头底部以上的高度应大于3米，以便有足够的光照来维持码头下方的鳗草床。除了码头高度外，方向和宽度也被发现是影响鳗草的重要因素。南北走向的窄码头能够最好地确保码头下方及附近鳗草的长期存活。关键词：码头；遮荫；鳗草床；大叶藻；海草
