MacIsaac Hugh J
Department of Biological Sciences, University of Windsor, N9B 3P4, Windsor, ON, Canada.
Great Lakes Institute for Environmental Research, University of Windsor, N9B 3P4, Windsor, ON, Canada.
Oecologia. 1996 Mar;105(4):484-492. doi: 10.1007/BF00330011.
The zebra mussel Dreissena polymorpha was introduced to North America during the mid-1980s, and is now a dominant member of many benthic communities in the lower Great Lakes. In this study, I explored the abundance, biomass, size structure and settlement of Dreissena inhabiting rocks along a wave-swept disturbance gradient near Middle Sister Island in western Lake Erie. Ten rocks were collected from quadrats at six sites along each of three transect lines oriented perpendicular to shore. Occurrence, abundance and biomass of Dreissena on smaller, movable rocks were positively associated with rock distance from shore (∼lake depth) and with rock area; rocks at nearshore sites supported little, if any, Dreissena, whereas those at offshore sites were heavily colonized. Mussel size distributions also differed in relation to shore distance. Large mussels (≥19 mm) were underrepresented or absent on rocks collected at nearshore sites, but were overrepresented at offshore locations (≥37 m). Settlement of larval mussels on settling pads was positively correlated with distance offshore and with time of exposure, though settlement was substantial even at a nearshore (10 m) location. Area-adjusted mussel dry mass increased more rapidly with distance offshore on large than on small rocks. Large rocks also required more force to displace and were significantly less likely to be disturbed when transplanted at the study site. Results from this study indicate that occurrence, abundance and size structure of Dreissena in nearshore waters of Lake Erie correspond with the frequency of habitat disturbance, though other factors including food limitation and larval supply may also contribute to these patterns. These patterns complement studies that established the significance of physical disturbance in other aquatic systems.
斑马贻贝（Dreissena polymorpha）于20世纪80年代中期被引入北美，如今已成为五大湖下游许多底栖生物群落的主要成员。在本研究中，我探究了伊利湖西部中姐妹岛附近沿波浪冲刷干扰梯度分布的栖息在岩石上的斑马贻贝的丰度、生物量、大小结构和附着情况。沿着与海岸垂直的三条样线，在六个地点的样方中采集了十块岩石。较小的可移动岩石上斑马贻贝的出现、丰度和生物量与岩石离海岸的距离（约湖水深度）以及岩石面积呈正相关；近岸地点的岩石上即使有斑马贻贝也很少，而离岸地点的岩石则被大量占据。贻贝的大小分布也因与海岸的距离而异。大型贻贝（≥19毫米）在近岸地点采集的岩石上数量不足或没有，而在离岸地点（≥37米）则数量过多。幼体贻贝在附着垫上的附着与离岸距离和暴露时间呈正相关，不过即使在近岸（10米）位置附着量也很大。面积调整后的贻贝干质量在大型岩石上随离岸距离增加的速度比在小型岩石上更快。大型岩石也需要更大的力才能移动，并且在研究地点移植时受到干扰的可能性显著更小。本研究结果表明，伊利湖近岸水域斑马贻贝的出现、丰度和大小结构与栖息地干扰频率相对应，不过包括食物限制和幼体供应在内的其他因素也可能导致这些模式。这些模式补充了确立物理干扰在其他水生系统中重要性的研究。
