Reusch Thorsten B H, Williams Susan L
Biology Department, San Diego State University, San Diego CA 92182-4614, USA, , , , , , US.
Oecologia. 1998 Jan;113(3):428-441. doi: 10.1007/s004420050395.
The transport and establishment of non-indigenous species in coastal marine environments are increasing worldwide, yet few studies have experimentally addressed the interactions between potentially dominant non-native species and native organisms. We studied the effects of the introduced mussel Musculista senhousia on leaf and rhizome growth and shoot density of eelgrass Zostera marina in San Diego Bay, California. We added M. senhousia over a natural range in biomass (0-1200 g dry mass/m) to eelgrass in transplanted and established beds. The effects of the non-indigenous mussel varied from facilitation to interference depending on time, the abundance of M. senhousia, and the response variable considered. Consistent results were that mussel additions linearly inhibited eelgrass rhizome elongation rates. With 800 g dry mass/m of M. senhousia, eelgrass rhizomes grew 40% less than controls in two eelgrass transplantations and in one established eelgrass bed. These results indicate that M. senhousia, could both impair the success of transplantations of eelgrass, which spread vegetatively by rhizomes, and the spread of established Z. marina beds to areas inhabited by M. senhousia. Although effects on leaf growth were not always significant, in August in both eelgrass transplantations and established meadows leaf growth was fertilized by mussels, and showed a saturation-type relationship to sediment ammonium concentrations. Ammonium concentrations and sediment organic content were linear functions of mussel biomass. We found only small, non-consistent effects of M. senhousia on shoot density of eelgrass over 6-month periods. In established eelgrass beds, but not in transplanted eelgrass patches (≈0.8 m in diameter), added mussels suffered large declines. Hence, eelgrass is likely to be affected by M. senhousia primarily where Z. marina beds are patchy and sparse. Our study has management and conservation implications for eelgrass because many beds are already seriously degraded and limited in southern California where the mussel is very abundant.
全球范围内，沿海海洋环境中非本土物种的迁移和定居现象日益增多，但很少有研究通过实验探讨潜在的优势非本土物种与本土生物之间的相互作用。我们研究了引进的贻贝（Musculista senhousia）对加利福尼亚州圣地亚哥湾大叶藻（Zostera marina）叶片和根茎生长以及茎密度的影响。我们在移植和已定植的大叶藻床中，按照生物量的自然范围（0 - 1200克干重/米）添加了贻贝。非本土贻贝的影响因时间、贻贝数量以及所考虑的响应变量而异，从促进作用到干扰作用都有。一致的结果是，添加贻贝会线性抑制大叶藻根茎的伸长率。在两次大叶藻移植和一个已定植的大叶藻床中，当添加800克干重/米的贻贝时，大叶藻根茎的生长量比对照组少40%。这些结果表明，贻贝既可能损害通过根茎进行无性繁殖的大叶藻的移植成功率，也可能影响已定植的大叶藻床向贻贝栖息区域的扩散。尽管对叶片生长的影响并非总是显著，但在8月，在大叶藻移植地和已定植的草甸中，贻贝都促进了叶片生长，并且与沉积物铵浓度呈现饱和型关系。铵浓度和沉积物有机含量是贻贝生物量的线性函数。我们发现，在6个月的时间里，贻贝对大叶藻茎密度的影响很小且不一致。在已定植的大叶藻床中，而不是在移植的大叶藻斑块（直径约0.8米）中，添加的贻贝数量大幅减少。因此，大叶藻可能主要在大叶藻床零散稀疏的地方受到贻贝的影响。我们的研究对大叶藻的管理和保护具有启示意义，因为在南加州许多大叶藻床已经严重退化且面积有限，而贻贝在那里非常丰富。
