Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, Burlington, Ontario, Canada, L7R 4A6.
Proc Biol Sci. 2012 Aug 7;279(1740):2990-7. doi: 10.1098/rspb.2011.2671. Epub 2012 Mar 28.
Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.e. colonization pressure) are key determinants of the number of species that successfully invade new habitats. In view of these relationships, and the possibility that ships transport whole communities of organisms, we collected 333 ballast water and sediment samples to investigate the relationship between propagule and colonization pressure for a variety of diverse taxonomic groups (diatoms, dinoflagellates and invertebrates). We also reviewed the scientific literature to compare the number of species transported by ships to those reported in nature. Here, we show that even though ships transport nearly entire local communities, a strong relationship between propagule and colonization pressure exists only for dinoflagellates. Our study provides evidence that colonization pressure of invertebrates and diatoms may fluctuate widely irrespective of propagule pressure. We suggest that the lack of correspondence is explained by reduced uptake of invertebrates into the transport vector and the sensitivity of invertebrates and diatoms to selective pressures during transportation. Selection during transportation is initially evident through decreases in propagule pressure, followed by decreased colonization pressure in the most sensitive taxa.
越来越多的经验证据表明，释放个体的数量（即繁殖体压力）和释放物种的数量（即定居压力）是决定成功入侵新栖息地的物种数量的关键因素。鉴于这些关系，以及船舶可能运输整个生物群落的可能性，我们采集了 333 个压载水和沉积物样本，以调查各种不同分类群（硅藻、甲藻和无脊椎动物）的繁殖体和定居压力之间的关系。我们还查阅了科学文献，比较了船舶运输的物种数量与自然界中报告的物种数量。在这里，我们表明，尽管船舶运输了几乎整个当地社区，但繁殖体和定居压力之间仅存在甲藻的强关系。我们的研究提供了证据，表明无脊椎动物和硅藻的定居压力可能会广泛波动，而与繁殖体压力无关。我们认为，缺乏对应关系的原因是无脊椎动物进入运输载体的摄取减少，以及无脊椎动物和硅藻在运输过程中对选择压力的敏感性。运输过程中的选择最初通过繁殖体压力的降低来体现，随后最敏感的类群的定居压力降低。
