Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada.
PLoS One. 2013 Jul 12;8(7):e69091. doi: 10.1371/journal.pone.0069091. Print 2013.
Dispersal, the movement of an individual away from its natal or breeding ground, has been studied extensively in birds and mammals to understand the costs and benefits of movement behavior. Whether or not invertebrates disperse in response to such attributes as habitat quality or density of conspecifics remains uncertain, due in part to the difficulties in marking and recapturing invertebrates. In the upper Bay of Fundy, Canada, the intertidal amphipod Corophium volutator swims at night around the new or full moon. Furthermore, this species is regionally widespread across a large spatial scale with site-to-site variation in population structure. Such variation provides a backdrop against which biological determinants of dispersal can be investigated. We conducted a large-scale study at nine mudflats, and used swimmer density, sampled using stationary plankton nets, as a proxy for dispersing individuals. We also sampled mud residents using sediment cores over 3 sampling rounds (20-28 June, 10-17 July, 2-11 August 2010). Density of swimmers was most variable at the largest spatial scales, indicating important population-level variation. The smallest juveniles and large juveniles or small adults (particularly females) were consistently overrepresented as swimmers. Small juveniles swam at most times and locations, whereas swimming of young females decreased with increasing mud presence of young males, and swimming of large juveniles decreased with increasing mud presence of adults. Swimming in most stages increased with density of mud residents; however, proportionally less swimming occurred as total mud resident density increased. We suggest small juveniles move in search of C. volutator aggregations which possibly act as a proxy for better habitat. We also suggest large juveniles and small adults move if potential mates are limiting. Future studies can use sampling designs over large spatial scales with varying population structure to help understand the behavioral ecology of movement, and dispersal in invertebrate taxa.
扩散，即个体远离出生地或繁殖地的运动，已在鸟类和哺乳动物中得到广泛研究，以了解运动行为的成本和收益。由于难以对无脊椎动物进行标记和回收，因此不确定无脊椎动物是否会因栖息地质量或同种密度等属性而扩散。在加拿大芬迪湾的潮间带，滨螺 Corophium volutator 在新月或满月前后的夜间游动。此外，该物种在很大的空间尺度上在整个区域内广泛分布，其种群结构在不同地点之间存在差异。这种变化为研究扩散的生物学决定因素提供了背景。我们在九个泥滩上进行了一项大规模研究，并使用固定浮游网采集的游泳者密度作为扩散个体的代表。我们还在三轮采样中（2010 年 6 月 20-28 日、7 月 10-17 日、8 月 2-11 日）使用沉积物芯对泥滩居民进行了采样。游泳者的密度在最大的空间尺度上变化最大，表明存在重要的种群水平变化。最小的幼体和较大的幼体或较小的成体（尤其是雌性）一直是游泳者的主要代表。最小的幼体在大多数时间和地点游泳，而年轻雌性的游泳次数随着年轻雄性在泥滩中存在的增加而减少，大幼体的游泳次数随着成年雄性在泥滩中存在的增加而减少。在大多数阶段，游泳的比例随着泥滩居民密度的增加而增加；然而，随着泥滩居民总密度的增加，游泳的比例却减少了。我们认为，小型幼体移动是为了寻找滨螺聚集区，滨螺聚集区可能是更好栖息地的代表。我们还认为，如果潜在的配偶受到限制，大型幼体和小型成体也会移动。未来的研究可以在具有不同种群结构的大空间尺度上使用采样设计，以帮助理解运动行为和无脊椎动物类群的扩散。
