Chamberlin Joshua W, Beckman Brian R, Greene Correigh M, Rice Casimir A, Hall Jason E
NOAA Fisheries Mukilteo Research Station Northwest Fisheries Science Center Mukilteo WA USA.
NOAA Fisheries Northwest Fisheries Science Center Seattle WA USA.
Ecol Evol. 2017 Jul 31;7(17):6981-6995. doi: 10.1002/ece3.3218. eCollection 2017 Sep.
While individual growth ultimately reflects the quality and quantity of food resources, intra and interspecific interactions for these resources, as well as individual size, may have dramatic impacts on growth opportunity. Out-migrating anadromous salmonids make rapid transitions between habitat types resulting in large pulses of individuals into a given location over a short period, which may have significant impact on demand for local resources. We evaluated the spatial and temporal variation in IGF-1 concentrations (a proxy for growth rate) and the relationship between size and concentration for juvenile Chinook salmon in Puget Sound, WA, USA, as a function of the relative size and abundance of both Chinook salmon and Pacific herring, a species which commonly co-occurs with salmonids in nearshore marine habitats. The abundance of Chinook salmon and Pacific herring varied substantially among the sub-basins as function of outmigration timing and spawn timing, respectively, while size varied systematically and consistently for both species. Mean IGF-1 concentrations were different among sub-basins, although patterns were not consistent through time. In general, size was positively correlated with IGF-1 concentration, although the slope of the relationship was considerably higher where Pacific herring were more abundant than Chinook salmon; specifically where smaller individual herring, relative to Chinook salmon, were more abundant. Where Pacific herring were less abundant than Chinook salmon, IGF-1 concentrations among small and large Chinook salmon were more variable and showed no consistent increase for larger individuals. The noticeable positive effect of relative Pacific herring abundance on the relationship between size and individual growth rates likely represents a shift to predation based on increased IGF-1 concentrations for individual Chinook salmon that are large enough to incorporate fish into their diet and co-occur with the highest abundances of Pacific herring.
虽然个体生长最终反映了食物资源的质量和数量，但对这些资源的种内和种间相互作用以及个体大小，可能会对生长机会产生巨大影响。洄游性溯河产卵鲑科鱼类在不同栖息地类型之间迅速转换，导致短期内大量个体涌入特定地点，这可能会对当地资源需求产生重大影响。我们评估了美国华盛顿州普吉特海湾幼年奇努克鲑鱼胰岛素样生长因子-1（IGF-1，生长速率的一个指标）浓度的时空变化，以及奇努克鲑鱼和太平洋鲱（一种在近岸海洋栖息地常与鲑科鱼类共生的物种）的相对大小和丰度与IGF-1浓度之间的关系。奇努克鲑鱼和太平洋鲱的丰度在不同子流域中差异很大，分别取决于洄游时间和产卵时间，而这两个物种的大小则呈现出系统且一致的变化。尽管不同时期的模式并不一致，但各子流域间的平均IGF-1浓度存在差异。一般来说，大小与IGF-1浓度呈正相关，不过在太平洋鲱比奇努克鲑鱼更丰富的地方，这种关系的斜率要高得多；特别是相对于奇努克鲑鱼，较小个体的太平洋鲱更为丰富的地方。在太平洋鲱比奇努克鲑鱼数量少的地方，大小不同的奇努克鲑鱼之间的IGF-1浓度变化更大，且较大个体并未呈现出一致的增加趋势。太平洋鲱相对丰度对个体大小与生长速率关系的显著积极影响，可能代表了一种向捕食的转变，这是基于对于个体足够大、能够将鱼类纳入其食谱且与太平洋鲱最高丰度共存的奇努克鲑鱼而言，IGF-1浓度增加。
