Response of ecosystem metabolism to low densities of spawning Chinook Salmon
Response of ecosystem metabolism to low densities of spawning Chinook Salmon
复制标题
生态系统代谢对产卵奇努克鲑鱼低密度的响应
DOI：
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发表时间：
2016
影响因子：
1.8
通讯作者：
Grace A. Watson
中科院分区：
文献类型：
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作者：
Joseph R. Benjamin;J. Bellmore;Grace A. Watson
人们认为，大规模返回的鲑鱼提供的海洋营养物质可以补贴支持幼鲑鱼的就地食物资源。在太平洋西北部，美国，鲑鱼已经下降到其历史丰度的10%以下，随后由大型鲑鱼群提供的海洋来源的营养物质也随之下降。我们探讨了低密度（<0.001产卵/m2）的自然产卵奇努克鲑鱼（Oncorhynchus tshawytscha）是否会影响生态系统的新陈代谢。我们测量总初级生产力（GPP）和生态系统呼吸（ER）连续之前，期间和之后鲑鱼产卵。我们比较了下游河段产卵鲑鱼密度低，上游河段产卵较少或没有在北方华盛顿3中型（4阶）河流。此外，我们测量了化学，物理和生物因素，可能是重要的控制率GPP和ER。我们观察到，低密度的产卵鲑鱼可以增加46%的GPP在产卵期间，但值迅速返回到产卵前观察到的。在ER之间没有差异观察上游和下游河段。根据我们的研究结果，鲑鱼密度，温度和接近鲑鱼红是最重要的因素控制率的GPP，而温度是最重要的ER。这些结果表明，即使在低产卵密度，鲑鱼可以刺激基础资源，可能会传播食物网。了解受体生态系统如何应对低水平的海洋衍生营养素可能会为旨在增加鱼类种群的营养素增加研究提供信息。
Marine derived nutrients delivered by large runs of returning salmon are thought to subsidize the in situ food resources that support juvenile salmon. In the Pacific Northwest, USA, salmon have declined to <10% of their historical abundance, with subsequent declines of marine derived nutrients once provided by large salmon runs. We explored whether low densities (<0.001 spawners/m2) of naturally spawning Chinook Salmon (Oncorhynchus tshawytscha) can affect ecosystem metabolism. We measured gross primary production (GPP) and ecosystem respiration (ER) continuously before, during, and after salmon spawning. We compared downstream reaches with low densities of spawning salmon to upstream reaches with fewer or no spawners in 3 mid-sized (4th-order) rivers in northern Washington. In addition, we measured chemical, physical, and biological factors that may be important in controlling rates of GPP and ER. We observed that low densities of spawning salmon can increase GPP by 46% during spawning, but values quickly return to those observed before spawning. No difference in ER was observed between up- and downstream reaches. Based on our results, salmon density, temperature, and the proximity to salmon redds were the most important factors controlling rates of GPP, whereas temperature was most important for ER. These results suggest that even at low spawning densities, salmon can stimulate basal resources that may propagate up the food web. Understanding how recipient ecosystems respond to low levels of marine derived nutrients may inform nutrient augmentation studies aimed at enhancing fish populations.