Sediment and Salmon Interactions: Implications for nutrient storage and downstream lake productivity

通过河道移动的沉积物充当载体，将营养物和污染物沿着同一路线移动到下游湖泊。一些可溶性化学物质松散地吸附在沉积物上，而其他物质则物理附着在细小的沉积物上。细小的无机沉积物定义为小于 63 微米，很容易与水柱中的有机颗粒结合形成聚集或絮凝的颗粒，这些颗粒比其组成材料更大且具有不同的沉降特性。这导致沉积物和附着的有机物的运输和沉降速率变化，因此预测不佳。本研究以鲑鱼腐烂产物作为当代例子，研究了沉积物和鲑鱼之间的相互作用，改变了鲑鱼来源的营养物质（SDN）从产卵场到下游育苗湖的输送。在不列颠哥伦比亚省内陆，鲑鱼培育湖需要一定水平的初级生产，以维持食物网以支持鲑鱼鱼苗。尚不确定返回的产卵鱼的腐烂产物对下游育苗湖的初级生产有多大贡献。鲑鱼腐烂营养物的命运对产卵场的管理产生影响，并可能对未来种群的成功产生影响。在捕获高密度和低密度产卵鱼返回的 5 年期间，我建议 i) 估计在产卵场和育苗湖之间的河流排放中转移的河道储存的 SDN 的数量和时间，ii) 量化上游河道和泛滥平原的 SDN 储存量，以及 iii) 测量和模拟与排入育苗湖的产卵溪流相关的物理混合过程，以确定 SDN 负荷对育苗湖初级生产力的影响。

Sediment moving through river channels acts as a vector, moving nutrients and contaminants along the same route to downstream lakes. Some soluble chemicals are loosely adsorbed to the sediment while other material is physically attached to the fine sediment. Fine inorganic sediment, defined as being smaller than 63 microns, readily combines with organic particles in the water column to form aggregated or flocculated particles which are larger and have different settling properties than their constituent materials. This results in variable, and therefore poorly predicted, transport and settling rates for both the sediment and the attached organic matter. Using salmon decay products as a contemporary example, this study investigates the interaction of sediment and salmon in altering the delivery of salmon-derived nutrients (SDN) from the spawning grounds to the downstream nursery lakes. In the interior of BC, salmonid nursery lakes require levels of primary production that can maintain the food web to support salmon fry. It is uncertain to what degree the decay products of returning spawners contribute to primary production in downstream nursery lakes. The fate of salmon decay nutrients has implications in the management of the spawning grounds and potentially for the success of future stocks. Over a 5-year period, which captures high- and low-density spawner returns, I propose to i) estimate the amount and timing of channel-stored SDN transferred in river discharge between the spawning grounds and nursery lake, ii) quantify the upstream river channel and floodplain storage of SDN, and iii) measure and model the physical mixing processes associated with a spawning stream emptying into a nursery lake in order to determine the effects of SDN loads on nursery lake primary productivity.