ABSTRACT

Estuaries are hotspots of primary productivity and nutrient transformation that contribute to food webs and ecosystem functioning locally and in adjacent ecosystems. The depth-dependence of nutrient transformation and primary productivity rates in the water column and the seafloor were investigated, and the lateral transport of solutes and materials across the estuary mouth were quantified. Using an estuary dominated by shallow soft-sediment habitats as a case study, the effects of sea level rise (SLR) on productivity and nutrient transformation processes were projected. The estuary was a net importer of dissolved nutrients from the coast, and a net exporter of suspended sediments and chlorophyll a, supporting the notion that estuaries are important nutrient transformation reactors. A significant depth (and light) effect on productivity indicates that increasing stressors associated with climate change that reduce light at the seafloor (SLR and increased turbidity) will negatively impact estuarine productivity. Intertidal and shallow subtidal benthic habitats were responsible for most of the productivity of the estuary and this is likely to be consistent for other shallow estuaries globally. SLR and anthropogenic intervention that prevents landward migration (i.e. seawalls and armouring), will result in the loss of these habitats and their significant contributions to adjacent coastal ecosystems.

摘要

河口是初级生产力和养分转化的热点，有助于食物网和生态系统在当地和邻近生态系统中发挥作用。研究了水体和海底养分转化和初级生产力的深度依赖性，并量化了跨河口的溶质和物质的横向迁移。以浅软沉积物栖息地为主的河口作为案例研究，预测了海平面上升 (SLR) 对生产力和养分转化过程的影响。河口是海岸溶解养分的净进口地，也是悬浮沉积物和叶绿素a的净出口地，支持河口是重要的养分转化反应器的观点。对生产力的显着深度（和光）影响表明，与气候变化相关的增加的压力源会减少海底光（SLR和增加的浊度）将对河口生产力产生负面影响。潮间带和浅潮下带底栖生境是河口大部分生产力的原因，这可能与全球其他浅水河口一致。SLR 和阻止向陆迁移的人为干预（即海堤和装甲）将导致这些栖息地的丧失及其对邻近沿海生态系统的重大贡献。