ABSTRACT: Fluxes of nutrients and organic matter between estuaries and the open coast comprise an important component of ecosystem connectivity. Nevertheless, relatively little is known about how oceanographic processes, for example onshore retention of water in the coastal boundary layer, interact with major sinks for particulate organic matter such as bivalve filter feeding within inlets and estuaries. To investigate this interaction, total fluxes of water, nutrients (NH₄, NO_x and PO₄) and chlorophyll a between Waitati Inlet on the wave-exposed coast of the South Island, New Zealand, and the coastal ocean were quantified over 40 tidal cycles. We found declines in total flux of phytoplankton and increases in flux of NH₄ between flood and ebb tides. Net declines in phytoplankton biomass followed a Type II functional response curve, consistent with consumption by the large biomass of filter feeding bivalves within the inlet; however, an asymptote was not reached for the highest concentrations, indicating that feeding was likely limited by exposure time rather than concentration of food relative to biomass. An information-theoretic framework was then used to infer the most likely combination of environmental conditions influencing total fluxes of phytoplankton into the inlet. Onshore wind stress, wave transport and salinity explained 90% of the variation in flux of phytoplankton entering the inlet on flood tides. These results highlight the importance of the interaction between oceanographic forcing and bivalve filter feeding in modulating material dynamics and connectivity between estuaries and the coastal ocean.

中文翻译：

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双瓣过滤器进食和海洋强迫之间的相互作用驱动河口-沿海界面的有机物和营养物通量

摘要：河口和开阔海岸之间的养分和有机质通量是生态系统连通性的重要组成部分。然而，对于海洋学过程（例如在海岸边界层中的陆上滞留水）如何与颗粒有机物的主要汇（例如进水口和河口的双瓣膜滤池进水）相互作用的信息知之甚少。为了研究这种相互作用，在40个潮汐中，对新西兰南岛波浪暴露海岸的威塔蒂入口与沿海海洋之间的水，养分（NH ₄，NO _x和PO ₄）和叶绿素a的总通量进行了量化。周期。我们发现浮游植物的总通量下降而NH _4的通量增加在洪水和退潮之间。浮游植物生物量的净下降遵循II型功能反应曲线，与进水口中捕食双壳类大生物量的消耗量一致；但是，最高浓度没有达到渐近线，这表明进食很可能受到暴露时间的限制，而不是食物相对于生物质的浓度。然后，使用信息理论框架来推断影响浮游植物进入总通量的环境条件的最可能组合。陆上风应力，波浪传输和盐度解释了潮汐进入入口的浮游植物通量变化的90％。