Reef-building eastern oysters, Crassostrea virginica, provide many ecosystem services, including production of valuable commercial products, formation of complex habitats, improved water quality and shoreline protection. Despite this, oyster populations have experienced dramatic declines throughout their range, spawning massive investment in management and restoration. Restoration efforts typically consider several well-studied metrics that normally influence oyster success; however, one potential factor that has not received much prior attention is submarine groundwater discharge (SGD). We conducted a series of field surveys and field experiments to explore the relationship between SGD and oysters in a marsh-lined tidal creek in Georgia, USA. SGD was mapped across multiple time points using a natural radon tracer (radon-222), and fluxes were paired with discrete measurements of oyster density, condition, size, recruitment and growth at multiple locations along the creek. Variation in oyster metrics was best explained by a combination of SGD, pH, and DO, which displayed a high degree of multicollinearity. We found an overall negative, nonlinear relationship between oyster density and groundwater flux. Interestingly, juvenile and adult condition and growth were not negatively impacted by groundwater. Rather, our results suggest that the likely mechanism for the density-flux relationship was interruption of the larval recruitment, which was also negatively related to flux. We hypothesize that larval interruption is due to the low dissolved oxygen and pH conditions of the groundwater at high flux sites. Overall, the interaction between SGD and oysters appears complex, and may be affected by other variables. This study provides evidence of a potential negative effect of a previously understudied natural phenomena on oyster demographics, and we suggest that SGD be considered in future management efforts.

造礁东部牡蛎，Crassostrea virginica，提供许多生态系统服务，包括生产有价值的商业产品、形成复杂的栖息地、改善水质和保护海岸线。尽管如此，牡蛎种群在其整个范围内经历了急剧下降，催生了对管理和恢复的大量投资。恢复工作通常会考虑几个通常会影响牡蛎成功的经过充分研究的指标；然而，一个尚未受到太多关注的潜在因素是海底地下水排放 (SGD)。我们进行了一系列实地调查和实地实验，以探索美国乔治亚州一条沼泽成排的潮汐小溪中 SGD 与牡蛎之间的关系。使用天然氡示踪剂 (radon-222) 在多个时间点绘制 SGD，并将通量与牡蛎密度的离散测量配对，河沿岸多个地点的状况、规模、招募和增长。牡蛎指标的变化最好通过 SGD、pH 和 DO 的组合来解释，这表现出高度的多重共线性。我们发现牡蛎密度和地下水通量之间存在总体负的非线性关系。有趣的是，地下水对幼鱼和成鱼的状况和生长没有负面影响。相反，我们的结果表明，密度-通量关系的可能机制是幼虫募集的中断，这也与通量呈负相关。我们假设幼虫中断是由于高通量地点地下水的低溶解氧和 pH 值条件。总体而言，SGD 和牡蛎之间的相互作用似乎很复杂，并且可能受其他变量的影响。