Subsurface mixing of seawater and terrestrial-borne meteoric waters on carbonate landscapes creates karst subterranean estuaries, an area of the coastal aquifer with poorly understood carbon cycling, ecosystem functioning, and impact on submarine groundwater discharge. Caves in karst platforms facilitate water and material exchange between the marine and terrestrial environments, and their internal sedimentation patterns document long-term environmental change. Sediment records from a flooded coastal cave in Cozumel Island (Mexico) documents decreasing terrestrial organic matter (OM) deposition within the karst subterranean estuary over the last ~1000 years, with older sediment likely exported out of the cave by intense storm events. While stable carbon isotopic values (δ13Corg ranging from −22.5‰ to −27.1‰) and C:N ratios (ranging from 9.9 to 18.9) indicate that mangrove and other terrestrial detritus surrounding an inland sinkhole are the primarily sedimentary OM supply, an upcore decrease in bulk OM and enrichment of δ13Corg values are observed. These patterns suggest that a reduction in the local mangrove habitat decreased the terrestrial particulate OM input to the cave over time. The benthic foraminiferal community in basal core sediment have higher proportions of infaunal taxa (i.e., Bolivina) and Ammonia, and assemblages shifted to increased miliolids and less infaunal taxa at the core-tops. The combined results suggest that a decrease in terrestrial OM through time had a concomitant impact on benthic meiofaunal habitats, potentially by impacting dissolved oxygen availability at the microhabitat scale or resource partitioning by foraminifera. The evidence presented here indicates that landscape and watershed level changes can impact ecosystem functioning within adjacent subterranean estuaries.

中文翻译：

---

有机质沉积的变化会影响喀斯特地下河口底栖海洋动物群

碳酸盐岩景观上的海水和陆地传播的地下水在地下的混合形成了喀斯特地下河口，这是一个海岸带水域，人们对碳循环，生态系统功能以及对海底地下水排放的影响了解得很少。岩溶平台中的洞穴促进了海洋和陆地环境之间的水和物质交换，并且它们的内部沉积模式证明了长期的环境变化。来自墨西哥科苏梅尔岛一个被洪水淹没的沿海洞穴的泥沙记录表明，在过去约1000年中，喀斯特地下河口内的陆地有机物（OM）沉积减少，并且由于强烈的风暴事件，较旧的沉积物很可能从洞穴中排出。碳同位素值稳定（δ13Corg为-22.5‰至-27.1‰）和C：N比（范围为9.9至18）。9）表明，内陆污水坑周围的红树林和其他陆地碎屑是主要的沉积性有机质供应，整体有机质的上层下降和δ13Corg值的富集被观察到。这些模式表明，随着时间的流逝，当地红树林生境的减少减少了向该洞穴输入的地面颗粒物OM。基础核心沉积物中的底栖有孔虫群落中，非生物分类群（即玻利维纳）和氨的比例较高，并且组合转移到增加的粟粒类动物和较少的非生物分类群。综合结果表明，随着时间的推移，陆地OM的降低对底栖的动植物的生境产生了伴随的影响，这可能是通过影响微生境规模上的溶解氧供应或有孔虫的资源分配而造成的。