Tidal flats play an essential role in the global carbon cycle. Intertidal environments are very dynamic and have several erosive landforms such as tidal depressions (TD), although TD genesis is still poorly understood. The tidal flats of the Bahía Blanca Estuary (BBE) are ideal for TD’s study since they are hardly altered by human activity. In this site is possible to distinguish a gradation from a non- bioturbed zone to one dominated by erosive landforms. This preliminary study aims to determine the origin and evolution of TD in tidal flats and evaluate their role as carbon sinks based on an integrated sedimentological and geomorphological study. We found that the origin of TD in siliciclastic tidal flat is associated with the activity of the Neohelice granulata crabs. N. granulata selects finer particles and organic matter to build burrows; also alter the physical properties of the sediment. The loss of sediment structure by the increase in the density of excavations added to the tidal dynamics favour the burrows's collapse giving rise to the tidal depression. Tidal dynamics affect sediment stability by exerting a hydrostatic pressure on the burrow when flooding and emptying of burrows. The effect of N. granulata in the sediment record is clearly identifies by an increase water content with a decrease in the sediment density. Furthermore, it is possible to identify changes in the grain size distribution curves of the typical tidal flat facies as a second mode at 10 μm. These features can be recognised and used as a tool to identify TD in the geological record. TD with occluded crab burrows can be important organic carbon sinks due to the organic matter fixation under suitable conditions that delay its decomposition. Due to the large number of TD (of the order of 35 million), we estimated that the C sequestration by these landforms might be of the order 1.8 × 10^–3 Gtn without considering that may be stored directly on the tidal flats themselves.

滩涂在全球碳循环中起着至关重要的作用。潮间带环境非常动态，并具有一些侵蚀性地形，例如潮汐洼地（TD），尽管对TD的成因仍然知之甚少。巴伊亚布兰卡河口（BBE）的滩涂是TD研究的理想之选，因为它们几乎不受人类活动的影响。在这个站点中，可以区分出从非生物扰动区到侵蚀性地貌为主的渐变。这项初步研究旨在确定潮滩中TD的起源和演变，并基于综合的沉积学和地貌学研究评估其作为碳汇的作用。我们发现，TD在硅质碎屑滩涂中的起源与新鳞片蟹的活动有关。颗粒猪笼草选择更细的颗粒和有机物来挖洞；也会改变沉积物的物理性质。潮汐动力学增加了开挖密度，使沉积物结构丧失，有利于洞穴的塌陷，从而引起潮汐洼地。潮汐动力学通过在淹没和排空洞穴时在洞穴上施加静水压力来影响沉积物的稳定性。颗粒状猪笼草的影响通过增加水含量和减少沉积物密度，可以清楚地识别出沉积物中的污染物。此外，有可能将典型潮汐相的晶粒尺寸分布曲线的变化识别为10μm的第二种模式。这些特征可以被识别并用作在地质记录中识别TD的工具。由于在合适的条件下将有机物固定在可延缓其分解的作用下，因此具有封闭蟹穴的TD可能是重要的有机碳汇。由于大量的TD（约3500万个），我们估计这些地貌的固碳量可能为1.8×10 ^{– 3} Gtn量级，而没有考虑可能直接存储在滩涂上。