Influence of Crab Burrow Morphology on Soil Water and Salt Transport Processes in Salt Marsh Wetlands of the Yellow River Delta

Examining the influence of crab burrows on water and salt transport processes under tidal conditions holds substantial theoretical and practical significance for the preservation and rehabilitation of salt marsh wetlands based on ecological processes in the Yellow River Delta. This study employed both field research and indoor experiments to investigate the morphology and distribution patterns of crab burrows in the intertidal zone. Moreover, the study aimed to assess the impact of crab burrow morphology on water-salt transportation under tidal action. The results show that: (1) The density of crab burrows in three tidal creeks varied under the influence of tides, with respective values of (15.50±4.65), (12.90±2.69) and (6.60±2.76) per 0.25 m². (2) By simplifying and categorizing the resin model of the crab burrows, five main morphologies I-type, L-type, S-type, X-type, and Y-type accounted for 85.7% of the 42 crab burrows collected. (3) Although no significant difference was observed in the trend of soil water content change for different crab burrow morphologies, soil conductivity exhibited varying increase and decrease processes during high and low tides. (4) Under the influence of tides, the quantity of tidal water infiltration and pore water discharge in the control experimental group was markedly lower than that in the experimental group with crab burrows. Notably, L-shaped burrows facilitated increased pore water discharge during the stable period due to their water storage capability. (5) Different crab burrow morphologies significantly impacted soil salt excretion, with the highest amount of salt excretion occurring in groups S2, X and I, and the lowest in the blank group which only excreted (0.403±0.003) g·d^-1. These results underscore the eco-hydrological importance of crab burrows and provide valuable insights for future studies on eco-hydrological processes in coastal wetlands.