What drives the distribution of crab burrows in different habitats of intertidal salt marshes, Yellow River Delta, China

Crabs play important roles in coastal ecosystems and are useful indicators for evaluating ecosystem health. Many previous studies have examined the distribution patterns of crabs among different habitats. However, we know little about what the key factors determining crab burrow distribution among types of habitats. Different kind of crab species may have different preferences of environmental conditions, here, we focus on the dominant crab species Helice tientsinensis in the Yellow River Delta. To identify the drivers of crab burrow distribution in intertidal marshes of the Yellow River Delta, we examined crab burrow density among seven habitats across different marsh zones, with reference to abiotic (water depth, soil hardness, water content, bulk density, porewater salinity, organic matter, total nitrogen and total carbon) and biotic (plant coverage, above- and belowground biomass, macrofauna species richness, abundance and biomass) factors that might explain crab burrow distribution patterns. Differences of all above factors were examined by one-way Analysis of Variance (ANOVA) among different habitats. The best single predictors of crab burrow density were tested by liner regression across the entire study area. Our results showed that patterns of crab burrow distribution were more strongly affected by abiotic drivers (water depth, water content, salinity, soil hardness, organic matter and total carbon) than biotic drivers. Crabs prefer habitats with softer and wetter edaphic conditions. In the future of coastal management, building habitats first, thereafter attracting crabs settling down and regulating feeding area of water birds and other benthic communities are good strategies to follow.