Does food partitioning vary in leaf-eating crabs in response to source quality?

Mangroves have a relevant ecosystem function due to their efficiency in blue carbon sequestration. Autotrophic carbon conservation in mangroves remains controversial. In this sense, autotrophic nutrient assimilation by crabs can highlight their ecosystem function. This study aims to identify the relationship between quality sources and food partitioning in two leaf-eating crabs, Ucides cordatus and Goniopsis cruentata. Quantification of the litterfall biomass, analysis of the soil, the C/N ratio and stable isotopes (δ13 C and δ15 N) were used to evaluate food sources and crab tissues in two mangrove forests. The litterfall and soil C contents and C/N ratios of the Pacoti River (PR) were higher than those of the Jaguaribe River. The higher C/N ratios of the litterfall of the PR led to higher nitrogen ingestion from complementary food sources (soil and omnivorous invertebrates). The nutritional requirements and food partitioning behavior of both species emphasize the ecosystem functions of leaf-eating crabs concerning the assimilation and conservation of autotrophic carbon and nitrogen in mangroves.