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The study of the energetic relationships between primary sources and consumers of mangroves provides an understanding of the functioning of these ecosystems, which are of high ecological and economic importance. In order to compare the structure and trophic dynamics of mangroves with different physiographic configurations and latitudinal distributions in the Eastern Pacific (Panama Bight: PB and Gulf of California: GC), we used carbon and nitrogen isotopic data from three mangroves in the PB: fringe, in ner-riverine, and external-riverine, and from two mangroves in the GC: bar and lagoon. The isotopic composition, trophic position, isotopic niche, and trophic pathways were analyzed in each mangrove using the Trophic Position, SIBER and Simmr statistical packages, respectively. A total of 4518 ?15N and ?13C values were obtained, distributed between primary sources and consumers, which were classified in to six invertebrate and four fish trophic guilds. The food web components of the PB mangroves presented depleted 13C and 15N values with respect to those of the CG, and this pattern is maintained throughout the entire food webs. The trophic position of the consumers and the number of food web’s trophic positions (4 to 5) were similar among the five mangroves, with some variations especially between Fringe and External riverine with the other mangroves. The isotopic niche of the fish community was higher in GC mangroves with respect to PB. The distribution of invertebrate trophic guilds in the iso-space is similar but the niche varies between guilds and between study sites. As a general pattern five trophic pathways support mangroves food webs derive from several primary sources: (1) MPB via porcelain crabs, bivalves and deposit feeders that are mainly consumers of benthic microalgae. (2) Seston mainly via filter feeders and shrimps, which as an intermediary in the food webs act as predators of small fauna. (3) detritus connecting to polychaetes and benthic microfauna as a primary food source for invertebrate predators and cryptobenthic fish. (4) Mangroves, via herbivorous crabs, that as demonstrated both consume and assimilate mangrove leaves, are fundamental in connecting mangrove-derived carbon to other levels of the food web. This pathway involves bacteria to processes. (5) Macroalgae, whose function is less clear and requires future study, although it is suggested that they may be entering the food web via herbivorous crabs and some fish. These pathways potentially support fish species (third to fifth trophic position), which due to their movements in and out of the mangroves export energy from these ecosystems to the coastal and oceanic food webs. The present research provides a detailed view of the complexity and dynamism of mangrove food webs.
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