Carbon sources supporting macrobenthic crustaceans in tropical eastern pacific mangroves

Abstract

In tropical mangroves, crustaceans are one of the most relevant components in terms of abundance, occurrence, biomass, function, and human welfare. Since these organisms are involved in the trophic dynamics of mangroves and also, are important fishery resources, the study of carbon used by crustaceans in mangrove ecosystems is important to understand the food web functioning of mangroves and estuaries, and how energy and matter flow through these organisms, via their participation in different trophic pathways. We compared the isotopic composition (δ13C/δ15N) of carbon sources and macrobenthic crustacean species of three macrotidal (fringe, internal and external riverine) mangroves, located in the central Colombian Pacific, and used a Bayesian aproached to evaluate if geomorphology induces differences in the isotopic composition and in the relative contribution of primary producers to different species of macrobenthic crustaceans. Differences were found in the isotopic composition between the three systems, with 13C values generally enriched for the external riverine mangrove, indicating a marine influence. The relative contribution of microphytobenthos with respect to other primary sources was highest in the three mangrove systems, followed by mangrove and seston in the internal and external riverine respectively, and macroalgae in fringe system. However, differences were found in the contribution of all sources depending on the species and type of mangrove but trophic pathways of the systems are the same. Our results confirm part of the hypothesis of this research, showing that geomorphological configuration of the habitat induces significative differences in the isotopic composition of primary sources and macrobenthic crustaceans but, the carbon utilization patterns of macrobenthic crustaceans show the same main trophic pathways (mangroves and microphytobenthos) in all three systems, due to the similar availability of carbon sources despite geomorphological differences.