Modeling trophic flows in the wettest mangroves of the world: the case of Bahía Málaga in the Colombian Pacific coast

Abstract

The structurally most developed Neotropical mangrove forests are found along the southern and central macrotidal Colombian Pacific coast. This extremely rainy area (>7,000 mm year−1) is sparsely populated and sustains a relatively small artisanal fishery. In this article, we present an ecosystem (trophic) model, built using Ecopath with Ecosim, containing 18 functional groups of a representative mangrove area of this coast. Similar to other mangrove ecosystem models, mangroves contribute most (96%) to total system biomass, providing the primary food source for other important compartments (e.g., crabs). However, most of the mangrove litterfall is constantly washed away by tidal currents, a possible reason for the very low mean transfer efficiencies to higher trophic levels and low biomass of epifauna and nekton found, compared with other Neotropical mangroves. Fish biomass is dominated by zoobenthivores (snappers, catfishes) and detritivores (mullets) which represent, together with mangrove cockles, the target resources of a low trophic level-based fishery. Very low salinities throughout the year may contribute to an impoverished community of primary and secondary consumers that is able to withstand but not flourish under these conditions. This mangrove ecosystem may be highly vulnerable to overexploitation according to the low energy reserve (overhead) of the system.