Primary Sources and Food Web Structure of a Tropical Wetland with High Density of Mangrove Forest

Victor M Muro-Torres,Lucinda Green,Martin Soto-Jiménez,Jana Rajnohova,Elisa Serviere-Zaragoza,Eduardo F Balart,Felipe Amezcua

doi:10.3390/w12113105

Abstract

The trophic ecology of wetlands with mangrove forests remains poorly understood. Through the use of stomach contents analysis, stable isotope signatures, and Bayesian mixing models, the food web of a tropical wetland in the gulf of California was investigated. Consumers had heterogeneous diets, omnivores were the most abundant species (47%), followed by planktivorous (21%), minor piscivores (10%), major piscivores (10%), macrobenthivores (9%), and herbivores (3%). The values of δ13C (from −12 to −29‰) and δ15N (from 4 to 24‰) showed a wide range of isotopic values of the consumers. Most of the species had a broad isotopic niche and there was a large diet overlap of species due to the exploitation of a common set of food resources. Five trophic levels were identified, with the weakfish (Cynoscion xanthulus) as the top predator of this system with detritus coming from the mangrove as the main source that supports the food chain. This highlights the importance of the mangrove forests to such ecosystems, because not only they are the most important primary food source, but also, they offer habitat to a large suite of fauna, which are important components of the trophic chain.

Highlights

Tropical wetlands with mangrove forests are highly threatened socio-ecological systems, where local communities rely heavily on aquatic animal protein, to meet food security [1]
We propose the hypothesis that the direct contribution of the mangrove forests is low in comparison to the different primary sources that sustain the food web of this ecosystem, and that the mangroves play an important role because of their structural complexity, which is essential for many species of fish and macroinvertebrates which eat and prey within this mangrove structure
Primary sources collected included phytoplankton, detritus/seston, two mangrove species the 70%, the restmangle was composed by euphausiids, larvae, and siphonophores), (Rizophora and Laguncularia racemosa), andchaetognatha, three species offish macroalgae (Gracilaria vermiculophylla, Caulerpa sertularoides, and Ulva lactuca)

Summary

Introduction

Tropical wetlands with mangrove forests are highly threatened socio-ecological systems, where local communities rely heavily on aquatic animal protein, (such as fish and crustaceans), to meet food security [1]. These systems are biologically productive with a high rate of primary productivity supporting a high species diversity and exhibiting complex trophic webs [2,3,4] and have long been recognized to be major nursery areas for numerous commercially and ecological important consumers as fish, crustaceans, etc. Other research indicates that carbon derived from mangroves is less important as an energy source for aquatic food webs in comparison to other primary sources [15,16,17,18,19,20,21].

Objectives

Methods

Results

Discussion

Conclusion