Young does not mean unstable: a trophic model for an estuarine lagoon system in the Southern Mexican Pacific

A trophic model is presented for the coastal lagoon system Chantuto-Panzacola, Southern Pacific Mexico, with the aim of estimating its degree of development and functionality. Thirty-four functional groups (one for birds, one crocodilians, 20 fishes, nine zoobenthos, two plankton, one detritus) were analyzed using Ecopath's approach, with species biomass, diet composition, and data of species' production and consumption. Diet was examined from stomach contents for the 39 most abundant fish species, the rest being determined from literature. Detritus was the most important component of the ecosystem in terms of biomass and flows, whereas diverse groups of zoobenthos linked detritus to upper functional groups. Consumers' trophic level fluctuated between 2.00 and 4.08, with crocodilians as top predators. The size of the system, in terms of matter flows, was 7,133gm(-2)year(-1); this value was greater than those recorded in other estuarine systems. Chantuto-Panzacola has a short geological age and is in an intermediate development stage; however, its youth and immaturity are accompanied by attributes which confer stability and environmental health, such as high productivity, high omnivory, and a great reserve potential that the system uses to face disturbances (overhead). The quality of the model was relatively high with respect to others.