Trophic network structure and dynamics simulations of the rocky–reef ecosystem of Yelapa, Mexican Pacific

Abstract

Background. Ecological Network Analysis has been used for defining aspects concerning the structure, health, and dynamics of marine ecosystems. Objectives. Evaluate the ecosystem’s structure, organization, and matu-rity in the shallow rocky reef ecosystem in Yelapa. Also, we determine the most affected functional groups by disturbances simulated and those which generate less resilience in the ecosystem. Methods. A mass-balan-ce trophic model Ecopath with Ecosim, was constructed, and Ascendency›s theory was used to evaluate the ecosystem properties. A Mixed Trophic Impacts matrix was used to assess direct and indirect trophic effects on the network. The functional groups more sensitive to disturbances were determined using Ecosim dynamics simulations in the short and long term with two mortality scenarios (an increase of 25 % and 50 %). Finally, the System Recovery Time was used as a measure of resilience. Results. The Yelapa rocky-reef ecosystem ex-hibits the feature of a mature, organized, and developing ecosystem but is less resistant to disturbances. Several fish groups, zooplankton, and phytoplankton produced the most remarkable effects in the trophic network. In addition, the phytoplankton, chlorophyta, and the group of other benthic invertebrates propagated more effects on other model components. Conclusions. Yelapa rocky reef would lose resilience if the functional groups eels & morays, other benthic invertebrates, snappers, and phytoplankton were disturbed.