Modeling of degraded reefs in Leyte Gulf, Philippines in the face of climate change and human-induced disturbances
Received: 07 February 2017 / Accepted: 08 June 2017/ Published online: 07 August 2017
- Leyte Gulf coastal and marine ecosystems are in a depleted and overfished state.
- Ecopath models of LGR ecosystems suggests that super-typhoons (e.g., Haiyan) and human-induced disturbances will further degrade the ecosystem by decreasing biomass of coral reef-associated functional groups due to coral reduction or by increasing the number of lower trophic functional groups (e.g., herbivores) as productivity increases (i.e., eutrophication).
- There is a great need to develop systematic monitoring (e.g., biomass and diet composition changes of various functional groups) in LGR ecosystem to generate more local data towards improving the Ecopath models and the predictions of the functioning and dynamics of the Philippine reef ecosystems. This will help assess future ecosystem responses based on implemented management and conservation strategies.
Philippine reefs are mega-diverse but, to date, few ecosystem models have been developed to understand their dynamics and functioning. This study assessed the status of reefs in 12 municipalities of Leyte Gulf, Philippines. It is an important fishing ground experiencing degradation and impacts of super typhoons—the strongest one was Haiyan (local name: Yolanda). Empirical and literature data were used to develop Ecopath (trophic) models and Ecosim simulations to evaluate the impacts of reduction and increase in coral cover or productivity on the Leyte Gulf Reef (LGR) ecosystem. Results showed that the LGR’s ecosystem is in a degraded state—dominated by small-medium herbivores and carnivores, with most productivity immediately returned to detritus. In addition, a comparative study of two Ecopath models showed that reduction in the coral cover (e.g., by Super-Typhoon Haiyan) will result in a decline in biomass of many functional groups. Changes in LGR’s productivity (e.g., eutrophication) will also strongly impact most functional groups (e.g., shift to overdominance of herbivores that take advantage of algal growth and extirpation of coral reef-dependent species). Moreover, additional climate-related or human-induced disturbances on the degraded LGR will further decrease the reef’s productivity. Therefore, effective recovery and management of degraded reef ecosystems is needed to sustain the LGR’s productivity (e.g., reef fisheries production).
conservation, climate change, ecological modelling, fisheries, Philippine reefs
Barron Cedric A. Tan
Institute of Biology, College of Science, University of the Philippines-Diliman