An integrated ecosystem model for the coral reefs around Guam

Coral reefs worldwide are declining as a result of human-induced disturbance including fishing, coastal sedimentation, pollution and global climate change. To address these impacts it is necessary to diagnose and treat the drivers at multiple levels over space and time. Ecosystem models provide new tools for better understanding relationships between stressors and coral reef responses. They provide insight in determining the contributions of individual stressors in a multi-stressor system and on the cumulative effects of simultaneous stressors acting on reef ecosystems. This presentation will highlight a proof-of-concept coral reef ecosystem model developed for the reefs around Guam and discuss how this model can be a decision-support tool for management strategy evaluation by evaluating socio-ecological tradeoffs of alternative management policies based on performance indicators.

Short bio:

Mariska Weijerman came from Big Island to Oahu in 2009 when she joined NOAA. On the Big Island she worked as a Marine Ecosystem Researcher for the National Park Service and now she works at the new EOD division at PIFSC as a Coral Reef Ecology Researcher. She will defend her PhD thesis in ecosystem modeling on Sep 16, 2015 at the Graduate School for Socio-Economic and Natural Sciences of the Environment of Wageningen University & Research. She has spent her career studying various ecosystems from plant-animal relationships in the tropical rainforest in Guyana to sea turtles on the beaches of Suriname to various coral reef ecosystems in the Caribbean and now in the Pacific. She has worked closely with indigenous people, government officials, traditional leaders, scientists and students.

1: Effective coral reef management must be based on proper understanding of coral reefs as ecosystems and of the complex and synergistic impacts of different stressors including climate change whilst taking into consideration that humans are an integral part of the ecosystem. For example, additional input of sediments and nutrients from increased runoff  or reduced grazing due to fishing favor algal growth and algae will overgrow and kill reef-building corals, reduce settlement potential of coral recruits, and in the longer term reduce habitat complexity. A reduction in habitat complexity will result in less hiding places for small fishes and ultimately in a decline of fish biomass affecting not only the socio-economic important reef-fish fishery but also the resilience of reefs to disturbances. This could potentially lead to a shift in ecosystem state from coral-dominance to a less human-desirable algal-dominance.