Linking terrigenous sediment delivery to declines in coral reef ecosystem services.

Abstract

Worldwide coral reef conditions continue to decline despite the valuable socio-economic benefits of these ecosystems. There is growing recognition that quantifying reefs in terms reflecting what stakeholders value is vital for comparing inherent tradeoffs among coastal management decisions. Terrestrial sediment runoff ranks high as a stressor to coral reefs and is a key concern in Puerto Rico where reefs are among the most threatened in the Caribbean. This research aimed to identify the degree to which sediment runoff impacts production of coral reef ecosystem services and the potential for watershed management actions to improve these services. Ecosystem service production functions were applied to map and translate metrics of ecological reef condition into ecosystem services production under a gradient of increasing sediment delivery. We found that higher sediment delivery decreased provisioning of most ecosystem services, including ecosystem integrity, bioprospecting discovery, and reef-based recreational opportunities and fisheries production. However shoreline protection and services with a strong contribution from non-reef habitats (e.g., mangroves, seagrasses) were higher in locations with high sediment delivery, although there was a strong inshore effect suggesting the influence of distance to shore, depth, and inshore habitats. Differences among services may indicate potential tradeoffs and the need to consider habitat connectivity, nursery habitat, accessibility, and sediment buffering. The relationships we have identified can be used to link stakeholder values to decision alternatives to ensure continued provisioning of these services and the well-being of communities.