A record of recent change in terrestrial sedimentation in a coral-reef environment, La Parguera, Puerto Rico: A response to coastal development?

Abstract

Increased sediment flux to the coastal ocean due to coastal development is considered a major threat to the viability of coral reefs. A change in the nature of sediment supply and storage has been identified in a variety of coastal settings, particularly in response to European colonization, but sedimentation around reefs has received less attention. This research examines the sedimentary record adjacent to a coastal village that has experienced considerable land-use change over the last few decades. Sediment cores were analyzed to characterize composition and sediment accumulation rates. Sedimentation rates decreased seaward across the shelf from 0.85 cm y −1 in a nearshore bay to 0.19 cm y −1 in a fore-reef setting. Data reflected a significant (up to 2×) increase over the last ∼80 years in terrestrial sediment accumulating in the back-reef setting, suggesting greater terrestrial sediment flux to the area. Reef health has declined, and increased turbidity is believed to be an important impact, particularly when combined with additional stressors.