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Physiological and ecological consequences of the water optical properties degradation on reef corals

Published Article

Colombia, Caribbean

Publication date: June 19, 2021

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This study shows how anthropogenic degradation of water optical properties reduces light penetration, limiting photosynthetic energy in Orbicella faveolata. Corals develop low-light phenotypes, experience energy loss, and face mortality and habitat compression, highlighting the importance of water quality for reef survival and ecosystem services.

Subject Tags

  • Reefs

Abstract

Degradation of water optical properties due to anthropogenic disturbances is a common phenomenon in coastal waters globally. Although this condition is associated with multiple drivers that affect corals health in multiple ways, its effect on light availability and photosynthetic energy acquisition has been largely neglected. Here, we describe how declining the water optical quality in a coastal reef exposed to a turbid plume of water originating from a man-made channel compromises the functionality of the keystone coral species Orbicella faveolata. We found highly variable water optical conditions with significant effects on the light quantity and quality available for corals. Low-light phenotypes close to theoretical limits of photoacclimation were found at shallow depths as a result of reduced light penetration. The estimated photosynthetically fixed energy depletion with increasing depth was associated with patterns of colony mortality and vertical habitat compression. A numerical model illustrates the potential effect of the progressive water quality degradation on coral mortality and population decline along the depth gradient. Collectively, our findings suggest that preserving the water properties seeking to maximize light penetration through the water column is essential for maintaining the coral reef structure and associated ecosystem services.

Keywords: Optical properties; Light limitation; Photo acclimation; Orbicella faveolata; Turbidity; Urban reefs; Mortality; Habitat compression

Citation

López‑Londoño T; Galindo‑Martínez CT; Gómez‑Campo K; González‑Guerrero LA; Roitman S; Pollock FJ; Pizarro V; López‑Victoria M; Medina M; Iglesias‑Prieto R (2021). Physiological and ecological consequences of degraded water optical properties on reef corals. Coral Reefs 40(4): 1243–1256.

TNC Authors