Mesophotic Coral Ecosystems

Chapter 6.

Threats to mesophotic coral ecosystems and management options Dominic Andradi-Brown , University of Oxford, UK Jack Laverick , University of Oxford, UK Ivonne Bejarano , University of Puerto Rico at Mayagüez, USA Thomas Bridge , Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University; Australian Institute of Marine Science, Australia Patrick L. Colin , Coral Reef Research Foundation, Palau Gal Eyal , Tel Aviv University; The Interuniversity Institute for Marine Sciences in Eilat, Israel

Rachel Jones , Zoological Society of London, UK Samuel E. Kahng , Hawai‘i Pacific University, USA John Reed , Harbor Branch Oceanographic Institute — Florida Atlantic University, USA Tyler B. Smith , University of the Virgin Islands, USA

Heather L. Spalding , University of Hawai‘i at Mānoa, USA ErnestoWeil , University of Puerto Rico at Mayagüez, USA ElizabethWood , Marine Conservation Society, UK

6.1. Introduction

MCEs are often considered to be buffered from many large-scale impacts known to directly affect shallow coral ecosystems, such as warm-water bleaching and tropical storms. Furthermore, by virtue of their depth, and in many cases their remote offshore locations, some MCEs are afforded greater protection from direct human impacts, such as overfishing and land-based runoff. However, there is increasing evidence to suggest that MCEs are vulnerable to

environmental disturbances, such as climate change impacts, overfishing, bottom fishing gear, capture of aquarium fish, precious coral trade, land-based pollution and invasive species (Table 6.1). Despite these threats, many MCEs are in good condition in comparison to their shallower counterparts. Strong management responses could mitigate at least some documented threats, thereby preventing future degradation of MCEs.

Table 6.1. Comparison of the major anthropogenic threats facing shallow-water reefs and MCEs.

Shallow-water coral reef ecosystems

Mesophotic coral ecosystems

• Fishing (overfishing, destructive fishing with dynamite and poison and damage from lost fishing gear) • Thermal stress (bleaching) from ocean warming • Diseases • Pollution (land-based) • Invasive species • Tourism and recreation • Anchor damage • Coral mining (for aggregate and lime) • Coastal development • Marine aquarium trade

• Fishing (overfishing and damage from lost fishing gear) • Thermal stress (bleaching) — reduced exposure to warm water stress • Diseases • Pollution — reduced exposure to land-based sources; exposed to deep-water sewage outfalls and dredging spoils • Invasive species • Tourism and recreation (reduced exposure) • Anchor damage (reduced exposure) • Coral mining (reduced to negligible exposure)

• Marine aquarium trade • Oil and gas exploration • Cables and pipelines

MESOPHOTIC CORAL ECOSYSTEMS – A LIFEBOAT FOR CORAL REEFS? 67

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