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Overall Assessment of the Condition and Health of Guam's Coral Reefs

Scientists' assessment of the health of Guam's coral reef ecosystems has not significantly changed in the years between the 2005 and 2008 The State of Coral Reef Ecosystems of Guam reports (Porter et al. 2005, Burdick et al. 2008). The health of Guam's coral reefs is highly variable across the island. Due to multiple stressors, some reefs show signs of poor health, while others appear to be relatively healthy with thriving reef communities. However, long-term monitoring programs have only recently begun, and baseline data are incomplete, making it difficult to objectively assess the actual health of the reefs. In general, coral reefs in the northern parts of the island that are sufficiently distant from river outflows appear to be in better condition than those in the south, which can be subject to higher nutrient levels because of groundwater discharge. In fact, large sections of coral reefs in the south that are close to river mouths are in fair to poor condition. Several other areas, which were otherwise healthy with high percentages of live coral cover, have been heavily impacted by Crown-of-thorns starfish (COTS) outbreaks.

Green Sea Turtle in the Tumon Bay Marine Preserve, Guam
Green Sea Turtle in the Tumon Bay Marine Preserve, Guam (Photo: David Burdick)

In recent years, Guam has made a great deal of progress in the protection and conservation of its coral reef ecosystems. The Guam Coral Reef Initiative Coordinating Committee (GCRICC) and a network of cooperating local and federal agencies, non-governmental organizations, academia, private enterprises, and concerned citizenry have partnered in addressing threats to Guam's coral reefs. Through monitoring and research programs, education and outreach activities, enforcement of existing conservation policies, implementation of new policies, establishment of marine protected reserves, watershed management, and erosion control programs, Guam is working to better the health and productivity of its reef ecosystems. Marine areas that are protected have seen significant increases in fish abundances, especially as the growth of suffocating macroalgae has been well controlled in some locations.

Although significant progress has been made in recent years, many challenges remain. The stressors affecting Guam's coral reef ecosystems are increasing with the likelihood of their continued amplification in the future. The abundance of medium and large reef fishes, especially herbivores, is very low compared with other islands in the Marianas Archipelago. Poor water quality and low coral recruitment may decrease the coral reefs' resiliency to recover from future ecological trauma. Pollution, coral diseases, COTS outbreaks, and factors leading to bleaching are also serious stressors.

A proposed major military build-up in Guam could have very serious consequences for Guam's shallow-water coral reefs. In addition to a new Marine base and airfield, the buildup includes port dredging for a nuclear-powered aircraft carrier, which would impact 71 acres of a coral reef. The military also wants to build a Marine firing range on property that includes one of the last undeveloped beachfront forests on Guam. This military buildup would also overtax Guam's sewage-treatment systems and could result in island-wide water shortages.

Wildland fires started by poachers also pose a continuing threat. Restoration of native vegetation in affected areas needs to be accelerated. The threat posed by global climate change is particularly troubling. The ability of Guam's coral reefs to cope with coral bleaching, ocean acidification, and stronger storms will set the stage for their future health and vitality.