Coral reefs in the War in the Pacific National Historical Park have incredible biodiversity

An astounding number of organisms make their homes on the coral reefs of War in the Pacific National Historical Park in the waters of Guam—in fact, more species of corals, fish, and invertebrates live on these reefs than on the coral reefs of Hawaii or Samoa. This incredible biodiversity makes for an amazing and complex ecosystem. On Guam reefs, you will find herbivores such as kichu, (convict tangs), and palakse (bullethead parrotfish), and predators such as Iʻe (jacks) or gadao, (groupers). Traditionally, these fish were an important part of the Chamorro diet, and are still fished for food today. The diversity of the plants and animals found on these reefs is rarely matched anywhere in the world.

Though there is high coral diversity, few juvenile corals are growing on the reef

map of War in the Pacific National Historical ParkNumber of units: 7
Total area: 2,037 acres
Marine area in park: 1,002 acres

In addition to historical resources, this park also contains over 1,000 acres of marine ecosystems. At War in the Pacific National Historical Park, acres of fringing coral reefs provide shelter and food for a wide diversity of corals and fish. Yet, scientists have observed a decrease in the number of new or juvenile corals on the reef. Monitoring suggests that low coralline algae cover (4%) could be one cause of this decrease in juveniles (NPS 2009). Corals settle and grow on coralline algae, and when there is not appropriate algae cover, fewer corals can grow. In this park, low coralline algae cover may be connected to low live stony coral cover (10%; NPS 2009). If the number of juvenile corals does not increase, live stony coral may become increasingly rare on these reefs.

Cover refers to the space covered by a particular organism on a reef or seafloor when viewed from above. Scientists often use  changes in coral cover over time to monitor the overall health of a coral reef.

pie chart of coral cover at War in the Pacific National Historical ParkGun Beach reef, Guam


table of physical features of parkWar in the Pacific National Historical Park

Since climate and geology play such an important role in coral reef health, scientists monitor conditions on land and on reefs. As climate change continues, scientists will study how changes in climate result in changes on the reef. For example, wet and dry seasons determine how much sediment is washed from land onto the reef. More rain means more sediment is transported to the ocean and blocks light to coral. In the face of climate change, the number of heavy rain storms and typhoons may increase and may even occur year round (Global Climate Change Impacts in the United States 2009). More frequent heavy rain storms would deliver larger amounts of sediments to coral reefs.