Benthic Monitoring

Coral-dominated reef benthos at Jarvis Island. NOAA Photo by Bernardo Vargas-Ángel.
Coral-dominated reef benthos at Jarvis Island. NOAA Photo by Bernardo Vargas-Ángel.

Benthos

Benthos refers to the community of organisms that lives in, on, or is somehow associated to the bottom of a reef. Given the great variety in the structure of coral reefs worldwide and the complex nature of physical and ecological processes that drive ecosystem changes, it is difficult to rely on a single metric when attempting to evaluate the status and long-term change of reef benthos. Therefore, as part of the Pacific Reef Assessment and Monitoring Program (Pacific RAMP), the benthic team of the Coral Reef Ecosystem Division (CRED) collects integrated information on benthic species composition (diversity), condition, abundance, size-structure, and distribution of these communities:

The benthic team also collects information on habitat complexity and substrate type. This combined use of community characteristics and functional attributes to detect change embodies the goals and objectives of the Coral Reef Conservation Program's National Coral Reef Monitoring Plan (NCRMP), which is designed to provide a consistent, long-term flow of information to assess and report the status and trends of environmental conditions, living reef resources, and processes that determine and interact with coral reef ecosystems. The CRED benthic team implements two principal methodologies to survey reef benthos: Rapid Ecological Assessment (REA) surveys, performed at selected hard-bottom locations with deployed transect lines as the focal point of these fine-scale surveys, and towed-diver surveys, which follow a depth contour of ~ 15 m. and encompass a broad variety of substrate types, and cover an area that is larger than the area surveyed using REA techniques. In addition, two types of monitoring installations, autonomous reef monitoring structures (ARMS) and calcification acidification units (CAUs), serve as mechanisms to quantify cryptic marine invertebrate diversity that is not easily identifiable during REA surveys and accretion rates of crustose coralline red algae and hard corals.

Scuba divers conducting benthic composition surveys at a Rapid Ecological Assessment (REA) site at Lehua Rock, Niʻihau. 
                 NOAA photo by Bernardo Vargas-Ángel.
Scuba divers conducting benthic composition surveys at a Rapid Ecological Assessment (REA) site at Lehua Rock, Niʻihau. NOAA photo by Bernardo Vargas-Ángel.
Algal-dominated benthos in the main Hawaiian Islands.
Algal-dominated benthos in the main Hawaiian Islands.