CRED REA Line Point Intercept Surveys of Benthic Parameter Assessments at Aguijan Island, Marianas Archipelago in 2009

REA surveys are investigations that provide a high degree of taxonomic resolution for coral, algae, other macroinvertebrate, and reef fish communities. The surveys were conducted using a combination of dive teams which generally included a two to three person fish team, a two person coral/coral disease team, and a combined team of two algae biologists and one macroinvertebrate biologist. The majority of REA surveys were conducted along the forereef slopes of individual islands at depths between 10 and 20 m. However, additional surveyed habitats included a lagoonal-type patch reef and offshore oceanic banks. During REA surveys, biological assessment teams follow highly structured protocols that are repeated at each REA site. Upon arrival at an REA site, three teams of divers enter the water over spaced time intervals. The fish team firstly enters the water and deploys a 25-m transect line. Two of the fish divers begin to survey along that transect while the remaining fish diver begins stationary point count assessments in the general vicinity. After approximately 20 min, the coral team enters the water and begins to work along the first transect line. By this time the fish team has deployed and begun surveys along a second 25-m transect. About 10 min later, the algal/invertebrate team enters the water and begins surveying the first transect. In total, the fish team surveys three transects at each site (transects 1, 2, and 3), and the coral and algal/invertebrate teams survey transects 1 and 2. The sampling effort takes between 60 and 80 min to complete. The selection of REA sites was made in close consultation with Coral Reef Advisory Group (CRAG) and local agencies. Factors considered during REA site selection included: (1) ensuring a range of sample sites representative of the benthic and reef fish habitats around each island; (2) selecting a mixture of sites within and outside of marine protected areas; (3) selecting a mixture of both 'impacted' and 'least impacted' sites; (4) selecting some sites adjacent to local villages, and (5) selecting a number of sites that could be compared to and complement previous assessment and monitoring work as well as future coral reef monitoring proposed by CRAG and local agencies. It is important to note that access to REA sites can be limited by wave exposure, weather conditions, and other environmental factors such as currents, which can affect the ability to resurvey sites between years. Transect placement was guided by: (1) a focus on hard-bottom communities; (2) deploying lines along an isobath to the extent possible at each site, and (3) laying the transect lines into the prevailing current.