National Coral Reef Monitoring Program: Erosion data from bioerosion monitoring units (BMUs) deployed at select coral reef sites in the Pacific Ocean

The erosion rates provided in this collection were gathered from bioerosion monitoring units (BMUs) retrieved at existing long-term monitoring sites at Wake Island and the Hawaiian and Mariana Archipelagos during NOAA Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) led National Coral Reef Monitoring Program (NCRMP) missions. The samples were analyzed at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML), as part of NOAA's ongoing NCRMP. BMUs are constructed from clean coral skeletons and left on the reef for a period of 3 years. This collection of data contains the first run of BMUs that has ever been produced, and as such, the protocol established at the time was shortly thereafter amended in order to give a more thorough picture of bioerosion rates. Early analysis procedures utilized a benchtop micro computed tomography scanner (microCT, Bruker) for initial scans (pre-deployment), while post collection analyses (including those in this collection) were analyzed by a larger Computed Tomography device (CT scanner, Siemens).

BMUs are CT scanned for changes in density, volume and mass in which rates of bioerosion can be assessed. Annual erosion and accretion rates can be determined from these data in terms of loss of reef structure volume as well as mass in grams of calcium carbonate. Accretion rates given in this collection are determined by finding the volume of non-original carbonate material found on the external surface of the BMUs divided by the number of years the BMU was deployed on the reef. These rates can detect accretion signals when calcifying organisms, such as corals or algae, have grown on their exteriors. Rates of macroboring were determined by changes in the internal volume of the BMUs (e.g., that removed by bore holes) divided by the number of years the BMU was deployed on the reef. Macroboring can occur from eroders such as clionaid sponges, annelids and other macroboring fauna.