National Coral Reef Monitoring Program: Bioerosion Monitoring Unit data from BMUs deployed at coral reef sites in Hawaiian Archipelago from 2016-08-07 to 2019-09-05. (NCEI Accession 0236235)

Ocean Acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems, nor how to accurately measure said manifestation. The term bioerosion refers to the biological destruction of hard structures, such as coral skeletons. On coral reefs, this process is the antithesis of coral calcification. If rates of bioerosion are higher than calcification, healthy reef habitats can erode into rubble and sand.
The erosion rates provided in this data set were collected from bioerosion monitoring units (BMUs) retrieved at existing long-term monitoring sites during NOAA Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) led NCRMP missions around the Hawaiian Archipelago.
This archive package contains BMU data from permanent long-term monitoring sites in Hawaiian Archipelago including the main Hawaiian Islands and the Northwestern Hawaiian Island area that were analyzed at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML), as part of the NOAA National Coral Reef Monitoring Program (NCRMP). BMUs are constructed from clean coral skeletons and left on the reef for a period of 3 years. This set of data is the third run of BMUs that has ever been produced during what was a testing phase of best practices, and as such, the protocol established at the time was shortly thereafter amended in order to give a more thorough picture of bioerosion rates. The majority of samples from this dataset were analyzed Siemens SOMATOM Volume Zoom MacroCT Scanner for pre and post deployment analysis. Two BMUs from this dataset use early analysis procedures at this stage utilized a benchtop 3D scanner (HDI Advance R2, 3D3 Solutions) for initial scans (pre-deployment) so will not have information for PreCTdensity. There was also unusually low retrieval this year due to storm activity in the area.
BMUs are CT scanned for changes in density, volume and mass in which rates of bioerosion can be assessed using Amira analysis software (Thermo Scientific). 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 data set were 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.