Environmental and Substrate Control on Paleozoic Bioerosion in Corals and Stromatoporoids, Anticosti Island, Eastern Canada

Abstract

Abstract Bioerosion was a common process affecting corals and stromatoporoids in reef and off-reef facies on the carbonate ramp that spanned the Ordovician–Silurian boundary on Anticosti Island. The probable worm boring Trypanites was the dominant macroboring, penetrating more than 40% of 2,500 massive tabulate corals and stromatoporoids examined, occasionally in dense concentrations. The frequency of macroboring was influenced by conditions at the facies level reflected by changes in grain size, water depth, storm reworking of sediments, and the nature of the skeletal mass bored. These factors regulated exposure time of the host-substrate surface to the watermass and thus influenced bioerosion. Bored specimens are most common in muddy off-reef facies, moderate in sandy off-reef facies, and less common in reefs. In off-reef facies, storm-enhanced deposition and reworking of sediments were most important in the burial of eligible host substrates. In reefs, the high competition for space by encrusting epizo...