Abstract

Vessel groundings are a source of disturbance to coral reefs worldwide. Documenting the extent of damage caused by groundings is a crucial first step in the reef restoration process. Underwater landscape mosaics, created by merging thousands of downward-looking images, combine quantitative and qualitative aspects of damage assessment and provide a georeferenced, high-resolution, spatially accurate, permanent record of an injury. We present a landscape mosaic from a scar along the south coast of Puerto Rico created by a 289 m (920 ft) long liquefied natural gas tanker. This mosaic is contrasted with an earlier one acquired in the Florida Keys where a 15 m (49 ft) long vessel impacted 150 m2 of reef. In both cases mosaics enabled observations at a new spatial scale, had spatial accuracy comparable to GPS, and provided context for traditional, smaller scale observations. The technical challenges addressed during the creation of these two mosaics were, first, combining individual mosaics to cover larger areas, second, removing wave-focused light artifacts, and third, color correcting multiple image sets.

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