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In 2003, a large Lophelia pertusa reef complex was discovered on the southeast edge of the Scotian Shelf, representing the only known cold-water coral reef in Canada. Extensive damage to the reef from bottom fishing activities was apparent, which resulted in the establishment of the 15-km2 Lophelia Coral Conservation Area (LCCA) in 2004 to prevent further damage and allow recovery. Since 2004, the effectiveness of the LCCA in achieving these objectives has never been assessed. Through the analysis of benthic images collected in 2003, 2009, and 2015, we evaluated the effectiveness of the LCCA in terms of its success in facilitating the recolonization and recovery of its target species, L. pertusa, and in conserving local benthic biodiversity. Using multivariate community analyses and generalized linear modelling techniques, we compared changes in the diversity, abundance, and composition of epibenthic megafauna within and outside its boundaries over the 12-year period. We observed an increase in epibenthic megafaunal species density and abundance over time that was higher inside the closure than outside, suggesting that the LCCA has facilitated the recruitment and recovery of the benthic communities within its confines. While recruitment of L. pertusa was low, the recent discovery of numerous undisturbed large mounds of live L. pertusa establishes a local recruitment source, a prerequisite for the reef structure to recover to its pre-disturbed state. We recommend that monitoring of the reef structure occur every 7–10 years to evaluate the settlement and growth of L. pertusa and the other deep-water corals that reside there.

Emerald Basin on the Scotian Shelf off Nova Scotia, Canada, is home to a globally unique aggregation of the glass sponge Vazella pourtalesi, first documented in the region in 1889. In 2009, Fisheries and Oceans Canada (DFO) implemented two Sponge Conservation Areas to protect these sponge grounds from bottom fishing activities. Together, the two conservation areas encompass 259 km2. In order to ascertain the degree to which the sponge grounds remain unprotected, we modelled the presence probability and predicted range distribution of V. pourtalesi on the Scotian Shelf using random forest modelling on presence-absence records. With a high degree of accuracy the random forest model predicted the highest probability of occurrence of V. pourtalesi in the inner basins on the central Scotian Shelf, with lower probabilities at the shelf break and in the Fundian and Northeast Channels. Bottom temperature was the most important determinant of its distribution in the model. Although the two DFO Sponge Conservation Areas protect some of the more significant concentrations of V. pourtalesi, much of its predicted distribution remains unprotected (over 99%). Examination of the hydrographic conditions in Emerald Basin revealed that the V. pourtalesi sponge grounds are associated with a warmer and more saline water mass compared to the surrounding shelf. Reconstruction of historical bottom temperature and salinity in Emerald Basin revealed strong multi-decadal variability, with average bottom temperatures varying by 8°C. We show that this species has persisted in the face of this climatic variability, possibly indicating how it will respond to future climate change.