Regional diversity and spatial patterns of epibenthic communities in the Laurentian Channel Marine Protected Area

Abstract

Megafauna, such as cold-water corals, can promote diversity through various processes, such as predation, bioturbation, competition, and facilitation as habitat engineers. Further investigation into their ecology and role in epifaunal community structure in the deep sea is needed. Diversity, abundance, and spatial patterns of epibenthic megafauna (≥2 cm) were quantified at regional-scales (100 s m – 100 s km) using high-resolution imagery from 15 stations in the Laurentian Channel Marine Protected Area, Canada. A patchy community structure was significantly associated with station and benthoscape class, which in turn was based on geological factors. Three types of assemblages included: (1) dominated by corals Pennatula sp. 2 and/or Hexacorallia (SC.) spp. in shallow eastern benthoscape classes with high abundance and low diversity; (2) a diverse mix of taxa (e.g. sea pens Anthoptilum spp. and Kophobelemnon spp., anemones/cerianthids, etc.) in deeper (>400 m) western benthoscape classes, with low abundance and high diversity; and (3) a unique community dominated by sponges. Overall, eight taxa contributed to most dissimilarities between stations, and communities were similar within 10 km but could differ at greater distances. Benthoscape classes captured environmental factors (e.g. depth and substrate) that may be responsible for changes in diversity and abundance, and are used as a proxy for different habitats. Our study advanced the understanding of regional spatial patterns in the abundance, composition, and diversity of epibenthic communities, by identifying spatial patterns particularly in the Laurentian Channel where data were limited, adding to interpretations of spatial ecology in a previous fine-scale study. Additionally, these spatial patterns reflect various underlying ecological processes that are mostly unknown. Our community analysis and observed changes in abundance and diversity have implications that can help inform future monitoring designs to promote representative and meaningful spatial assessments.