Fine-scale spatial patterns of deep-sea epibenthic fauna in the Laurentian Channel Marine Protected area

Abstract

Ecological processes at local to global scales impact spatial patterns in abundance and distribution of megafauna. Fine-scale patterns have rarely been investigated through explicitly spatial analytical methods in the deep sea and have been assumed random, uniform, or similar to neighbouring areas. We used spatial statistics (Moran's I, Gi*, and local Moran's I) to identify significant megafaunal patterns (0–100s of meters; 8 focal taxa) in the Laurentian Channel Marine Protected Area, based on imagery from a remotely operated vehicle, using 8 parallel transects at each of 7 stations. Our results included 2 spatial scales, station level (0.256 km2) and paired transect level (0.004 km2). We found local areas with significant aggregations (e.g., Pennatula sp. 2 and Hexacorallia (SC.) spp.) and patches extending for ∼7–27 m, and in one case for ∼155 m. Patchiness also existed between neighbouring images (≤10 m apart). Patterns varied among taxa within stations and for the same taxon among transect pairs. Station-level patterns appear to be related to geological factors, such as BPI (bathymetric position index), benthoscape, pockmarks, and slope. We propose that patterns at the transect level were likely caused by biological factors, possibly related to reproduction due to local currents and retention, or community interactions (e.g., competition). Fine-scale patterns should be considered to ensure effective sampling designs when using fine-scale tools (e.g., imagery), and for establishing accurate community metrics (e.g., abundance and diversity). Our study is relevant to future ecological research, linking patterns to processes, as well as monitoring and conservation in deep-sea ecosystems.