Biodiversity of the Deep-Sea Continental Margin Bordering the Gulf of Maine (NW Atlantic): Relationships among Sub-Regions and to Shelf Systems

Abstract

BackgroundIn contrast to the well-studied continental shelf region of the Gulf of Maine, fundamental questions regarding the diversity, distribution, and abundance of species living in deep-sea habitats along the adjacent continental margin remain unanswered. Lack of such knowledge precludes a greater understanding of the Gulf of Maine ecosystem and limits development of alternatives for conservation and management.Methodology/Principal FindingsWe use data from the published literature, unpublished studies, museum records and online sources, to: (1) assess the current state of knowledge of species diversity in the deep-sea habitats adjacent to the Gulf of Maine (39–43°N, 63–71°W, 150–3000 m depth); (2) compare patterns of taxonomic diversity and distribution of megafaunal and macrofaunal species among six distinct sub-regions and to the continental shelf; and (3) estimate the amount of unknown diversity in the region. Known diversity for the deep-sea region is 1,671 species; most are narrowly distributed and known to occur within only one sub-region. The number of species varies by sub-region and is directly related to sampling effort occurring within each. Fishes, corals, decapod crustaceans, molluscs, and echinoderms are relatively well known, while most other taxonomic groups are poorly known. Taxonomic diversity decreases with increasing distance from the continental shelf and with changes in benthic topography. Low similarity in faunal composition suggests the deep-sea region harbours faunal communities distinct from those of the continental shelf. Non-parametric estimators of species richness suggest a minimum of 50% of the deep-sea species inventory remains to be discovered.Conclusions/SignificanceThe current state of knowledge of biodiversity in this deep-sea region is rudimentary. Our ability to answer questions is hampered by a lack of sufficient data for many taxonomic groups, which is constrained by sampling biases, life-history characteristics of target species, and the lack of trained taxonomists.

Demersal fish distribution and habitat use within and near Baltimore and Norfolk Canyons, U.S. middle Atlantic slope

“…Submarine canyons can support different fish or invertebrate assemblages compared with neighboring open slopes, but such differences sometimes only pertained to certain depth zones or faunal groups (Rowe 1971(Rowe , 1972Vetter andDayton 1998, 1999;De Leo et al 2010;Kelly et al 2010;Vetter et al 2010). In contrast, other studies failed to detect differences in faunal composition between canyons and nearby slopes (Haedrich et al 1975;Hecker et al 1983;Houston and Haedrick 1984;King et al 2008).…”

Habitat Differences in Deep-Sea Megafaunal Communities off New Zealand: Implications for Vulnerability to Anthropogenic Disturbance and Management

“…These differences among habitats were generally consistent across all depth strata, and levels of community dissimilarity among habitats were generally high: 80-86 % on the Hikurangi Margin and 92-96% in the (Ramirez-Llodra et al, 2010) but with levels of dissimilarity among habitats ranging between 40 and 48% (Ramirez-Llodra pers comm.). Kelly et al (2010) compared community similarity of deep-sea habitats in the Gulf of Maine (northeast USA/Canada), using presence-absence data that included megafauna sampled by trawls. Comparisons among habitats were not controlled for depth, so dissimilarity values might be expected to be higher than those observed in the present study.…”

“…Only relatively recently, has the need to consider biodiversity patterns and the potential linkages between multiple deep-sea habitats been identified and addressed (e.g., Vanreusel et al, 2010;Kelly et al, 2010;Sevastou et al, 2013). The need to understand connectivity between habitats arises not only from scientific interest in obtaining greater ecological understanding of the deep sea, but also from social pressures to generate information for the effective management of the growing industrial use of the deep sea (Ramirez-Llodra et al, 2011).…”

“…If benthic communities of different habitats in the deep sea are generally dissimilar to one another in terms of community structure, this may indicate that they are relatively unconnected (Kelly et al, 2010). Consequently they may be vulnerable to anthropogenic impacts because they have limited ability to recover via dispersal if disturbed at a habitat-level scale.…”

“…Consequently they may be vulnerable to anthropogenic impacts because they have limited ability to recover via dispersal if disturbed at a habitat-level scale. Faunal dissimilarity among habitats could also indicate that a habitat's environmental characteristics are distinct enough to allow the development of specific communities (Kelly et al, 2010). Some functional or trophic groups within megafaunal communities are particularly sensitive to disturbance, which may result in the community of deep-sea habitats being more vulnerable to disturbance than others if the proportion of these taxa is relatively high or of particular importance for the structure and function of the community.…”