Kelly NE et al. (2010), Biodiversity of the deep-sea continental margin...

ECB-ART-50164

PLoS One 2010 Nov 19;511:e13832. doi: 10.1371/journal.pone.0013832.

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Biodiversity of the deep-sea continental margin bordering the Gulf of Maine (NW Atlantic): relationships among sub-regions and to shelf systems.

Kelly NE , Shea EK , Metaxas A , Haedrich RL , Auster PJ .

Abstract
BACKGROUND: In 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 METHODOLOGY/PRINCIPAL FINDINGS: We use data from the published literature, unpublished studies, museum records and online sources, to: (1) assess the current state of knowledge of species diversity in the deep-sea habitats adjacent to the Gulf of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/SIGNIFICANCE: The 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.

PubMed ID: 21124960
PMC ID: PMC2988790
Article link: PLoS One

Article Images: [+] show captions

	Figure 1. The deep-sea Gulf of Maine census area.A) The deep-sea Gulf of Maine census area, showing eastern and western boundaries of Gulf of Maine Area Program in white. Note use of two depth scales in the color bar. B) Canyons, continental slope and shelf edge of Georges Bank NW of Bear Seamount. Depth scale is shown on the right-hand side. C) NE Channel and slope. Depth scale is same as in B. D) Bear Seamount (summit depth ∼1100 m). Other seamounts shown are Physalia (to the east) and Mytilus (southeast). Depths in panels A, B and C are from the USGS Digital Bathymetry for the Gulf of Maine (∼500m/pixel). Panel A was augmented with data from the General Bathymetric Chart of the Oceans [GEBCO (∼1000m/pixel)]. Depths in panel D are from high resolution (100m/pixel) bathymetric data processed by the Center for Coastal and Ocean Mapping/Joint Hydrographic Center, University of New Hampshire.
	Figure 2. The number of database records in relation to known species.Positive correlation (Pearson's r = 0.86, p<0.025) between the number of records compiled within the deep-sea database (representing the number of times a sub-region has been sampled, used as a proxy for sampling effort) and the number of known species within each sub-region.
	Figure 3. Cumulative number of known species in the deep-sea database within six sub-regions since 1950.
	Figure 4. Cumulative number of species records in the deep-sea database within six sub-regions since 1950.
	Figure 5. Spatial distribution of the number of known species across the deep-sea Gulf of Maine region.Grid squares are 0.2 degrees and include species records throughout the water column (from 150 m to the seafloor). Species counts are not corrected for effort or sampling method. Dots represent a species record. The names and locations of the major canyons and Bear Seamount are identified by arrows.
	Figure 6. Average taxonomic distinctness (Δ+) by number of species for each sub-region.Central line is average taxonomic distinctness for the total list. Funnel lines are confidence limits within which 95% of simulated values lie.
	Figure 7. Variation in taxonomic distinctness (Λ+) by the number of species for each sub-region.Central line is variation in taxonomic distinctness for the total list. Funnel lines are confidence limits within which 95% of simulated values lie.
	Figure 8. Taxonomic distinctness values by sub-region.Scatter plot of variation in taxonomic distinctness (Λ+) against average taxonomic distinctness (Δ+) values for species lists from 6 sub-regions, showing a strong negative correlation (Pearson's r = −0.87, p<0.05). Dotted lines denote Δ+ and Λ+ values of the master species list from Figs 6 & 7.
	Figure 9. Similarity of species lists.Bray-Curtis similarity (%) of the total deep-sea region species list and the species lists for 6 different sub-regions to the continental shelf Gulf of Maine species list.
	Figure 10. Estimated species richness (Sobs) curves by number of samples.(A) Canyon sub-region for epibenthic macro- and megafauna, as imaged in submersible photographs in Lydonia, Oceanographer and Veatch canyons in 1984 (data from [29]); Continental Rise sub-region for (B) demersal megafauna, collected from trawls using a 41′ Gulf of Mexico net between 2150–2650 m (data from [43], [44]), and (C) epibenthic and demersal macro- and megafauna, as imaged in submersible photographs between 2500–2600 m (data from Metaxas, unpublished); (D) Continental Slope sub-region for infaunal macrofauna sampled with box cores in 1983–84 at different depth stations (data from [26]); (E) NE Channel sub-region for epibenthic and demersal macro- and megafauna, as imaged in submersible photographs across different depths (data from Metaxas, unpublished); and (F) Seamount sub-region (Bear Seamount) for meso- and bathypelagic megafauna sampled using IGYPT nets, collected July 2002 (data from [30]).
	Figure 11. Asymptotic species richness estimates.Comparison of the asymptotic species richness estimates (Chao 1 and Chao 2) for 5 different sub-regions in the deep-sea region of the Gulf of Maine. The Chao 1 estimate for Bear Seamount could not be calculated due to lack of singletons within the data.

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