Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Holothurians: Table 2. Holothurian species, number of individuals by station

Data tables for:
Wagstaff, M., Howell, K.L., Bett, B. J., Billett, D. S. M., Brault, S., Stuart, C. T. & Rex, M.  (2014) β-diversity of deep-sea holothurians and asteroids along a bathymetric gradient (NE Atlantic). Marine Ecology Progress Series, 508,177–185.

Taxonomic Note                            
Zoroaster longicauda = Zoroaster fulgens (long armed morph) of Howell et al 2004**
Zoroaster fulgens (robust morph) = Zoroaster fulgens (robust morph) of Howell et al 2004**
Zoroaster fulgens (slender morph) = Zoroaster fulgens (slender morph) of Howell et al 2004**

**Howell, K.L., Rogers, A., Tyler, P.A. and Billett, D.S.M. (2004).  Reproductive isolation among morphotypes of the cosmopolitan species Zoroaster fulgens (Asteroidea:Echinodermata).

We compare depth distributions, and β-diversity of holothurians and asteroids collected from the Porcupine Seabight (PSB) and Porcupine Abyssal Plain (PAP) in the eastern North Atlantic. The data represent 160 and 209 epibenthic sledge and semi-balloon otter trawl samples for holothurians and asteroids respectively taken from 1977 to 1998 as part of the Institute of Oceanographic Sciences Biology Programme in the PSB (Rice et al. 1991) and the BENGAL Program in the PAP (Billett & Rice 2001). The samples include 43 species of holothurians (Billett 1991) and 43 species of asteroids (Howell et al. 2002).

We performed analyses of nested order by applying BINMATNEST (Rodríguez-Gironés & Santamaría 2006.  Baselga (2010, 2012) showed that β-diversity, can be decomposed into 2 terms: dissimilarity resulting from turnover (spatial replacement) and dissimilarity attributed to nestedness. We used these measures to examine the differences in composition between 2 sites (pair-wise dissimilarity). To determine the general trend in species composition over all depths, we performed non-metric multi-dimensional scaling (NMDS) on species presence absence matrices (Bray-Curtis dissimilarity index scaling) using the metaMDS function in R.

Baselga A (2010) Partitioning the turnover and nestedness components of β diversity. Glob Ecol Biogeogr 19: 134−143

Baselga A (2012) The relationship between species replacement, dissimilarity derived from nestedness, and nestedness. Glob Ecol Biogeogr 21: 1223−1232

Billett DSM (1991) Deep-sea holothurians. Oceanogr Mar Biol Annu Rev 29: 259−317

Billett DSM, Rice AL (2001) The BENGAL programme: introduction and overview. Prog Oceanogr 50: 13−25

Howell KL, Billett DS, Tyler PA (2002) Depth-related distribution and abundance of seastars (Echinodermata: Asteroidea) in the Porcupine Seabight and Porcupine Abyssal Plain, NE Atlantic. Deep-Sea Res I 49: 1901−1920

Rice AL, Billett DSM, Thurston MH, Lampitt RS (1991) The Institute of Oceanographic Sciences biology programme in the Porcupine Seabight: background and general introduction. J Mar Biol Assoc UK 71: 281−310

Rodríguez-Gironés MA, Santamaría L (2006) A new algorithm to calculate the nestedness temperature of presence-absence matrices. J Biogeogr 33: 924−935

Wagstaff, M., Howell, K.L., Bett, B. J., Billett, D. S. M., Brault, S., Stuart, C. T. & Rex, M.  (2014) β-diversity of deep-sea holothurians and asteroids along a bathymetric gradient (NE Atlantic). Marine Ecology Progress Series, 508,177–185.

Gear code Gear type
BN1.5/3F Epibenthic sled
BN1.5/3M Epibenthic sled
BN1.5/C Epibenthic sled
BN1.5/P Epibenthic sled
BNC Epibenthic sled
BNF Epibenthic sled
GT Otter trawl
OT Otter trawl
OTSB14 Otter trawl
OTSB14D Otter trawl
ST Otter trawl

BCO-DMO Processing Notes
- Generated from original file "Data Asteroid Holothurian for Wagstaff et al paper 2014.xlsx, Sheet 2" contributed by Carol Stuart
- Parameter names edited to conform to BCO-DMO naming convention found at Choosing Parameter Name
- Date reformatted to YYYYMMDD
- Misc dates corrected (mis-entered originally)

Description from NSF award abstract:
Many hypotheses have been proposed to explain deep-sea species diversity including competition, predation, physical disturbance, patch mosaics, coarse-grained environmental heterogeneity, metapopulation dynamics mediated by dispersal, and a host of abiotic factors. Evidence supporting these ideas comes largely from spatio-temporal patterns of alpha- (local) diversity. This investigator and collaborators proposed an alternative explanation based on species depth ranges. Abyssal populations of mollusks do not comprise a unique assemblage, but are mainly deeper attenuated range extensions of bathyal populations. Densities of many abyssal populations are so extraordinarily low, especially for minute organisms with low mobility and separate sexes, that it is implausible they could be reproductively viable. Most have larval dispersal ability. This suggested that many abyssal populations are maintained by source-sink dynamics. They suffer chronic local extinction from vulnerabilities to Allee effects, and persist through continued immigration from more abundant bathyal source populations. Source-sink dynamics provides a broad synthetic framework within which other potential causes of diversity (above) can act. It also resolves the long-standing paradox of how abyssal diversity could be shaped by interactions when density is so low. The theory does not require that abyssal communities be ecologically structured. They may be mostly a passive consequence of dispersal.

This project will apply two tests for source-sink dynamics: 1. The investigators will perform a direct test by examining reproductive patterns in molluscan species whose bathymetric ranges span the lower bathyal zone and the abyss. Since rare abyssal populations are predicted not to be reproductively viable, they should show diminished gamete production, and no evidence of mating. 2. They will conduct an extensive new synthesis of geographic evidence for source-sink dynamics. Geographic patterns, are currently the primary evidence available on very large spatial scales, and are invaluable for identifying taxonomic and geographical scenarios for future reproductive studies. Recent advances in nested analysis allow us to determine statistically whether abyssal communities are nested subsets of bathyal communities as predicted by source-sink theory. Newly available large datasets include Pan Atlantic distributions of gastropods, bivalves, and cumaceans from the Woods Hole Oceanographic Institution's Benthic Sampling Program; mollusks, asteroids and holothurians from Southampton Oceanography Centre's sampling program in the Porcupine Seabight and Abyssal Plains, and macrofaunal taxa from Texas A&M's Deep Gulf of Mexico Benthic Program. The investigator makes specific predictions about which groups should show geographic evidence of source-sink dynamics based on their natural history and the productivity regime. This synthesis will also contribute significantly to documenting and understanding beta diversity, the most important remaining challenge in deep-sea community ecology.

The source-sink hypothesis has the potential to unify and synthesize the large number of disparate theories of community structure in the deep-sea benthos. The research will also dramatically increase the number of computerized datasets on biogeographic distributions. The single greatest obstacle to expanding our understanding of macroecology in the deep sea is the near absence of data on species ranges. This also has vital implications for conservation and sustainable development of the deep-sea ecosystem. Without much more information on geographic ranges, it is currently impossible to gauge the extinction potential of deep-sea species.

References for the Data Analyses:
Brault, S., Stuart, C.T., Wagstaff, M.C. & Rex, M.A. (2012) Geographic evidence for source-sink dynamics in deep-sea neogastropods of the eastern North Atlantic: an approach using nested analysis. Global Ecology and Biogeography, 22,433−439. doi:10.1111/geb.12005

Brault, S., Stuart, C.T., Wagstaff, M.C., McClain, C.R., Allen, J.A. & Rex, M.A. (2013) Contrasting patterns of α-and β-diversity in deep-sea bivalves of the eastern and western North Atlantic. Deep-Sea Research II, 92,157−164. doi:10.1016/j.dsr2.2013.01.018

Wagstaff, M., Howell, K.L., Bett, B. J., Billett, D. S. M., Brault, S., Stuart, C. T. & Rex, M. (2014) β-diversity of deep-sea holothurians and asteroids along a bathymetric gradient (NE Atlantic). Marine Ecology Progress Series, 508,177–185. doi:10.3354/meps10877

Stuart, C.T., Brault, S., Rowe, G.T., Wei, C-L., Wagstaff, M., McClain, C.R., & Rex, M.A. Nestedness and species replacement along bathymetric gradients in the deep sea reflect productivity: a test with polychaete assemblages in the oligotrophic NW Gulf of Mexico. Journal of Biogeography (to be submitted)