Meiobenthic nematode assemblages were examined at 16 stations along two transects on the eastern and western boundaries of the deep northern Gulf of Mexico (dNGOM) at depths of 212–3000？m. The highest abundance (297 individuals 10？cm？2) and number of genera (71) occurred at stations near the Mississippi River delta. Number of genera decreased with increasing depth, and showed differences in community composition between the east and west regions. The dominant family, Comesomatidae, was represented by Sabatieria that was present at most shallow stations but absent at greater water depths. A significant difference in nematode feeding morphology was observed between depth groups but not between the two transects at different longitudes. Patterns of nematode community structure are congruent with harpacticoid copepods. Overall, the higher abundance and diversity of nematodes in the north-central Gulf of Mexico is consistent with findings of other benthic taxa and reflects organic material loading from the Mississippi River driving deep sea communities in the Gulf. The east-west gradient in composition of nematode communities suggests that nematode assemblages have well-defined distribution patterns similar to other meiobenthic taxa in the GOM but they are not aligned in the bathymetric zones observed in macrofauna, megafauna and demersal fishes. 1. Introduction Deep-sea biodiversity remains woefully understudied, and it is estimated that only 1% of marine species is currently described [3]. Most studies of deep-sea benthic diversity are based on mega- or macrofaunal organisms, but studies of the meiobenthos and nannobenthos have revealed a diverse fauna [4–6]. Meiobenthic abundance and diversity exceed that of macrofauna and megafauna, and the biomass of the meiofauna community dominates that of macro- and megafauna with increasing water depth [7]. Comparison of biomass and respiration rates also suggests that meiofauna have greater rates of carbon flow through food webs in deeper waters in the Gulf of Mexico than the larger macrofauna and megafauna [8, 9]. As the numerically dominant meiofaunal taxon in deep-sea sediments, nematodes play significant roles in marine biogeochemical cycles through bioturbation and related processes that enhance sediment oxygenation and solute transport, thereby increasing rates of demineralization [10–12]. However, despite their numerical dominance, high diversity, and functional significance [13, 14], studies of this ubiquitous phylum are rare. Studies of nematode biodiversity in the deep sea conducted in the Pacific and
References
[1]
P. de Ley and M. Blaxter, “Systematic position and phylogeny,” in The Biology of Nematodes, D. L. Lee, Ed., pp. 1–30, Taylor & Francis, New York, NY, USA, 2002.
[2]
W. D. Hope, “An annotated checklist of the marine nematodes of the Western North Atlantic and Gulf of Mexico,” Journal of Nematology, vol. 37, no. 4, pp. 1–208, 2005.
[3]
P. V. R. Snelgrove and C. R. Smith, “A riot of species in an environmental calm: the paradox of the species-rich deep-sea floor,” Oceanography and Marine Biology, vol. 40, pp. 311–342, 2002.
[4]
H. Thiel, “Meiobenthos and nanobenthos of the deep sea,” in The Sea, G. T. Rowe, Ed., vol. 8, pp. 167–229, John Wiley & Sons, New York, NY, USA, 1983.
[5]
J. G. Baguley, P. A. Montagna, W. Lee, L. J. Hyde, and G. T. Rowe, “Spatial and bathymetric trends in harpacticoida (Copepoda) community structure in the Northern Gulf of Mexico deep-sea,” Journal of Experimental Marine Biology and Ecology, vol. 330, no. 1, pp. 327–341, 2006.
[6]
A. Vanreusel, G. Fonseca, R. Danovaro, et al., “The contribution of deep-sea macrohabitat heterogeneity to global nematode diversity,” Marine Ecology—An Evolutionary Perspective, vol. 31, no. 1, pp. 6–20, 2010.
[7]
M. A. Rex and R. J. Etter, Deep-Sea Biodiversity Pattern and Scale, Harvard University Press, Cambridge, Mass, USA, 2010.
[8]
J. G. Baguley, P. A. Montagna, L. J. Hyde, and G. T. Rowe, “Metazoan meiofauna biomass, grazing, and weight-dependent respiration in the Northern Gulf of Mexico deep sea,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2607–2616, 2008.
[9]
G. T. Rowe, C. Wei, C. Nunnally et al., “Comparative biomass structure and estimated carbon flow in food webs in the deep Gulf of Mexico,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2699–2711, 2008.
[10]
R. C. Aller and J. Y. Aller, “Meiofauna and solute transport in marine muds,” Limonology and Oceanography, vol. 37, no. 5, pp. 1018–1033, 1992.
[11]
D. J. Cullen, “Bioturbation of superficial marine sediments by interstitial meiobenthos,” Nature, vol. 242, no. 5396, pp. 323–324, 1973.
[12]
J. Pike, J. M. Bernhard, S. G. Moreton, and I. B. Butler, “Microbioirrigation of marine sediments in dysoxic environments: implications for early sediment fabric formation and diagenetic processes,” Geology, vol. 29, no. 10, pp. 923–926, 2001.
[13]
V. O. Mokievsky, A. A. Udalov, and A. I. Azovsky, “On the quantitative distribution of meiobenthos on the shelf of the World Ocean,” Oceanology, vol. 44, no. 1, pp. 99–109, 2004.
[14]
D. M. Miljutin, G. Gad, M. M. Miljutina, V. O. Mokievsky, V. Fonseca-Genevois, and A. M. Esteves, “The state of knowledge on deep-sea nematode taxonomy: how many valid species are known down there?” Marine Biodiversity, vol. 40, no. 3, pp. 143–159, 2010.
[15]
Y. Shirayama, “The abundance of deep-sea meiobenthos in the western Pacific in relation to environmental factors,” Oceanologica Acta, vol. 7, no. 1, pp. 113–121, 1984.
[16]
D. Thistle and K. M. Sherman, “The nematode fauna of a deep-sea site exposed to strong near-bottom currents,” Deep-Sea Research, vol. 32, no. 9, pp. 1077–1088, 1985.
[17]
J. H. Tietjen, J. W. Deming, G. T. Rowe, S. Macko, and R. J. Wilke, “Meiobenthos of the hatteras abyssal plain and Puerto Rico trench: abundance, biomass and associations with bacteria and particulate fluxes,” Deep-Sea Research Part A, vol. 36, no. 10, pp. 1567–1577, 1989.
[18]
K. Vopel and H. Thiel, “Abyssal nematode assemblages in physically disturbed and adjacent sites of the Eastern equatorial Pacific,” Deep-Sea Research Part II, vol. 48, no. 17-18, pp. 3795–3808, 2001.
[19]
R. Danovaro, S. Bianchelli, C. Gambi, M. Mea, and D. Zeppilli, “α-, β-, γ-, δ-and ε-diversity of deep-sea nematodes in canyons and open slopes of NorthEast Atlantic and Mediterranean margins,” Marine Ecology Progress Series, vol. 396, pp. 197–209, 2009.
[20]
P. J. D. Lambshead, C. J. Brown, T. J. Ferrero et al., “Latitudinal diversity patterns of deep-sea marine nematodes and organic fluxes: a test from the central equatorial Pacific,” Marine Ecology Progress Series, vol. 236, pp. 129–135, 2002.
[21]
K. Soetaert, C. Heip, and M. Vincx, “Diversity of nematode assemblages along a Mediterranean deep-sea transect,” Marine Ecology Progress Series, vol. 75, no. 2-3, pp. 275–282, 1991.
[22]
T. Soltwedel, “Metazoan meiobenthos along continental margins: a review,” Progress in Oceanography, vol. 46, no. 1, pp. 59–84, 2000.
[23]
S. Vanhove, H. Vermeeren, and A. Vanreusel, “Meiofauna towards the South Sandwich Trench (750–6300？m), focus on nematodes,” Deep-Sea Research Part II, vol. 51, no. 14–16, pp. 1665–1687, 2004.
[24]
R. Danovaro, C. Gambi, N. Lampadariou, and A. Tselepides, “Deep-sea nematode biodiversity in the Mediterranean basin: testing for longitudinal, bathymetric and energetic gradients,” Ecography, vol. 31, no. 2, pp. 231–244, 2008.
[25]
L. A. Levin, R. J. Etter, M. A. Rex, et al., “Environmental influences on regional deep-sea species diversity,” Annual Review of Ecology and Systematics, vol. 32, pp. 51–93, 2001.
[26]
W. D. Hope, “Free-living marine nematoda of the Gulf of Mexico,” in Gulf of Mexico Origin, Waters, and Biota: Volume I, Biodiversity, D. L. Felder and D. K. Camp, Eds., p. 1393, Texas A & M University Press, College Station, Tex, USA, 2009.
[27]
N. A. Cobb, “One hundred new nematodes,” in Contributions to Science of Nematology, pp. 217–343, 1920.
[28]
B. G. Chitwood, “North American marine nematodes,” Texas Journal of Science, vol. 4, pp. 617–672, 1951.
[29]
B. G. Chitwood and R. W. Timm, “Free-living nematodes of the Gulf of Mexico,” Fishery Bulletin, vol. 55, no. 89, pp. 313–323, 1954.
[30]
C. E. King, “Some aspects of the ecology of psammolittoral nematodes in the Northeastern Gulf of Mexico,” Ecology, vol. 43, no. 3, pp. 515–523, 1962.
[31]
B. Hopper, “Marine nematodes from the coast line of the Gulf of Mexico,” Canadian Journal of Zoology, vol. 39, pp. 183–199, 1961.
[32]
E. J. Keppner, “New species of free-living marine nematode (Nematoda: Enoplidae) from Bay County, Florida, USA,” Transactions of the American Microscopical Society, vol. 105, no. 4, pp. 319–337, 1986.
[33]
P. Jensen, “The nematode fauna in the sulphide-rich brine seep and adjacent bottoms of the East Flower Garden, NW Gulf of Mexico. I. Chromadorida,” Zoologica Scripta, vol. 14, no. 4, pp. 247–264, 1985.
[34]
P. Jensen, “The nematode fauna in the sulphide-rich brine seep and adjacent bottoms of the East Flower Garden, NW Gulf of Mexico. II. Monhysterida,” Zoologica Scripta, vol. 15, no. 1, pp. 1–11, 1986.
[35]
P. Jensen, “The nematode fauna in the sulphide-rich brine seep and adjacent bottoms of the East Flower Garden, NW Gulf of Mexico. III. Enoplida,” Zoologica Scripta, vol. 15, no. 2, pp. 93–99, 1986.
[36]
P. Jensen, “Nematode fauna in the sulphide-rich brine seep and adjacent bottoms of the East Flower Garden, NW Gulf of Mexico IV. Ecological Aspects,” Marine Biology, vol. 92, no. 4, pp. 489–503, 1986.
[37]
G. Boucher and N. Gourbault, “Sublittoral meiofauna and diversity of nematode assemblages off Guadeloupe Islands (French West Indies),” Bulletin of Marine Science, vol. 47, no. 2, pp. 448–463, 1990.
[38]
A. de Jesus-Navarrete and J. Herrera-Gomez, “Vertical distribution and feeding types of nematodes from Chetumal Bay, Quintana Roo, Mexico,” Estuaries, vol. 25, no. 6, pp. 1131–1137, 2002.
[39]
A. de Jesus-Navarrete, “Nematodes from Isla Mujeres and Banco Chinchorro reefs, Quintana Roo, Mexico,” Revista de Biologia Marina y Oceanografia, vol. 42, no. 2, pp. 193–200, 2007.
[40]
D. Castillo-Fernandez and P. J. D. Lambshead, “Revision of the genus Elzalia Gerlach, 1957 (Nematoda: Xyalidae) including three new species from an oil producing zone in the Gulf of Mexico, with a discussion of the sibling species problem,” Bulletin of the British Museum (Natural History), Zoology Series, vol. 56, no. 1, pp. 63–71, 1990.
[41]
J. G. Baguley, P. A. Montagna, L. J. Hyde, R. D. Kalke, and G. T. Rowe, “Metazoan meiofauna abundance in relation to environmental variables in the Northern Gulf of Mexico deep sea,” Deep-Sea Research Part I, vol. 53, no. 8, pp. 1344–1362, 2006.
[42]
D. C. Biggs, C. Hu, and F. E. Müller-Karger, “Remotely sensed sea-surface chlorophyll and POC flux at Deep Gulf of Mexico Benthos sampling stations,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2555–2562, 2008.
[43]
A. E. Jochens and S. F. DiMarco, “Physical oceanographic conditions in the deepwater Gulf of Mexico in summer 2000–2002,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2541–2554, 2008.
[44]
C. L. Wei, G. T. Rowe, G. Fain Hubbard et al., “Bathymetric zonation of deep-sea macrofauna in relation to export of surface phytoplankton production,” Marine Ecology Progress Series, vol. 399, pp. 1–14, 2010.
[45]
G. T. Rowe and M. C. Kennicutt, “Northern Gulf of Mexico continental slope habitats and benthic ecology study: final report,” Study MMS 2009-039, U.S. Department of the Interior Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, La, USA, 2009.
[46]
V. N. de Jonge and L. A. Bouwman, “A simple density separation technique for quantitative isolation of meiobenthos using the colloidal silica Ludox-TM,” Marine Biology, vol. 42, no. 2, pp. 143–148, 1977.
[47]
J. W. Seinhorst, “A rapid method for the transfer of nematodes from fixative to anhydrous glycerin,” Nematologica, vol. 4, no. 1, pp. 67–69, 1959.
[48]
H. M. Platt and R. M. Warwick, Free Living Marine Nematodes. Part II. British Chromadorids, Synopses of the British Fauna, no. 38, The Linnean Society of London, 1988.
[49]
M. Mundo-Ocampo, P. J. D. Lambshead, N. Debenham et al., “Biodiversity of littoral nematodes from two sites in the Gulf of California,” Hydrobiologia, vol. 586, no. 1, pp. 179–189, 2007.
[50]
W. Wieser, “Die beziehung zwischen munhohlengestalt, ernahrungsweise und vorkommen beifreilebenden marinen nematoden,” Archives de Zoologie, vol. 2, pp. 439–484, 1953.
[51]
T. Moens and M. Vincx, “Observations on the feeding ecology of estuarine nematodes,” Journal of the Marine Biological Association of the United Kingdom, vol. 77, no. 1, pp. 211–227, 1997.
[52]
K. R. Clarke and R. N. Gorley, “PRIMER v6: User Manual/Tutorial,” PRIMER-E, Plymouth, UK, 2006.
[53]
K. R. Clarke and R. M. Warwick, Change in Marine Communities: An Approach to Statistical Analysis and Interpretation, PRIMER-E, Plymouth, UK, 2nd edition, 2001.
[54]
K. Soetaert and C. Heip, “Nematode assemblages of deep-sea and shelf break sites in the North Atlantic and Mediterranean Sea,” Marine Ecology Progress Series, vol. 125, no. 1–3, pp. 171–183, 1995.
[55]
T. Soltwedel, V. Mokievsky, and I. Schewe, “Benthic activity and biomass on the Yermak Plateau and in adjacent deep-sea regions northwest of Svalbard,” Deep-Sea Research Part I, vol. 47, no. 9, pp. 1761–1785, 2000.
[56]
S. A. Netto, F. Gallucci, and G. F. C. Fonseca, “Meiofauna communities of continental slope and deep-sea sites off SE Brazil,” Deep-Sea Research Part I, vol. 52, no. 5, pp. 845–859, 2005.
[57]
M. Vincx, B. J. Bett, A. Dinet, et al., “Meiobenthos of the deep Northeast Atlantic,” in Advances in Marine Biology, J. H. S. Blaxter and A. J. Southward, Eds., vol. 30, pp. 2–88, Academic Press, London, UK, 1994.
[58]
J. H. Tietjen, “Abundance and biomass of metazoan meiobenthos in the deep sea,” in Deep-Sea food Chains and the Global Carbon Cycle, G. T. Rowe and V. Pariente, Eds., pp. 45–620, Kluwer Academic, Dodrecht, The Netherlands, 1992.
[59]
J. W. Morse and M. J. Beazley, “Organic matter in deepwater sediments of the Northern Gulf of Mexico and its relationship to the distribution of benthic organisms,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2563–2571, 2008.
[60]
S. Bianchelli, C. Gambi, D. Zeppilli, and R. Danovaro, “Metazoan meiofauna in deep-sea canyons and adjacent open slopes: a large-scale comparison with focus on the rare taxa,” Deep-Sea Research Part I, vol. 57, no. 3, pp. 420–433, 2010.
[61]
K. M. Yeager, P. H. Santschi, and G. T. Rowe, “Sediment accumulation and radionuclide inventories (239,240Pu, 210Pb and 234Th) in the Northern Gulf of Mexico, as influenced by organic matter and macrofaunal density,” Marine Chemistry, vol. 91, no. 1–4, pp. 1–14, 2004.
[62]
A. W. Muthumbi, A. Vanreusel, G. Duineveld, K. Soetaert, and M. Vincx, “Nematode community structure along the continental slope off the Kenyan Coast, Western Indian Ocean,” International Review of Hydrobiology, vol. 89, no. 2, pp. 188–205, 2004.
[63]
P. Jensen, “Nematode assemblages in the deep-sea benthos of the Norwegian Sea,” Deep Sea Research Part A, vol. 35, no. 7, pp. 1173–1184, 1988.
[64]
J. Sharma, J. Baguley, B. A. Bluhm, and G. Rowe, “Do meio- and macrobenthic nematodes differ in community composition and body weight trends with depth?” Plos ONE, vol. 6, no. 1, Article ID e14491, 2011.
[65]
C. Gambi, A. Vanreusel, and R. Danovaro, “Biodiversity of nematode assemblages from deep-sea sediments of the Atacama Slope and Trench (South Pacific Ocean),” Deep-Sea Research Part I, vol. 50, no. 1, pp. 103–117, 2003.
[66]
G. T. Rowe and M. C. Kennicutt, “Introduction to the deep Gulf of Mexico Benthos program,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2536–2540, 2008.
[67]
G. T. Rowe, J. Morse, C. Nunnally, and G. S. Boland, “Sediment community oxygen consumption in the deep Gulf of Mexico,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2686–2691, 2008.
[68]
R. L. Haedrich, J. A. Devine, and V. J. Kendall, “Predictors of species richness in the deep-benthic fauna of the Northern Gulf of Mexico,” Deep-Sea Research Part II, vol. 55, no. 24–26, pp. 2650–2656, 2008.
[69]
K. Fauchald and P. A. Jumars, “Diet of worms: a study of polychaete feeding guilds,” Oceanography and Marine Biology, vol. 17, pp. 193–284, 1979.
[70]
C. L. Wei, G. T. Rowe, E. Escobar-Briones, C. Nunnally, and Y. S. Soliman, “Standing stocks and body size of deep-sea macrofauna: predicting the baseline of 2010 deepwater horizon oil spill in the Northern Gulf of Mexico,” Deep-Sea Research Part II. In press.
