Diversity and composition of macrobenthic community associated with sandy shoals of the Louisiana continental shelf

Along the Louisiana, USA continental shelf, sandy shoals are shallow, possibly oxygen-rich “islands” surrounded by deeper muddy deposits prone to hypoxia. Shoals also contain significant quantities of fine sand that may be mined in the future for coastal restoration. The ecological role of shoals remains poorly understood and we hypothesized that shoals provide critical habitat for benthic invertebrates. Using Ship Shoal as a model system, we assessed the diversity and structure of macrobenthic assemblages and how community structure varies with season and environmental parameters. High biomass (averaging 26.7 g m−2) and high diversity (161 species) of macrobenthos was found in 2006. Polychaetes (45%—72 species) and crustaceans comprised most of the species (28%—46 species); spionids and amphipods dominated the polychaete and crustacean groups respectively, both in terms of number of species and abundances. Sharp decreases in diversity, abundance and biomass occurred from spring to autumn. Species diversity and total abundance significantly increased with decreasing sediment grain size and increasing bottom water dissolved oxygen. Across seasons, mole crabs Albunea paretii and amphioxus Branchiostoma floridae typified the community and contributed most of the biomass. The polychaetes Nephtys simoni, Neanthes micromma, Dispio uncinata, Mediomastus californiensis and Magelona sp. A, the amphipod Acanthohautorius sp. A and the burrowing shrimp Ogyrides alphaerostris also contributed to variation in community composition. Cluster analyses quantified seasonal variation, mainly based on sharp decreases in abundance, as well as spatial differences in species composition oriented along both east–west and north–south gradients. Variation in benthic assemblages was correlated with water depth and sediment characteristics (mean grain size and percentage of gravel-sized shell debris). We conclude that Ship Shoal is an unrecognized biodiversity hotspot and a hypoxia refuge compared to the immediate surrounding area where the benthic community is affected by seasonal hypoxia events and we discuss how sand-mining may influence this community.

[1]  M. Church,et al.  Physical and ecological response to disturbance by gravel mining in a large alluvial river , 2009 .

[2]  M. Baustian.  Benthic communities in the northern Gulf of Mexico hypoxic area: potential prey for demersal fish , 2005 .

[3]  Jean-Claude Dauvin,et al.  Amphipods are good bioindicators of the impact of oil spills on soft-bottom macrobenthic communities , 2000 .

[4]  R. Wu,et al.  Bioenergetics, growth and reproduction of amphipods are affected by moderately low oxygen regimes , 2005 .

[5]  G. Stone,et al.  Storm layer deposition on the Mississippi–Atchafalaya subaqueous delta generated by Hurricane Lili in 2002 , 2005 .

[6]  R. Whittaker.  Evolution and measurement of species diversity , 1972 .

[7]  K. R. Clarke,et al.  A Method Of Linking Multivariate Community Structure To Environmental Variables , 1993 .

[8]  C. Heip,et al.  Macrobenthos of a Sublittoral Sandbank in the Southern Bight of the North Sea , 1982, Journal of the Marine Biological Association of the United Kingdom.

[9]  Steven Degraer,et al.  Macrobenthic community structure of soft-bottom sediments at the Belgian Continental Shelf , 2004 .

[10]  Claude E. Shannon,et al.  A Mathematical Theory of Communications , 1948 .

[11]  D. Eggleston,et al.  Behavioral responses of free-ranging blue crabs to episodic hypoxia . II . Feeding , 2003 .

[12]  K. Pye,et al.  GRADISTAT: a grain size distribution and statistics package for the analysis of unconsolidated sediments , 2001 .

[13]  J. Fleeger,et al.  High Benthic Microalgal Biomass Found on Ship Shoal, North-central Gulf of Mexico , 2009 .

[14]  P. Montagna,et al.  The Effects of a Dredge Excavation Pit on Benthic Macrofauna in Offshore Louisiana , 2008, Environmental management.

[15]  R.,et al.  Faunal assemblages of benthic megainvertebrates inhabiting sea scallop grounds from eastern Georges Bank , in relation to environmental factors , 2022 .

[16]  Eric R. Pianka,et al.  On r- and K-Selection , 1970, The American Naturalist.

[17]  Teresa E. Thornton,et al.  Sand and gravel mining: effects on ground water resources in Hancock county, Maine, USA , 2008 .

[18]  E. Pinn,et al.  Macro-infaunal biodiversity and analysis of associated feeding guilds in the Greater Minch area, Scottish west coast , 2003, Journal of the Marine Biological Association of the United Kingdom.

[19]  R. Wheatcroft,et al.  River sediment flux and shelf sediment accumulation rates on the Pacific Northwest margin , 2005 .

[20]  Melissa M. Baustian,et al.  Effects of summer 2003 hypoxia on macrobenthos and Atlantic croaker foraging selectivity in the northern Gulf of Mexico , 2009 .

[21]  R. Heard,et al.  AN ILLUSTRATED IDENTIFICATION GUIDE TO THE NEARSHORE MARINE AND ESTUARINE GAMMARIDEAN AMPHIPODA OF FLORIDA , 2005 .

[22]  G. Rowe,et al.  Deep-sea benthic sampling with the GOMEX box corer , 1991 .

[23]  P. Johnson,et al.  Taxonomic Guide to the Polychaetes of the Northern Gulf of Mexico , 2015 .

[24]  D. Zeppelini,et al.  Collembola as bioindicators of restoration in mined sand dunes of Northeastern Brazil , 2009, Biodiversity and Conservation.

[25]  R. Folk,et al.  Brazos River bar [Texas]; a study in the significance of grain size parameters , 1957 .

[26]  D. Schoeman,et al.  Sandy beaches at the brink , 2007 .

[27]  Stanislas F. Dubois,et al.  Biodiversity associated with Sabellaria alveolata (Polychaeta: Sabellariidae) reefs: effects of human disturbances , 2002, Journal of the Marine Biological Association of the United Kingdom.

[28]  Magda Vincx,et al.  Spatial patterns of the hyperbenthos of subtidal sandbanks in the southern North Sea , 2003 .

[29]  P. Fong,et al.  Do life history traits account for diversity of polychaete annelids , 2005 .

[30]  P. Montagna,et al.  Small-scale spatial variation of macrobenthic community structure , 1997 .

[31]  C. Rakocinski,et al.  Nested spatiotemporal scales of variation in sandy-shore macrobenthic community structure , 1998 .

[32]  S. Bell,et al.  The benthic community of the eastern US continental shelf: A literature synopsis of benthic faunal resources , 2006 .

[33]  Magda Vincx,et al.  Changes in nematode communities at the long-term sand extraction site of the Kwintebank (southern bight of the north sea). , 2007, Marine pollution bulletin.

[34]  P. Montagna,et al.  Direct and indirect effects of hypoxia on benthos in Corpus Christi Bay, Texas, U.S.A. , 2006 .

[35]  P. Qian,et al.  Effects of food concentration on larval growth and development, of two polychaete worms, Capitella capitata (Fabricius) and Polydora ligni Webster. , 1991 .

[36]  M. J. Kaisera,et al.  Demersal fish and epifauna associated with sandbank habitats , 2004 .

[37]  B. Jørgensen,et al.  Oxygen distribution and bioirrigation in Arctic fjord sediments (Svalbard, Barents Sea) , 2005 .

[38]  G. Stone,et al.  Impacts of Fluvial Fine Sediments and Winter Storms on a Transgressive Shoal, off South-Central Louisiana, U.S.A. , 2007 .

[39]  Mark R. Byrnes,et al.  The U.S. Minerals Management Service Outer Continental Shelf Sand and Gravel Program: Environmental Studies to Assess the Potential Effects of Offshore Dredging Operations in Federal Waters , 2004 .

[40]  G. Thouzeau,et al.  Faunal assemblages of benthic mega-invertebrates inhabiting sea scallop grounds from eastern Georges Bank, in relation to environmental factors , 1991 .

[41]  K. Winemiller,et al.  Occurrence Patterns, Habitat Associations, and Potential Prey of the River Dolphin, Inia geoffrensis, in the Cinaruco River, Venezuela 1 , 1998 .

[42]  Gray,et al.  The measurement of marine species diversity, with an application to the benthic fauna of the Norwegian continental shelf. , 2000, Journal of experimental marine biology and ecology.

[43]  K. R. Clarke,et al.  Change in marine communities : an approach to statistical analysis and interpretation , 2001 .

[44]  C. Pattiaratchi,et al.  Maintenance of headland-associated linear sandbanks: modelling the secondary flows and sediment transport , 2005 .

[45]  Mark V. Lomolino,et al.  Species Diversity in Space and Time. , 1996 .

[46]  R. Newell,et al.  THE IMPACT OF DREDGING WORKS IN COASTAL WATERS: A REVIEW OF THE SENSITIVITY TO DISTURBANCE AND SUBSEQUENT RECOVERY OF BIOLOGICAL RESOURCES ON THE SEA BED , 2000 .

[47]  M. Anderson,et al.  REEF-ASSOCIATED PREDATORS INFLUENCE ADJACENT SOFT-SEDIMENT COMMUNITIES , 2005 .

[48]  B. Sainte‐Marie.  A review of the reproductive bionomics of aquatic gammaridean amphipods: variation of life history traits with latitude, depth, salinity and superfamily , 1991, Hydrobiologia.

[49]  N. Rabalais,et al.  Effects of climate change on hypoxia in coastal waters: A doubled CO2 scenario for the northern Gulf of Mexico , 1996 .

[50]  R. Zühlke.  Polychaete tubes create ephemeral community patterns: Lanice conchilega (Pallas, 1766) associations studied over six years , 2001 .

[51]  G. Gaston.  Effects of hypoxia on macrobenthos of the inner shelf off Cameron, Louisiana , 1985 .

[52]  Cheryl Ann Butman,et al.  Animal-sediment relationships revisited: cause versus effect , 1994 .

[53]  D. McLusky.  Editorial – Invited Feature by Defeo, McLachlan, Schoeman, Schlacher, Dugan, Jones, Lastra and Scapini , 2009 .

[54]  K. Fauchald.  The diet of worms : A study of polychaete feeding guilds , 1979 .

[55]  D. Eggleston,et al.  Behavioral responses of free-ranging blue crabs to episodic hypoxia. I. Movement , 2003 .

[56]  P. Niiler,et al.  Circulation over the continental shelf in the northern Gulf of Mexico , 2005 .

[57]  G. Stone,et al.  Hydrodynamic and sedimentary responses to two contrasting winter storms on the inner shelf of the northern Gulf of Mexico , 2004 .

[58]  J. Pechenik.  Biology of the Invertebrates , 1991 .

[59]  D. Schoeman,et al.  Threats to sandy beach ecosystems: A review , 2009 .

[60]  John S. Gray,et al.  ANIMAL-SEDIMENT RELATIONSHIPS. , 1974 .

[61]  J. Hsu.  Multiple Comparisons: Theory and Methods , 1996 .

[62]  C. E. SHANNON,et al.  A mathematical theory of communication , 1948, MOCO.

[63]  L.J.Seiderer D.R.Hitchcock R.C.Newell.  The impact of dredging works in coastal waters : A review of the sensitivity to disturbance and subsequent recovery of biological resources on the sea bed , 1998 .

[64]  W. Wiseman,et al.  Comparison of continuous records of near-bottom dissolved oxygen from the hypoxia zone along the Louisiana coast , 1994 .

[65]  P. Hutchings.  Biodiversity and functioning of polychaetes in benthic sediments , 1998, Biodiversity & Conservation.

[66]  M. Hill.  Diversity and Evenness: A Unifying Notation and Its Consequences , 1973 .

[67]  P. Rona.  The changing vision of marine minerals , 2008 .

[68]  J. Kube,et al.  Effects of severe oxygen depletion on macrobenthos in the Pomeranian Bay (southern Baltic Sea): a case study in a shallow, sublittoral habitat characterised by low species richness , 1999 .

[69]  M. Kaiser,et al.  Demersal fish and epifauna associated with sandbank habitats , 2004 .

[70]  T. E. Thompson,et al.  Living marine molluscs , 1976 .

[71]  E. H. Simpson.  Measurement of Diversity , 1949, Nature.

[72]  K. R. Clarke,et al.  Non‐parametric multivariate analyses of changes in community structure , 1993 .

[73]  A. Sheldon,et al.  Equitability Indices: Dependence on the Species Count , 1969 .