Effects of physical disturbance on infaunal and epifaunal assemblages in subtropical, intertidal seagrass beds

We assessed the impact of large-scale commercial and recreational harvesting of polychaete worms Marphysa spp. on macrobenthic assemblages in a subtropical estuary in Queensland, Australia, by examining: (1) the spatial extent of harvesting activities and the rate of recovery of the seagrass habitat over an 18 to 20 mo period; (2) the recovery of infauna in and around commercial pits of known age; (3) the indirect effects of physical disturbance from trampling and deposition of sediments during harvesting on epibenthos in areas adjacent to commercial and recreational pits; (4) impacts of potential indirect effects through manipulative experimentation. Harvesting caused a loss of seagrass, changes to the topography and compaction of the sediments associated with the creation of walls around commercial pits, and the deposition of rubble dug from within the pit. The walls and rubble were still evident after 1.8 to 20 mo, but comprised only a small proportion of the total area on the intertidal banks. There was a shift from an intertidal area dominated by Zostera capricorni to one with a mixture of Z. capricorni, Halophila spp. and Halodule uninervis, but there was no overall decline in the biomass of seagrass in these areas. There were distinct impacts from harvesting on the abundance of benthic infauna, especially amphipods, polychaetes and gastropods, and these effects were still detectable after 4 mo of potential recovery. After 12 me, there were no detectable differences in the abundances of these infauna between dug areas and reference areas, which suggested that infauna had recovered from impacts of harvesting; however, an extensive bloom of toxic fireweed Lyngbya majsucula may have masked any remaining impacts. There were no detectable impacts of harvesting on epifauna living in the seagrass immediately around commercial or recreational pits.

[1]  M. Fonseca.  Sediment stabilization by Halophila decipiens in comparison to other seagrasses , 1989 .

[2]  M. Rasheed.  Recovery of experimentally created gaps within a tropical Zostera capricorni (Aschers.) seagrass meadow, Queensland Australia , 1999 .

[3]  J. Zieman,et al.  The ecological effects of physical damage from motor boats on turtle grass beds in Southern Florida , 1976 .

[4]  David A. Clifford,et al.  The size frequency and abundance of subtidal bloodworms (Glycera dibranchiata, ehlers) in Montsweag Bay, Woolwich-Wiscasset, Maine , 1986 .

[5]  C. Peterson,et al.  Role of predation in organizing benthic communities of a temperate-zone seagrass bed , 1984 .

[6]  J. Holmquist,et al.  Trampling in a seagrass assemblage: direct effects, response of associated fauna, and the role of substrate characteristics , 2000 .

[7]  A. Rowden,et al.  Effect of patch size and in-patch location on the infaunal macroinvertebrate assemblages of Zostera marina seagrass beds. , 2001, Journal of experimental marine biology and ecology.

[8]  R. Vadas,et al.  Genetic variability in bloodworm (Glycera dibranchiata) populations in the Gulf of Maine , 1991 .

[9]  R. Blake.  EXPLOITATION OF A NATURAL POPULATION OF ARENICOLA MARINA (L.) FROM THE NORTH-EAST COAST OF ENGLAND , 1979 .

[10]  C. Peterson.  Patterns of lagoonal bivalve mortality after heavy sedimentation and their paleoecological significance , 1985 .

[11]  J. Fisher,et al.  The role of current velocity in structuring eelgrass (Zostera marina L.) meadows , 1983 .

[12]  A. Hines,et al.  Vertical distribution of infauna in sediments of a subestuary of central Chesapeake Bay , 1985 .

[13]  H. L. Sanders.  BENTHIC STUDIES IN BUZZARDS BAY III. THE STRUCTURE OF THE SOFT‐BOTTOM COMMUNITY1 , 1960 .

[14]  W. S. Arnold.  The effects of prey size, predator size, and sediment composition on the rate of predation of the blue crab, Callinectes Sapidus Rathbun, on the hard clam, MercenariaMercenaria (Linné) , 1984 .

[15]  C. Peterson,et al.  ECOLOGICAL CONSEQUENCES OF MECHANICAL HARVESTING OF CLAMS , 1987 .

[16]  Kristian Fauchald,et al.  The Polychaete Worms: Definitions and Keys to the Orders, Families and Genera , 1977 .

[17]  Fortes,et al.  Response of a mixed Philippine seagrass meadow to experimental burial , 1997 .

[18]  D. Maurer,et al.  Vertical migration and mortality of benthos in dredged material—part I: Mollusca , 1981 .

[19]  K. Able,et al.  Deep burial as a refuge for lady crabs Ovalipes ocellatus: comparisons with blue crabs Callinectes sapidus , 1990 .

[20]  V. Paul,et al.  Chemical defense of a marine cyanobacterial bloom , 1998 .

[21]  J. Brouns.  Growth patterns in some indo-west-pacific seagrasses , 1987 .

[22]  R. Blake.  On the exploitation of a natural population of Nereis virens Sars from the north-east coast of England , 1979 .

[23]  William C. Dennison,et al.  Blooms of the cyanobacterium Lyngbya majuscula in coastal waters of Queensland, Australia , 1999 .

[24]  K. Leber.  The Influence of Predatory Decapods, Refuge, and Microhabitat Selection on Seagrass Communities , 1985 .

[25]  J. Dirnberger.  Influences of Larval Settlement Location and Rate on Later Growth and Mortality in a Sessile Marine Invertebrate Population (Spirorbis spirillum) , 1994 .

[26]  D. Maurer,et al.  Vertical migration and mortality of benthos in dredged material: Part III—polychaeta☆ , 1982 .

[27]  E. May.  Environmental effects of hydraulic dredging in estuaries. , 1973 .

[28]  C. Dawes,et al.  Regrowth of the seagrass Thalassia testudinum into propeller scars , 1997 .

[29]  D. Rhoads,et al.  Animal-sediment relations in Cape Cod Bay, Massachusetts II. Reworking by Molpadia oolitica (Holothuroidea) , 1971 .

[30]  D. Thistle.  Natural Physical Disturbances and Communities of Marine Soft Bottoms , 1981 .

[31]  G. Skilleter.  Refuges from predation and the persistence of estuarine clam populations , 1994 .

[32]  E. P. Creaser.  Reproduction of the Bloodworm (Glycera dibranchiata) in the Sheepscot Estuary, Maine , 1973 .

[33]  Fortes,et al.  Meadow maintenance, growth and productivity of a mixed Philippine seagrass bed , 1995 .

[34]  P. Abrams.  Resource partitioning and interspecific competition in a tropical hermit crab community , 1980, Oecologia.

[35]  D. Wildish,et al.  Effects of dredging and dumping on benthos of Saint John Harbour, Canada , 1985 .

[36]  Timothy A. Thoman,et al.  Experiments on predator-prey interactions in vegetated aquatic habitats , 1981 .

[37]  Frederick T. Short,et al.  Natural and human-induced disturbance of seagrasses , 1996, Environmental Conservation.

[38]  L. G. Abele,et al.  Experiments on Competition and Predation Among Shrimps of Seagrass Meadows , 1981 .

[39]  P. Abrams,et al.  Resource partitioning and competition for shells in a subtidal hermit crab species assemblage , 1986, Oecologia.

[40]  A. Mccomb,et al.  Decline of seagrasses , 1989 .

[41]  W. F. Boer,et al.  The community structure of a tropical intertidal mudflat under human exploitation , 2002 .

[42]  G. Brenchley.  Disturbance and community structure an experimental study of bioturbation in marine soft bottom environments , 1981 .

[43]  J. Creed,et al.  Disturbance and recovery of the macroflora of a seagrass (Halodule wrightii Ascherson) meadow in the Abrolhos Marine National Park, Brazil: an experimental evaluation of anchor damage , 1999 .

[44]  W. Kenworthy,et al.  Comparisons of fauna among natural and transplanted eelgrass Zostera marIna meadows: criteria for mitigation , 1990 .

[45]  Anthony W. D. Larkum,et al.  Biology of seagrasses : a treatise on the biology of seagrasses with special reference to the Australian region , 1989 .

[46]  D. Armstrong,et al.  Use of Oyster Shell to Enhance Intertidal Habitat and Mitigate Loss of Dungeness Crab (Cancer magister) Caused by Dredging , 1993 .

[47]  R. Ginsburg,et al.  The Influence of Marine bottom Communities on the Depositional Environment of Sediments , 1958, The Journal of Geology.

[48]  K. Sand‐Jensen.  Biomass, net production and growth dynamics in an eelgrass (Zostera marina L.) population in Vellerup Vig, Denmark , 1975 .

[49]  S. Wolfe-Murphy,et al.  Distribution and population recovery of Arenicola marina and other benthic fauna after bait digging , 1983 .

[50]  Taco van den Heiligenberg.  Effects of mechanical and manual harvesting of lugworms Arenicola marina L. on the benthic fauna of tidal flats in the Dutch Wadden sea , 1987 .

[51]  Yuri Zharikov,et al.  Potential interactions between humans and non-breeding shorebirds on a subtropical intertidal flat , 2004 .

[52]  H. L. Sanders,et al.  Benthic Studies in Buzzards Bay. I. Animal‐Sediment Relationships1 , 1958 .

[53]  M. Keough.  The Distribution of a Bryozoan on Seagrass Blades: Settlement, Growth, and Mortality , 1986 .

[54]  G. Skilleter,et al.  An experimental test of artifacts from repeated sampling in soft-sediments , 1996 .

[55]  D. Rhoads,et al.  Organism-sediment relations on the muddy sea floor , 1974 .

[56]  Robert J. Orth,et al.  Faunal communities in seagrass beds: A review of the influence of plant structure and prey characteristics on predator-prey relationships , 1984 .

[57]  A. Mccomb,et al.  The distribution, biomass and primary production of the seagrass Halophila ovalis in the Swan/Canning Estuary, Western Australia. , 1995 .

[58]  G. Shaw,et al.  The toxins of Lyngbya majuscula and their human and ecological health effects. , 2001, Environment international.