Polerecky, L.

Reise, Karsten

Volkenborn, Nils

English

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Mya arenaria 01000200030004000Mid Intertidal Low IntertidalInd. m-2ExclusionControlAmbientMacoma balthica 05001000150020002500Mid Intertidal Low IntertidalInd. m-2ExclusionControlAmbientexperimental setup: 2-factorial nested block designEcosystem engineering in intertidal sand by the lugwormArenicola marinaNils Volkenborn, Lubos Polerecky*, Karsten ReiseAWI, Wadden Sea Station Sylt, *MPI for Marine Microbiology, BremenAlfred Wegener Institute for Polar- und Marine Research, Wadden Sea Station Sylt,  contact: nvolkenborn@awi-bremerhaven.deDeposit-feeding lugworms are widespread the dominant large burrowing macrofaunal species and consequently the major source of sediment reworking and bioirrigation of intertidal sediments in the Wadden Sea. In 2002 an ongoing large-scale, long-term lugworm exclusion experiment was started, by meshing the sediment in 10 cm depth on 6 exclusion plots, each with an area of 400m2 to reveal significant effects of lugworms on ecosystem functioning.…biogeochemical processesConclusions and perspectives• Effects of ‘ecosystem engineering’ by lugworms extend beyond the vicinity of individual burrows with considerable implications for sediment properties, biogeochemical processes, and the benthic community.• Effects are variable in space and time.• The experiment offers ideal testing ground for further research regarding key species, biodiversity and ecosystem functioning.• The experiment is a contribution to the European network of Marine Biodiversity and Ecosystem Functioning (MarBEF) and one part of the BMBF project NEBROC (Netherlands Bremen Oceanography).20 metersExclusion plots, December 2002                                     500 meters Exclusion (netted) Ambient (undisturbed) Control (disturbed, without net) Low intertidal fine sand Emersion period  3-4 h grain size median ~220 µm Mid intertidal medium sandemersion period  6-7 h grain size median ~340 µm  20 meters  BLOCK 1 BLOCK 2BLOCK 3 BLOCK 4 BLOCK 5 BLOCK 6 Lugworms affect...…intertidal habitat succession…functional diversity …structural habitat complexity                         012345Exclusion Control AmbientInd. in 1.000 m-20246810Exclusion Control Ambient0123Exclusion Control Ambient1st year 2nd year 3rd year carnivorous motile wormssubsurface deposit-feeding discretely motile wormssurface deposit-feeding discretely motile wormsmixed suspension and surface deposit feeding tube wormsM ud Fine Sand M edium  Sand Coarse Sand HW L LW LO2 (nmol cm-3)O2 (nmol cm-3)Lugworms maintainsediment permeabilityand facilitate oxygenpenetration withincreasing hydrostaticpressuresh = 20Exclusion siteh = 0h = 20 h = 30 h = 40 h = 50h = 10 h = 30 h = 40h = 01 cmLugworm siteBerkeleya rutilans spring 2003Enteromorpha spp. Ulva specc.  summer 2004Algae fixed to protrudingpolychaete tubes on lugworm exclusion plotsLugworms facilitate sulphide sensitive species and inhibit tube building speciesEnhanced recruitmentof byssus driftingbivalves-1001020300 100 200 300 400µmol L-1depth (cm0.00.51.01.52.0Medium Sand Fine SandFine Fraction % ExclusionControlAmbientLugworms inhibitaccumulation of fine particles, porewater nutrients, and sulphideHypothsized expansion of permeable sandflats at the cost of cohesive mudflats2003 mid intertidal2004lowintertidalSediment fraction < 63 µm Porewater nutirents (NH4)Lugworms tidal flat and lugworm burrow

Ecosystem engineering in intertidal sand by the lugworm Arenicola marina

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