Effects of dredged material placement on intertidal meiofauna

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Effects of dredged material placement on
intertidal meiofauna
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Dredged material placement

• The predominant effect is the direct burial of
  resident biota
• The fate of buried organisms is important in
  terms of possible recolonisation of a beneficial
  use site
• Recolonisation
• - passive via the water column
• - active via migration

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Objective
To conduct studies into processes affecting
biological recovery of benthic meiofauna in
response to the beneficial placement of dredged
material in the coastal environment
Field study Muddy intertidal beneficial use
site
Field experiment Intertidal mudflat
Laboratory experiment Intertidal mud communitiy
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Meiofauna
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Field study

• Aim
• To describe spatial and temporal changes in
  natural communities in response to dredged
  material placement
• Approach
• Collection of samples at 3 reference sites and 3
  recharge sites 3, 6, 9 and 12 months after
  recharge
• Study site
• Beneficial use site at Tichmarsh Marina

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Field study Results
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Field experiment

• Aim
• To assess the effects of particle size
  distribution and organic content on the
  recolonisation of meiofauna for a period of 12
  months
• Approach
• Exposure of communities to different
  experimental treatments
• Study site
• Mud flat in North Fambridge

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Field experiment Results
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Laboratory experiment

• Aim
• To assess the species-specific preference of
  various sediment characteristics
• Approach
• Monitoring of migration rates of mud species
  into several types of defaunated sediment
  differing in sediment granulometry
• Natural assemblage
• Intertidal mud community from Creeksea

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Experimental set-up
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Laboratory experiment Results
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Conclusions and outlook

• Combined approach (field study field experiment
  laboratory experiment) is useful in assessing
  ecological effects of dredged material placement
• Gain information on how dredged material
  placement is critical for creating ecologically
  functional environments
• - Structure of assemblages (e.g. number of
• species, diversity, species composition)
• - Function (e.g. trophic relationships,
• biomass, growth patterns)