Alien%20species%20on%20Sylt

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Alien species on Sylt

• Seaweeds

Maria Redeker, Carolin Barz, Olga Kolychalow
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Native Phaeophycea (brown alga)
http//www.arkive.org/species/ARK/plants_and_algae
/Fucus_vesiculosus/
Fucus vesiculosus
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Alien Algae on Sylt

• Gracilaria vermiculophylla
• Since 2002 in Wadden Sea

• Sargassum muticum
• Since 1993 on Sylt

http//www.algaebase.org/search/species/detail/?sp
ecies_id4417
http//www.issg.org/database/species/ecology.asp?s
i727fr1stssss
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Aims

• Do the species differ in length?
• Does any species prefer any specific attachment
  type?
• Does the length of the alga depend on the
  attachment type?
• Is there any competition between native and
  non-native species?
• Does the length reflect any habitat provision?
• May the non-native species have any effect on
  biodiversity?

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Study sites

1. Oyster bed
2. Former military area
3. Boulders
4. Oyster farm

http//www.welt-atlas.de/datenbank/karten/karte-1-
227.gif
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Methods

• Measuring length of thalli
• Determine attachment type

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Length of macroalgae
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Length of F. vesiculosus relating to attachment
type
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Length of G. vermiculophylla relating to
attachment type
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Length of S. muticum relating to attachment type
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Results

• No obvious dependence of length and attachment
  type
• Attachment type does not influence growth
• Not possible to state if species prefer any
  specific attachment type

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Discussion

• Notably longer thalli and complexity of structure
  of both invasive species may imply a larger
  surface, i.e. habitat
• S. muticum supports twice as many species (local)
  as F.vesiculosus
• S. muticum provides habitat for species which
  otherwise would be rare or absent (e.g. several
  species of red algae)

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Discussion

• No competition between S. muticum and F.
  vesiculosus as they occur at different water
  levels
• G. vermiculophylla and F. vesiculosus occur in
  the same spots

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Conclusions

• Up to now no replacement of native species
  recorded in SE Wadden Sea
• Seem to have positive effects on habitat
  formation and biodiversity
• As non-native algae species are expected to
  increase in abundance, this might affect
  competitive ability of native species

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Conclusions

• Species have the potential to alter the ecology
  of Wadden Sea
• Attempts to eradicate S. muticum likely to fail
• Due to insufficient knowledge it is not possible
  to predict the future effects
• More research is needed !!!!!!

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Thank you for your attention!!