Post on 12-Feb-2016
description
Native Phaeophycea (brown alga)
Fucus vesiculosushttp://www.arkive.org/species/ARK/plants_and_algae/Fucus_vesiculosus/
Alien Algae on Sylt
Gracilaria vermiculophyllaSince 2002 in Wadden Sea
Sargassum muticumSince 1993 on Sylt
http://www.algaebase.org/search/species/detail/?species_id=4417 http://www.issg.org/database/species/ecology.asp?si=727&fr=1&sts=sss
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?
Study sites
http://www.welt-atlas.de/datenbank/karten/karte-1-227.gif
a. Oyster bed
b. Former military area
c. Boulders
d. Oyster farm
Length of macroalgae
Median 25%-75% Range without outliers
FucusGracilaria
Sargassum
Species
-50
0
50
100
150
200
250
300
350
Leng
th
Length of F. vesiculosus relating to attachment type
Median 25%-75% Range without outliersbrick oyster mussel stone
Substrate
5
10
15
20
25
30
35
40
45
50
55
Leng
th [c
m]
Length of G. vermiculophylla relating to attachment type
Median 25%-75% Range without outliers Outlier
stonerazor clam
musselrotten
oyster
Substrate
20
40
60
80
100
120
140
160
180
Leng
th [c
m]
Length of S. muticum relating to attachment type
Median 25%-75% Range without outliers
stoneoyster
slipper limpetmussel
Substrate
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
Leng
th [c
m]
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
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)
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
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
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 !!!!!!