Invasion history of Fucus evanescens C. Ag. in the Baltic Sea region

and effects on the native biota

Ishavstång (Fucus evanescens)

Blåstång(Fucus vesiculosus)

Spridning och etablering av ishavstång i Sverige

Faktorer som påverkar etableringen

Effekter på inhemska arter

Invasion history of Fucus evanescens C. Ag. in the Baltic Sea region

and effects on the native biota

Biological invasions

A geographical expansion of a species to an area it has previously not inhabited

Caulerpa taxifolia

Fucus evanescens

Bladder-wrack(Fucus vesiculosus)

1 cm

Questions

Paper I Wikström SA, von Wachenfeldt T & Kautsky L: Establishment of the exotic species Fucus evanescens C. Ag. (Phaeophyceae) in Öresund, Southern Sweden.

(1) How has Fucus evanescens spread and established in Sweden?

(2) Which factors influence the invasion success of F. evanescens?

Paper II Wikström SA & Kautsky L: Effects of the invading brown alga Fucus evanescens on associated biota

(3) Does the introduction affect the native biota?

Study area

(1) How has F. evanescens spread and established in Öresund?

First documentation 1948 (harbour of Copenhagen)

Distribution and abundance of F. evanescens investigated 1966-72 and 2000

30 sites investigated

(1) Pattern of spread

1972 2000

(1) Pattern of spread

(2) Which factors influence the invasion success of F. evanescens?

(2) Restricting factors

F. evanescens mostly found

- in northern Öresund

- at sheltered sites (harbours)

Salinity?

Wave exposure?

(2) Restricting factors

Salinity

(2) Restricting factors

Salinity

0

20

40

60

80

100

6 8 10 12 14 16 18 20 22 24

salinity (psu)

% g

erm

inat

ed

(2) Restricting factors

Salinity

0.10

0.15

0.20

0.25

0.30

8 10 12 14 16 18 20 22 24 26

salinity (psu)

len

gth

(m

m)

Wave exposure

(2) Restricting factors

Wave exposure

Attachment strength - F. evanescens

- F.vesiculosus

- F. serratus

(2) Restricting factors

No difference

(2) Which factors influence the invasion success of F. evanescens?

Wave exposure? No

Salinity? Probably in southern Öresund

Competition?

(2) Restricting factors

(3) Associated epibiota

(3) Does the introduction of F. evanescens affect the native biota?

Does the epiphytic and epifaunal community of F. evanescens differ from that of the native F. vesiculosus?

?

(3) Associated epibiota

0

50

100

150

200

250

300

350

Fv Fe

bio

ma

ss (

mg

g-1

Fu

cus)

epiphytic fauna

epiphytic algae

Biomass

0

1

2

3

4

5

Fv Fe

No

of

spe

cie

s

Species number

14

7

Epiphytes

(3) Associated epibiota

0

50

100

150

200

250

300

350

Fv Fe

bio

ma

ss (

mg

g-1

Fu

cus)

epiphytic fauna

epiphytic algae

Epiphytes

0

10

20

30

40

50

60

70

80

90

100

Fv Fe

bio

ma

ss (

mg

g-1

Fu

cus

)

isopods

gammarids

gastropods

remaining

Infauna

(3) Does the introduction of F. evanescens affect the native biota?

Fucus evanescens has

- fewer epiphytic species- less epiphytic biomass- less biomass of motile fauna

(3) Associated epibiota

Does F. evanescens replace F. vesiculosus?

Thanks to…

My supervisors Lena Kautsky and Ove Eriksson and all people who have contributed with field and

laboratory assistance, statistical advice and scientific discussions.

My family for their support.

Stockholm Marine Research Centre (SMF) provided financial support.

Why important?

Wave exposure

0

20

40

60

80

100

120

140

0 10 20 30 40 50

Dry weight (g)

Att

ac

hm

en

t s

tre

ng

th (

N)

F. evanescens

F. vesiculosus

F. serratus

(2) Restricting factors

Detrended correspondence analysis (DCA)

(3) Associated epibiota

-1

0

1

2

3

-1 0 1 2 3

Axis 1 (24.6%)

Ax

is 2

(11

.6%

)F. evanescens

F. vesiculosus