introduced macroalgae in denmark when, where, how and which effects? peter a. stæhr...
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Introduced macroalgae in Denmark
When, where, how and
which effects?
Peter A. StæhrFreshwaterbiological Laboratory
Biological Institute, Univ. Copenhagen
Some ”basic” questions:
What is a macroalgae?
What characterizes an invasive macroalgae?
Which steps are involved in macroalgal invasions?
What are the likely impacts of an invasion?
Macroalgae?
Macroalgae?
Steneck & Dethier 1994
Invasive macroalgae?
Williams & Smith 2006
Invasive macroalgae?
Williams & Smith 2006
Num
ber
of in
trod
uctio
ns
Macroalgae in Danish waters
Ns = North SeaSk = SkagerrakK = KattegatLf = LimfjordenSa = Northern beltseaSb+Sm = Great beltLb = Little beltSu = OresoundBm+Bb = Baltic sea
Map of diving locations in the Danish marine monitoring program.
From 19892003: 9738 observations with 290 taxa, including 9 invasive
Which macroalgal NIS?
Red(159)
Bonnemaisonia hamifera Dasya baillouviana Gracilaria vermiculophyllaHeterosiphonia japonica= Dasysiphonia sp.
Neosiphonia harveyi
Polysiphonia elongella new!
Red(159)
Brown(126)
Bonnemaisonia hamifera Dasya baillouviana Gracilaria vermiculophyllaHeterosiphonia japonica= Dasysiphonia sp.
Neosiphonia harveyi
Colpomenia peregrina Sargassum muticum Fucus evanescensDictyota dichotoma
Which macroalgal NIS?
Red(159)
Brown(126)
Green(91)
Bonnemaisonia hamifera Dasya baillouviana Gracilaria vermiculophyllaHeterosiphonia japonica= Dasysiphonia sp.
Neosiphonia harveyi
Colpomenia peregrina Sargassum muticum Fucus evanescens
Codium fragile ssp. tomentosiodes / scandiavicum
Dictyota dichotoma
Which macroalgal NIS?
Class Species Origin Transport Year Europe Year DK
RedBonnemaisonia
hamiferaPacifics (Japan) Ship?
1890(England) 1900
RedDasya
baillouviana Mediterranean Ship?/oysters? Natural 1961
RedHeterosiphonia
japonica Pacifics Ship?/oysters?1994
(Holland) 2005
RedNeosiphonia
harveyi
Pacifics / NW Atlantics
Epiphytes?1908
(England?) 1986
RedGracilaria
vermiculophylla Pacifics Ship?/oysters?1935
(Norway?) 2003
BrownColpomenia
peregrina Pacifics Oysters?1905
(France) 1939
BrownFucus
evanescens North Atlantics Ship / natural Natural 1948
BrownSargassum
muticumPacifics(Japan) Oysters?
1960s (France?) 1984
BrownDictyota
dichotomaAtlantic Oysters /
natural? Natural 1939
Green
Codium fragile ssp.
tomentosoidesAtlantics (Japan) Ship/oysters?
1900 ca (Holland)
1919Green
Codium fragile ssp.
scandinavicumAtlantics
(Sibiria, Japan) Ship/oysters?1919
(Denmark)
Where from, how and when?
Where and how much?Regional distribution
Regioner
Ns K+Lf Sa Lb Sb+Sm Su Bw Bm+BbRel
ativ
dæ
knin
g (%
af s
amfu
nd)
0.001
0.01
0.1
1
10
Bonnemaisonia hamiferaCodium fragileColpomenia peregrinaDasya baillouvianaDictyota dichotomaFucus evanescensGracilaria vermiculophyllaNeosiphonia harveyiSargassum muticum
Regions
Re
lativ
e c
ove
r (%
of c
om
mun
ity)
Salty (34 ppm) Fresh (5-10ppm)
Dybdeinterval (m)
0-2
2-4
4-6
6-8
8-10
10-1
2
12-1
4
14-1
6
16-1
8
18-2
0
20-2
2
22-2
4
24-2
6
26-2
8Rel
ativ
dæ
knin
g (%
af s
amfu
nd)
0.001
0.01
0.1
1
10
Bonnemaisonia hamiferaCodium fragileColpomenia peregrinaDasya baillouvianaDictyota dichotomaFucus evanescensGracilaria vermiculophyllaNeosiphonia harveyiSargassum muticum
Re
lativ
e c
ove
r (%
of c
om
mun
ity)
Depth interval (m)
Where and how much?Depth distribution
Årstal
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Rel
ativ
dæ
knin
g (%
af s
amfu
nd)
0.001
0.01
0.1
1
10
Bonnemaisonia hamiferaCodium fragileColpomenia peregrinaDasya baillouvianaDictyota dichotomaFucus evanescensGracilaria vermiculophyllaNeosiphonia harveyiSargassum muticum
Where and how much?Development in time
Year
Re
lativ
e c
ove
r (%
of c
om
mun
ity)
• 10-12 ”new” species out of 376 total• NIS species amount to 3.75% of total
cover • Most NIS in salty regions• Most at 2-4m (7%) and 20-22m (6%)• No obvious increase during recent years • Gracilaria is expected to spread fast• Lack of knowledge about NIS ecological
impact in Dk more research
Summary on Danish NIS
Donor population
Invasion of new populations
(2) Release and establisment
(1) Uptake, transport
(3) Spread (natural/associated)
(4) Impacts (large)
Invasion phases:
Time
E
ffec
t
1 2 43
Donor region
Recipient region
Physiological
Geographical
Life-history
Biotic resistance
Barriers of invasion:
Sargassum muticum in Denmark
– invasion and ecological effects
• Large (>2m) brown macroalgae (order Fucales)
• Related to Fucus vesiculosus and Halidrys siliquosa
• Floating vesicles
• Broad temperature (10-30 oC) and salinity (18-34 o/oo) tolerance
• Monoecious ~self fertilizing
• High regeneration ability
• Pseudo-perenial life-cycle
Sargassum muticum - phenology
2000?
Invasionhistory
• 60’ies – North America-> Oysters
• Origin – Asia (Japan)
• 70’ies – Europe (English Channel)-> oysters
• 1984 - Denmark-> oysters?-> sekundary spread (drifting)?
??
Ran
g no
.
% of total m
acroalgal cover
Temporal development in community structure
Relative change 1990– 97
Sargassum muticum
Halidrys siliquosa
No clustering
Epibionts on Sargassum (S) and Halidrys (H)
Species richness
Individual density
Biomass
0
500
1000
1500
2000
2500
Uroch
ordata
Crusta
cea
Echin
oder
mata
Moll
usca
Porife
ra
Polych
aeta
Cnidaria
mg
AF
DW
/ 1
00g
FW
alg
ae ±
SE
Sargassum muticum Halidrys siliquosa
Same epifauna but more on Sargassum
Large fluctuation in growth, production and loss
Loss to grazers = 1-2% 99% of production is accumulates as detritus
Even growht, production and loss
Sargassum
Halidrys
Seasonal variation in standing biomass
Fast decomposition
fast release
Impacts of S. muticum in Denmark
• Since the introduction in 1984, Sargassum muticum has become the most common macroalgae in Limfjorden
• The invasion has changed the macroalgal community structure with significant reductions in the cover of other large perennial browalgae
• The invasionen has not changed the epifaunal species composition, but has increased epifaunal abundance and seasonal variation
• The invasionen has resulted in a more unstabil and fluctuating biomass, with faster growth, turnover and nutrient release, similar to systems experiencing eutrophication
Litterature:• Wernberg-Møller, Thomsen & Stæhr (1998). Master thesis, RUC.
• Wernberg-Møller, Thomsen & Stæhr (1998). Urt 22:128-132.
• Stæhr, Pedersen, Thomsen, Wernberg & Krause-Jensen (2000). Mar Ecol-Prog Ser 207:79-88.
• Wernberg, Thomsen, Stæhr & Pedersen (2001). Botanica Marina 44:31-39.
• Wernberg, Thomsen, Stæhr & Pedersen (2004). Helgoland Marine Research 58:154-161.
• Pedersen, Stæhr, Wernberg & Thomsen (2005). Aquatic Botany 83:31-47.
•Thomsen M., Krause-Jensen D., Wernberg T., Stæhr P.A. og Nils Risgaard-Petersen. (2005) Fremmede tangarter i Danmark: Hvilke? Hvor udbredte? Hvornår? Urt 29: 110-115
• Thomsen, Wernberg, Stæhr & Pedersen (2006). Helgoland Marine Research 60:50-58.
•Thomsen MS, Wernberg T, Stæhr PA, Krause-Jensen D, Risgaard-Petersen N, Silliman BR. 2007. Alien macroalgae in Denmark - a national perspective. Marine Biology Research 3: 61-72
Further information (Mads Thomsen website on NIS):
http://cem.ecu.edu.au/coastal-marine/themes/reef-ecology/marine_invaders_bibliography.php