Fucus vesiculosus (Linnaeus 1753), Bladderwrack (Phaeophyta)

Compiled by: Georg Martin, Estonia

1. Description of the habitat/autecology of the species

Bladder wrack, Fucus vesiculosus, is widely distributed in the Arctic and the cold temperate region (Lüning, 1990). In the Baltic Sea, F. vesiculosus is wide-spread on hard substrata and often dominates shallow macroalgal communities. The alga requires firm substrate and low-moderate exposure to ice and waves in order to form stable and healthy communities (Rosemarin and Notini, 1996). The species has very short dispersal distances (in average few metres), why it is slow to recover from local extinctions.

2. Distribution (past and present)

F. vesiculosus occurs in the Baltic Sea from the south to the Gulf of Bothnia in the north and to the Gulf of Finland in the east. The species is restricted to salinities above 4 psu, with occasional reports of isolated and sparse populations at salinities down to 2 psu. Decreases in distribution and abundance or even disappearances of F. vesiculosus have been reported from locally polluted areas such as the inner Stockholm Archipelago, the Tallinn Bay, the Gulf of Gdansk, the Helsinki Archipelago and the Gulf of Riga. Decreases have also been reported from areas with little local pollution, e.g. the Lågskär skerries, the Tvärminne area, southern coast of Saaremaa island and the Öregrund Archipelagos (see Torn et al., 2006 for recent overview) and it has been suggested that large-scale hydrographical changes (i.e. eutrophication) have contributed to the negative development in Fucus communities (Kangas et al., 1982; Hällfors et al., 1984; Rönnberg et al., 1985).

3. Importance (sub-regional, Baltic-wide, global)

F. vesiculosus is often characterised as one of the most important phytobenthic species in the Baltic coastal zone. This is due to its wide distribution and high biomass and productivity along rocky and stony coasts where Fucus belts play an important structuring role and have a positive effect on biodiversity, being habitats for species-rich epiphytic and epibenthic communities (e.g. Haage, 1975, 1976; Kautsky and Kautsky, 1989; Wallentinus, 1991). As a consequence, changes in the distribution and abundance of F. vesiculosus are likely to markedly influence the coastal Baltic ecosystem, including coastal fish catches (Aneer et al., 1983; Haahtela, 1984).

4. Status of threat/decline

Several studies indicate that F. vesiculosus in the Baltic Sea is threatened by pollution both locally close to point sources and on a larger scale due to a general eutrophication of the Baltic Sea (e.g. Cederwall and Elmgren, 1990; Kautsky et al., 1992; Schramm, 1996).

5. Threat/decline factors

Eutrophication has a complex effect on distribution charactersitics of F. vesiculosus. Among the direct effects of eutrophication are increased sedimentation preventing settlement on the hard substrate, decrease in light depth penetration due to increased pelagic primary productivity affecting the suitable settlement depth,  mass occurences of grazing invertebrates causing local extinctions, and mass ocurrence of filamentous macroalgal species competing for light, nutrients and space (e.g. Korpinen & Jormalainen, 2008). Therefore, persistent changes in the trophic structure of the Baltic ecosystem may be important also for F. vesiculosus. Recently, it has also been suggested that high nutrient levels may directly inhibit spore settlement and initial development of F. vesiculosus (Bergström et al., 2003). Eventually, toxic substances may prevent F. vesiculosus from colonising otherwise suitable habitats (Kautsky et al., 1992). Direct habitat destruction from various human activities have also a major impact on the species distribution in many areas along the Baltic Sea coast.

6. Options for improvement

Since eutrophication is the main threat for bladderwrack, reductions in nutrient loading are essential for the species. Because recolonisation of bladderwrack is very slow due to its short dispersal distances, reintroductions of the species to its former distribution areas should be considered after ameliorated environmental conditions.

7. References

Aneer G., Florell G., Kautsky U., Nellbring S., Sjöstedt L., 1983: In situ observations of Baltic herring (Clupea harengus membras) spawning behaviour in the Askö-Landsort area, northern Baltic proper. Mar. Biol. 74, 105–110.

Bergström L., Berger R., Kautsky L., 2003: Negative direct effects of nutrient enrichment on the establishment of Fucus vesiculosus in the Baltic Sea. Eur. J. Phycol. 38, 41–46.

Cederwall H., Elmgren R., 1990: Biological effects of eutrophication in the Baltic Sea, particularly the coastal zone. Ambio 19, 109–112.

Haage P., 197:. Quantitative investigations of the Baltic Fucus belt macrofauna. 2. Quantitative seasonal fluctations. Contr. Askö Lab. Univ. Stockholm 9, 1–88.

Haage P., 1976: Quantitative investigations of the Baltic Fucus belt macrofauna. 3. Seasonal variation in biomass, reproduction and population dynamics of the dominant taxa. Contr. Askö Lab. Univ. Stockholm 10, 1–84.

Haahtela I., 1984: A hypothesis of the decline of the Bladder Wrack (Fucus vesiculosus L.) in SW Finland in 1975–1981. Limnologica 15 (2), 345–350.

Hällfors G., Kangas P., Niemi Å., 1984: Recent changes in the phytal at the south coast of Finland. Ophelia 3, 51–59.

Kangas P., Autio H., Hällfors G., Luther H., Niemi Å., Salemaa H., 1982: A general model of the decline of Fucus vesiculosus at Tvärminne, south coast of Finland in 1977–1981. Acta Bot. Fenn. 118, 1–27.

Kautsky H., Kautsky L., Kautsky N., Kautsky U., Lindblad C., 1992: Studies on the Fucus vesiculosus community in the Baltic Sea. Acta Phytogeogr. Suec. 78, 33–48.

Kautsky L., Kautsky H., 1989: Algal diversity and dominance along gradients of stress and disturbance in marine environments. Vegetatio 83, 259–267.

Korpinen S., Jormalainen V., 2008. Grazing and nutrients reduce recruitment success of Fucus vesiculosus L. (Fucales: Phaeophyceae). Estuarine, Coastal and Shelf Science 78: 437-444.

Lüning K., 1990: Seaweeds—Their Environment, Biogeography and Ecophysiology. John Wiley & Sons, Inc., New York.

Rosemarin A., Notini M., 1996: Factors determining the occurrence of bladderwrack (Fucus vesiculosus L.) in the Baltic Sea Proper and Bothnian Sea. In: Proceeding of the 13th Symposium of the Baltic Marine Biologists. pp. 101–112.

Rönnberg O., Lehto J., Haahtela I., 1985: Recent changes in the occurrence of Fucus vesiculosus in the Archipelago Sea, SW Finland. Ann. Bot. Fenn. 22, 231–244.

Schramm W., 1996: Marine benthic vegetation. Recent changes and the effects of eutrophication Ecological Studies, vol. 123. Springer.

Torn K., Krause-Jensen D. & Martin G. 2006: Present and past depth distribution of bladder-wrack (Fucus vesiculosus) in the Baltic Sea. Aquatic Botany, 84: 53-62.

Wallentinus I., 1991: The Baltic Sea gradient. In: Mathieson, A.C., Nienhuis, P.H. (Eds.), Ecosystems of the World 24—Intertidal and Littoral Ecosystems. Elsevier, Amsterdam, pp. 83–108.