| 1. |
- Ardehed, Angelica, et al.
(författare)
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Divergence within and among Seaweed Siblings (Fucus vesiculosus and F. radicans) in the Baltic Sea
- 2016
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Closely related taxa provide significant case studies for understanding evolution of new species but may simultaneously challenge species identification and definition. In the Baltic Sea, two dominant and perennial brown algae share a very recent ancestry. Fucus vesiculosus invaded this recently formed postglacial sea 8000 years ago and shortly thereafter Fucus radicans diverged from this lineage as an endemic species. In the Baltic Sea both species reproduce sexually but also recruit fully fertile new individuals by asexual fragmentation. Earlier studies have shown local differences in morphology and genetics between the two taxa in the northern and western Bothnian Sea, and around the island of Saaremaa in Estonia, but geographic patterns seemin conflict with a single origin of F. radicans. To investigate the relationship between northern and Estonian distributions, we analysed the genetic variation using 9 microsatellite loci in populations from eastern Bothnian Sea, Archipelago Sea and the Gulf of Finland. These populations are located in between earlier studied populations. However, instead of bridging the disparate genetic gap between N-W Bothnian Sea and Estonia, as expected from a simple isolation-by-distance model, the new populations substantially increased overall genetic diversity and showed to be strongly divergent from the two earlier analysed regions, showing signs of additional distinct populations. Contrasting earlier findings of increased asexual recruitment in low salinity in the Bothnian Sea, we found high levels of sexual reproduction in some of the Gulf of Finland populations that inhabit extremely low salinity. The new data generated in this study supports the earlier conclusion of two reproductively isolated but very closely related species. However, the new results also add considerable genetic and morphological complexity within species. This makes species separation at geographic scales more demanding and suggests a need for more comprehensive approaches to further disentangle the intriguing relationship and history of the Baltic Sea fucoids.
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| 2. |
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| 3. |
- Bergström, Lena, et al.
(författare)
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Effects of offshore wind farms on marine wildlife-a generalized impact assessment
- 2014
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 9:3
-
Tidskriftsartikel (refereegranskat)abstract
- Marine management plans over the world express high expectations to the development of offshore wind energy. This would obviously contribute to renewable energy production, but potential conflicts with other usages of the marine landscape, as well as conservation interests, are evident. The present study synthesizes the current state of understanding on the effects of offshore wind farms on marine wildlife, in order to identify general versus local conclusions in published studies. The results were translated into a generalized impact assessment for coastal waters in Sweden, which covers a range of salinity conditions from marine to nearly fresh waters. Hence, the conclusions are potentially applicable to marine planning situations in various aquatic ecosystems. The assessment considered impact with respect to temporal and spatial extent of the pressure, effect within each ecosystem component, and level of certainty. Research on the environmental effects of offshore wind farms has gone through a rapid maturation and learning process, with the bulk of knowledge being developed within the past ten years. The studies showed a high level of consensus with respect to the construction phase, indicating that potential impacts on marine life should be carefully considered in marine spatial planning. Potential impacts during the operational phase were more locally variable, and could be either negative or positive depending on biological conditions as well as prevailing management goals. There was paucity in studies on cumulative impacts and long-term effects on the food web, as well as on combined effects with other human activities, such as the fisheries. These aspects remain key open issues for a sustainable marine spatial planning.
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| 4. |
- Bergström, Lena, et al.
(författare)
-
Effekter av havsbaserad vindkraft på marint liv : En syntesrapport om kunskapsläget 2021
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Att öka tillgången på förnybar energi är nödvändigt för att motverka klimatförändringarna. Här förväntas havsbaserad vindkraft ha en viktig roll. Samtidigt medför planer på att bygga ut havsbaserad vindkraft viktiga frågeställningar kring hur marint liv och biologisk mångfald kan påverkas. I den här rapporten sammanställs det nuvarande kunskapsläget om hur havsbaserad vindkraft skulle kunna påverka marint liv, med fokus på svenska havsområden. Temamässigt omfattar rapporten bottennära miljöer, fisk, marina däggdjur och sjöfågel. Den strävar även efter att belysa kunskapsläget kring kumulativa effekter, samt frågor om under vilka förutsättningar havsbaserad vindkraft skulle kunna gynna marint liv.Bedömningarna beaktar även hur det tekniska utförandet har utvecklats, till exempel när det gäller vindparkernas utformning och dimensionering. Planeringen idag omfattar större vindparker och kraftverk, och bottenfasta vindkraftverk kan lokaliseras på allt större djup. De har hittills främst etablerats inom djupintervallet 5–40 meter, men kan numera anläggas på omkring 40–60 meters djup. Därtill förväntas flytande fundament, som klarar ännu större djup, bli vanligare. En annan viktig aspekt är hur tillämpningen av skadelindrande åtgärder har utvecklats.Havsbaserad vindkraft förväntas påverka marint liv på olika sätt under anläggnings- och driftsfasen, varför det är relevant att tydligt särskilja dessa i riskbedömningar. Rapporten berör även effekter under avvecklingsfasen.Under anläggningsfasen, som pågår någon dag per kraftverk, kan högintensivt ljud uppstå till exempel i samband med pålning av vindkraftverkens fundament. Åtgärder för att minska skadeverkningar av högintensivt ljud är viktiga, och kan förutsättas vara standard idag. Ofta finns det även behov att förbereda havsbotten, vilket leder till spridning av sedimentpartiklar. Omfattningen av både ljud- och sedimentspridning beror på lokala förhållanden. Därför behöver de lokala förhållandena beaktas för att ta fram en mer detaljerad kännedom om risker för marint liv. I synnerhet tumlare kan påverkas negativt av höga ljudnivåer vid anläggningsfasen, med risk för hörselpåverkan och kraftiga beteendestörningar om inte skadelindrande åtgärder används. Särskilda hänsyn i lokalisering och utförande kan även behövas för sälar, samt för fisk när det gäller områden och årstider som är viktiga för deras reproduktion. Under driftsfasen, som pågår upp emot cirka 40 år, bildar vindkraftverkens fundament och eventuella erosionsskydd fasta strukturer. Detta kan ge upphov till reveffekter då ytorna skapar plats för fastsittande arter. Med tiden kan även fiskar och marina däggdjur lockas dit, om förhållandena medger det. En viktig skillnad jämfört med andra typer av rev är att fundamenten går hela vägen upp till ytan, vilket ökar tillgången på hårda substrat i hela vattenpelaren. En möjlig risk är att de nya substraten skulle kunna gynna oönskade främmande arter, även om det saknas belägg för vindparkernas roll som en sådan spridningsväg.När elen produceras genereras undervattensljud, och överföringen av el i sjökablar kan leda till ett visst mått av elektromagnetiska fält i kablarnas närhet. Effekter av dessa påverkansfaktorer har varit svåra, om inte omöjliga, att notera i fältundersökningar. En generell slutsats skulle kunna vara att, om det förekommer negativa effekter av undervattensljud och elektromagnetiska fält, så är de oftast i styrka underordnade den attraktion som kommer av reveffekten. Aktuella studier tyder sammanfattningsvis på att havsbaserad vindkraft under driftsfasen inte är ett hot mot fiskar, säl eller tumlare. Särskild hänsyn när det gäller lokalisering kan dock behövas för skyddsvärda bottenmiljöer samt sjöfågel. Vissa sjöfågelarter kommer sannolikt att undvika området där vindparken etableras. Även åtgärder för att minska dödlighet kopplad till att fåglar kolliderar med kraftverken kan vara viktiga i vissa områden. Eftersom slutsatserna baseras på studier i andra miljöer än de som kan bli aktuella i Sverige framöver är en uppföljning av miljöeffekter viktig i de parker som etableras, för att ha möjlighet att säkerställa eller vid behov revidera kunskapsläget.Utveckling av kunskapsläget När det gäller vindkraftens effekter på bottennära livsmiljöer har kunskapsläget förbättrats angående mer långsiktig påverkan, liksom hur alg- och djursamhället i vindparken förändras över tid. Med åren blir det mer och mer likt det naturliga samhället på hårda bottnar i den aktuella regionen, även om arter med långlivade larvstadier främjas relativt sett mer. I viss mån saknas kunskap om vilken påverkan som kan förväntas om man bygger på större djup och om vindkraftverken står glesare, som planeras idag. Inga studier tyder dock på att etablering av vindkraftverk är ett hot mot vegetation eller bottenlevande djur i den här typen av miljöer, så länge särskilt skyddsvärda livsmiljöer undviks.Angående fisk och fisksamhällen har förståelsen för reveffekter ökat. Forskningen har övergått till att belysa reveffekter mer ingående, från att tidigare främst bekräfta om det blir en reveffekt eller inte. Sådana studier saknas dock idag för flera svenska havsområden eftersom det inte finns vindparker där.För marina däggdjur har kunskapsläget förbättrats framför allt när det gäller förståelsen av hur sälar och tumlare uppfattar och använder sig av ljud, samt hur ljud av olika frekvens och intensitet påverkar djuren.Kunskapen som hur havsbaserad vindkraft kan påverka sjöfågel har förbättrats framför allt för kustnära områden, men bedömningar begränsas fortfarande av otillräcklig kunskap om olika sjöfågelarters utbredning och dynamik i förekomst mellan år. Det här gäller speciellt områden längre ut till havs och med större djup än 30 meter. Den internationella forskningen har varit fokuserad på att bedöma kollisionsrisk, och ny teknik har gett ökad kunskap om fåglars flyghöjder och beteenden i förhållande till vindkraftverk.Kumulativa effekterFör att göra en sammanvägd bedömning av vindkraftens miljöeffekter är det relevant att sätta de enskilda bedömningarna i ett vidare sammanhang, där även till exempel aktuell miljöstatus och effekter av annan verksamhet ingår, så som omfattningen av fiske och sjöfart. I ett sådant perspektiv skulle införandet av en vindpark kunna leda till att den totala omfattningen av påverkan antingen ökar eller minskar i ett visst område. Etableringen kan också påverka samspelet mellan arter, med efterföljande indirekta effekter i ekosystemet. Att förstå sådana sammanvägda effekter är ett fortsatt viktigt forskningsområde. Det finns även ett behov av att utveckla metoder för att skatta kumulativa effekter i samband med havsbaserad vindkraft på olika rumsliga och tidsmässiga skalor. Utgående från det befintliga kunskapsläget kan risken för att havsbaserade vindparker bidrar med negativa kumulativa effekter på havsmiljön förväntas vara låg, under förutsättning att skadelindrande åtgärder tillämpas och bästa möjliga hänsyn tas. Under anläggningsfasen innebär sådana förutsättningar att skadliga nivåer av påverkansfaktorn minimeras, och att anläggningen sker under sådana rumsliga och tidsmässiga förhållanden att risken för ansamling av känsliga populationer av fisk och marina däggdjur minimeras. Bedömningen beror på att påverkan under anläggningsfasen är tidsmässigt övergående och inte förväntas upprepas vid mer än ett tillfälle per plats. Det baseras därför också på förutsättningen att annan motsvarande verksamhet inte sker samtidigt i området. För driftsfasen innebär förutsättningarna att driften sker med sådan teknik att nivån av elektromagnetiska fält är låg och att undervattensljud inte leder till negativa effekter på fisk eller marina däggdjur, och med undantag av att det fortsatt finns oklarheter kring hur sjöfågel kan påverkas.Vid en omfattande utbyggnad kommer gradvis högre hänsyn och anpassningar för att undvika kumulativa effekter att vara motiverade. Det ställer även ökade krav på nationell och internationell samordning för att undvika risker för kumulativ påverkan i samband med anläggningsfasen, till exempel om flera vindparker anläggs parallellt. Eftersom vindkraftens långsiktiga bidrag till kumulativ påverkan är svårbedömda i dagsläget, och förväntas variera både lokalt och mellan olika havsområden, vore det mycket viktigt att följa utvecklingen över tid i sådana parker som etableras, för att öka kunskapen och skapa möjlighet att vid behov införa åtgärder för att minska risker för specifika arter.Kan vindkraften ha positiva effekter på marint liv?Forskningen innehåller även exempel på när införandet av havsbaserad vindkraft kan ha gynnat arter, eller aspekter av biologisk mångfald och ekosystemtjänster. Det finns dock en svårighet med att generalisera kring om havsbaserad vindkraft kan gynna marint liv, eftersom utfallet i hög grad beror på vindparkens lokalisering, ekologiska förutsättningar, samt vilka andra aktiviteter som förekommer i närområdet. En viktig aspekt är även att mänskliga preferenser påverkar definitionen av om viss förändring i artsammansättning är ”positiv” eller ”negativ”, eftersom det här beror på hur olika arter och ekosystemstjänster värdesätts, det vill säga vilken typ av biologisk mångfald som är önskvärd i ett visst område. Rapporten redogör för olika typer av anpassningar som har förslagits för att gynna särskilda arter i samband med havsbaserad vindkraft, även om utvecklingen av sådana naturanpassade lösningar fortfarande är i sin linda.
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| 5. |
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| 6. |
- Bergström, Lena, 1973-
(författare)
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Macroalgae in the Baltic Sea : responses to low salinity and nutrient enrichment in Ceramium and Fucus
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The brackish Baltic Sea is a marginal environment for both marine and freshwater species. The rate of ecological differentiation is presumably high due to strong selection pressure from a gradient of decreasing salinity that has been present in its current state for only about 3 000 years. Even more recently, increased nutrient loading due to human activities has affected the growth rate of species, with potential effects on their competitive interactions and responses to other regulating factors. I have investigated the potential effects of low salinity and nutrient enrichment on the distributional ranges of two marine macroalgae with a wide distribution in the Baltic Sea, the red alga Ceramium tenuicorne (Kütz.) Wærn and the brown alga Fucus vesiculosus L. A field study in the northern Baltic Sea indicated a strong relationship between the community structure of macroalgae and abiotic factors even on a small, local scale. The abiotic factors are potentially modulated by eutrophication, which may have a strong effect on the depth distribution and abundance of macroalgae. On a regional scale, laboratory experiments suggested that nutrient enrichment is unlikely to affect the distribution of Ceramium and Fucus along the salinity gradient. Growth in Ceramium from the Baltic Proper was enhanced by nitrate and phosphate, but the response did not override growth constraints due to low salinity. Ceramium from the Gulf of Bothnia had an inherently lower growth rate that was not positively affected by nitrate and phosphate increase. In Fucus vesiculosus, reproductive performance was impaired by nitrate and phosphate levels corresponding to ambient levels in eutrophicated areas of the Baltic Sea, when measured by their effect on zygote attachment, germination, and rhizoid development.The wide distribution of Ceramium in the inner Baltic Sea is probably related to local adaptation, rather than a generalized tolerance of different salinity levels. Ecotypic differences were observed when comparing strains from the Baltic Proper (salinity 7 psu) and the Gulf of Bothnia (4 psu). A high rate of vegetative reproduction was evident, although sexual reproduction was occasionally observed in salinity 4. In Fucus vesiculosus, genetic and morphological analyses of sympatric and allopatric populations of the common, vesicular, morphotype and a dwarf morphotype, characteristic for the Gulf of Bothnia, showed that the dwarf morphotype represents a separate evolutionary lineage. Also, vegetative reproduction was observed in Fucus for the first time, as supported by genetic and experimental data. The results show that the biota of the inner Baltic Sea may have unique adaptive and genetic properties, and that it is highly relevant to consider subspecies diversity in Baltic Sea management.
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| 7. |
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| 8. |
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| 9. |
- Bergström, Lena, et al.
(författare)
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The effects of wind power on marine life : A Synthesis
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- As in many other countries, an expansion of wind power is expected in Sweden during the coming decades. The expansion is driven by rising prices on electricity and the need for an increased production of renewable energy. Since wind conditions at sea are good and relatively constant, several offshore wind farms are planned in Swedish waters. Offshore wind power with a total effect of about 2500 MW has been granted permission and an additional 5500 MW are being planned for. Examples of granted projects are Storgrundet with an effect of 265 MW, Stora Middelgrund with an effect of 860 MW and Kårehamn with an effect of 48 MW. The largest offshore wind farm in Sweden today is Lillgrund in Öresund, with its 48 turbines with an installed effect of 110 MW.Prior to this expected expansion, it is important to investigate the environmental impact of offshore wind power, and how possible negative effects can be minimized. This synopsis about the impact of wind power on the marine life in Swedish waters is based on more than 600 studies, most of which are scientific articles, but also reports by companies and authorities.Habitats and species in Swedish marine areasSwedish marine areas are characterized by a unique salinity gradient that varies from marine conditions in Skagerrak to almost limnic environments in the Gulf of Bothnia. There are also vast differences between areas in terms of environmental factors such as insolation, temperature and wave exposure. This entails variation in species composition, dominance by different populations and structural differences in plant and animal communities. Therefore, this synopsis provides environment descriptions of three widely separated marine areas: the Swedish West Coast (Kattegat and Skagerrak), the Baltic Proper and the Gulf of Bothnia (Bothnian Sea and Bothnian Bay). The main focus is on occurrence of species and communities within the depth interval that is of interest for establishing offshore wind power in Sweden.Offshore wind powerThere are mainly two types of foundation structures used in Sweden today: gravity-based foundations and monopile foundations. These are also the most commercially viable. Offshore wind farm projects affect the environment in different ways during installation, operation and decommissioning. The installation phase is assessed as having the largest impact on the environment, since high noise levels and sediment dispersal can affect marine organisms. A wind farm during operation can cause barrier effects as well as changes in the natural environment. The decommissioning phase can again enhance noise levels and lead to sediment dispersal in the wind park and its adjacent area. Effects on marine organisms and communities Since marine environmental conditions vary between different locations as well as over time, it is difficult to make universal assessments of the effects of offshore wind power. This increases the importance of well-designed pilot studies and monitoring programs of the local environment. Also, location-specific surveys minimize the risk that costly measures to reduce negative impact are used when they are not needed. In general, installation and decommissioning of offshore wind farms should be planned so that sensitive reproductive periods for marine species are avoided. Particular consideration might also be needed for constructions in important growth and spawning areas for fish and marine mammals, or specific environments, such as offshore banks with high natural values. Below is a list of the effects that, according to existing knowledge and accessible literature, might affect marine organisms and communities. Each effect has been assessed after how long, and to what scale, it affects the marine life in the wind farm area.Acoustic disturbances during the installationAs monopile foundations are being driven into the sea floor, a lot of noise is generated that spreads in the water. Cod and herring can potentially perceive noise from pile driving at a distance of 80 kilometres, experiencing physical damage and death at just a few meters from the place of installation. For all types of work involving noise, flight reactions in fish are expected within a distance of about one kilometre from the source. The greatest risk of significant harm to fish populations exists if the installation overlaps with important recruitment areas for threatened or weak populations. Among the marine mammals, porpoises have proved to get both impaired hearing and behavioural disturbances from noise associated with pile driving. There are no studies indicating any long-term negative effects on any of the seal species occurring in Swedish waters. It is not possible to draw any general conclusions of the effects on invertebrates from pile driving noise, since the group is too large and diverse. The few studies that exist, however, show that oysters are relatively sensitive, whilst mussels are not affected at all. The effects of high noise levels can be reduced by, for example, successively increasing the power and thus the noise during piling, so that larger animals such as fish, seal and porpoises are intimidated at an early stage and leave the construction area well before high noise levels are reached.Sediment dispersalDredging work during the construction of gravitational foundations, and laying of cables between the wind turbines and land, can cause sediment from the bottom to whirl up and disperse in the water mass. The amount of sediment dispersed depends on the type of sediment, water currents and which dredging method is being used. Increased concentrations of sediment in the water affect mainly fish fry and larval stages negatively. Invertebrates are often adapted to re-suspension of sediment, since it occurs naturally in their environment. The sediment dispersal at the construction of a wind farm is often confined to a short period. The effects are also relatively small due to the fact that the bottom sediment is usually coarse-grained. The overall assessment is therefore that sediment dispersal is a limited problem for most animal and plant communities, but specific consideration should be taken and fish recruitment periods should be avoided.Introduction of a new habitatThe foundations of wind turbines can function as artificial reefs and attract many fish species, particularly around gravitational foundations which have a structurally complex erosion protection. At first there is often a redistribution of fish from nearby areas to the wind park foundations, but over time an actual increased fish production within the park is possible, as long as the park is large enough and the fishing pressure is low. The structure of the erosion protection can bring local positive effects for crustaceans such as lobster and crab, by functioning as shelter as well as increasing their foraging area. One example of a species that seems to increase locally around foundation structures on the Swedish West Coast and the Baltic Proper is the blue mussel. Which species that will dominate depends on the salinity in the area. There are no studies showing that foundation structures will facilitate the distribution of new species to Swedish marine areas. One reason for this might be that the total amount of hard bottom surface formed by the foundations and their structures is relatively small compared to natural hard bottoms.Turbine noise and boat trafficMaintenance work on the wind turbines causes a certain increase in boat traffic in the area of an operating wind farm. Also, different parts of the turbines generate noise during operation that spreads through the water. The reactions of fish on noise from turbines and boat engines vary, but study results indicate that the effect on most fish species from noise produced in a wind farm is low. There are, however, no studies on long-term effects of stress due to an increased noise level or effects of noise disturbance on fish spawning behaviour. Porpoises especially, but to some extent also seals, are sensitive to noise disturbance. Today there are no studies showing negative effects from the operational sounds from a wind farm on populations of marine mammals. The noise of both strong winds and engines from ships often exceeds the underwater noise generated by operating wind farms.Electromagnetic fieldsThe electric cables leading from a wind turbine generates a magnetic field that decreases with distance from the cable. The expected effect on most fish species is low, but since the effect is ongoing throughout the entire operational stage, the risk should be considered in areas that are important to migrating fish species. No studies have been found that show how electromagnetic fields affect marine mammals. The few studies that have been found on invertebrates indicate that the electromagnetic fields around common transmission cables have no effect on either reproduction or survival.Exclusion of birdsMost birds do not avoid wind farm areas. An exception is several common diving ducks that avoid flying or swimming within wind farms and keep a safe distance of at least 500 meters to a turbine tower. The most common food for these species in the Baltic Sea is blue mussels. Areas within the Swedish economic zone where a large-scale expansion of wind power would have the greatest effect on the ducks, and thereby indirectly affect the benthic community, are the offshore banks in the central Baltic Proper, mainly Hoburg Bank and Northern Midsjö Bank, where two thirds of the oldsquaw populations in Europe overwinters. The level of impact will depend on the total area of the park, and the distance between the turbine towers. Large-scale studies are needed in order to assess if the effect might lead to substantial changes for the benthic community.Gaps of knowledgeThe basis of this synopsis is research results from studies concerning single wind turbines or small wind farms, which in many
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| 10. |
- Bergström, Lena, et al.
(författare)
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Vindkraftens effekter på marint liv : En syntesrapport
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Precis som i manga andra lander forvantas en utbyggnad av vindkraft i Sverige under de narmaste decennierna. Expansionen drivs bland annat av stigande elpriser och behovet av okad produktion av fornybar el. I Sverige har havsbaserad vindkraft med en total effekt pa ungefar 2500 MW fatt tillstand och ytterligare 5500 MW ar under utveckling. Exempel pa vindkraftsprojekt med fardiga tillstand ar Storgrundet med en effekt pa 265 MW, Stora Middelgrund med en effekt pa 860 MW och Karehamn med en effekt pa 48 MW. I dag utgor Lillgrund i Oresund med sina 48 vindkraftverk och 110 MW i installerad effekt, Sveriges storstahavsbaserade vindkraftpark. Infor denna forvantade expansion ar det viktigt att undersoka vindkraftens miljoeffekter, och hur eventuella negativa effekter kan minimeras. Over 600 studier, huvudsakligen vetenskapliga artiklar, men aven rapporter fran foretag och myndigheter, ligger till grund for slutsatserna och rekommendationerna i denna syntesrapport om paverkan av vindkraft pa det marina livet i svenska havsomraden. [...]
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| 11. |
- Florin, Ann-Britt, et al.
(författare)
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First records of Conrad´s false mussel, Mytilopsis leucophaeata (Conrad, 1831) in the southern Bothnian Sea, Sweden, near a nuclear power plant
- 2013
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Ingår i: BioInvasions Records. - : Regional Euro-Asian Biological Invasions Centre Oy (REABIC). - 2242-1300. ; 2:4, s. 303-309
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Tidskriftsartikel (refereegranskat)abstract
- The invasive, biofouling, Conrad's false mussel Mytilopsis leucophaeata was first recorded in Sweden during spring 2011 in the cooling water system of the power plant of Forsmark in the southern Bothnian Sea. The cooling water discharge area offers a favourable environment for growth, survival, and reproduction of M. leucophaeata and may provide a stepping stone for further spread. We present three different studies in the area, revealing a rapid increase in mussels in the artificially heated area, with densities of the magnitude of thousands of individuals m-2, as well as mussels living in surrounding waters, indicating an on-going expansion in the region.
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| 12. |
- Kautsky, Lena, et al.
(författare)
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Rapid speciation in a newly opened postglacial marine environment, the Baltic Sea
- 2009
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 9:70
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Tidskriftsartikel (refereegranskat)abstract
- Background: Theory predicts that speciation can be quite rapid. Previous examples comprise a wide range of organisms such as sockeye salmon, polyploid hybrid plants, fruit flies and cichlid fishes. However, few studies have shown natural examples of rapid evolution giving rise to new species in marine environments. Results: Using microsatellite markers, we show the evolution of a new species of brown macroalga (Fucus radicans) in the Baltic Sea in the last 400 years, well after the formation of this brackish water body ~8–10 thousand years ago. Sympatric individuals of F. radicans and F. vesiculosus (bladder wrack) show significant reproductive isolation. Fucus radicans, which is endemic to the Baltic, is most closely related to Baltic Sea F. vesiculosus among north Atlantic populations, supporting the hypothesis of a recent divergence. Fucus radicans exhibits considerable clonal reproduction, probably induced by the extreme conditions of the Baltic. This reproductive mode is likely to have facilitated the rapid foundation of the new taxon. Conclusion: This study represents an unparalleled example of rapid speciation in a species-poor open marine ecosystem and highlights the importance of increasing our understanding on the role of these habitats in species formation. This observation also challenges presumptions that rapid speciation takes place only in hybrid plants or in relatively confined geographical places such as postglacial or crater lakes, oceanic islands or rivers.
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| 13. |
- Lilliesköld Sjöö, Gustaf, 1981-
(författare)
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Macroalgae in tropical seascapes : regulating factors and functions in the coastal ecosystem
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although macroalgae usually are inconspicuous on pristine coral reefs, they often thrive on reefs that are subjected to various types of anthropogenic disturbance. This thesis consists of five papers and investigates how biomass and composition of macroalgal communities on coral reefs are affected by regulating factors, such as nutrient availability, herbivory, substrate availability and hydrodynamic forces. In addition, ecological functions and potential impacts of both wild and farmed macroalgal communities are evaluated. Paper I describes a method for using macroalgal tissue nutrient concentrations as bioindicator for nutrient availability, with the possibility to map nutrient loading from larger coastal cities. Papers II and III are manipulative studies comparing top-down and bottom-up regulation of macroalgal communities, where herbivore consumption seems to be the main regulator of biomass whereas nutrient availability mainly influences community composition. Exclosure of large-bodied herbivores had a positive influence on algal biomass in both studies, and during different climatic periods. Paper III also includes the influence of hydrodynamic forces on algal community biomass and structure by comparing a reef crest and a back reef-habitat. Alterations of top-down and bottom-up regulation generally had a stronger effect within the protected back reef-habitat, suggesting that such environments may be more sensitive to anthropogenic influence. Paper IV confirms the general conclusions from papers II and III by studying macroalgal biomass and composition on reef sites with different environmental prerequisites. This study also supports the notion that herbivorous fish can suppress accumulation of macroalgal biomass if substrate availability is low, but not where coral cover is reduced and plenty of substrate is open to macroalgal colonization. The study also found a large temporal variation of macroalgal standing stock and associated nutrients at sites with low top-down regulation. Paper V evaluates potential impacts of seaweed farming on coral reefs and nutrients in the seascape by experimentally studying growth, survival and nutrient binding capacity of Eucheuma denticulatum. This study showed that seaweed farms counteract eutrophication through nutrient extraction and that the risk of farmed algae colonizing local reefs seems to be small as they were rapidly consumed. In conclusion, the studies in this thesis contribute to the understanding of macroalgal regulation and function in tropical seascapes, thereby adding to the knowledge base for coastal management.
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| 14. |
- Qvarfordt, Susanne, 1976-
(författare)
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Phytobenthic communities in the Baltic Sea - seasonal patterns in settlement and succession
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Seasonal changes in reproduction, recruitment, occurrence and growth of marine plant and animal species is a common phenomenon world-wide. This thesis investigates whether such seasonal changes could determine the succession in subtidal phytobenthic communities on free space in the Baltic Sea. My results showed circular seasonal patterns both in the settlement of species and in the annual appearance of communities. The circular seasonal pattern was also observed in the succession. Initial species assemblages were determined by the time space became available for colonisation. Although the succession seemed to be directed towards one site-specific final community structure determined by physical factors, the time of the year when space became available influenced the rate of the succession through species interactions. Rapid growth and timing of settlement and free space occurrence allowed early species to occupy all available space and prevent further colonisation, thereby slowing the succession. My results also showed that both settlement and community structure are influenced by substrate characteristics. Studying community development on vertical artificial structures revealed communities with few species and different composition compared to communities on vertical natural substrates. A field study showed that settlement and community structure changed significantly between 60º and 90º substrate slopes. This thesis shows that some differences in the final community structure are determined already at the settlement stage and that the succession pattern varies depending on when free space occurs. However, small inter-annual and site-specific differences in seasonal settlement periods and site-specific final communities mainly determined by physical factors, suggest that succession patterns are relatively predictable. Seasonal changes seem to cause a spiralling succession towards a final, seasonally undulating, state.
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| 15. |
- Ardehed, Angelica, et al.
(författare)
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Complex spatial clonal structure in the macroalgae Fucus radicans with both sexual and asexual recruitment
- 2015
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 5:19, s. 4233-4245
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Tidskriftsartikel (refereegranskat)abstract
- In dioecious species with both sexual and asexual reproduction, the spatial distribution of individual clones affects the potential for sexual reproduction and local adaptation. The seaweed Fucus radicans, endemic to the Baltic Sea, has separate sexes, but new attached thalli may also form asexually. We mapped the spatial distribution of clones (multilocus genotypes, MLGs) over macrogeographic (>500km) and microgeographic (<100m) scales in the Baltic Sea to assess the relationship between clonal spatial structure, sexual recruitment, and the potential for natural selection. Sexual recruitment was predominant in some areas, while in others asexual recruitment dominated. Where clones of both sexes were locally intermingled, sexual recruitment was nevertheless low. In some highly clonal populations, the sex ratio was strongly skewed due to dominance of one or a few clones of the same sex. The two largest clones (one female and one male) were distributed over 100-550km of coast and accompanied by small and local MLGs formed by somatic mutations and differing by 1-2 mutations from the large clones. Rare sexual events, occasional long-distance migration, and somatic mutations contribute new genotypic variation potentially available to natural selection. However, dominance of a few very large (and presumably old) clones over extensive spatial and temporal scales suggested that either these have superior traits or natural selection has only been marginally involved in the structuring of genotypes.
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| 16. |
- Austin, Åsa N., 1988-, et al.
(författare)
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Stronger effect of individual species’ traits than shading on aquatic plant community productivity and interspecific competition
- 2023
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Ingår i: Aquatic Botany. - : Elsevier BV. - 0304-3770 .- 1879-1522. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- Competition is one of the major factors structuring plant communities. Species with similar traits generally compete more intensely and have more similar yield than functionally dissimilar species, which often respond differently to environmental change. Little is known about how the interacting species’ traits influence the effect of environmental change on interspecific competition. However, theory predicts that environmental change should lead to more asymmetric competition, by favouring the species best adapted to the particular environmental change. Here we used a mesocosm experiment with three common aquatic plant species from the Baltic Sea (Northern Europe), to test how community productivity and competition asymmetry were affected by functional dissimilarity, individual species’ traits and a common stressor: shading. Competition asymmetry was defined as the absolute difference in reductions in yield relative to monocultures of two interacting species. Community productivity decreased and competition asymmetry increased with functional dissimilarity of the interacting species, possibly explained by the traits of the superior species, which had higher specific leaf area, maximum canopy height and primary production rate than the subordinate species. Community productivity was not affected by shading, contrary to our expectation, while competition asymmetry was higher in shaded than ambient conditions. Individual species yield depended on species identity and species combination. Only the shortest species was negatively affected by shading. Thus, by favouring tall-growing species, shading can alter interspecific competition. Together, these findings suggest that non-random species loss following environmental change can be caused by competitive exclusion, in addition to a direct effect of abiotic filtering.
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| 17. |
- Barboza, F. R., et al.
(författare)
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Geographic variation in fitness-related traits of the bladderwrack Fucus vesiculosus along the Baltic Sea-North Sea salinity gradient
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:16, s. 9225-9238
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Tidskriftsartikel (refereegranskat)abstract
- In the course of the ongoing global intensification and diversification of human pressures, the study of variation patterns of biological traits along environmental gradients can provide relevant information on the performance of species under shifting conditions. The pronounced salinity gradient, co-occurrence of multiple stressors, and accelerated rates of change make the Baltic Sea and its transition to North Sea a suitable region for this type of study. Focusing on the bladderwrack Fucus vesiculosus, one of the main foundation species on hard-bottoms of the Baltic Sea, we analyzed the phenotypic variation among populations occurring along 2,000km of coasts subjected to salinities from 4 to >30 and a variety of other stressors. Morphological and biochemical traits, including palatability for grazers, were recorded at 20 stations along the Baltic Sea and four stations in the North Sea. We evaluated in a common modeling framework the relative contribution of multiple environmental drivers to the observed trait patterns. Salinity was the main and, in some cases, the only environmental driver of the geographic trait variation in F.vesiculosus. The decrease in salinity from North Sea to Baltic Sea stations was accompanied by a decline in thallus size, photosynthetic pigments, and energy storage compounds, and affected the interaction of the alga with herbivores and epibiota. For some traits, drivers that vary locally such as wave exposure, light availability or nutrient enrichment were also important. The strong genetic population structure in this macroalgae might play a role in the generation and maintenance of phenotypic patterns across geographic scales. In light of our results, the desalination process projected for the Baltic Sea could have detrimental impacts on F.vesiculosus in areas close to its tolerance limit, affecting ecosystem functions such as habitat formation, primary production, and food supply.
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| 18. |
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| 19. |
- Dahlgren, Stefan, et al.
(författare)
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Visual interpretation and digital classification of aerialphotographs, a tool to monitor submerged vegetation in shallow coastal areas in the Baltic Sea proper?
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This project is aimed to test, 1) how well visual interpretation and digital classification fromaerial photographs fits inventoried field data, 2) if these interpretation of aerial photographscould be used to map and monitor vegetation in shallow coastal areas and be used as a toolassessing the state of shallow coastal areas. Based on our results a modified method formapping and monitoring shallow coastal areas by interpretation and classification of aerialphotographs is presented and the time demand of the method is discussed. Further we suggestthat this method will be a useful tool in mapping and assessing the state of shallow coastalareas.The visual interpretation aimed to investigate at what time in the growth season aerialphotographs preferably should be taken and to what depth visual interpretation, and digitalclassification, of aerial photographs could be used in Baltic waters with comparably highturbidity. It also aimed to describe the inventoried species from the aerial photographsfocusing on their colour, height, texture, zone-structure and discrepancy in cover betweenestimated cover in field and estimated cover from photographs. The results from the visualinterpretation are descriptive and focus on synthesising the description of interpretablespecies. A comparison between early (July) and late (August) photographs showed that thecover of the vegetation was less legible on the early pictures then on the late. Large speciesand perennials appeared clearer in the early pictures, due to lower abundance of coveringfilamentous and sheet-like algae in July than in August. Plant cover, for all species, wasobviously lower in the early photographs than in the late and the transparency was slightlybetter in the early photographs. The aerial photographs should preferably be taken in late Julyor August when the submersed vegetation reaches maximum cover.The accuracy of the digital classification was initially tested on different taxonomic levels tofind a level that visually would predict vegetation with an acceptable accuracy. As a result ofthe digital classification the submerged macrophytes were first classified into 7 categories(Level 1). The seven categories for the classification are composed of two types of barebottom, i.e. Bare bottom, sand and Bare bottom, mud,≤ 25 % plant cover, and five types ofvegetated bottom, i.e. Dense filamentous algae,≥ 50 % cover, Thin sheet-like algae, ≥ 50 %cover,Najas marina, ≥ 50 % cover, Mixed stands of phanerogams, ≥ 50 % cover and Fucusvesiculosus, ≥ 50 % cover. The overall classification accuracy at Level 1 was 72 %. The bestaccuracy of the classification, in Level 1, had category 5, 3 and 6, i.e.Najas marina, ≥ 50 %cover, Dense filamentous algae,≥ 50 % cover and Mixed stands of phanerogams, ≥ 50 %cover.To further improve the accuracy of the classification the classes in Level 1 was reduced, byadding categories together, to three and two categories at Level 2 and Level 3. The sevencategories were reduced to three categories in Level 2, Bare bottom, sand and mud,≤ 25 %cover, Dense filamentous algae, thin sheet-like algae included,≥ 50 % cover and Mixedstands of phanerogams,Fucus vesiculosus and Najas marina included, ≥ 50 % cover. The twocategories in Level 3 are, Bare bottom, sand and mud,≤ 25 % (category 1) and Vegetatedareas,≥ 50 %, category 2 and 3 in Level 2 included. The overall accuracy improved from 72%, Level 1, to 85 % and 87 % in Level 2 and 3 respectively. At Level 2, both vegetatedcategories have a producer's and a user's accuracy above 85 % while the combined mud andsand category amount to 77 %, producer's accuracy, and have a user's accuracy of 81 %. AtLevel 3, the category 2, Vegetated areas, 50 % cover, have a producer's accuracy of 96 % andA combined analysis with both visual interpretation and digital classification would befavourable but would also be more time consuming then a digital classification only. Theresult shows that digital classification seems to be appropriate to use as monitoring-methodfor low detailed information, i.e. when monitoring functional groups of vegetation, such asmats of green alga or mixed stands of canopy forming species, but does not seem to be angood method to monitor single species or specific species combinations. On the other hand,calibration data have to be collected for the digital classification and the reference plots couldbe more thoroughly inventoried than needed for the digital analysis. Thus, species abundancedata from the reference plots could, after the digital classification, be interpolated within theclassified categories, which make it possible to use aerial photographs as monitoring methodat species level.
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| 20. |
- Dias, P. Joana, et al.
(författare)
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Establishment of a taxonomic and molecular reference collection to support the identification of species regulated by the Western Australian Prevention List for Introduced Marine Pests
- 2017
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Ingår i: Management of Biological Invasions. - : Regional Euro-Asian Biological Invasions Centre Oy (REABIC). - 1989-8649. ; 8:2, s. 215-225
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Tidskriftsartikel (refereegranskat)abstract
- Introduced Marine Pests (IMP, = non-indigenous marine species) prevention, early detection and risk-based management strategies have become the priority for biosecurity operations worldwide, in recognition of the fact that, once established, the effective management of marine pests can rapidly become cost prohibitive or impractical. In Western Australia (WA), biosecurity management is guided by the Western Australian Prevention List for Introduced Marine Pests which is a policy tool that details species or genera as being of high risk to the region. This list forms the basis of management efforts to prevent introduction of these species, monitoring efforts to detect them at an early stage, and rapid response should they be detected. It is therefore essential that the species listed can be rapid and confidently identified and discriminated from native species by a range of government and industry stakeholders. Recognising that identification of these species requires very specialist expertise which may be in short supply and not readily accessible in a regulatory environment, and the fact that much publicly available data is not verifiable or suitable for regulatory enforcement, the WA government commissioned the current project to collate a reference collection of these marine pest specimens. In this work, we thus established collaboration with researchers worldwide in order to source representative specimens of the species listed. Our main objective was to build a reference collection of taxonomically vouchered specimens and subsequently to generate species-specific DNA barcodes suited to supporting their future identification. To date, we were able to obtain specimens of 75 species (representative of all but four of the pests listed) which have been identified by experts and placed with the WA Government Department of Fisheries and, where possible, in accessible museums and institutions in Australasia. The reference collection supports the fast and reliable taxonomic and molecular identification of marine pests in WA and constitutes a valuable resource for training of stakeholders with interest in IMP recognition in Australia. The reference collection is also useful in supporting the development of a variety of DNA-based detection strategies such as real-time PCR and metabarcoding of complex environmental samples (e.g. biofouling communities). The Prevention List is under regular review to ensure its continued relevance and that it remains evidence and risk-based. Similarly, its associated reference collection also remains to some extent a work in progress. In recognition of this fact, this report seeks to provide details of this continually evolving information repository publicly available to the biosecurity management community worldwide.
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| 21. |
- Erichsen, Anders Christian, et al.
(författare)
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Radionuclide Transport and Uptake in Coastal Aquatic Ecosystems : A Comparison of a 3D Dynamic Model and a Compartment Model
- 2013
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 42:4, s. 464-475
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Tidskriftsartikel (refereegranskat)abstract
- In safety assessments of underground radioactive waste repositories, understanding radionuclide fate in ecosystems is necessary to determine the impacts of potential releases. Here, the reliability of two mechanistic models (the compartmental K-model and the 3D dynamic D-model) in describing the fate of radionuclides released into a Baltic Sea bay is tested. Both are based on ecosystem models that simulate the cycling of organic matter (carbon). Radionuclide transfer is linked to adsorption and flows of carbon in food chains. Accumulation of Th-230, Cs-135, and Ni-59 in biological compartments was comparable between the models and site measurements despite differences in temporal resolution, biological state variables, and partition coefficients. Both models provided confidence limits for their modeled concentration ratios, an improvement over models that only estimate means. The D-model enables estimates at high spatio-temporal resolution. The K-model, being coarser but faster, allows estimates centuries ahead. Future developments could integrate the two models to take advantage of their respective strengths.
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| 22. |
- Eriksson, Britas Klemens, et al.
(författare)
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Omnivory and grazer functional composition moderate cascading trophic effects in experimental Fucus vesiculosus habitats
- 2011
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 158:4, s. 747-756
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Tidskriftsartikel (refereegranskat)abstract
- We tested the relative strength of direct versus indirect effects of an aquatic omnivore depending on the functional composition of grazers by manipulating the presence of gastropod and amphipod grazers and omnivorous shrimp in outdoor mesocosms. By selectively preying upon amphipods and reducing their abundance by 70-80%, omnivorous shrimp favoured the dominance of gastropods. While gastropods were the main microalgal grazers, amphipods controlled macroalgal biomass in the experiment. However, strong predation on the amphipod by the shrimp had no significant indirect effects on macroalgal biomass, indicating that when amphipod abundances declined, complementary feeding by the omnivore on macroalgae may have suppressed a trophic cascade. Accordingly, in the absence of amphipods, the shrimp grazed significantly on green algae and thereby suppressed the diversity of the macroalgal community. Our experiment demonstrates direct consumer effects by an omnivore on both the grazer and producer trophic levels in an aquatic food web, regulated by prey availability.
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| 23. |
- Forslund, Helena, 1978-, et al.
(författare)
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Grazing and geographic range of the Baltic seaweed Fucus radicans (Phaeophyceae)
- 2012
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 8:4, s. 322-330
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Tidskriftsartikel (refereegranskat)abstract
- The range of the recently described seaweed Fucus radicans is limited to the Bothnian Sea and the northern Baltic Sea while the range of the sympatric Fucus vesiculosus extends outside the Baltic Sea. Here we present results from a survey of the distribution and relative abundance of F. radicans and F. vesiculosus and abundance of associated herbivores along the range of F. radicans in Sweden. Both Fucus species were equally common. Herbivores were found in significantly higher numbers on F. radicans. The range of the herbivore Idotea balthica overlaps the southern range of F. radicans and is known to decrease the abundance of fucoids through grazing. We therefore hypothesized that if I. balthica has a preference for F. radicans it could affect the range of F. radicans. To test the preference of I. balthica we performed a bioassay where it had a choice between F. radicans and F. vesiculosus. Another bioassay was performed with the most common herbivore in our survey, Gammarus spp. Both herbivores consumed significantly more F. radicans than F. vesiculosus. Our results indicate that grazing may be an important factor in limiting the southern range of F. radicans along the Swedish coast.
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| 24. |
- Forslund, Helena, 1978-
(författare)
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Grazing and the geographical range of seaweeds : The introduced Fucus evanescens and the newly described Fucus radicans
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Along the coast of temperate oceans brown algae of the genus Fucus form dense stands on rocky shores and are keystone species of the coastal ecosystem. These large seaweeds are perennial and function as substrate for many sessile marine organisms, provide shelter for fauna and juvenile fish, and are food source. A number of abiotic (e.g. wave-exposure, salinity and substrate) and biotic (e.g. herbivory and competition) factors structures these communities and determines the abundance and composition of fucoids at each specific site. Earlier studies have shown that herbivores may reduce growth of fucoids, thus affecting their distribution, and at high densities eliminate the species from previously occupied sites. In my thesis I focused on investigating herbivore-seaweed interactions and whether such interactions could influence the geographical range limits of Fucus species. A set of laboratory bioassays and a field survey were conducted (1) to investigate the resistance to grazing by a generalist gastropod between introduced (to Sweden) and native (Iceland) Fucus evanescens (Paper I), (2) to study the distribution pattern of F. radicans and F. vesiculosus along the Swedish coast and specifically the southern limit of F. radicans, (3) to examine the abundance of herbivores in these two species, and (4) to test the hypothesis that Idotea baltica may contribute to restrict F. radicans to the Bothnian Sea (objective 2-4; Paper II). Fucus evanescens, a species that was introduced to the Swedish coast about 100 years ago, was found to be more resistant to grazing by L. littorea compared to F. evanescens from the native Icelandic populations. It was also shown to contain a higher amount of phlorotannins; a putative chemical defence to herbivory. This indicates that development of resistance to herbivory could be important for a successful introduction and survival in a new range. No gradual change in the proportion, measured as % cover of either F. radicans or F. vesiculosus was found inside the range of F. radicans and its southernmost limit was abrupt without any corresponding abrupt change in any abiotic factor, e.g. salinity. Herbivores, i.e. Idotea spp., Gammarus spp. and Theodoxus fluviatils were found to be more abundant in F. radicans than in F. vesiculosus thalli indicating a habitat preference for F. radicans. Further, Idotea baltica, whose range only overlaps with that of F. radicans in the south, was shown to prefer F. radicans over F. vesiculosus, possibly due to its lower content of phlorotannins. Based on these findings I propose that Idotea species may contribute in restricting the southern range of F. radicans, although further experiments, especially regarding competition with the larger F. vesiculosus need to be performed. In conclusion, biotic interactions e.g. the ability of to resist herbivore grazing by e.g. high phlorotannin content or having a structure less attractive as habitat to herbivores may be of importance in determining the geographic range of fucoids.
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| 25. |
- Forslund, Helena, 1978-
(författare)
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Herbivory, phenotypic variation, and reproductive barriers in fucoids
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Along the shores of the Northern hemisphere Fucus (Phaeophyceae) species are a prominent presence, providing substrate, shelter, and food for many species. Fucus evanescens, a non-indigenous species (NIS) in Sweden, and F. radicans, a recently described species that so far has only been found inside the species poor Baltic Sea, are the focus of this thesis.Interactions with enemies (e.g. predators, herbivores, parasites) have been shown to play a role in the success of NIS. The low consumption of Fucus evanescens by the generalist gastropod Littorina littorea in Sweden was found to depend on high levels of chemical defense in the introduced population, not the failure of the herbivore to recognize F. evanescens as suitable food.A survey of the relative abundance of F. radicans and F. vesiculosus and the most common associated fauna along the Swedish Bothnian Sea coast showed that F. radicans and F. vesiculosus are equally abundant throughout the range of F. radicans. The most common associated fauna were found to be more abundant on F. radicans compared to F. vesiculosus. In Sweden, where F. radicans had lower levels of defense chemicals than F. vesiculosus, F. radicans was grazed more than F. vesiculosus in bioassays. This could, together with other factors, influence the range of F. radicans.Fucus radicans and F. vesiculosus are closely related, recently separated, and growing sympatrically, therefore, possible reproductive barriers between F. radicans and F. vesiculosus were studied. In Estonia F. radicans and F. vesiculosus reproduces at different times of the year. No such clear reproductive barrier was found between the two species in Sweden where they reproduce at the same time and fertilization success and germling survival were the same for hybrids as for F. vesiculosus.Since the high clonality of F. radicans means that the gentic diversity in F. radicans populations is low I investigated how genetic diversity translates to phenotypic diversity in nine traits. Phlorotannin levels, recovery after desiccation, and recovery after freezing showed inherited variation, while the other six traits showed no variation related to genetic diversity. Phenotypic variation in populations of F. radicans will be higher in populations with higher genetic diversity and this might be beneficial to the community.
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