| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- Clements, J. C., et al.
(författare)
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Roll, right, repeat: short-term repeatability in the self-righting behaviour of a cold-water sea cucumber
- 2020
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Ingår i: Journal of the Marine Biological Association of the United Kingdom. - : Cambridge University Press (CUP). - 0025-3154 .- 1469-7769. ; 100:1, s. 115-120
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Tidskriftsartikel (refereegranskat)abstract
- For many benthic marine invertebrates, inversion (being turned upside-down) is a common event that can increase vulnerability to predation, desiccation and unwanted spatial transport, and requires behavioural 'self-righting' to correct. While self-righting behaviour has been studied for more than a century, the repeatability (R) - the portion of behavioural variance due to inter-individual differences - of this trait is not well understood. Heritability and the evolution of animal behaviour rely on behavioural repeatability. Here, we examined the self-righting technique of a cold-water holothurid, Parastichopus tremulus, and assessed the repeatability of this behaviour. Under laboratory conditions, P. tremulus consistently used muscle contractions to curl its body and roll itself back to an upright position, which provided for rapid (x +/- SD = 96.7 +/- 49.8 s) and highly repeatable (R = 0.75) self-righting in the short term that varied between individuals (range of individual average righting times = 34.8-217.0 s). Righting time tended to increase with animal size; however, substantial variation was evident at comparable sizes, as average righting time ranged from 34.8-155.5 s for animals similar to 20 cm in body length. Contrary to previous studies on other echinoderms, we found no evidence of improved righting times for P. tremulus over time. This study ultimately provides the first detailed documentation of self-righting behaviour for P. tremulus and suggests that this species displays a high degree of repeatability for this trait in the short term.
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| 6. |
- 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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| 7. |
- Kautsky, Lena, et al.
(författare)
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Fucus vesiculosus adapted to a life in the Baltic Sea : impacts on recruitment, growth, re-establishment and restoration
- 2019
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 62:1, s. 17-30
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Tidskriftsartikel (refereegranskat)abstract
- Fucus vesiculosus is common both on the tidal coasts of the North Atlantic and in the Baltic Sea, where it has adapted to low salinity and nontidal conditions over the last 7000 years. During the late 1970s and early 1980s, extensive declines of F. vesiculosus populations were reported in the Baltic Proper, mainly attributed to high nutrient loads. During the past 30-40 years, considerable efforts have been made to reduce nutrient runoff to coastal areas but few successful initiatives to restore F. vesiculosus populations have been performed. In this paper, we present how substratum manipulation, i.e. clean rocky surfaces, brushing rocks, Hildenbrandia rubra cover and different filamentous algae, as well as different algal exudates, affect the recruitment and survival of juvenile F.vesiculosus. Further, we show through a 5-year field experiment that it will take at least 4-5 years to reach reproductive age for F. vesiculosus in the Baltic Sea. We also present transplantation studies from two different areas, showing that epiphytic load, light, grazing and type of substratum are some of the factors that need to be taken into consideration in order to achieve successful restoration of F. vesiculosus.
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| 8. |
- Kautsky, Lena, et al.
(författare)
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Restaurering av blåstångssamhällen i Östersjön
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Handbokens syfte är att vara ett stöd inför planering och genomförande av projekt med avsikten att restaurera blåstångssamhällen i Östersjön. Alternativt, för att etablera ett blåstångssamhälle som en kompensationsåtgärd vid byggnationer och anläggningar i havet. En restaurering av ett blåstångssamhälle innebär att med insatta åtgärder hjälpa blåstång att återetablera sig i ett område där den tidigare funnits men försvunnit från på grund av mänsklig påverkan i form av till exempel övergödning och/eller föroreningar. En restaureringsåtgärd kan också innebära att den naturliga återhämtningen av ett blåstångssamhälle sker snabbare, dvs. att beståndets utbredning och/eller täthet ökar. Etablering av blåstångssamhällen som kompensationsåtgärd vid byggnationer i havet är högaktuellt i kustområden där exploateringstrycket är stort. Byggande av hamnar, vågbrytare och pirer skapar nya hårdbottnar som snabbt kan koloniseras av fintrådiga alger. Blåstången har sämre spridningsförmåga och kommer därmed att ha svårare att kolonisera nya ytor, vilket innebär att det kan ta lång tid innan ett tätt blåstångssamhälle etableras.I handboken presenteras metoder för att etablera blåstångsamhällen i miljöer där den försvunnit, för att påskynda blåstångens naturliga kolonisering och etablering där den minskat, samt som kompensationsåtgärd vid byggnationer i havet. Inför planering av restaurerings- eller kompensationsåtgärder krävs grundläggande kunskaper om naturliga begränsningar och biologiska förutsättningar för blåstångens utbredning tillsammans med kunskap om blåstångens biologi och funktion i Östersjöns ekosystem. Denna bakgrundsinformation presenteras i första delen av handboken. Metodiken för att genomföra en restaureringsåtgärd av ett blåstångsamhälle är en process i flera steg och beskrivs i andra delen av handboken. Här beskrivs de förstudier av miljöförhållanden och biologiska förutsättningar som måste finnas innan en åtgärd att restaurera/nyetablera ett blåstångssamhälle initieras. Handboken bygger på sammanställda data från forskningslitteratur och miljöövervakning om blåstångens ekosystem i Östersjön samt författarnas egna erfarenheter från fältförsök, tester och observationer.Handboken avser främst restaurering- och kompensationsåtgärder utifrån miljöförhållanden i Egentliga Östersjön, men bör kunna tillämpas i hela blåstångens utbredningsområde även i Bottenhavet med hänsyn till lokala förhållanden. Handboken är en handledning för att hjälpa utföraren att undvika kända problem vid återetablering av blåstång och ge konkreta förslag på metodik. Författarna vill dock påpeka att handboken inte garanterar att ett restaureringsförsök lyckas eftersom det fortfarande finns luckor i kunskapen om vad som krävs för att restaurera ett blåstångssamhälle. Arbetet med att genomföra fältstudier och underlag till handboken har finansierats av stiftelsen BalticSea2020 med stöd av Stockholms universitets Östersjöcentrum.
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| 9. |
- Liénart, Camilla, et al.
(författare)
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Long‐term changes in trophic ecology of blue mussels in a rapidly changing ecosystem
- 2021
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 66:3, s. 694-710
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Tidskriftsartikel (refereegranskat)abstract
- Ocean climate change strongly affects organisms and ecosystems, and the causes, consequences, and underlying mechanisms need to be documented. In the Baltic Sea, a marginal sea under severe eutrophication stress, a longer productive season, and changes in the phytoplankton community over the last few decades have likely impacted diet and condition of keystone species, from individual to population level. This study uses stable isotopes (δ13C, δ15N, and derived isotope niche metrics) to trace energy and nutrient flows in archived samples of blue mussel (Mytilus edulis trossulus) spanning 24 yr (1993–2016). We test if long-term changes in isotope and elemental composition in mussels, as well as population abundance and biomass, can be explained by changes in abiotic and biotic variables, using partial least square regressions and structural equation modeling. We found decreasing trends in δ13C and δ15N as well as in mean size and total biomass of mussels, but no unidirectional changes in their stoichiometry or condition index. Changes in isotope composition were best explained by nitrogen-fixing cyanobacteria, by increased terrestrial organic carbon from land runoff (reflecting precipitation) and by decreases in dissolved inorganic nitrogen (indicative of successful eutrophication mitigation) and in biomass of a mixotrophic ciliate species. The trophic niche (assessed from isotope niche) was included as the best predictor for both mussel body condition and the observed decline in their total biomass. This study reveals that altered trophic relationships from climate-induced changes in the productivity base may strongly impact keystone species, with potential knock-on effects on ecosystem functions.
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| 10. |
- Preston, Roxana, et al.
(författare)
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Clonality, polyploidy and spatial population structure in Baltic Sea Fucus vesiculosus
- 2022
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- Genetic characteristics of populations can have substantial impacts on the adaptive potential of a species. Species are heterogeneous, often defined by variability at a range of scales including at the genetic, individual and population level. Using microsatellite genotyping, we characterize patterns underlying the genetic heterogeneity in marine macroalga Fucus vesiculosus, with a particular focus on two forms: attached and free-living. Here we demonstrate that sympatric populations representing the two forms display marked differences in characteristics of reproduction and genetic diversity. Asexual reproduction was ubiquitous in the free-living form despite being almost entirely absent in the attached form, while signals of polyploidy were common in both forms despite the distinct reproductive modes. Gene flow within and between the forms differed, with barriers to gene flow occurring between forms at various spatial scales due to the reproductive modes employed by individuals of each form. The divergent genetic characteristics of F. vesiculosus demonstrate that intraspecific differences can influence the properties of populations with consequential effects on the whole ecosystem. The differing genetic patterns and habitat requirements of the two forms define separate but closely associated ecological entities that will likely display divergent responses to future changes in environmental conditions.
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| 11. |
- Preston, Roxana, et al.
(författare)
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Phylogeographic patterns in attached and free-living marine macroalga Fucus vesiculosus (Fucaceae, Phaeophyceae) in the Baltic Sea
- 2022
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 65:6, s. 419-432
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Tidskriftsartikel (refereegranskat)abstract
- Sequencing of a mitochondrial intergenic spacer and 23S subunit was used to investigate the phylogeographic patterns in Fucus vesiculosus. Samples originated from 21 sites spanning six subbasins of the Baltic Sea. We identify a putative ancestral mitochondrial haplotype that entered the Baltic Sea from the Atlantic, colonising extensively throughout the species’ distribution. The dominance of this haplotype is seen in the low overall haplotype diversity (Hd = 0.29). Moreover, there is indication of few spatially aggregated patterns in the deeper demographic time scales (Fct = 0.040; Fst = 0.049). Tajima’s D (−0.685, p-value 0.297) and Fu’s FS (0.267, p-value 0.591) showed no significant signals of extreme demographic changes. The Baltic Sea free-living Fucus is confirmed as F. vesiculosus or a closely related species. Haplotype diversities are comparable between forms (attached Hd = 0.306; free-living Hd = 0.268). The relatively short temporal scale for colonisation alongside low variance in the Fucus mitochondrial genome results in a rather panmictic structure across the Baltic Sea. Our data suggest that the mitochondrial intergenic spacer and 23S poorly describe the evolutionary dynamics of Fucus spp. in such a young, postglacial environment, yet this concatenated-barcode advances our understanding of the colonisation dynamics of F. vesiculosus over deeper demographic timescales.
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| 12. |
- Schagerström, Ellen, et al.
(författare)
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Controlled spawning and rearing of the sea cucumber, Parastichopus tremulus
- 2022
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Ingår i: Journal of the World Aquaculture Society. - : Wiley. - 0893-8849 .- 1749-7345. ; 53:1, s. 224-240
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Tidskriftsartikel (refereegranskat)abstract
- The red sea cucumber, Parastichopus tremulus, a cold water species with commercial potential, has recently attracted attention for wild harvest as well as for potential use in integrated multi-trophic aquaculture in Scandinavian countries. Overharvesting has put natural stocks of sea cucumbers at risk in several countries. Our goal was to develop a rearing protocol for P. tremulus to enable sustainable production of this species. This study presents results from spawning and larval rearing conducted in both Norway (NO) and Sweden (SWE) during May-August 2019. We describe spawning induction and behavior, fertilization success, embryonic and auricularia larval development rate for this species under laboratory conditions. The larvae were fed a mixture of three species of live microalgae (SWE) and algal paste (NO). Larval development rate and survival were monitored at four different temperatures (7, 10, 13, and 16 degrees C). Results showed faster development with increasing temperature. Daily food consumption rate was highest at the highest temperature. The combined effects of temperature and food availability on survival were investigated for the same four temperatures and three different feed concentrations. Only food availability affected the mortality rate, with the highest mortality in the low feeding regime of 1,000-2,000 cells ml(-1) day(-1).
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| 13. |
- Schagerström, Ellen, et al.
(författare)
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Despite marine traits, the endemic Fucus radicans (Phaeophyceae) is restricted to the brackish Baltic Sea
- 2016
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Ingår i: European journal of phycology. - : Informa UK Limited. - 0967-0262 .- 1469-4433. ; 51:4, s. 378-386
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Tidskriftsartikel (refereegranskat)abstract
- Many of the marine species that were introduced to the Baltic Sea during the Littorina stage (c. 8500-3000 years BP), e.g. Fucus vesiculosus and F. serratus, have adapted to the present low salinity. These marine species have gone from marine conditions into lower salinity environments. In this paper we ask why the recently discovered endemic brown alga Fucus radicans shows the opposite pattern. Fucus radicans is only present in the northern parts of the Baltic Sea, the low salinity Bothnian Sea (4-6 psu). Potentially, the fitness of F. radicans might be reduced in higher salinities if it is better adapted to brackish conditions. We hypothesize, however, that the southern distribution limit of F. radicans is set by biotic factors, e.g. competition with F. vesiculosus and higher grazing pressure by Idotea balthica and not by salinity. Our results show that the reproductive output of F. radicans is limited by low salinity (4 psu) but increases in higher salinities. However, the southern distribution limit, i.e. the northern Baltic Proper, is regulated by biotic factors, where the additive effects from shading by taller F. vesiculosus thalli and grazing on F. radicans by the isopod I. balthica limit the biomass production of F. radicans. We suggest that F. radicans still maintains marine traits due to its ability to propagate clonally and is restricted to the Bothnian Sea by interactions with F. vesiculosus and I. balthica. We also propose that increased precipitation due to climate change might affect the northern range limit and that the distribution of F. radicans could be expected to shift further south into the Baltic Proper.
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| 14. |
- Schagerström, Ellen, et al.
(författare)
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Does thalli complexity and biomass affect the associated flora and fauna of two co-occurring Fucus species in the Baltic Sea?
- 2014
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 149, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- On rocky shores, fucoids provide habitat, shelter and food for associated biota. In the northern parts of the Baltic, the Bothnian Sea, the new fucoid species Fucus radicans (Bergstrom et Kautsky) was recently described. This study compares the thallus complexity and size as well as quantified the abundance and biomass of epiphytic algae and invertebrate taxa of the two fucoid species F. radicans and Fucus vesiculosus L. from sympatric sites in the Bothnian Sea on the Swedish coast and around the Estonian island Saaremaa. We found that F. radicans was more complex than F. vesiculosus within the whole study range, but both species had a more complex thallus structure in the Bothnian Sea compared to Estonia. The complexity of host algae did not contribute to their associated flora and fauna taxon richness; instead, the size of thalli was a good proxy for associated communities. Specifically, on a biomass basis, F. vesiculosus displayed highest species richness and highest faunal abundance in the Bothnian Sea, whereas no such differences were found around Saaremaa, probably because both Focus species had similar height around Saaremaa whereas F. vesiculosus grew much taller and larger in the Bothnian Sea. There were some unique associated macroalgal and invertebrate species that were found only on either of the fucoids, indicating the importance of separating them as species in surveys and monitoring.
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| 15. |
- Schagerström, Ellen
(författare)
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Fucus radicans : Reproduction, adaptation & distribution patterns
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Baltic Sea is considered an ecological marginal environment, where both marine and freshwater species struggle to adapt to its ever changing conditions. Fucus vesiculosus (bladderwrack) is commonly seen as the foundation species in the Baltic Sea, as it is the only large perennial macroalgae, forming vast belts down to a depth of about 10 meters. The salinity gradient results in an increasing salinity stress for all marine organisms. This is commonly seen in many species as a reduction in size. What was previously described as a low salinity induced dwarf morph of F. vesiculosus was recently proved to be a separate species, when genetic tools were used. This new species, Fucus radicans (narrow wrack) might be the first endemic species to the Baltic Sea, having separated from its mother species F. vesiculosus as recent as 400 years ago. Fucus radicans is only found in the Bothnian Sea and around the Estonian island Saaremaa. The Swedish/Finnish populations have a surprisingly high level of clonality. As much as up to 80% of the individuals on the Swedish side are clones, dominated by one female clone that has been found over a range of 550 km. In spite of this ability to asexual propagation, we do not find F. radicans further south than Öregrund in Sweden, and even further north in Finland. I attempt to find out why.
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| 16. |
- Schagerström, Ellen, et al.
(författare)
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Interactive effects of temperature and light on reattachment success in the brown alga Fucus radicans
- 2019
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Ingår i: Botanica Marina. - : WALTER DE GRUYTER GMBH. - 0006-8055 .- 1437-4323. ; 62:1, s. 43-50
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Tidskriftsartikel (refereegranskat)abstract
- Fucus radicans is an endemic habitat-forming brown macroalga in the Baltic Sea that commonly complements its sexual reproduction with asexual reproduction. Asexual reproduction in F. radicans takes place through formation of adventitious branches (hereafter fragments), but the exact mechanisms behind it remain unknown. We assessed experimentally the importance of two environmental factors determining the re-attachment success of F. radicans fragments. By combining different light conditions (daylength and irradiance; high or low light) and water temperature (+14 degrees C and +4 degrees C), we mimicked ambient light and temperature conditions of winter, spring/autumn and summer for F. radicans. Fragments were able to re-attach in all tested conditions. Temperature and light had an interactive impact on re-attachment: the combination of high temperature and high light level resulted in the highest re-attachment success, while light level had no effects on re-attachment success in cooler water temperature and the re-attachment success in high temperature under low light levels was very low. The results suggest that rhizoid formation, and thus re-attachment success, may depend on the net primary production (metabolic balance) of the fragment. However, whether the re-attachment and asexual reproduction success simply depends on photosynthetic capacity warrants further mechanistic studies. Understanding the mechanisms of asexual reproduction in F. radicans is important in order to assess the dispersal capacity of this foundation species.
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| 17. |
- Schagerström, Ellen, et al.
(författare)
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Macroscopic sexual dimorphism in Fucus radicans (Phaeophyceae) with implications for its reproductive ecology
- 2016
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 59:6, s. 485-490
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Tidskriftsartikel (refereegranskat)abstract
- Sexual dimorphism on a macroscopic scale is unusual within the Phaeophyceae. We report for the first time macroscopic sexual dimorphism in Fucus radicans. A set of morphological characters was measured on three dioecious Fucus species, F. radicans, Fucus serratus and Fucus vesiculosus, to determine if sexual dimorphism occurs in the endemic F. radicans in the Baltic Sea and if it also is found in the other fucoids. F. radicans was sampled from highly clonal populations of the Bothnian Sea and from populations in the Vainameri Sea where no clones have been found. In both locations, sexual dimorphism was recorded in receptacle size and weight in F. radicans. Also, the receptacle dry weight to wet weight ratio was higher in males than in females, showing that male receptacles have a lower water content than females. The dimorphism was more pronounced in the Bothnian Sea populations, where further differences between the sexes in thallus width and fertility index also were present. This has not been shown for any member of the genus Fucus before, but seems to be a species-specific character in F. radicans, as there were no differences between the sexes in either F. serratus or F. vesiculosus.
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| 18. |
- Schagerström, Ellen, 1978-
(författare)
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On the endemic Fucus radicans in the Baltic Sea
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The brown macroalgae Fucus radicans is endemic to the Baltic Sea, but little is known about this newly described species. This thesis investigates the ecology and role of F. radicans within the species poor Baltic Sea ecosystem. The thallus of F. radicans had a more complex structure but was smaller than F. vesiculosus, the other important foundation species with which it grows in sympatry at several sites. The variability of the associated flora and fauna communities of these two Fucus species, however, was explained by the thallus size, not the complexity. Comparisons between the populations of F. radicans in the Bothnian Sea with those in Väinameri Sea on the Estonian coast, showed that the Estonian thalli were smaller, less complex and lacking the numerous adventitious branches which occur extensively in the Bothnian Sea populations.The distribution of F. radicans in Sweden is limited to the Bothnian Sea coast. The low salinity at the northern limit prevented successful fertilization, while increased salinity did not restrict F. radicans but improved its reproductive success. The southern distribution limit was instead shown to be negatively impacted by a combination of grazing and competition. The asexual reproduction through settling of detached fragments was favoured by high light levels and high temperature in laboratory conditions. Re-attachment occurred by basally formed rhizoids but settling also occurred through a calcium-rich substance, seemingly secreted by the fragment. Genetic spatial distribution of F. radicans showed a dominance of a few widespread clones both within and between sites with an intermingled rather than clustered pattern. The extensive female clone, common in most sites, is most likely old and several clonal lineages have derived from her. Although more clearly expressed in the clonal populations, the macroscopic sexual dimorphism discovered appears to be a species specific trait in F. radicans. This thesis presents further insight in F. radicans role within the Baltic Sea ecosystem and its value as a study species for adaptation, clonality and speciation.
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| 19. |
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| 20. |
- Schagerström, Ellen, et al.
(författare)
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Temperature and light affect asexual reproduction in brown algae Fucus radicans
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Fucus radicans is a habitat forming brown macroalgae that utilizes asexual reproduction to complement its sexual reproduction. While asexual reproduction by adventitious branches (hereafter fragments) is common in F. radicans, the mechanisms behind it remain unknown. We conducted an experiment to study if water temperature and light intensity together with day length affect the re-attachment success of F. radicans fragments by using the light and temperature average conditions of the four seasons. Fragments were able to re-attach in all tested conditions. The fragments attached mostly by rhizoids but an alternative form of attachment was also observed, where an opaque substance cemented the fragment to the substrate. Temperature and light had an interactive impact on re-attachment, and re-attachment was highest under conditions of combined high temperature and high light. Although re-attachment was observed in all different temperature and light treatments, our results suggest that re-attachment success is favoured during warm temperatures and light conditions, i.e. the summer period. Understanding the mechanisms of asexual reproduction in F. radicans is important in order to assess the future dispersal patterns of this endemic foundation species.
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| 21. |
- Schagerström, Ellen, et al.
(författare)
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Var finns den frilevande blåstången?
- 2020
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 114:5, s. 260-263
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Flera äldre marinbotanister har skrivit om en frilevande form av blåstång. Nu arbetar forskare inom projektet FunkVeg på Stockholms och Helsingfors universitet med att kartlägga och dokumentera den frilevande blåstången som bildar viktiga livsmiljöer för många arter i Östersjöns kustnära vatten.V i vill ta reda på vilken utbredning den frilevande formen av blåstång Fucus vesiculosus har i Sverige och Finland. Vår forskning strävar också efter att ta reda på vilken roll den spelar i Östersjöns grunda kustekosystem och hur bestånden förändras över tid och påverkas av klimatförändringen. Inventeringar i Tyskland på 2000-talet visade att de frilevande bestånden av blåstång gått tillbaka kraftigt, framförallt på grund av att övergödning och småskalig exploatering av grunda områden försämrat deras livsmiljö. Det ledde till att deras habitat klassats som hotat i Helsingforskommissionens rödlista för biotoper (Helcom 2013). Men vad vet vi egentligen om den frilevande blåstångens utbredning på en Östersjöskala och vilken funktion har den som habitat?
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