| 1. |
- Olsson, Matilda, 1973, et al.
(författare)
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Feeding behaviour in Littorina littorea: the red seaweed Osmundea ramosissima may not prevent trematode infection.
- 2007
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Ingår i: Marine Ecology Progress Series. ; 348, s. 221-228
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial herbivores can use anthelmintic properties of plant secondary metabolites to decrease parasite/parasitoid infections. Secondary metabolites with potential anthelmintic properties have also been described from different seaweed species, but the effects of diet on parasitism in marine herbivores has not been studied previously. In the present study, a combination of laboratory and field experiments was used to test the hypotheses that infection by digenean trematode parasites affects the feeding pattern of herbivorous gastropods (Littorina littorea), and that the seaweed diet prevents parasitism in the snails. Heavily infected snails consumed less of the red seaweed Osmundea ramosissima than uninfected snails, but there was no difference in consumption when snails were offered the green seaweed Ulva lactuca. Healthy snails placed in cages with different food treatments and transplanted to different field sites became infected by trematodes, but there was no significant difference in parasite resistance between snails offered different foods. Furthermore, there was no significant negative relationship between infection abundance and consumption when O. ramosissima was incorporated into agar-based artificial diets, indicating that the difference in feeding pattern found in the initial consumption experiment was due to the morphology, and not the chemistry of the seaweeds. In conclusion, these preliminary results do not indicate that parasitized L. littorea feeds on O. ramosissima to prevent parasite infection. However, the hypothesis that algal chemical compounds prevent or decrease parasite infections in herbivores should be tested using additional candidate species before drawing general conclusions about the effect of diet on parasitism in marine systems.
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| 2. |
- Pavia, Henrik, 1964, et al.
(författare)
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Chemical defences against herbivores
- 2012
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Ingår i: Chemical ecology in aquatic systems. - New York, US : Oxford University Press. - 9780199583096 ; , s. 210-235
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Bokkapitel (refereegranskat)abstract
- In recent years it has become increasingly clear that chemical interactions play a fundamental role in aquatic habitats and have far-reaching evolutionary and ecological consequences. A plethora of studies have shown that aquatic organisms from most taxa and functional groups respond to minute concentrations of chemical substances released by other organisms. However, our knowledge of this 'chemical network' is still negligible. Chemical interactions can be divided into two larger sub-areas based on the function of the chemical substance. First, there are interactions where chemical substances are toxic to other organisms and are used as a defense against consumers (including both herbivores and predators) or a weapon against competitors (allelopathy). Second, chemical substances mey be used as a source for information of the environment; for example: how can I find the optimal habitat, the best food, the nicest partner, and avoid being eaten? Aquatic organisms are able to detect and respond to extremely low concentrations of chemical cues to answer all these questions. The book aims at connecting these intriguing chemical interactions with traditional knowledge of organism interactions. Chemical ecology in aquatic systems covers a wide range of studies, both plant and animal, from different geographic regions and habitats-pelagic as well as benthic. Most of the chemical interactions are similar in freshwater and marine habitats and this book therefor strives at integrating work on both systems. This accessible, research-level text is aimed at graduate students and professional researchers in the fields of limnology, marine ecology, evolutionary biology, behavioral ecology, and chemical ecology.
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| 3. |
- Selander, Erik, 1973, et al.
(författare)
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Copepods induce paralytic shellfish toxin production in marine dinoflagellates
- 2006
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Ingår i: Proceedings of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 273:1594, s. 1673-1680
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Tidskriftsartikel (refereegranskat)abstract
- Among the thousands of unicellular phytoplankton species described in the sea, some frequently occurring and bloom-forming marine dinoflagellates are known to produce the potent neurotoxins causing paralytic shellfish poisoning. The natural function of these toxins is not clear, although they have been hypothesized to act as a chemical defence towards grazers. Here, we show that waterborne cues from the copepod Acartia tonsa induce paralytic shellfish toxin (PST) production in the harmful algal bloom-forming dinoflagellate Alexandrium minutum. Induced A. minutum contained up to 2.5 times more toxins than controls and was more resistant to further copepod grazing. Ingestion of non-toxic alternative prey was not affected by the presence of induced A. minutum. The ability of A. minutum to sense and respond to the presence of grazers by increased PST production and increased resistance to grazing may facilitate the formation of harmful algal blooms in the sea.
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| 4. |
- Toth, Gunilla B., 1973, et al.
(författare)
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Marine dinoflagellates show induced life-history shifts to escape parasite infection in response to water-borne signals
- 2004
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Ingår i: Proceedings of the Royal Society of London Series B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 271:1540, s. 733-738
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Tidskriftsartikel (refereegranskat)abstract
- Many dinoflagellate species form dormant resting cysts as a part of their life cycle, and in some freshwater species, hatching of these cysts can be delayed by the presence of water-borne signals from grazing zooplankton. Some marine dinoflagellates can form temporary cysts, which may function to resist unfavourable short-term environmental conditions. We investigated whether the marine dinoflagellate Alexandrium ostenfeldii is able to induce an increased resistance to the parasitic flagellate Parvilucifera infectans by forming temporary cysts. We performed several laboratory experiments where dinoflagellates were exposed either to direct contact with parasites or to filtered water from cultures of parasite-infected conspecifics (parasite-derived signals). Infection by P. infectans is lethal to motile A. ostenfeldii cells, but temporary cysts were more resistant to parasite infection. Furthermore, A. ostenfeldii induced a shift in life-history stage (from motile cells to temporary cysts) when exposed to parasite-derived water-borne signals. The response was relaxed within a couple of hours, indicating that A. ostenfeldii may use this behaviour as a short-term escape mechanism to avoid parasite infection. The results suggest that intraspecies chemical communication evoked by biotic interactions can be an important mechanism controlling life-history shifts in marine dinoflagellates, which may have implications for the development of toxic algal blooms.
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| 5. |
- Appelqvist, Christin, 1972, et al.
(författare)
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Distribution and abundance of teredinid recruits along the Swedish coast - are shipworms invading the Baltic Sea?
- 2015
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Ingår i: Journal of the Marine Biological Association of the United Kingdom. - 0025-3154 .- 1469-7769. ; 95:4, s. 783-790
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Tidskriftsartikel (refereegranskat)abstract
- Shipworms (teredinids) are highly specialized marine bivalves that consume terrestrially derived wood. Changes in environmental variables may result in shipworms spreading into the Baltic Sea – which would have devastating consequences for maritime cultural heritage and submerged wooden structures. We investigated the distribution and abundance of the shipworms Teredo navalis and Psiloteredo megotara along the Swedish coast in 2006–2008, and compared our findings with data collected at partly the same locations in 1971–1973. Wooden test panels were submerged in near-surface waters at 18 harbours. The presence of shipworms was determined by X-ray radiography of each panel. Sea surface temperature and salinity data were analysed to investigate whether any changes in distribution were correlated to changes in environmental variables. We found that past and present distributions of T. navalis were similar – indicating that no range expansion of shipworms into the Baltic Sea has taken place the last 35 years. The abundance of T. navalis was similar between decades at all investigated sites except two (Arild and Barsebäckshamn), where abundances were higher in 2006–2008. The abundance of T. navalis varied along the coast and was positively correlated to mean sea surface salinity, but not to mean sea surface temperature (2006–2008 data). The distribution and abundance of P. megotara were similar during the two study periods with only single observations at a few sites. In conclusion, we found no evidence of range expansion of shipworms along the Swedish coast.
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| 6. |
- Araujo, R., et al.
(författare)
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TRADE-OFFS BETWEEN LIFE-HISTORY TRAITS AT RANGE-EDGE AND CENTRAL LOCATIONS
- 2015
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Ingår i: Journal of Phycology. - : Wiley. - 0022-3646. ; 51:4, s. 808-818
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Tidskriftsartikel (refereegranskat)abstract
- The allocation of resources to different life-history traits should represent the best compromise in fitness investment for organisms in their local environment. When resources are limiting, the investment in a specific trait must carry a cost that is expressed in trade-offs with other traits. In this study, the relative investment in the fitness-related traits, growth, reproduction and defence were compared at central and range-edge locations, using the seaweed Ascophyllum nodosum as a model system. Individual growth rates were similar at both sites, whereas edge populations showed a higher relative investment in reproduction (demonstrated by a higher reproductive allocation and extended reproductive periods) when compared to central populations that invested more in defence. These results show the capability of A. nodosum to differentially allocate resources for different traits under different habitat conditions, suggesting that reproduction and defence have different fitness values under the specific living conditions experienced at edge and central locations. However, ongoing climate change may threaten edge populations by increasing the selective pressure on specific traits, forcing these populations to lower the investment in other traits that are also potentially important for population fitness.
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| 7. |
- Baumgartner, Finn A., 1982, et al.
(författare)
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Abundance and Size Distribution of the Sacoglossan Elysia viridis on Co-Occurring Algal Hosts on the Swedish West Coast
- 2014
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Ingår i: PLoS ONE. - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Sacoglossans are specialized marine herbivores that tend to have a close evolutionary relationship with their macroalgal hosts, but the widely distributed species Elysia viridis can associate with several algal species. However, most previous investigations on the field abundance and size distribution of E. viridis have focussed on Codium spp. in the British Isles, and algae from this genus are considered superior hosts for E. viridis. In the present study, we investigated the abundance and size distribution of E. viridis on 6 potential host algae with differing morphologies (the septate species Cladophora sericea, Cladophora rupestris, Chaetomorpha melagonium, and Ceramium virgatum, as well as the siphonaceous species Codium fragile and Bryopsis sp.) at 2 sites on the Swedish west coast over the course of a year. In spring, slugs were almost absent from all algal hosts. In summer and autumn, E. viridis consistently occurred on several of the algal species at both sites. The highest number of small E. viridis were found on C. sericea, intermediate numbers of significantly larger E. viridis were found on C. rupestris, while fewer, intermediate sized animals were found on C. fragile. Throughout the study period, only a few E. viridis individuals were found on C. melagonium, Bryopsis sp., and C. virgatum. Our results indicate that E. viridis is an annual species in Sweden, capable of exploiting co-occurring congeneric and intergeneric algal hosts with differing morphologies. These results corroborate previous findings that E. viridis can exploit several different algal species, but does not indicate that C. fragile is a superior host.
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| 8. |
- Baumgartner, Finn A., 1982, et al.
(författare)
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Acquired Phototrophy through Retention of Functional Chloroplasts Increases Growth Efficiency of the Sea Slug Elysia viridis
- 2015
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthesis is a fundamental process sustaining heterotrophic organisms at all trophic levels. Some mixotrophs can retain functional chloroplasts from food (kleptoplasty), and it is hypothesized that carbon acquired through kleptoplasty may enhance trophic energy transfer through increased host growth efficiency. Sacoglossan sea slugs are the only known metazoans capable of kleptoplasty, but the relative fitness contributions of heterotrophy through grazing, and phototrophy via kleptoplasts, are not well understood. Fitness benefits (i.e. increased survival or growth) of kleptoplasty in sacoglossans are commonly studied in ecologically unrealistic conditions under extended periods of complete darkness and/or starvation. We compared the growth efficiency of the sacoglossan Elysia viridis with access to algal diets providing kleptoplasts of differing functionality under ecologically relevant light conditions. Individuals fed Codium fragile, which provide highly functional kleptoplasts, nearly doubled their growth efficiency under high compared to low light. In contrast, individuals fed Cladophora rupestris, which provided kleptoplasts of limited functionality, showed no difference in growth efficiency between light treatments. Slugs feeding on Codium, but not on Cladophora, showed higher relative electron transport rates (rETR) in high compared to low light. Furthermore, there were no differences in the consumption rates of the slugs between different light treatments, and only small differences in nutritional traits of algal diets, indicating that the increased growth efficiency of E. viridis feeding on Codium was due to retention of functional kleptoplasts. Our results show that functional kleptoplasts from Codium can provide sacoglossan sea slugs with fitness advantages through photosynthesis.
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| 9. |
- Baumgartner, Finn A., 1982, et al.
(författare)
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Individual Specialization to Non-Optimal Hosts in a Polyphagous Marine Invertebrate Herbivore
- 2014
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:8
-
Tidskriftsartikel (refereegranskat)abstract
- Factors determining the degree of dietary generalism versus specialism are central in ecology. Species that are generalists at the population level may in fact be composed of specialized individuals. The optimal diet theory assumes that individuals choose diets that maximize fitness, and individual specialization may occur if individuals' ability to locate, recognize, and handle different food types differ. We investigate if individuals of the marine herbivorous slug Elysia viridis, which co-occur at different densities on several green macroalgal species in the field, are specialized to different algal hosts. Individual slugs were collected from three original algal host species (Cladophora sericea, Cladophora rupestris and Codium fragile) in the field, and short-term habitat choice and consumption, as well as long-term growth (proxy for fitness), on four algal diet species (the original algal host species and Chaetomorpha melagonium) were studied in laboratory experiments. Nutritional (protein, nitrogen, and carbon content) and morphological (dry weight, and cell/utricle volume) algal traits were also measured to investigate if they correlated with the growth value of the different algal diets. E. viridis individuals tended to choose and consume algal species that were similar to their original algal host. Long-term growth of E. viridis, however, was mostly independent of original algal host, as all individuals reached a larger size on the non-host C. melagonium. E. viridis growth was positively correlated to algal cell/utricle volume but not to any of the other measured algal traits. Because E. viridis feeds by piercing individual algal cells, the results indicate that slugs may receive more cytoplasm, and thus more energy per unit time, on algal species with large cells/utricles. We conclude that E. viridis individuals are specialized on different hosts, but host choice in natural E. viridis populations is not determined by the energetic value of seaweed diets as predicted by the ODT.
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| 10. |
- Engelen, A. H., et al.
(författare)
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Circumglobal invasion by the brown seaweed Sargassum muticum
- 2015
-
Ingår i: Oceanography and Marine Biology: An Annual Review. R. N. Hughes, D. J. Hughes, I. P. Smith, and A. C. Dale (eds.). - Boca Raton : Crc Press-Taylor & Francis Group. - 9781498705455 ; 53, s. 81-126
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Hundreds of macroalgal species have been spread outside their natural range by human activities, and many of these introductions are occurring at a worldwide scale. This review considers one of the best-studied and most widespread invasive macroalgae, Sargassum muticum, to determine the traits and processes important in marine invasions and to identify important lines of future research. Particular emphasis is placed on the ecology of S. muticum in its native range and on the four stages of invasion transport, colonization, establishment, and spread integrating taxonomy, invasion history, dispersal, impact, invasiveness and invasibility, and general ecology. Although S. muticum has received a lot of scientific attention, with more than 650 papers on this species, key information on its taxonomy, invasive biology, and evolutionary potential is still lacking. Most previous studies have been local or descriptive or provide circumstantial evidence, and too few have been hypothesis driven. Only by local-scale research conducted in different geographical regions, especially including the native range, and developed in an eco-evolutionary framework, will it be possible to greatly improve our understanding of the complex of factors, traits, and processes involved in macroalgal invasions. ERG P, 1992, ECOLOGY, V73, P1488 ERG P, 1992, ECOLOGY, V73, P1473
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| 11. |
- Harrysson, Hanna, 1987, et al.
(författare)
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Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kutzing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods
- 2018
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 30:6, s. 3565-3580
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Tidskriftsartikel (refereegranskat)abstract
- The demand for vegetable proteins increases globally and seaweeds are considered novel and promising protein sources. However, the tough polysaccharide-rich cell walls and the abundance of polyphenols reduce the extractability and digestibility of seaweed proteins. Therefore, food grade, scalable, and environmentally friendly protein extraction techniques are required. To date, little work has been carried out on developing such methods taking into consideration the structural differences between seaweed species. In this work, three different protein extraction methods were applied to three Swedish seaweeds (Porphyra umbilicalis, Ulva lactuca, and Saccharina latissima). These methods included (I) a traditional method using sonication in water and subsequent ammonium sulfate-induced protein precipitation, (II) the pH-shift protein extraction method using alkaline protein solubilization followed by isoelectric precipitation, and (III) the accelerated solvent extraction (ASE (R)) method where proteins are extracted after pre-removal of lipids and phlorotannins. The highest protein yields were achieved using the pH-shift method applied to P. umbilicalis (22.6 +/- 7.3%) and S. latissima (25.1 +/- 0.9%). The traditional method resulted in the greatest protein yield when applied to U. lactuca (19.6 +/- 0.8%). However, the protein concentration in the produced extracts was highest for all three species using the pH-shift method (71.0 +/- 3.7%, 51.2 +/- 2.1%, and 40.7 +/- 0.5% for P. umbilicalis, U. lactuca, and S. latissima, respectively). In addition, the pH-shift method was found to concentrate the fatty acids in U. lactuca and S. latissima by 2.2 and 1.6 times, respectively. The pH-shift method can therefore be considered a promising strategy for producing seaweed protein ingredients for use in food and feed.
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| 12. |
- Harrysson, Hanna, 1987, et al.
(författare)
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Strategies for Improving the Protein Yield in pH-Shift Processing of Ulva lactuca Linnaeus: Effects of Ulvan Lyases, pH-Exposure Time, and Temperature
- 2019
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Ingår i: Acs Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 7:15, s. 12688-12691
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Tidskriftsartikel (refereegranskat)abstract
- Globally, there is a need for novel vegetarian protein sources. We recently showed that the pH-shift process, using alkaline protein solubilization followed by isoelectric precipitation, is an efficient way to produce extracts with high protein concentrations from Ulva lactuca (>50% on a dry matter basis). However, the total protein yield was low, and to improve this, the effects of adding ulvan lyase, preincubating the seaweed homogenate at pH 8.5 and using different protein extraction temperatures (8 degrees C, RT and 40 degrees C), were evaluated in this study. Addition of ulvan lyase reduced protein solubility but increased the precipitation. Incubation at pH 8.5, without ulvan lyase added, significantly increased both protein solubility and precipitation at 8 degrees C and RT. Temperature per se had no effect on protein solubility, while protein precipitation increased with decreasing temperature. Highest protein yield (29%) was achieved when keeping the process at 8 degrees C with a preincubation step at pH 8.5 for 1 h. By these process modifications, the yield was 3.2 times higher than achieved by the control process (9.2%).
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| 13. |
- Ianora, A., et al.
(författare)
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New Trends in Marine Chemical Ecology
- 2006
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Ingår i: Estuaries and Coasts. ; 29:4, s. 531-551
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Tidskriftsartikel (refereegranskat)abstract
- This essay is the outcome of a colloquium convened in November 2005 at the Benthos Laboratory of the Stazione Zoologica Anton Dohrn in Ischia, Italy, on chemical ecology and the role of secondary metabolites in the structuring and functioning of marine biodiversity. The participants of the workshop are part of the European Network of Excellence MarBEF (Marine Biodiversity and Ecosystem Function), a consortium of 56 European marine institutes to integrate and disseminate knowledge and expertise on marine biodiversity. Here we review some of the new trends and emerging topics in marine chemical ecology. The first section deals with microbial chemical interactions. Microbes communicate with each other using diffusible molecules such as N-acylhomoserine lactones (AHL). These are regulators in cell-density-dependent gene regulation (quorum sensing) controlling microbial processes. In chemical interactions with higher organisms, microbes can act either as harmful pathogens that are repelled by the host’s chemical defense or as beneficial symbionts. These symbionts are sometimes the true producers of the host’s secondary metabolites that have defensive and protective functions for their hosts. We also describe how allelochemicals can shape phytoplankton communities by regulating competition for available resources, and also interactions among individuals of the same species. Compounds such as the diatom-derived unsaturated aldehydes have been demonstrated to act as infochemicals, and they possibly function as a diffusible bloom-termination signal that triggers an active cell death and bloom termination at sea. The same molecules have also been shown to interfere with the reproductive capacity of grazing animals deterring future generations of potential predators. Such compounds differ from those that act as feeding deterrents since they do not target the predator but its offspring. Many of the neurotoxins produced by dinoflagellates act as feeding deterrents, and laboratory experiments have shown that ingestion of these algae by some microzooplankton and macrozooplankton can cause acute responses such as death, incapacitation, altered swimming behavior, and reduced fecundity and egg-hatching success. These effects may rarely occur in nature because of low individual grazing rates on dinoflagellate cells and grazing on other food sources such as microflagellates and diatoms. We also consider the nutritional component of marine plant-herbivore interactions, especially in the plankton, and the information available on the effects of growing conditions of algae on the production of toxic metabolites. Species producing saxitoxins seem to consistently produce the highest amounts of toxins (on a per cell basis) in the exponential phase of growth, and there is a decrease in their production under nitrogen, but not under phosphorus stress, where the production actually increases. We try to explain the circumstances under which organisms defend themselves chemically and argue that the most likely explanatory model for the production of secondary metabolites used for defense in planktonic organisms is the carbon nutrient balance hypothesis, which predicts that most algae produce their toxins mainly under conditions where carbon is in excess and nitrogen (or other nutrients) is limiting. We also discuss chemically mediated macroalgal-herbivore interactions in the benthos and the large variation in concentration of seaweed defense metabolites at different spatial and temporal scales. Seaweeds have been shown to produce a large variety of secondary metabolites with highly variable chemical structures such as terpenoids, acetogenins, amino acid derivates, and polyphenols. Many of these compounds probably have multiple simultaneous functions for the seaweeds and can act as allelopathic, antimicrobial, and antifouling or ultraviolet-screening agents, as well as herbivore deterrents. We also provide examples of interactions between marine benthic invertebrates, especially sponges, molluscs, and cnidarians, that are mediated by specific secondary metabolites and discuss the role of these in shaping benthic communities
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| 14. |
- Jakobsson-Thor, Stina, et al.
(författare)
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Seagrass wasting disease along a naturally occurring salinity gradient
- 2019
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 614, s. 67-77
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Tidskriftsartikel (refereegranskat)abstract
- In the 1930s, outbreaks of the wasting disease pathogen Labyrinthula zosterae caused a severe reduction of the eelgrass Zostera marina meadows in the Atlantic Ocean. Many surviving populations were found in low-salinity environments, and low-salinity environments have therefore been hypothesized to act as a refuge for eelgrass against L. zosterae infection. Here, we investigated L. zosterae pathogen load and wasting disease symptoms in eelgrass over a similar to 970 km salinity gradient (6-25 PSU) along the Swedish coast. Furthermore, laboratory infection experiments and studies of inhibitory compounds were carried out to investigated whether resistance against the pathogen is correlated to differences in natural pathogen pressure among eelgrass populations. The degree of L. zosterae infection was positively correlated to salinity and the pathogen was absent in several of the eelgrass meadows in lower salinity (7-8 PSU). However, a low L. zosterae pathogen load was also found in some eelgrass populations in the lowest salinity (6 PSU). No correlation between resistance and pathogen pressure in situ was detected, and all eelgrass shoots produced chemical compounds that inhibited L. zosterae growth. These results imply that positive correlations between L. zosterae and salinity are not due to eelgrass resistance, but rather to the poor ability of L. zosterae to cope with low salinity. However, our results also indicate that some strains of L. zosterae may adapt to low salinity, and therefore there may also be a risk of wasting disease outbreaks in low-salinity eelgrass meadows, in contrast to what so far has been the general hypothesis.
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| 15. |
- Jakobsson-Thor, Stina, et al.
(författare)
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Seagrass wasting disease varies with salinity and depth in natural Zostera marina populations
- 2018
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 587, s. 105-115
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Tidskriftsartikel (refereegranskat)abstract
- In the 1930s, the wasting disease pathogen Labyrinthula zosterae is believed to have killed 90% of the temperate seagrass Zostera marina in the Atlantic Ocean. Despite the devastating impact of this disease, the host?pathogen interaction is still poorly understood, and few field studies have investigated factors correlating with the prevalence and abundance of L. zosterae. The present study measured wasting disease in natural populations of Z. marina on the Swedish west coast, and showed a strong correlation between the disease and both salinity and water depth. No infection was detected in Z. marina shoots from low-salinity (13?25 PSU) meadows, whereas most shoots carried the disease in high-salinity (25?29 PSU) meadows. Shallow (1 m) living Z. marina shoots were also more infected compared to shoots in deeper (5 m) meadows. In addition, infection and transplantation experiments showed that Z. marina shoots from low-salinity meadows with low pathogen pressure were more susceptible to L. zosterae infection. The higher susceptibility could not be explained by lower content of inhibitory defense compounds in the shoots. Instead, extracts from all Z. marina shoots significantly reduced pathogen growth, suggesting that Z. marina contains inhibitory compounds that function as a constitutive defense. Overall, the results show that seagrass wasting disease is common in natural Z. marina populations in the study area and that it increases with salinity and decreases with depth. Our findings also suggest that low-salinity areas can act as a refuge against seagrass wasting disease. © The authors 2018.
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| 16. |
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| 17. |
- Kinnby, Alexandra, 1990, et al.
(författare)
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Climate Change Increases Susceptibility to Grazers in a Foundation Seaweed : Increased Seaweed Susceptibility to Grazers
- 2021
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Climate change leads to multiple effects caused by simultaneous shifts in several physical factors which will interact with species and ecosystems in complex ways. In marine systems the effects of climate change include altered salinity, increased temperature, and elevated pCO2 which are currently affecting and will continue to affect marine species and ecosystems. Seaweeds are primary producers and foundation species in coastal ecosystems, which are particularly vulnerable to climate change. The brown seaweed Fucus vesiculosus (bladderwrack) is an important foundation species in nearshore ecosystems throughout its natural range in the North Atlantic Ocean and the Baltic Sea. This study investigates how individual and interactive effects of temperature, salinity, and pCO2 affect F. vesiculosus, using a fully crossed experimental design. We assessed the effects on F. vesiculosus in terms of growth, biochemical composition (phlorotannin content, C:N ratio, and ∂13C), and susceptibility to the specialized grazer Littorina obtusata. We observed that elevated pCO2 had a positive effect on seaweed growth in ambient temperature, but not in elevated temperature, while growth increased in low salinity at ambient but not high temperature, regardless of pCO2-level. In parallel to the statistically significant, but relatively small, positive effects on F. vesiculosus growth, we found that the seaweeds became much more susceptible to grazing in elevated pCO2 and reduced salinity, regardless of temperature. Furthermore, the ability of the seaweeds to induce chemical defenses (phlorotannins) was strongly reduced by all the climate stressors. Seaweeds exposed to ambient conditions more than doubled their phlorotannin content in the presence of grazers, while seaweeds exposed to any single or combined stress conditions showed only minor increases in phlorotannin content, or none at all. Despite the minor positive effects on seaweed growth, the results of this study imply that climate change can strongly affect the ability of fucoid seaweeds to induce chemical defenses and increase their susceptibility to grazers. This will likely lead to widespread consequences under future climate conditions, considering the important role of F. vesiculosus and other fucoids in many coastal ecosystems.
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| 18. |
- Kinnby, Alexandra, 1990, et al.
(författare)
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Ocean acidification decreases grazing pressure but alters morphological structure in a dominant coastal seaweed.
- 2021
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification driven by anthropogenic climate change is causing a global decrease in pH, which is projected to be 0.4 units lower in coastal shallow waters by the year 2100. Previous studies have shown that seaweeds grown under such conditions may alter their growth and photosynthetic capacity. It is not clear how such alterations might impact interactions between seaweed and herbivores, e.g. through changes in feeding rates, nutritional value, or defense levels. Changes in seaweeds are particularly important for coastal food webs, as they are key primary producers and often habitat-forming species. We cultured the habitat-forming brown seaweed Fucus vesiculosus for 30 days in projected future pCO2 (1100 μatm) with genetically identical controls in ambient pCO2 (400 μatm). Thereafter the macroalgae were exposed to grazing by Littorina littorea, acclimated to the relevant pCO2-treatment. We found increased growth (measured as surface area increase), decreased tissue strength in a tensile strength test, and decreased chemical defense (phlorotannins) levels in seaweeds exposed to high pCO2-levels. The herbivores exposed to elevated pCO2-levels showed improved condition index, decreased consumption, but no significant change in feeding preference. Fucoid seaweeds such as F. vesiculosus play important ecological roles in coastal habitats and are often foundation species, with a key role for ecosystem structure and function. The change in surface area and associated decrease in breaking force, as demonstrated by our results, indicate that F. vesiculosus grown under elevated levels of pCO2 may acquire an altered morphology and reduced tissue strength. This, together with increased wave energy in coastal ecosystems due to climate change, could have detrimental effects by reducing both habitat and food availability for herbivores.
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| 19. |
- Long, JD, et al.
(författare)
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Proximate and ultimate causes for transatlantic variation in seaweed defenses
- 2013
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 493, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- Previous tests of theories predicting tradeoffs between constitutive and inducible defenses are inconclusive. This may result from focusing on individual traits or using cultivated plants subjected to artificial selection. We examined this tradeoff in the seaweed Ascophyllum nodosum (hereafter Ascophyllum)—one of the best-studied seaweeds with inducible defenses. Although several European populations respond to grazing with induced resistance, a US population failed to express inducible defenses. This variation may be related to corresponding variation in constitutive resistance and consumer pressure. We compared the constitutive resistance of Ascophyllum from an inducing and a non-inducing population (Sweden and USA, respectively). We quantified constitutive resistance by conducting choice feeding assays on seaweed from both populations after inducible defenses had relaxed, rather than focusing on single traits. We measured constitutive phlorotannins to confirm that defenses had relaxed and to compare between-population levels. Periwinkles consistently preferred relaxed Swedish Ascophyllum, suggesting that US Ascophyllum without inducible resistance had higher constitutive resistance. Neither snail source nor experimental arena influenced this result. Phlorotannins were also higher in relaxed US Ascophyllum. To test the hypothesis that defense type may be related to current consumer pressure, we compared per capita grazing rates and average snail densities from both locations. US snails grazed more and were more abundant in the USA, suggesting that current consumer pressure may be higher on US Ascophyllum. Consistent with theory, constitutive and inducible resistance were negatively related between our sites. Inducible resistance may be absent from the US population because these individuals have high constitutive resistance, perhaps because they encounter greater consumer pressure.
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| 20. |
- Olsson, Joakim, 1988, et al.
(författare)
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Biochemical composition of red, green and brown seaweeds common at the Swedish west coast
- 2016
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Ingår i: International Seaweed Symposium, 19-24 June, Copenhagen.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Fossil resources are still important to provide fuels and commodities in our society. However, a transition to bio-based fuels and chemicals are needed. In Sweden, e.g. biofuels still account for 4 % of the total petroleum consumption. About two thirds of our consumed biofuels are made using domestic rapeseed, wheat, barley and left-over wine as raw materials, while the rest is imported. All of these resources are from traditional agriculture and requires land, fertilizers, and freshwater. While these types of biomasses will surely play a role in a sustainable future, making not only transport fuels, but also fine and bulk chemicals as well as materials, other biomass alternatives are also needed. Macroalgae require no arable land and need no other fertilizer than what the sea provides naturally. However, to realise algae bio-products targeted technological research efforts regarding cultivation and refining processes are required.To further explore the potential of the sea and the use of marine resources for biorefining, further knowledge on biochemical content of algal biomass is needed to be gathered. This is especially true for the Western coast of Sweden. Filling these knowledge gaps will give the opportunity to find novel utilizations of macroalgae, making it possible to find new species suitable for food, feed, chemical or biofuel production.In this project, 23 seaweed and filamentous algae species of green, red and brown algae have been collected from and around the national park of Kosterhavet. The biochemical content of these has been determined to gain knowledge regarding the variation in biomass composition between algae species in Swedish waters. Analyses have been conducted for both elementals (C, H, N, S, P and metals) and macromolecular composition (total carbohydrates, total proteins, ash) as well as dry weight. Hopefully, our data can result in future research leading to novel applications and potential marine industries.
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| 21. |
- Olsson, Joakim, 1988, et al.
(författare)
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Biochemical composition of red, green and brown seaweeds on the Swedish west coast
- 2020
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 32:5, s. 3305-3317
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed biomass has the potential to become an important raw material for bio-based production. The aim of this study was to screen the overall composition of several seaweed species on the Swedish west coast, including some scarcely studied species, to provide fundamentals for evaluation of biorefining potential and to benchmark with already potentially industrially relevant species and commercially important land-based biomasses. Twenty-two common seaweed species (green, red, brown) were collected and the carbohydrate, ash, protein, water and metal contents were measured. Carbohydrate content varied between 237 and 557 g kg(-1) dry weight (dw), making it the largest constituent, on a dry weight basis, of most species in the study. Ash, which is considered unwanted in biorefining, ranged between 118 and 419 g kg(-1) dw and was the largest constituent in several seaweeds, which were therefore considered unsuitable for biorefining. Protein content was most abundant in the red seaweeds but was generally low in all species (59-201 g kg(-1) dw). High contents of several unwanted metals for processing or human consumption were found (e.g. aluminium, arsenic, copper, chromium and nickel), which need to be considered when utilizing seaweeds for certain applications. Potential targets for further biorefinery development mostly include species already known for their potential (Saccharina latissima, Laminaria digitata and Chondrus crispus) while some, such as Halidrys siliquosa and Dilsea carnosa, have not been previously noted. However, more detailed studies are required to explore biorefinery processes for these seaweeds, as well as how to potentially cultivate them.
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| 22. |
- Olsson, Joakim, 1988, et al.
(författare)
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Cultivation conditions affect the monosaccharide composition in Ulva fenestrata
- 2020
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 32, s. 3255-3263
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, the interest in using seaweed for the sustainable production of commodities has been increasing as seaweeds contain many potentially worthwhile compounds. Thus, the extraction and refining processes of interesting compounds from seaweeds is a hot research topic but has been found to have problems with profitability for novel applications. To increase the economic potential of refining seaweed biomass, the content of the compounds of interest should be maximized, which can potentially be achieved through optimization of cultivation conditions. In this study, we studied how the monosaccharide composition of the green seaweed species Ulva fenestrata is influenced by the abiotic factors; irradiance, temperature, nitrate, phosphate, and pCO(2). It was evident that lower nitrate concentration and cultivation at elevated temperature increased monosaccharide contents. A 70% increase in iduronic acid and a 26% increase in rhamnose content were seen under elevated irradiance and temperature conditions, though the absolute differences in monosaccharide concentration were small. Irradiance and nitrate impacted the ratio between iduronic and rhamnose, which is an indicator of the ulvan structure. These results could potentially be utilized to coax the ulvan towards specific bioactivities, and thus have a considerable impact on a potential biorefinery centered around Ulva.
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| 23. |
- Olsson, Joakim, 1988, et al.
(författare)
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Seaweeds for biorefinery on the Swedish west coast
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In a sustainable future, the reliance on oil for the production of fuels, chemicals and commodities has to change to renewable resources. However, replacing the 97 million barrels used each day is no easy feat and multiple biorefinery concepts based on a variety of biomasses should be part of the solution. One limitation for terrestrial biomasses, such as forestry and various crops for which these concepts are already in place, is land use. Seaweed does not require land to be grown and could provide a substantial portion of the future biomass needs. For seaweeds there are other limitations, but to a large extent these relate to them not being domesticized and studied to the same extent as crops or terrestrial plants. Which means they could possibly be overcome. There are industrial processes for alginate and carrageenan already, but the variety of seaweeds gives possibility of new innovation in areas such as materials, food components and bioenergy. To be able to evaluate the potential and identify targets for cultivation as well as breeding the basic composition of a variety of seaweeds has to be known. Studies have shown great intra-species variation in composition depending on abiotic and biotic factors. Hence, suitable targets for future production of seaweed biomass could differ from place to place and not only by natural occurrence. In this study, 22 seaweed species were collected from and around the national park of Kosterhavet in Sweden to elucidate their basic biochemical composition. Analyses included major constituents (total carbohydrates, total protein, ash and water content) and elemental composition (C, H, N, S, P and 17 heavy metals/micronutrients). From these analyses the picture becomes clear that the main problems with seaweed biomass for biorefinary is the ash (118-419 g(kg dry weight)-1) and its water content (633-875 g(kg wet weight)-1). However, the sugar content (267- 646 g(kg dry weight)-1) makes the biomass very interesting for utilization in a biotechnological process based on a sugar platform as well as materials. With this study, we hope to have lain the ground for future innovation and potential marine industries on the Swedish west coast.
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| 24. |
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| 25. |
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