| 1. |
- Abbas, Aamer, 1973, et al.
(författare)
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Chemical images of marine bio-active compounds by surface enhanced Raman spectroscopy and transposed orthogonal partial least squares (T-OPLS)
- 2012
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 737, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- Surface enhanced Raman spectroscopy combined with transposed Orthogonal Partial Least Squares (T-OPLS) was shown to produce chemical images of the natural antibacterial surface-active compound 1,1,3,3-tetrabromo-2-heptanone (TBH) on Bonnemaisonia hamifera. The use of gold colloids function-alised with the internal standard 4-mercapto-benzonitrile (MBN) made it possible to create images of the relative concentration of TBH over the surfaces. A gradient of TBH could be mapped over and in the close vicinity of the B. hamifera algal vesicles at the attomol/pixel level. T-OPLS produced a measure of the spectral correlation for each pixel of the hyperspectral images whilst not including spectral variation that was linearly independent of the target spectrum. In this paper we show the possibility to retrieve specific spectral information with a low magnitude in a complex matrix.
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| 2. |
- Albers, Eva, 1966, et al.
(författare)
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Influence of preservation methods on biochemical composition and downstream processing of cultivated Saccharina latissima biomass
- 2021
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Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 55
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Tidskriftsartikel (refereegranskat)abstract
- Saccharina latissima biomass cultivated along the Swedish west coast was subjected to four different scalable preservation methods after harvest; freezing, sun-drying, oven-drying and ensiling. Freeze-drying and freezing at -80 ?C were also included to provide dry and wet references. The effects of the different preservation methods on the composition of Saccharina biomass (on dry weight, DW, basis), and the recovery as well as properties of high-quality protein, alginate and biogas were evaluated. Sun-drying significantly reduced protein, alginate and fatty acid content of the seaweeds and thereby concentrated ash in the biomass compared to the other methods. Protein/amino acids and fatty acids were significantly concentrated in ensiled biomass, while mannitol and laminarin were reduced compared to the other biomasses. Oven-drying and -20 ?C freezing affected the composition the least, with lower ash content and alterations in some specific amino and fatty acids. Sun-drying and ensiling resulted in significantly lower protein solubility at high pH compared to the other biomasses which translated into the lowest total seaweed protein recovery using the pH-shift process. Highest protein yield was obtained with the freeze-dried reference. Ensiling lead to a significant decrease in the molecular weight of alginate, while sun-drying caused a negative effect on alginate by inducing a shift in the guluronic and mannuronic acids composition of alginate. Sun-drying gave the lowest methane yield in the anaerobic digestion experiments while freezing at -80 ?C gave the highest yield, closely followed by freezing at -20 ?C and ensiling. To conclude, preservation methods must be carefully chosen to protect the valuable component in Saccharina latissima, and to achieve an efficient downstream processing ultimately yielding high quality products as part of a seaweed biorefinery.
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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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
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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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| 6. |
- Baumgartner, Finn A., 1982, et al.
(författare)
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Individual Specialization to Non-Optimal Hosts in a Polyphagous Marine Invertebrate Herbivore
- 2014
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:8
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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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| 7. |
- Berdan, Emma L, 1983, et al.
(författare)
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A large chromosomal inversion shapes gene expression in seaweed flies (Coelopa frigida)
- 2021
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Ingår i: EVOLUTION LETTERS. - : Oxford University Press (OUP). - 2056-3744. ; 5:6, s. 607-624
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Tidskriftsartikel (refereegranskat)abstract
- Inversions often underlie complex adaptive traits, but the genic targets inside them are largely unknown. Gene expression profiling provides a powerful way to link inversions with their phenotypic consequences. We examined the effects of the Cf-Inv(1) inversion in the seaweed fly Coelopa frigida on gene expression variation across sexes and life stages. Our analyses revealed that Cf-Inv(1) shapes global expression patterns, most likely via linked variation, but the extent of this effect is variable, with much stronger effects in adults than larvae. Furthermore, within adults, both common as well as sex-specific patterns were found. The vast majority of these differentially expressed genes mapped to Cf-Inv(1). However, genes that were differentially expressed in a single context (i.e., in males, females, or larvae) were more likely to be located outside of Cf-Inv(1). By combining our findings with genomic scans for environmentally associated SNPs, we were able to pinpoint candidate variants in the inversion that may underlie mechanistic pathways that determine phenotypes. Together the results of this study, combined with previous findings, support the notion that the polymorphic Cf-Inv(1) inversion in this species is a major factor shaping both coding and regulatory variation resulting in highly complex adaptive effects.
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| 8. |
- Berdan, Emma L, 1983, et al.
(författare)
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Genetic divergence and phenotypic plasticity contribute to variation in cuticular hydrocarbons in the seaweed fly Coelopa frigida
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:21, s. 12156-12170
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Tidskriftsartikel (refereegranskat)abstract
- Cuticular hydrocarbons (CHCs) form the boundary between insects and their environments and often act as essential cues for species, mate, and kin recognition. This complex polygenic trait can be highly variable both among and within species, but the causes of this variation, especially the genetic basis, are largely unknown. In this study, we investigated phenotypic and genetic variation of CHCs in the seaweed fly, Coelopa frigida, and found that composition was affected by both genetic (sex and population) and environmental (larval diet) factors. We subsequently conducted behavioral trials that show CHCs are likely used as a sexual signal. We identified general shifts in CHC chemistry as well as individual compounds and found that the methylated compounds, mean chain length, proportion of alkenes, and normalized total CHCs differed between sexes and populations. We combined these data with whole genome resequencing data to examine the genetic underpinnings of these differences. We identified 11 genes related to CHC synthesis and found population-level outlier SNPs in 5 that are concordant with phenotypic differences. Together these results reveal that the CHC composition of C. frigida is dynamic, strongly affected by the larval environment, and likely under natural and sexual selection.
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| 9. |
- Bergkvist, Johanna, 1980, et al.
(författare)
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Induction of toxin production in dinoflagellates: the grazer makes a difference
- 2008
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 156:1, s. 147-154
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Tidskriftsartikel (refereegranskat)abstract
- The dinoflagellate Alexandrium minutum has previously been shown to produce paralytic shellfish toxins (PST) in response to waterborne cues from the copepod Acartia tonsa. In order to investigate if grazer-induced toxin production is a general or grazer-specific response of A. minutum to calanoid copepods, we exposed two strains of A. minutum to waterborne cues from three other species of calanoid copepods, Acartia clausi, Centropages typicus and Pseudocalanus sp. Both A. minutum strains responded to waterborne cues from Centropages and Acartia with significantly increased cell-specific toxicity. Waterborne cues from Centropages caused the strongest response in the A. minutum cells, with 5 to > 20 times higher toxin concentrations compared to controls. In contrast, neither of the A. minutum strains responded with significantly increased toxicity to waterborne cues from Pseudocalanus. The absolute increase in PST content was proportional to the intrinsic toxicity of the different A. minutum strains that were used. The results show that grazer-induced PST production is a grazer-specific response in A. minutum, and its potential ecological importance will thus depend on the composition of the zooplankton community, as well as the intrinsic toxin-producing properties of the A. minutum population.
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| 10. |
- Brock, Elisabet, 1949, et al.
(författare)
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Chemical inhibition of barnacle larval settlement by the brown alga Fucus vesiculosus
- 2007
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 337, s. 165-174
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Tidskriftsartikel (refereegranskat)abstract
- The possible importance of larval settlement inhibition by Fucus vesiculosus in explaining the low abundance of the barnacle Balanus improvisus on algal fronds compared to adjacent rock was investigated by a combination of field and laboratory studies. A field survey showed that the abundance of adult barnacles was significantly lower on F vesiculosus than on rocks and settlement preference experiments strongly suggested that settlement avoidance for algal fronds during the natural settlement season was chemically mediated. By using a multi-step approach, whereby both exuded and surface associated metabolites were tested on larval settlement, we further investigated the possible existence of chemical antifouling processes in E vesiculosus. For exuded metabolites, seawater was conditioned for 1 and 3 h with both submerged and desiccated algae, Surface extracts at natural concentrations and seawater conditioned with submerged algae had no significant effect on larval settlement, although there was a tendency for reduced settlement in the 3 h samples. Seawater conditioned with desiccated algae consistently inhibited settlement and chemical analyses showed that the mean phlorotannin level in the water was 31.5 mu g ml(-1), which is ca. 30x higher than concentrations previously shown to inhibit barnacle settlement. Seawater conditioned with submerged algae had a mean phlorotannin content of 0.85 mu g ml(-1) and in samples conditioned for 3 h there was a strong and significant negative relationship between phlorotannin concentration and larval settlement, suggesting that the phlorotannin concentration varied around a level inhibitory to barnacle settlement. Altogether, the results from the laboratory experiments strongly suggested that the low larval preference for algae was caused by exudation of waterborne metabolites, primarily phlorotannins. Finally, field measurements showed that phlorotannins exuded from F. vesiculosus can under natural conditions reach concentrations inhibitory to settlement of barnacle larvae.
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| 11. |
- Brooke, Darby G., et al.
(författare)
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Antifouling activity of portimine, select semisynthetic analogues, and other microalga-derived spirocyclic imines
- 2018
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 34:8, s. 950-961
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Tidskriftsartikel (refereegranskat)abstract
- © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. A range of natural products from marine invertebrates, bacteria and fungi have been assessed as leads for nature-inspired antifouling (AF) biocides, but little attention has been paid to microalgal-derived compounds. This study assessed the AF activity of the spirocyclic imine portimine (1), which is produced by the benthic mat-forming dinoflagellate Vulcanodinium rugosum. Portimine displayed potent AF activity in a panel of four macrofouling bioassays (EC 50 0.06–62.5 ng ml −1 ), and this activity was distinct from that of the related compounds gymnodimine-A (2), 13-desmethyl spirolide C (3), and pinnatoxin-F (4). The proposed mechanism of action for portimine is induction of apoptosis, based on the observation that portimine inhibited macrofouling organisms at developmental stages known to involve apoptotic processes. Semisynthetic modification of select portions of the portimine molecule was subsequently undertaken. Observed changes in bioactivity of the resulting semisynthetic analogues of portimine were consistent with portimine’s unprecedented 5-membered imine ring structure playing a central role in its AF activity.
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| 12. |
- Cahill, P. L., et al.
(författare)
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Creating New Antifoulants Using the Tools and Tactics of Medicinal Chemistry
- 2024
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Ingår i: Accounts of Chemical Research. - : American Chemical Society. - 0001-4842 .- 1520-4898. ; 57:3, s. 399-
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Tidskriftsartikel (refereegranskat)abstract
- Conspectus The unwanted accumulation of marine micro- and macroorganisms such as algae and barnacles on submerged man-made structures and vessel hulls is a major challenge for any marine operation. Known as biofouling, this problem leads to reduced hydrodynamic efficiency, significantly increased fuel usage, microbially induced corrosion, and, if not managed appropriately, eventual loss of both performance and structural integrity. Ship hull biofouling in the international maritime transport network conservatively accounts for 0.6% of global carbon emissions, highlighting the global scale and the importance of this problem. Improved antifouling strategies to limit surface colonization are paramount for essential activities such as shipping, aquaculture, desalination, and the marine renewable energy sector, representing both a multibillion dollar cost and a substantial practical challenge. From an ecological perspective, biofouling is a primary contributor to the global spread of invasive marine species, which has extensive implications for the marine environment. Historically, heavy metal-based toxic biocides have been used to control biofouling. However, their unwanted collateral ecological damage on nontarget species and bioaccumulation has led to recent global bans. With expanding human activities within aquaculture and offshore energy, it is both urgent and apparent that environmentally friendly surface protection remains key for maintaining the function of both moving and stationary marine structures. Biofouling communities are typically a highly complex network of both micro- and macroorganisms, representing a broad section of life from bacteria to macrophytes and animals. Given this diversity, it is unrealistic to expect that a single antifouling “silver bullet” will prevent colonization with the exception of generally toxic biocides. For that reason, modern and future antifouling solutions are anticipated to rely on novel coating technologies and “combination therapies” where mixtures of narrow-spectrum bioactive components are used to provide coverage across fouling species. In contrast to the existing cohort of outdated, toxic antifouling strategies, such as copper- and tributyltin-releasing paints, modern drug discovery techniques are increasingly being employed for the rational design of effective yet safe alternatives. The challenge for a medicinal chemistry approach is to effectively account for the large taxonomic diversity among fouling organisms combined with a lack of well-defined conserved molecular targets within most taxa. The current Account summarizes our work employing the tools of modern medicinal chemistry to discover, modify, and develop optimized and scalable antifouling solutions based on naturally occurring antifouling and repelling compounds from both marine and terrestrial sources. Inspiration for rational design comes from targeted studies on allelopathic natural products, natural repelling peptides, and secondary metabolites from sessile marine organisms with clean exteriors, which has yielded several efficient and promising antifouling leads.
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| 13. |
- Chopin, Thierry, et al.
(författare)
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Deep-ocean seaweed dumping for carbon sequestration: Questionable, risky, and not the best use of valuable biomass
- 2024
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Ingår i: One Earth. - : Elsevier BV. - 2590-3330 .- 2590-3322. ; 7:3, s. 359-364
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Tidskriftsartikel (refereegranskat)abstract
- Deep-ocean seaweed dumping is not an ecological, economical, or ethical answer to climate-change mitigation via carbon “sequestration.” Without sound science and sufficient knowledge on impacts to these fragile ecosystems, it distracts from more rational and effective blue-carbon interventions. We call for a moratorium on sinking seaweeds to deep-ocean ecosystems until its efficacy is established, and there is robust, evidence-based assessment of its environmental, economic, and societal sustainability.
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| 14. |
- Davis, R. A., et al.
(författare)
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Evaluation of natural resveratrol multimers as marine antifoulants
- 2023
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Ingår i: Biofouling. - : Taylor and Francis Ltd.. - 0892-7014 .- 1029-2454. ; 39:8, s. 775-784
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Tidskriftsartikel (refereegranskat)abstract
- In the current study we investigate the antifouling potential of three polyphenolic resveratrol multimers (-)-hopeaphenol, vaticanol B and vatalbinoside A, isolated from two species of Anisoptera found in the Papua New Guinean rainforest. The compounds were evaluated against the growth and settlement of eight marine microfoulers and against the settlement and metamorphosis of Amphibalanus improvisus barnacle cyprids. The two isomeric compounds (-)-hopeaphenol and vaticanol B displayed a high inhibitory potential against the cyprid larvae metamorphosis at 2.8 and 1.1 mu M. (-)-Hopeaphenol was also shown to be a strong inhibitor of both microalgal and bacterial adhesion at submicromolar concentrations with low toxicity. Resveratrol displayed a lower antifouling activity compared to the multimers and had higher off target toxicity against MCR-5 fibroblasts. This study illustrates the potential of natural products as a valuable source for the discovery of novel antifouling leads with low toxicity.
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| 15. |
- Eliasson, Eliska, et al.
(författare)
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No colonization resistance to Campylobacter jejuni in broilers fed brown algal extract-supplemented diets
- 2024
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Campylobacter jejuni gastroenteritis is the most commonly reported zoonosis within the EU, with poultry products regarded as the primary source of transmission to humans. Therefore, finding strategies to reduce Campylobacter colonization in broilers holds importance for public health. Recent studies suggest that supplementation of broiler feed with brown algal extracts, particularly laminarin, can provide beneficial effects on broiler gut health, growth performance, and gut microbiota. However, its effect on gut microbiota development and subsequent reduction of Campylobacter loads in broiler caeca during the later stages of the birds' lives remains unclear.Methods Experimental colonization of Ross 308 broilers with two different strains of C. jejuni was conducted, with groups fed either a basal diet or the same basal diet supplemented with 725 ppm algal extract from Saccharina latissima to provide 290 ppm laminarin. Fecal samples were collected for bacterial enumeration, and caecal samples were obtained before and after the C. jejuni challenge for the determination of microbiota development.Results and discussion No significant differences in fecal C. jejuni concentrations between the groups fed different diets or exposed to different C. jejuni strains were observed. This suggests that both strains colonized the birds equally well and that the laminarin rich algal extract did not have any inhibitory effect on C. jejuni colonization. Notably, 16S rRNA amplicon sequencing revealed detailed data on the caecal microbiota development, likely influenced by both bird age and C. jejuni colonization, which can be valuable for further development of broiler feed formulations aimed at promoting gut health.
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| 16. |
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| 17. |
- Enge, S., et al.
(författare)
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A REVIEW OF HERBIVORE EFFECTS ON SEAWEED INVASIONS
- 2017
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Ingår i: OCEANOGRAPHY AND MARINE BIOLOGY: AN ANNUAL REVIEW, VOL 55. - BOCA RATON : Taylor and Francis. - 9781138197862 - 9781351987592 ; , s. 421-440
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Almost 300 non-native seaweeds are identified worldwide and an increasing number of these are classified as invasive with potential negative effects on the diversity and functioning of native ecosystems. Marine herbivores affect seaweed biomass and community structure in marine habitats across the globe. Consequently, herbivore-seaweed interactions are expected to be important for the establishment and invasion success of non-native seaweeds. To synthesize current knowledge of consumer effects on non-native seaweeds, we performed a meta-analysis on feeding preferences of native herbivores for non-native versus native seaweeds. Data were included from 35 studies, published from 1992-2015 and comprising 18 non-native seaweeds. Results showed that overall, native herbivores tended to prefer to feed on native rather than non-native seaweeds. Preferences were, however, variable across studies with significant differences between taxonomic and functional groups of seaweeds. In particular, filamentous red non-native seaweeds were of low palatability to native herbivores. No general feeding preferences were apparent between natives and non-natives for brown and green seaweeds, or for leathery and corticated seaweeds. In addition, we reviewed the existing studies on the effects of consumers on the performance of native and non-native seaweeds in invaded communities. This indicated that non-native seaweeds performed better than their native competitors in the presence of grazers, but in many cases had superior competitive abilities also in the absence of herbivory. To achieve a comprehensive evaluation of consumers' role in seaweed invasion success, future research should have a larger focus on manipulative community experiments, ideally on time scales that include seasonal changes and complete life cycles of the seaweeds.
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| 18. |
- Enge, Swantje, et al.
(författare)
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A supergene in seaweed flies modulates male traits and female perception
- 2023
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 0962-8452 .- 1471-2954. ; 290:2008
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Tidskriftsartikel (refereegranskat)abstract
- Supergenes, tightly linked sets of alleles, offer some of the most spectacular examples of polymorphism persisting under long-term balancing selection. However, we still do not understand their evolution and persistence, especially in the face of accumulation of deleterious elements. Here, we show that an overdominant supergene in seaweed flies, Coelopa frigida, modulates male traits, potentially facilitating disassortative mating and promoting intraspecific polymorphism. Across two continents, the Cf-Inv(1) supergene strongly affected the composition of male cuticular hydrocarbons (CHCs) but only weakly affected CHC composition in females. Using gas chromatography-electroantennographic detection, we show that females can sense male CHCs and that there may be differential perception between genotypes. Combining our phenotypic results with RNA-seq data, we show that candidate genes for CHC biosynthesis primarily show differential expression for Cf-Inv(1) in males but not females. Conversely, candidate genes for odorant detection were differentially expressed in both sexes but showed high levels of divergence between supergene haplotypes. We suggest that the reduced recombination between supergene haplotypes may have led to rapid divergence in mate preferences as well as increasing linkage between male traits, and overdominant loci. Together this probably helped to maintain the polymorphism despite deleterious effects in homozygotes.
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| 19. |
- Enge, Swantje, 1981, et al.
(författare)
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An exotic chemical weapon explains low herbivore damage in an invasive alga
- 2012
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Ingår i: Ecology. - : Wiley. - 0012-9658. ; 93:12, s. 2736-2745
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Tidskriftsartikel (refereegranskat)abstract
- Invasion success of introduced species is often attributed to a lack of natural enemies as stated by the enemy release hypothesis (ERH). The ERH intuitively makes sense for specialized enemies, but it is less evident why invaders in their new area escape attacks by generalist enemies. A recent hypothesis explains low herbivore damage on invasive plants with plant defense chemicals that are evolutionarily novel to native herbivores. Support for this novel weapon hypothesis (NWH) is so far based on circumstantial evidence. To corroborate the NWH, there is a need for direct evidence through explicit characterizations of the novel chemicals and their effects on native consumers. This study evaluated the NWH using the highly invasive red alga Bonnemaisonia hamifera. In pairwise feeding experiments, preferences between B. hamifera and native competitors were assessed for four common generalist herbivores in the invaded area. Through a bioassay-guided fractionation, we identified the deterrent compound and verified its effect in an experiment with the synthesized compound at natural concentrations. The results showed that native herbivores strongly preferred native algae to B. hamifera. The resistance against herbivores could be tracked down to the algal metabolite 1,1,3,3-tetrabromo-2-heptanone, a compound not known from native algae in the invaded area. The importance of the chemical defense was further underlined by the feeding preference of herbivores for individuals with a depleted content of 1,1,3,3-tetrabromo-2-heptanone. This study thus provides the first conclusive example of a highly successful invader where low consumption in the new range can be directly attributed to a specific chemical defense against evolutionarily naive native generalists. In conclusion, our results support the notion that novel chemical weapons against naive herbivores can provide a mechanistic explanation for plant invasion success.
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| 20. |
- Enge, Swantje, 1981, et al.
(författare)
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Native generalist herbivores promote invasion of a chemically defended seaweed via refuge-mediated apparent competition
- 2013
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Ingår i: Ecology Letters. - 1461-023X .- 1461-0248. ; 16:4, s. 487-492
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Tidskriftsartikel (refereegranskat)abstract
- Refuge-mediated apparent competition was recently suggested as a mechanism that enables plant invasions. The refuge characteristics of introduced plants are predicted to enhance impacts of generalist herbivores on native competitors and thereby result in an increased abundance of the invader. However, this prediction has so far not been experimentally verified. This study tested if the invasion of a chemically defended seaweed is promoted by native generalist herbivores via refuge-mediated apparent competition. The invader was shown to offer herbivores a significantly better refuge against fish predation compared with native seaweeds. Furthermore, in an experimental community, the presence of herbivores decreased the performance of neighbouring native seaweeds, but increased growth and relative abundance of the invader. These results provides the first experimental evidence that native generalist herbivores can shift a community towards a dominance of a well-defended invader, inferior to native species in direct competitive interactions, by means of refuge-mediated apparent competition.
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| 21. |
- Engelen, A. H., et al.
(författare)
-
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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| 22. |
- Forslund, Helena, 1978-, et al.
(författare)
-
Higher resistance to herbivory in introduced compared to native populations of a seaweed
- 2010
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 164:3, s. 833-840
-
Tidskriftsartikel (refereegranskat)abstract
- Non-indigenous species (NIS) are important components of global change, and in order to manage such species it is important to understand which factors affect their success. Interactions with enemies in the new range have been shown to be important for the outcome of introductions, but thus far most studies on NIS-enemy interactions have considered only specialist herbivores in terrestrial systems. Here we present the results from the first biogeographic study that compares herbivore resistance between populations in the native and new region of a non-indigenous seaweed. We show that low consumption of the non-indigenous seaweed by a generalist herbivore is caused by higher chemical defence levels and herbivore resistance in the new range-and not by the failure of the herbivore to recognise the non-indigenous seaweed as a suitable host. Since most seaweed-herbivore interactions are dominated by generalist herbivores, this pattern could be common in marine communities. Our results also reveal that traits used to predict the invasive potential of species, such as their resistance to enemies, can change during the invasion process, but not always in the way predicted by dominant theories.
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| 23. |
- Granéli, E., et al.
(författare)
-
Allelopathy in marine ecosystems
- 2003
-
Ingår i: Allelopathy: a physiological process with ecological implications. - : Kluwer Academic Publishers.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 24. |
- Granéli, Edna, et al.
(författare)
-
Allelopathy in marine ecosystems
- 2006
-
Ingår i: Allelopathy. - Dordrecht : Springer Netherlands. - 9781402042799 ; , s. 415-431
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 25. |
- Grant, T. M., et al.
(författare)
-
Towards eco-friendly marine antifouling biocides-Nature inspired tetrasubstituted 2,5-diketopiperazines
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 812
-
Tidskriftsartikel (refereegranskat)abstract
- Marine biofouling plagues all maritime industries at vast economic and environmental cost. Previous and most current methods to control biofouling have employed highly persistent toxins and heavy metals, including tin, copper, and zinc. These toxic methods are resulting in unacceptable environmental harm and are coming under immense regulatory pressure. Eco-friendly alternatives are urgently required to effectively mitigate the negative consequence of biofouling without causing collateral harm. Amphiphilic micropeptides have recently been shown to exhibit excellent broad-spectrum antifouling activity, with a non-toxic mode of action and innate biodegradability. The present work focused on incorporating the pharmacophore derived from amphiphilic micropeptides into a 2,5-diketopiperazine (DKP) scaffold. This privileged structure is present in a vast number of natural products, including marine natural product antifoulants, and provides advantages of synthetic accessibility and adaptability. A novel route to symmetrical tetrasubstituted DKPs was developed and a library of amphiphilic 2,5-DKPs were subsequently synthesised. These biodegradable compounds were demonstrated to be potent marine antifoulants displaying broad-spectrum activity in the low micromolar range against a range of common marine fouling organisms. The outcome of planned coating and field trials will dictate the future development of the lead compounds.
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| 26. |
- Hanssen, Kine Œ, et al.
(författare)
-
The Bromotyrosine derivative Ianthelline isolated from the arctic marine sponge Stryphnus fortis inhibits marine micro- and macrobiofouling
- 2014
-
Ingår i: Marine Biotechnology. - : Springer Science and Business Media LLC. - 1436-2228 .- 1436-2236. ; 16:6, s. 684-694
-
Tidskriftsartikel (refereegranskat)abstract
- The inhibition of marine biofouling by the bromotyrosine derivative ianthelline, isolated from the Arctic marine sponge Stryphnus fortis, is described. All major stages of the fouling process are investigated. The effect of ianthelline on adhesion and growth of marine bacteria and microalgae is tested to investigate its influence on the initial microfouling process comparing with the known marine antifoulant barettin as a reference. Macrofouling is studied via barnacle (Balanus improvisus) settlement assays and blue mussel (Mytilus edulis) phenoloxidase inhibition. Ianthelline is shown to inhibit both marine micro- and macrofoulers with a pronounced effect on marine bacteria (minimum inhibitory concentration (MIC) values 0.1–10 μg/mL) and barnacle larval settlement (IC50=3.0 μg/mL). Moderate effects are recorded on M. edulis (IC50=45.2 μg/mL) and microalgae, where growth is more affected than surface adhesion. The effect of ianthelline is also investigated against human pathogenic bacteria. Ianthelline displayed low micromolar MIC values against several bacterial strains, both Gram positive and Gram negative, down to 2.5 μg/mL. In summary, the effect of ianthelline on 20 different representative marine antifouling organisms and seven human pathogenic bacterial strains is presented.
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| 27. |
- Hargrave, Matthew, et al.
(författare)
-
Co-cultivation with blue mussels increases yield and biomass quality of kelp
- 2022
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 550
-
Tidskriftsartikel (refereegranskat)abstract
- Integrated multi-trophic aquaculture (IMTA) has to date largely centred on a fed species, often finfish or shrimps, alongside which extractive species, such as bivalves or seaweeds, have been placed. In comparison, IMTA systems excluding a fed component have received little research. Here we report a field study of an IMTA cultivation of the sugar kelp, Saccharina latissima, and the blue mussel, Mytilus edulis, on the Swedish west coast. Kelp were cultivated at two depths, 1-2 m and 3-4 m, either 10 m downstream of commercial scale blue mussel farms, or at control (monoculture) sites at least 500 m from the nearest farm. Significant enhancement of kelp yields in terms of both blade length and biomass was observed in IMTA treatments compared to monoculture, with a mean increase in length of 22% and biomass of 38%. Moreover, kelps co-cultivated with mussels displayed an epiphyte reduction of more than half compared to kelps grown in monoculture, with a 15% coverage in monoculture compared to 6% in co-culture. Significant increases in pigment content were also detected, with higher levels of chlorophyll a, fucoxanthin and phaeophytin in IMTA treatment kelps in comparison to monoculture. This study provides evidence for the potential of IMTA systems containing solely extractive species and presents factors beyond nutrient enrichment as drivers for enhanced growth in these systems. © 2021 The Authors
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| 28. |
- Hargrave, Matthew, et al.
(författare)
-
Filtration and fertilisation effects of the bivalves Mytilus edulis and Magallana gigas on the kelp Saccharina latissima in tank culture
- 2021
-
Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176.
-
Tidskriftsartikel (refereegranskat)abstract
- Biofouling by opportunistic epiphytes is a major concern in seaweed aquaculture. Colonisation of fouling organisms contributes to a reduction in algal performance as well as a lower quality crop. Further, epiphyte removal techniques often increase maintenance costs of cultivation systems. There have been a variety of methods to mitigate fouling in tank cultivations of seaweed, including the use of biological controls. Here, we present the use of filter feeding bivalves, the blue mussel (Mytilus edulis) and Pacific oyster (Magallana gigas), as a novel biofilter that also serves as a source of dissolved inorganic nitrogen in tank cultivations of the sugar kelp, Saccharina latissima. We observed significant reductions of fouling epiphytes on seaweed blades of around 50% by bivalve filtration, significant elevations of ammonium (NH4+) and phosphate (PO43-) by bivalves and alterations to kelp tissue quality when co-cultivated with bivalves rather than supplied with ambient seawater. Stable isotope ratios and seawater chlorophyll a concentrations provided evidence for bivalve biofiltration and the incorporation of their by-products into kelp tissue.
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| 29. |
- Harrysson, Hanna, 1987, et al.
(författare)
-
Effect of storage conditions on lipid oxidation, nutrient loss and colour of dried seaweeds, Porphyra umbilicalis and Ulva fenestrata, subjected to different pretreatments
- 2021
-
Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 56
-
Tidskriftsartikel (refereegranskat)abstract
- Here we evaluated the levels of lipid oxidation products, fatty acids, ascorbic acid and colour of Porphyra and Ulva after oven-drying at 40 degrees C, and during subsequent storage for >= 370 days under light, semi-light and dark conditions. Part of the seaweed was pre-soaked in freshwater or pre-coated with a whey protein mixture. Controls consisted of freeze-dried seaweeds. Throughout storage there was a moderate development of the lipid oxidation-derived aldehydes, malondialdehyde, 4-hydroxy-trans-2-hexenal and 4-hydroxy-trans-2-nonenal, while there was a great loss of unsaturated fatty acids and ascorbic acid. Light storage and freeze-drying stimulated the fatty acid loss as well as pigment bleaching, seen as increased a*-values. For Ulva, the coating reduced malondialdehyde, 4-hydroxy-trans-2-hexenal and 4-hydroxy-trans-2-nonenal formation during drying and slightly prevented loss of polyunsaturated fatty acids during light storage. Pre-soaking in freshwater had no effect on the seaweed stability, although it reduced the ash content and thereby increased the relative content of ascorbic acid and fatty acids of the biomasses.
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| 30. |
- Harrysson, Hanna, 1987, et al.
(författare)
-
Strategies for Improving the Protein Yield in pH-Shift Processing of Ulva lactuca Linnaeus: Effects of Ulvan Lyases, pH-Exposure Time, and Temperature
- 2019
-
Ingår i: Acs Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 7:15, s. 12688-12691
-
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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| 31. |
- Hasselström, Linus, et al.
(författare)
-
Socioeconomic prospects of a seaweed bioeconomy in Sweden
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Seaweed cultivation is a large industry worldwide, but production in Europe is small compared to production in Asian countries. In the EU, the motivations for seaweed farming may be seen from two perspectives; one being economic growth through biomass production and the other being the provisioning of ecosystem services such as mitigating eutrophication. In this paper, we assess the economic potential of large-scale cultivation of kelp, Saccharina latissima, along the Swedish west coast, including the value of externalities. The findings suggest that seaweed farming has the potential of becoming a profitable industry in Sweden. Furthermore, large-scale seaweed farming can sequester asignificant share of annual anthropogenic nitrogen and phosphorus inflows to the basins of the Swedish west coast (8% of N and 60% of P). Concerning the valuation of externalities, positive values generated from sequestration of nitrogen and phosphorus are potentially counteracted by negative values frominterference with recreational values. Despite the large N and P uptake, the socioeconomic value of this sequestration is only a minor share of the potential financial value from biomass production. This suggests that e.g. payment schemes for nutrient uptake based on the socioeconomic values generatedis not likely to be a tipping point for the industry. Additionally, seaweed cultivation is not a cost-efficient measure in itself to remove nutrients. Policy should thus be oriented towards industry development, as the market potential of the biomass will be the driver that may unlock these bioremediationopportunities.
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| 32. |
- Hasselström, Linus, et al.
(författare)
-
The impact of seaweed cultivation on ecosystem services - a case study from the west coast of Sweden
- 2018
-
Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X .- 1879-3363. ; 133, s. 53-64
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Authors Seaweed cultivation attracts growing interest and sustainability assessments from various perspectives are needed. The paper presents a holistic qualitative assessment of ecosystem services affected by seaweed cultivation on the Swedish west coast. Results suggest that supporting, regulating and provisioning services are mainly positively or non-affected while some of the cultural services are likely negatively affected. The analysis opens for a discussion on the framing of seaweed cultivation – is it a w ay of supplying ecosystem services and/or a way of generating valuable biomass? Exploring these framings further in local contexts may be valuable for identifying trade-offs and designing appropriate policies and development strategies. Many of the found impacts are likely generalizable in their character across sites and scales of cultivation, but for some services, including most of the supporting services, the character of impacts is likely to be site-specific and not generalizable.
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| 33. |
- Ianora, A., et al.
(författare)
-
New Trends in Marine Chemical Ecology
- 2006
-
Ingår i: Estuaries and Coasts. ; 29:4, s. 531-551
-
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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| 34. |
- Ivarsson, Emma, et al.
(författare)
-
Effects of algal supplementation in feed to broiler breeders on transfer of nutrients and antibodies to chicks and quality of hatchlings
- 2023
-
Ingår i: Animal. - 1751-7311 .- 1751-732X. ; 17:12
-
Tidskriftsartikel (refereegranskat)abstract
- Breeder nutrition is an important factor for chick quality since the chick embryo relies on nutrients available in the egg for growth and development. In addition, the egg is providing the chick with important antibodies that are vital during the first weeks of life. Brown algae contains several bioactive compounds, and dietary supplementation with algal extracts have shown improved gut health and immune responses in both pigs and poultry. The aim of this study was to investigate if feeding the brown algae Saccharina latissima, intact or as an extract, to broiler breeders can affect breeder hens’ antibody responses to vaccination, egg quality and transfer of antibodies and nutrients to the egg and thereby improve the quality of newly hatched chicks. Forty-five hens and nine roosters of the parent lines of the fast-growing broiler Ross 308 were included in the experiment where hens were 31 weeks at the start. The hens were housed individually and fed one of three dietary treatments for seven weeks; (a) control, (b) addition of 0.6% algal meal or (c) addition of 0.08% algal extract. The hens were given a booster vaccination against infectious bronchitis virus (IBV) 21 days after the start of experiment. During experimental days 32–42, hens were naturally mated every 5th day and hatching eggs were collected. A total of 255 chicks were hatched, and chick quality was assessed. Moreover, on chick day three, blood was collected from 48 focal chickens and total immunoglobulin Y levels and specific titres to IBV in serum were determined. The results showed that feeding the brown algae Saccharina latissima, intact or as an extract to broiler breeders did not affect egg production, egg quality, antibody responses to vaccination or transfer of antibodies from hen to chick. However, feeding intact algae significantly increased the levels of iodine and decreased the level of selenium in the eggs and resulted in a lower proportion of chicks with maximum quality score. Interestingly, algal feeding, both intact and as an extract, increased the abdominal fat pad in broiler breeders by about 17% without affecting BW. In conclusion, supplementation of broiler breeder diets with algal extract from Saccharina latissima, but not intact algal meal is a promising dietary strategy to increase the abdominal fat pad without causing any adverse effects on nutrient level in eggs or chick quality.
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| 35. |
- Ivarsson, E., et al.
(författare)
-
Evaluation of early feed access and algal extract on growth performance, organ development, gut microbiota and vaccine-induced antibody responses in broiler chickens
- 2022
-
Ingår i: Animal. - : Elsevier BV. - 1751-7311. ; 16:5
-
Tidskriftsartikel (refereegranskat)abstract
- Hatching concepts such as on-farm hatching provide an opportunity to supply newly hatched chickens with optimal nutrition that support growth and development of a healthy gut. Brown algae contain bioactive compounds, especially laminarin and fucoidan that may improve intestinal health and immune responses. This study aimed to examine the effects of early access to feed and water posthatch and feed supplementation with algal extract rich in laminarin from Laminaria digitata, on growth performance, organ and microbiota development and antibody production. A total of 432 Ross 308 chicks were allotted to 36 rearing pens in a 2 x 3 factorial design with two hatching treatments and three dietary treatments. During chick placement, half of the pens were directly provided access to feed and water (Early) while half of the pens were deprived of feed and water for 38 h (Late). The chicks were fed three different starter diets until day 6; a wheat-soybean meal-based control diet, a diet with low inclusion of algal extract (0.057%) and a diet with high inclusion of algal extract (0.114%). Feed intake and BW were registered on pen basis at placement, days 1, 6, 12, 19, 26, 33 and 40. To induce antibody responses, all chicks were vaccinated against avian pneumovirus on day 10. Three chicks per pen were selected as focal animals and used for blood sampling on days 10 and 39. On days 6, 19, and 40, two birds per pen were killed and used for organ measurement and caecal digesta sampling for gut microbiota analysis using the Illumina Miseq PE 250 sequencing platform. Results showed that algal extract did not influence gut microbiota, gut development or vaccine-induced antibody responses. However, during the first 38 h, early-fed chicks consumed on average 19.6 g of feed and gained 27% in BW, while late-fed chicks lost 9.1% in BW which lowered BW and feed intake throughout the study (P < 0.05). Late chicks also had longer relative intestine, higher relative (g/kg BW) weight of gizzard and proventriculus but lower relative bursa weight on day 6 (P < 0.05). No effects of hatching treatment on microbiota or antibody response were detected. The microbiota was affected by age, where alpha diversity increased with age. In conclusion, this study showed that early access to feed but not algal extract improved the growth performance throughout the 40-day growing period, and stimulated early bursa development.(c) 2022 The Authors. Published by Elsevier B.V. on behalf of The Animal Consortium. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 36. |
- Jakobsson-Thor, Stina, et al.
(författare)
-
Complex Interactions of Temperature, Light and Tissue Damage on Seagrass Wasting Disease in Zostera marina
- 2020
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- The temperate seagrass species eelgrass Zostera marina can be infected by the wasting disease pathogen Labyrinthula zosterae, which is believed to have killed about 90% of the seagrass in the Atlantic Ocean in the 1930s. It is not known why this opportunistic pathogen sometimes becomes virulent, but the recurrent outbreaks may be due to a weakening of the Z. marina plants from adverse environmental changes. This study investigated the individual and interactive effects of multiple extrinsic factors (temperature, light, and tissue damage) on the host-pathogen interaction between Z. marina and L. zosterae in a fully crossed infection experiment. The degree of infection was measured as both lesion coverage and L. zosterae cell concentration. We also investigated if the treatment factors affect the chemical defense of the host, measured as the inhibitory capacity of seagrass extracts in bioassays with L. zosterae. Finally, gene expression of a set of targeted genes was quantified in order to investigate how the treatments change Z. marina's response to infection. Light had a pronounced effect on L. zosterae infection measured as lesion coverage, where reduced light conditions increased lesions by 35%. The response to light on L. zosterae cell concentration was more complex and showed significant interaction with the temperature treatment. Cell concentration was also significantly affected by physical damage, where damage surprisingly resulted in a reduced cell concentration of the pathogen. No treatment factor caused detectable decrease in the inhibitory capacity of the seagrass extracts. There were several interactive effects between L. zosterae infection and the treatment factors on Z. marina growth, and on the expression of genes associated with immune defense, phenol synthesis and primary metabolism, showing that the molecular reaction toward L. zosterae infection depends on prevailing environmental conditions. Our study shows that individual or interactive effects of light, temperature and tissue damage can affect multiple aspects of host-pathogen interactions in seagrasses. These results highlight the complexity of marine host-pathogen systems, showing that more multi-factorial investigations are needed to gain a better understanding of disease in marine plants under different environmental conditions.
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| 37. |
- Jakobsson-Thor, Stina, et al.
(författare)
-
Seagrass wasting disease along a naturally occurring salinity gradient
- 2019
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 614, s. 67-77
-
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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| 38. |
- Jakobsson-Thor, Stina, et al.
(författare)
-
Seagrass wasting disease varies with salinity and depth in natural Zostera marina populations
- 2018
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 587, s. 105-115
-
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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| 39. |
- Johannesson, Kerstin, 1955, et al.
(författare)
-
Ten years of marine evolutionary biology - challenges and achievements of a multidisciplinary research initiative
- 2023
-
Ingår i: Evolutionary Applications. - : Wiley. - 1752-4571. ; 16:2, s. 530-41
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Tidskriftsartikel (refereegranskat)abstract
- The Centre for Marine Evolutionary Biology (CeMEB) at the University of Gothenburg, Sweden, was established in 2008 through a 10-year research grant of 8.7 m€ to a team of senior researchers. Today, CeMEB members have contributed >500 scientific publications, 30 PhD theses and have organised 75 meetings and courses, including 18 three-day meetings and four conferences. What are the footprints of CeMEB, and how will the centre continue to play a national and international role as an important node of marine evolutionary research? In this perspective arcticle we first look back over the 10 years of CeMEB activities and briefly survey some of the many achievements of CeMEB. We furthermore compare the initial goals, as formulated in the grant application, with what has been achieved, and discuss challenges and milestones along the way. Finally, we bring forward some general lessons that can be learnt from a research funding of this type, and we take also look ahead, discussing how CeMEB’s achievements and lessons can be used as a springboard to the future of marine evolutionary biology.
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| 40. |
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| 41. |
- 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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| 42. |
- Kinnby, Alexandra, 1990, et al.
(författare)
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Combining an Ecological Experiment and a Genome Scan Show Idiosyncratic Responses to Salinity Stress in Local Populations of a Seaweed
- 2020
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Climate change-related effects threaten species worldwide; within-species populations may react differently to climate-induced stress due to local adaptation and partial isolation, particularly in areas with steep environmental gradients. Populations of the marine foundation seaweed Fucus vesiculosus are established over a steep salinity gradient at the entrance of the brackish water in the Baltic Sea (NE Atlantic). First, we analyzed the genetic differentiation among populations using thousands of genetic markers. Second, we measured the physiological tolerance to reduced salinity, a predicted effect of climate change in the study area, by measuring growth, phlorotannin (defense compounds) content, and maximum photochemical yield in tissue of the same individuals exposed to both current and projected future salinities. Our results show that despite short geographic distances (max 100 km), most populations were genetically well separated. Furthermore, populations responded very differently to a salinity decrease of four practical salinity units (psu) corresponding to projected future salinity. At the high salinity end of the gradient, some populations maintained growth at the cost of reduced phlorotannin production. However, at the low salinity end, mortality increased and growth was strongly reduced in one population, while a second population from similar salinity instead maintained growth and phlorotannin production. Among genetic markers that appeared as outliers (showing more genetic differentiation than the majority of loci), we found that four were associated with genes that were potential candidates for being under selection. One of these, a calcium-binding protein gene, also showed a significant genotype-phenotype relationship in the population where this genetic marker was variable. We concluded that local selection pressure, genetic affinity, and possibly also population history could explain the very different responses to reduced salinity among these populations, despite being from the same geographic area. Our results highlight the importance of local perspective in the management of species.
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| 43. |
- Kinnby, Alexandra, 1990, et al.
(författare)
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Factors affecting formation of adventitious branches in the seaweeds Fucus vesiculosus and F. radicans
- 2019
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Ingår i: Bmc Ecology. - : Springer Science and Business Media LLC. - 1472-6785. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn the brackish Baltic Sea, shedding of adventitious branches is central to asexual recruitment of new thalli in the brown algae Fucus vesiculosus and F. radicans. To test which factors influence the formation of adventitious branches in brackish and in more marine conditions, we sampled 29 Fucus sites in the Baltic Sea (salinity 3-11) and 18 sites from the Danish straits, Kattegat, Skagerrak, and the North Sea (salinity 15-35). Separately for each area, we used structural equation modelling to determine which of eight predictor factors (phosphate, nitrate, chlorophyll-a (as a proxy for turbidity), temperature, salinity, oxygen, grazing pressure, and thallus area) best explained observed numbers of adventitious branches.ResultsIn more marine waters, high yearly average values of phosphate, salinity and turbidity had positive effects on the formation of adventitious branches. In brackish-waters, however, high numbers of adventitious branches were found in areas with low yearly average values of temperature, salinity and oxygen. Grazing intensity had no significant effect in either of the two study areas, contrasting findings from studies in other areas. In areas with both sexually and asexually reproducing Fucus individuals, clones had on average more adventitious branches than unique genotypes, although there was strong variation among clonal lineages.ConclusionThis study is the first to investigate multiple potential drivers of formation of adventitious branches in natural populations of Fucus. Our results suggest that several different factors synergistically and antagonistically affect the growth of adventitious branches in a complex way, and that the same factor (salinity) can have opposing effects in different areas.
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| 44. |
- 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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| 45. |
- Kinnby, Alexandra, et al.
(författare)
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Ocean acidification reduces thallus strength in a non-calcifying foundation seaweed
- 2023
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 33:18, s. 941-942
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is causing unprecedented changes in terrestrial and aquatic ecosystems through the emission of greenhouse gases, including carbon dioxide (CO2). Approximately 30% of CO2 is taken up by the ocean (‘ocean acidification’, OA)1, which has profound effects on foundation seaweed species. Negative physical effects on calcifying algae are clear2, but studies on habitat-forming fleshy seaweeds have mainly focused on growth and less on thallus strength3,4. We exposed the habitat-forming brown seaweed Fucus vesiculosus to OA corresponding to projected climate change effects for the year 2100, and observed reduced apical thallus strength and greater loss of exposed individuals in the field. The tissue contained less calcium and magnesium, both of which are important for creating structural alginate matrices. Scanning electron microscopy (SEM) revealed tissue voids in the OA samples that were not present in seaweeds grown under ambient pCO2. We conclude that under OA, weakened F. vesiculosus will be at a significantly higher risk of physical damage and detachment.
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| 46. |
- Kotta, Jonne, et al.
(författare)
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Assessing the potential for sea-based macroalgae cultivation and its application for nutrient removal in the Baltic Sea
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 839
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Tidskriftsartikel (refereegranskat)abstract
- Marine eutrophication is a pervasive and growing threat to global sustainability. Macroalgal cultivation is a promising circular economy solution to achieve nutrient reduction and food security. However, the location of production hotspots is not well known. In this paper the production potential of macroalgae of high commercial value was predicted across the Baltic Sea region. In addition, the nutrient limitation within and adjacent to macroalgal farms was investigated to suggest optimal site-specific configuration of farms. The production potential of Saccharina latissima was largely driven by salinity and the highest production yields are expected in the westernmost Baltic Sea areas where salinity is >23. The direct and interactive effects of light availability, temperature, salinity and nutrient concentrations regulated the predicted changes in the production of Ulva intestinalis and Fucus vesiculosus. The western and southern Baltic Sea exhibited the highest farming potential for these species, with promising areas also in the eastern Baltic Sea. Macroalgal farming did not induce significant nutrient limitation. The expected spatial propagation of nutrient limitation caused by macroalgal farming was less than 100–250 m. Higher propagation distances were found in areas of low nutrient and low water exchange (e.g. offshore areas in the Baltic Proper) and smaller distances in areas of high nutrient and high water exchange (e.g. western Baltic Sea and Gulf of Riga). The generated maps provide the most sought-after input to support blue growth initiatives that foster the sustainable development of macroalgal cultivation and reduction of in situ nutrient loads in the Baltic Sea.
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| 47. |
- Labriere, Chrostophe, et al.
(författare)
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Phidianidine A and synthetic analogues as naturally inspired marine antifoulants
- 2020
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Ingår i: Journal of Natural Products. - : American Chemical Society. - 0163-3864 .- 1520-6025. ; 83:11, s. 3413-3423
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Tidskriftsartikel (refereegranskat)abstract
- Stationary and slow-moving marine organisms regularly employ a natural product chemical defense to prevent being colonized by marine micro- and macroorganisms. While these natural antifoulants can be structurally diverse, they often display highly conserved chemistries and physicochemical properties, suggesting a natural marine antifouling pharmacophore. In our current report, we investigate the marine natural product phidianidine A, which displays several chemical properties found in highly potent marine antifoulants. Phidianidine A and synthetic analogues were screened against the settlement and metamorphosis of Amphibalanus improvisus cyprids, and several of the compounds displayed inhibitory activities at low micromolar concentrations with IC50 values down to 0.7 μg/mL observed. The settlement study highlights that phidianidine A is a potent natural antifoulant and that the scaffold can be tuned to generate simpler and improved synthetic analogues. The bioactivity is closely linked to the size of the compound and to its basicity. The study also illustrates that active analogues can be prepared in the absence of the natural constrained 1,2,4-oxadiazole ring. A synthetic lead analogue of phidianidine A was incorporated in a coating and included in antifouling field trials, where it was shown that the coating induced potent inhibition of marine bacteria and microalgae settlement.
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| 48. |
- Labriere, C., et al.
(författare)
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Structure-Activity Relationship Probing of the Natural Marine Antifoulant Barettin
- 2021
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Ingår i: Marine Biotechnology. - : Springer Science and Business Media LLC. - 1436-2228 .- 1436-2236. ; 23:6, s. 904-916
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Tidskriftsartikel (refereegranskat)abstract
- The sponge derived 2,5-diketopiperazine metabolite barettin is a potent antifouling compound effective against the settlement and metamorphosis of barnacles. Simplified derivatives of barettin have previously been shown to display similar inhibitory properties. The synthetic derivative benzo[g]dipodazine has been reported to display significantly improved antifouling properties in comparison with the native barettin with inhibitory activities as low a 0.034 mu M reported against barnacle cyprid settlement. In the current study we report the antifouling activity of 29 synthetic analogs designed and inspired by the potent antifouling effect seen for benzo[g]dipodazine. The library contains mainly not only dipodazine derivatives but also disubstituted diketopiperazines and compounds incorporating alternative heterocyclic cores such as hydantoin, creatinine, and rhodanine. Several of the prepared compounds inhibit the settlement of Amphibalanus improvisus cyprids at low micromolar concentrations, in parity with the natural barettin. While several highly active compounds were prepared by incorporating the benzo[g]indole as hydrophobic substituent, the remarkable antifouling effect reported for benzo[g]dipodazine was not observed when evaluated in our study.
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| 49. |
- Lindgren, Annelie, 1966, et al.
(författare)
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Susceptibility to grazing in different life cycle stages of the red alga Chondrus crispus
- 2003
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Ingår i: Proceedings of the 17th International Seaweed Symposium. - 0 19 850742 9 ; , s. 349-356
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Konferensbidrag (refereegranskat)abstract
- Grazing susceptibilities of gametophytic and tetrasporophytic fronds of Chondrus crispus Stack. from the Swedish west coast were examined in laboratory experiments. The overall consumption, irrespective of stage, as well as the feeding preference was tested on both adult and juvenile fronds. The mesoherbivores used in the experiments were the gastropods Littorina littorea, Lacuna vincta and the crustaceans Idotea granulosa and Gammarus locusta, since they are among the most abundant herbivore species within and among C. crispus stands in the study area. The results showed that all four mesoherbivore species were capable of consuming both adult and juvenile tissue. However, none of the herbivores showed a significant pref erence for a specific stage of adult fronds. For juvenile fronds, it was found that I. granulosa significantly preferred gametophytes to tetrasporophytes and there was a tendency for L. littorea to consume more of juvenile tetrasporophytes than gametophytes. This suggests that grazing could have an influence on the ploidy ratio of C. crispus.
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| 50. |
- 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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