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Schneider, L. D., Nilsson, P. A., Höjesjö, J. & Österling, M. (2018). Effects of mussel and host fish density on reproduction potential of a threatened unionoid mussel: Prioritization of conservation locations in management trade-offs. Biodiversity and Conservation
Open this publication in new window or tab >>Effects of mussel and host fish density on reproduction potential of a threatened unionoid mussel: Prioritization of conservation locations in management trade-offs
2018 (English)In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710Article in journal (Refereed) Epub ahead of print
Abstract [en]

Management decisions in conservation of threatened species require trading off social needs against biodiversity values, including the prioritization of conservation locations, i.e. where conservation efforts should take place. To improve conservation decisions for the thick-shelled river mussel, Unio crassus, a highly threatened temporary parasite on fish, we performed a field study on how mussel and host fish density (European bullhead, Cottus gobio, and common minnow, Phoxinus phoxinus) affect reproduction potential of the mussel at different sites along a river. We assumed that the proportions of gravid mussels would be higher at high mussel density, and result in enhanced glochidia (mussel larvae) encapsulation rates on fish. We also expected the highest ‘glochidia density’—a proxy for the potential number of recruits per stream area, assessed by multiplying glochidia encapsulation rates on fish by fish density, to occur at high mussel density sites. Such river sites, producing many offspring and conveying important conservation values, may thus be prioritized. However, contrary to our assumptions, higher glochidia density and higher proportions of gravid mussels occurred at lower density mussel sites. We also found that P. phoxinus had higher glochidia encapsulation rates than C. gobio, possibly related to species-specific behavioural and life-history traits. Even so, glochidia density was similar for both fish species, reflecting comparable ecological functions in hosts. The results of this study suggest that mussel and host fish densities should be considered along with glochidia density in conservation prioritization and management trade-offs.

Place, publisher, year, edition, pages
Springer Netherlands, 2018
Keywords
Endangered species, Host-parasite system, Host fish availability, Unio crassus, Unionoida
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-70354 (URN)10.1007/s10531-018-1652-5 (DOI)000454777600001 ()2-s2.0-85055991288 (Scopus ID)
Note

Artikeln ingick som manuskript i Schneiders (2017) doktorsavhandling Conservation ecology of the thick-shelled river mussel Unio crassus: The importance of parasite-host interactions

Available from: 2018-11-29 Created: 2018-11-29 Last updated: 2019-02-14Bibliographically approved
Nylin, S., Österling, M. & Janz, N. (2018). Embracing Colonizations: A New Paradigm for Species Association Dynamics. Trends in Ecology & Evolution, 33(1), 4-14
Open this publication in new window or tab >>Embracing Colonizations: A New Paradigm for Species Association Dynamics
2018 (English)In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 33, no 1, p. 4-14Article in journal (Refereed) Published
Abstract [en]

Parasitehost and insectplant research have divergent traditions despite the fact that most phytophagous insects live parasitically on their host plants. In parasitology it is a traditional assumption that parasites are typically highly specialized; cospeciation between parasites and hosts is a frequently expressed default expectation. Insectplant theory has been more concerned with host shifts than with cospeciation, and more with hierarchies among hosts than with extreme specialization. We suggest that the divergent assumptions in the respective fields have hidden a fundamental similarity with an important role for potential as well as actual hosts, and hence for host colonizations via ecological fitting. A common research program is proposed which better prepares us for the challenges from introduced species and global change.

Place, publisher, year, edition, pages
Elsevier: , 2018
National Category
Evolutionary Biology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65967 (URN)10.1016/j.tree.2017.10.005 (DOI)000419242100002 ()29113696 (PubMedID)
Available from: 2018-01-25 Created: 2018-01-25 Last updated: 2018-06-29Bibliographically approved
Filipsson, K., Petersson, T., Hojesjo, J., Piccolo, J., Naslund, J., Wengstrom, N. & Österling, M. (2018). Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.). Ecology of Freshwater Fish, 27(1), 70-77
Open this publication in new window or tab >>Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.)
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2018 (English)In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 27, no 1, p. 70-77Article in journal (Refereed) Published
Abstract [en]

The life cycle of the endangered freshwater pearl mussel (Margaritifera margaritifera) includes a parasitic larval phase (glochidia) on the gills of a salmonid host. Glochidia encystment has been shown to affect both swimming ability and prey capture success of brown trout (Salmo trutta), which suggests possible fitness consequences for host fish. To further investigate the relationship between glochidia encystment and behavioural parameters in brown trout, pairs (n = 14) of wild-caught trout (infested vs. uninfested) were allowed to drift feed in large stream aquaria and foraging success, activity, agonistic behaviour and fish coloration were observed. No differences were found between infested and uninfested fish except for in coloration, where infested fish were significantly darker than uninfested fish. Glochidia load per fish varied from one to several hundred glochidia, however, and high loads had significant effects on foraging, activity and behaviour. Trout with high glochidia loads captured less prey, were less active and showed more subordinate behaviour than did fish with lower loads. Heavy glochidia loads therefore may negatively influence host fitness due to reduced competitive ability. These findings have implications not only for management of mussel populations in the streams, but also for captive breeding programmes which perhaps should avoid high infestation rates. Thus, low levels of infestation on host fish which do not affect trout behaviour but maintains mussel populations may be optimal in these cases.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65930 (URN)10.1111/eff.12324 (DOI)000417191100006 ()
Available from: 2018-01-25 Created: 2018-01-25 Last updated: 2018-07-02Bibliographically approved
Filipsson, K., Brijs, J., Näslund, J., Wengström, N., Adamsson, M., Závorka, L., . . . Höjesjö, J. (2017). Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta). Parasitology Research, 116, 1353-1360
Open this publication in new window or tab >>Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta)
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2017 (English)In: Parasitology Research, ISSN 0932-0113, E-ISSN 1432-1955, Vol. 116, p. 1353-1360Article in journal (Refereed) Published
Abstract [en]

Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects of FPM glochidia encystment on the metabolism and haematology of brown trout (Salmo trutta Linnaeus,1758). Specifically, we measured whole-animal oxygen uptake rates at rest and following an exhaustive exercise protocol using intermittent flow-through respirometry, as well as haematocrit, in infested and uninfested trout. Glochidia encystment significantly affected whole-animal metabolic rate, as infested trout exhibited higher standard and maximum metabolic rates. Furthermore, glochidia-infested trout also had elevated levels of haematocrit.The combination of an increased metabolism and haematocrit in infested fish indicates that glochidia encystment has a physiological effect on the trout, perhaps as a compensatory response to the potential respiratory stress caused by the glochidia. When relating glochidia load to metabolism and haematocrit, fish with low numbers of encysted glochidia were the ones with particularly elevated metabolism and haematocrit. Standard metabolic rate decreased with substantial glochidia loads towards levels similar to those of uninfested fish. This suggests that initial effects visible at low levels of encystment may be countered by additional physiological effects at high loads, e.g. potential changes in energy utilization, and also that high numbers of glochidia may restrict oxygen uptake by the gills.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Glochidia, Haematocrit, Host, Margaritifera, Metabolic rate, Parasite
National Category
Zoology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-69608 (URN)10.1007/s00436-017-5413-2 (DOI)000398734700024 ()
Available from: 2018-10-12 Created: 2018-10-12 Last updated: 2018-10-16Bibliographically approved
Schneider, L. D., Nilsson, P. A. & Österling, M. (2017). Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus. Hydrobiologia, 810(1), 283-293
Open this publication in new window or tab >>Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus
2017 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 810, no 1, p. 283-293Article in journal (Refereed) Published
Abstract [en]

Adaptation to temperature regimes and host presence may enhance fitness in parasites. In an experimental study, we evaluated the timing of glochidia release by Unio crassus subjected to three spring water temperature regimes in the presence and absence of the host fish Cottus gobio. The timing of glochidia release was delayed at (i) constantly low temperatures (<10°C), in contrast to earlier and pronounced releases at (ii) natural temperature increases that level off at intermediate temperatures (10–15°C), and (iii) higher-than-normal temperatures (10–20°C). Mussels from treatment (i) that had not released glochidia during the experiment did so soon after being moved to the temperature in (ii), indicating a temperature threshold for glochidia release. Neither host fish presence nor the combined effect of temperature and host fish presence significantly affected the timing of glochidia release. The treatment with natural spring water temperatures indicated possible fitness benefits for U. crassus through combined effects of high intensities of glochidia releases and high survival of released glochidia. The furthered understanding of climate change effects on mussel and host phenology in seasonal environments, potentially inducing temporal mismatches of glochidia release to host availability, is key to mussel conservation

Place, publisher, year, edition, pages
Springer, 2017
National Category
Ecology Zoology
Identifiers
urn:nbn:se:kau:diva-65810 (URN)10.1007/s10750-017-3217-0 (DOI)
Available from: 2018-01-24 Created: 2018-01-24 Last updated: 2018-07-06Bibliographically approved
Schneider, L. D., Nilsson, P. A., Höjesjö, J. & Österling, M. (2017). Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish. Aquatic conservation, 27, 1261-1269
Open this publication in new window or tab >>Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish
2017 (English)In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 27, p. 1261-1269Article in journal (Refereed) Published
Abstract [en]

1.Parasite–host interactions can involve strong reciprocal selection pressure, and may lead to locally adapted specializations. The highly threatened unionoid mussels are temporary parasites on fish, but local adaptation has not yet been investigated for many species. 2.Patterns of local adaptation of one of Europe's most threatened unionoids, the thick‐shelled river mussel (Unio crassus) were investigated. Eurasian minnows (Phoxinus phoxinus) from two rivers (separate drainage areas) were cross‐infested in the laboratory with sympatric and allopatric mussel larvae, while bullheads (Cottus gobio), inhabiting only one of the rivers, were infested with sympatric or allopatric mussel larvae. Larval encystment, juvenile mussel excystment and survival were measured. 3.For one river, but not the other, juvenile excystment from P. phoxinus was highest when infested with sympatric mussels. The opposite pattern was found for C. gobio in this river, where juvenile excystment and post‐parasitic juvenile survival from allopatric C. gobio were highest. The results thus cannot confirm local adaptation of U. crassus to P. phoxinus in the study rivers, as excystment was not consistently higher in all sympatric mussel–host combinations, whereas there were potential maladaptive signs of U. crassus in relation to C. gobio. There was no loss of encysted larvae 3 days after infestation until juvenile excystment. Most juveniles were excysted between 17 and 29 days after infestation, and the numbers of excysted juveniles increased with fish size. 4.The results have implications for parasite–host ecology and conservation management with regard to unionoid propagation and re‐introduction. This includes the need to (1) test suitability and adaptation patterns between U. crassus and multiple host fish species, (2) evaluate the suitability of certain unionoids and host fish strains after more than 3 days, and (3) determine whether large fish produce more juvenile mussels than smaller fish

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
MARGARITIFERA-MARGARITIFERA L.; LIFE-HISTORY; PEARL MUSSEL; POPULATION-SIZE; BIVALVIA; COEVOLUTION; UNIONIDAE; REQUIREMENTS; TEMPERATURE; RECRUITMENT
National Category
Ecology Zoology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65811 (URN)10.1002/aqc.2816 (DOI)000418653700017 ()
Available from: 2018-01-24 Created: 2018-01-24 Last updated: 2018-08-20Bibliographically approved
Shafer, A. B. A., Wolf, J. B. W., Alves, P. C., Bergstrom, L., Colling, G., Dalen, L., . . . Zielinski, P. (2016). Genomics in Conservation: Case Studies and Bridging the Gap between Data and Application Reply [Letter to the editor]. Trends in Ecology & Evolution, 31(2), 83-84
Open this publication in new window or tab >>Genomics in Conservation: Case Studies and Bridging the Gap between Data and Application Reply
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2016 (English)In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 31, no 2, p. 83-84Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2016
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-41176 (URN)10.1016/j.tree.2015.11.010 (DOI)000369462400002 ()26704456 (PubMedID)
Available from: 2016-03-30 Created: 2016-03-30 Last updated: 2017-11-30Bibliographically approved
Shafer, A. B. A., Wolf, J. B. W., Alves, P. C., Bergstrom, L., Bruford, M. W., Brannstrom, I., . . . Zielinski, P. (2015). Genomics and the challenging translation into conservation practice. Trends in Ecology & Evolution, 30(2), 78-87
Open this publication in new window or tab >>Genomics and the challenging translation into conservation practice
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2015 (English)In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 30, no 2, p. 78-87Article in journal (Refereed) Published
Abstract [en]

The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and interpretations remain challenging and largely confined to academic research in ecology and evolution. This generates a gap between basic research and applicable solutions for conservation managers faced with multifaceted problems. Before the real-world conservation potential of genomic research can be realized, we suggest that current infrastructures need to be modified, methods must mature, analytical pipelines need to be developed, and successful case studies must be disseminated to practitioners.

Place, publisher, year, edition, pages
Elsevier, 2015
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-41638 (URN)10.1016/j.tree.2014.11.009 (DOI)000349270700003 ()25534246 (PubMedID)
Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-11-30Bibliographically approved
Watz, J., Bergman, E., Calles, O., Enefalk, Å., Gustafsson, S., Hagelin, A., . . . Bror, J. (2015). Ice cover alters the behavior and stress level of brown trout Salmo trutta. Behavioral Ecology, 26(3), 820-827
Open this publication in new window or tab >>Ice cover alters the behavior and stress level of brown trout Salmo trutta
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2015 (English)In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 26, no 3, p. 820-827Article in journal (Refereed) Published
Abstract [en]

Surface ice in rivers and lakes buffers the thermal environment and provides overhead cover, protecting aquatic animals from terrestrial predators. We tested if surface ice influenced the behavior (swimming activity, aggressive encounters, and number of food items eaten) and stress level (coloration of eyes and body) of stream-living brown trout Salmo trutta at temperatures of 3–4 °C in indoor experimental flumes. We hypothesized that an individual’s resting metabolic rate (RMR, as measured by resting ventilation rate) would affect winter behavior. Therefore, groups of 4 trout, consisting of individuals with high, low, or mixed (2 individuals each) RMR, were exposed to experimental conditions with or without ice cover. Ice cover reduced stress responses, as evaluated by body coloration. Also, trout in low RMR groups had a paler body color than those in both mixed and high RMR groups. Trout increased their swimming activity under ice cover, with the highest activity found in high RMR groups. Ice cover increased the number of aggressive encounters but did not influence the number of drifting food items taken by each group. In mixed RMR groups, however, single individuals were better able to monopolize food than in the other groups. As the presence of surface ice increases the activity level and reduces stress in stream-living trout, ice cover should influence their energy budgets and production. The results should be viewed in light of ongoing global warming that reduces the duration of ice cover, especially at high latitudes and altitudes.

Place, publisher, year, edition, pages
Oxford: Oxford University Press, 2015
Keywords
aggression, climate change, energy budget, metabolic rate, winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-35931 (URN)10.1093/beheco/arv019 (DOI)000356585100024 ()
Available from: 2015-04-29 Created: 2015-04-29 Last updated: 2018-09-10Bibliographically approved
Österling, M. (2015). Influence of host fish age on a mussel parasite differs among rivers: Implications for conservation. Limnologica, 50, 75-79
Open this publication in new window or tab >>Influence of host fish age on a mussel parasite differs among rivers: Implications for conservation
2015 (English)In: Limnologica, ISSN 0075-9511, E-ISSN 1873-5851, Vol. 50, p. 75-79Article in journal (Refereed) Published
Abstract [en]

Unionoid mussels are obligate parasites on one or more fish species. The objective was to compare growth and survival of encysted mussel larvae of the freshwater pearl mussel (Margaritifera margaritifera) on young-of-the-year (YOY) versus one-year old brown trout (Salmo trutta). YOY and one-year old trout from the Brattefors and Lade Rivers, Sweden, were infested with mussel larvae from their home river. The mass-normalized encystment abundance was higher on YOY trout than on one-year old trout. The proportional decrease in mass-normalized encystment abundance was larger on YOY brown trout from the Brattefors River than on YOY brown trout from the Lark River. Encystment per individual fish was higher on YOY trout than on one-year old trout from the Brattefors River, whereas this relationship was reversed for trout from the Larje River. Larval growth was higher on YOY trout than on one-year old trout. There was a larger difference in larval growth between YOY trout and one-year old trout from the Brattefors River than on the brown trout from the Lade River. The ability to use both YOY and older fish, such as in the Ude River, may increase the reproduction potential of mussel populations, compared to a reduced ability to use more than one year class, such as in the Brattefors River. This may also affect the dispersal of mussels, as older brown trout often move and migrate to a higher degree within and between rivers. The dispersal potential of mussels may therefore be relatively high in the Lade River, but low in the Brattefors River. In rivers where the mussels have to rely on YOY brown trout, it could be worth facilitating passage through migration obstacles for YOY brown trout. Infested YOY brown trout could be artificially re-distributed within rivers, to places with former mussel distributions. It could also be worth testing the suitability of brown trout of different age classes when starting breeding programs.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Glochidia larvae, Unionoid mussels, Threatened species, Host, Parasite, Margaritifera, Salmo
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-41655 (URN)10.1016/j.limno.2014.11.001 (DOI)000350780500010 ()
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Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-11-30Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6758-5857

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