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  • 1.
    Andersen, K. H.
    et al.
    Tech Univ Denmark, Denmark.
    Berge, T.
    Tech Univ Denmark, Denmark ; Univ Copenhagen, Denmark.
    Goncalves, R. J.
    Tech Univ Denmark, Denmark ;Consejo Nacl Invest Cient & Tecn, Argentina ; Estn Fotobiol Playa Union, Argentina.
    Hartvig, M.
    Tech Univ Denmark, Denmark ; Univ Copenhagen, Denmark ; Univ Göttingen, Germany.
    Heuschele, J.
    Tech Univ Denmark, Denmark.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Tech Univ Denmark, Denmark.
    Jacobsen, N. S.
    Tech Univ Denmark, Denmark.
    Lindemann, C.
    Tech Univ Denmark, Denmark.
    Martens, E. A.
    Tech Univ Denmark, Denmark ; Univ Copenhagen, Denmark.
    Neuheimer, A. B.
    Tech Univ Denmark, Denmark ; Univ Hawaii Manoa, USA.
    Olsson, K.
    Tech Univ Denmark, Denmark.
    Palacz, A.
    Tech Univ Denmark, Denmark.
    Prowe, A. E. F.
    Tech Univ Denmark, Denmark ; GEOMAR Helmholtz Ctr Ocean Res Kiel, Germany.
    Sainmont, J.
    Tech Univ Denmark, Denmark.
    Traving, S. J.
    Tech Univ Denmark, Denmark ; Univ Copenhagen, Denmark.
    Visser, A. W.
    Tech Univ Denmark, Denmark.
    Wadhwa, N.
    Tech Univ Denmark, Denmark.
    Kiorboe, T.
    Tech Univ Denmark, Denmark.
    Characteristic Sizes of Life in the Oceans, from Bacteria to Whales2016In: Annual Review of Marine Science, ISSN 1941-1405, E-ISSN 1941-0611, Vol. 8, p. 217-241Article in journal (Refereed)
    Abstract [en]

    The size of an individual organism is a key trait to characterize its physiology and feeding ecology. Size-based scaling laws may have a limited size range of validity or undergo a transition from one scaling exponent to another at some characteristic size. We collate and review data on size-based scaling laws for resource acquisition, mobility, sensory range, and progeny size for all pelagic marine life, from bacteria to whales. Further, we review and develop simple theoretical arguments for observed scaling laws and the characteristic sizes of a change or breakdown of power laws. We divide life in the ocean into seven major realms based on trophic strategy, physiology, and life history strategy. Such a categorization represents a move away from a taxonomically oriented description toward a trait-based description of life in the oceans. Finally, we discuss life forms that transgress the simple size-based rules and identify unanswered questions.

  • 2. Andrady, Anthony
    et al.
    Aucamp, Pieter J.
    Austin, Amy T.
    Bais, Alkiviadis F.
    Ballare, Carlos L.
    Barnes, Paul W.
    Bernhard, Germar H.
    Bjoern, Lars Olof
    Bornman, Janet F.
    Congdon, Nathan
    Cory, Rose M.
    Flint, Stephan D.
    de Gruijl, Frank R.
    Haeder, Donat-P.
    Heikkilae, Anu
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Longstreth, Janice
    Lucas, Robyn M.
    Madronich, Sasha
    McKenzie, Richard L.
    Neale, Patrick
    Neale, Rachel
    Norval, Mary
    Pandey, Krishna K.
    Paul, Nigel
    Rautio, Milla
    Redhwi, Halim Hamid
    Robinson, Sharon A.
    Rose, Kevin C.
    Solomon, Keith R.
    Sulzberger, Barbara
    Waengberg, Sten-Ake
    Williamson, Craig E.
    Wilson, Stephen R.
    Worrest, Robert C.
    Young, Antony R.
    Zepp, Richard G.
    Environmental effects of ozone depletion and its interactions with climate change: Progress report, 20162017In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 16, no 2, p. 107-145Article in journal (Refereed)
    Abstract [en]

    The Parties to the Montreal Protocol are informed by three Panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with two focal issues. The first focus is the effects of UV radiation on human health, animals, plants, biogeochemistry, air quality, and materials. The second focus is on interactions between UV radiation and global climate change and how these may affect humans and the environment. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously believed. As a result of this, human health and environmental issues will be longer-lasting and more regionally variable. Like the other Panels, the EEAP produces a detailed report every four years; the most recent was published as a series of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1-184). In the years in between, the EEAP produces less detailed and shorter Progress Reports of the relevant scientific findings. The most recent of these was for 2015 (Photochem. Photobiol. Sci., 2016, 15, 141-147). The present Progress Report for 2016 assesses some of the highlights and new insights with regard to the interactive nature of the direct and indirect effects of UV radiation, atmospheric processes, and climate change. The more detailed Quadrennial Assessment will bemade available in 2018.

  • 3.
    Bais, A. F.
    et al.
    Aristotle Univ Thessaloniki, Greece.
    Lucas, R. M.
    Australian Natl Univ, Australia.
    Bornman, J. F.
    Curtin Univ, Australia.
    Williamson, C. E.
    Miami Univ, USA.
    Sulzberger, B.
    Swiss Fed Inst Aquat Sci & Technol, Switzerland.
    Austin, A. T.
    Univ Buenos Aires, Argentina;IFEVA CONICET, Argentina.
    Wilson, S. R.
    Univ Wollongong, Australia.
    Andrady, A. L.
    North Carolina State Univ, USA.
    Bernhard, G.
    Biospher Inc, USA.
    McKenzie, R. L.
    NIWA, New Zealand.
    Aucamp, P. J.
    Ptersa Environm Consultants, South Africa.
    Madronich, S.
    Natl Ctr Atmospher Res, USA.
    Neale, R. E.
    Royal Brisbane Hosp, Australia.
    Yazar, S.
    Univ Western Australia, Australia.
    Young, A. R.
    Kings Coll London, UK.
    de Gruijl, F. R.
    Leiden Univ, Netherlands.
    Norval, M.
    Univ Edinburgh, UK.
    Takizawa, Y.
    Akita Univ, Japan.
    Barnes, P. W.
    Loyola Univ, USA.
    Robson, T. M.
    Univ Helsinki, Finland.
    Robinson, S. A.
    Univ Wollongong, Australia.
    Ballare, C. L.
    Univ Buenos Aires, Argentina;IFEVA CONICET, Argentina.
    Flint, S. D.
    Univ Idaho, USA.
    Neale, P. J.
    Smithsonian Environm Res Ctr, USA.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Rose, K. C.
    Rensselaer Polytech Inst, USA.
    Wängber, S. -A
    University of Gothenburg.
    Häder, D. -P
    Friedrich-Alexander Univ, Germany.
    Worrest, R. C.
    Columbia Univ, USA.
    Zepp, R. G.
    US EPA, USA.
    Paul, N. D.
    Univ Lancaster, UK.
    Cory, R. M.
    Univ Michigan, USA.
    Solomon, K. R.
    Univ Guelph, Canada.
    Longstreth, J.
    Inst Global Risk Res, USA.
    Pandey, K. K.
    Inst Wood Sci & Technol, India.
    Redhwi, H. H.
    King Fahd Univ Petr & Minerals, Saudi Arabia.
    Torikaiaj, A.
    Mat Life Soc Japan, Japan.
    Heikkila, A. M.
    Finnish Meteorol Inst R&D Climate Res, Finland.
    Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 20172018In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 17, no 2, p. 127-179Article in journal (Refereed)
    Abstract [en]

    The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held. Because of the Montreal Protocol, there are now indications of the beginnings of a recovery of stratospheric ozone, although the time required to reach levels like those before the 1960s is still uncertain, particularly as the effects of stratospheric ozone on climate change and vice versa, are not yet fully understood. Some regions will likely receive enhanced levels of UV radiation, while other areas will likely experience a reduction in UV radiation as ozone- and climate-driven changes affect the amounts of UV radiation reaching the Earth's surface. Like the other Panels, the EEAP produces detailed Quadrennial Reports every four years; the most recent was published as a series of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1-184). In the years in between, the EEAP produces less detailed and shorter Update Reports of recent and relevant scientific findings. The most recent of these was for 2016 (Photochem. Photobiol. Sci., 2017, 16, 107-145). The present 2017 Update Report assesses some of the highlights and new insights about the interactive nature of the direct and indirect effects of UV radiation, atmospheric processes, and climate change. A full 2018 Quadrennial Assessment, will be made available in 2018/2019.

  • 4.
    Barnes, Paul W.
    et al.
    Loyola Univ, USA..
    Williamson, Craig E.
    Miami Univ, USA.
    Lucas, Robyn M.
    Australian Natl Univ, Australia.
    Robinson, Sharon A.
    Univ Wollongong, Australia.
    Madronich, Sasha
    Natl Ctr Atmospher Res, USA.
    Paul, Nigel D.
    Univ Lancaster, UK.
    Bornman, Janet F.
    Murdoch Univ, Australia.
    Bais, Alkiviadis F.
    Aristotle Univ Thessaloniki, Greece.
    Sulzberger, Barbara
    Swiss Fed Inst Aquat Sci & Technol Eawag, Switzerland.
    Wilson, Stephen R.
    Univ Wollongong, Australia.
    Andrady, Anthony L.
    North Carolina State Univ, USA.
    McKenzie, Richard L.
    Natl Inst Water & Atmospher Res, New Zealand.
    Neale, Patrick J.
    Smithsonian Environm Res Ctr, USA.
    Austin, Amy T.
    Univ Buenos Aires, Argentina.
    Bernhard, Germar H.
    Biospher Inc, USA.
    Solomon, Keith R.
    Univ Guelph, Canada.
    Neale, Rachel E.
    QIMR Berghofer Med Res Inst, Australia.
    Young, Paul J.
    Univ Lancaster, UK.
    Norval, Mary
    Univ Edinburgh, UK.
    Rhodes, Lesley E.
    Univ Manchester, UK.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Salford Royal NHS Fdn Trust, UK.
    Rose, Kevin C.
    Rensselaer Polytech Inst, USA.
    Longstreth, Janice
    Inst Global Risk Res, USA.
    Aucamp, Pieter J.
    Ptersa Environm Consultants, South Africa.
    Ballare, Carlos L.
    Univ Buenos Aires, Argentina.
    Cory, Rose M.
    Univ Michigan, USA.
    Flint, Stephan D.
    Univ Idaho, USA.
    de Gruijl, Frank R.
    Leiden Univ, Netherlands.
    Haeder, Donat-P
    Friedrich Alexander Univ, Germany.
    Heikkila, Anu M.
    Finnish Meteorol Inst R&D Climate Res, Finland.
    Jansen, Marcel A. K.
    Univ Coll Cork, Ireland.
    Pandey, Krishna K.
    Inst Wood Sci & Technol, India.
    Robson, T. Matthew
    Univ Helsinki, Finland.
    Sinclair, Craig A.
    Canc Council Victoria, Australia.
    Wangberg, Sten-Ake
    University of Gothenburg, Sweden.
    Worrest, Robert C.
    Columbia Univ, USA.
    Yazar, Seyhan
    Univ Western Australia, Australia.
    Young, Antony R.
    Kings Coll London, UK.
    Zepp, Richard G.
    US EPA, USA.
    Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future2019In: Nature Sustainability, E-ISSN 2398-9629, Vol. 2, no 7, p. 569-579Article, review/survey (Refereed)
    Abstract [en]

    Changes in stratospheric ozone and climate over the past 40-plus years have altered the solar ultraviolet (UV) radiation conditions at the Earth's surface. Ozone depletion has also contributed to climate change across the Southern Hemisphere. These changes are interacting in complex ways to affect human health, food and water security, and ecosystem services. Many adverse effects of high UV exposure have been avoided thanks to the Montreal Protocol with its Amendments and Adjustments, which have effectively controlled the production and use of ozone-depleting substances. This international treaty has also played an important role in mitigating climate change. Climate change is modifying UV exposure and affecting how people and ecosystems respond to UV; these effects will become more pronounced in the future. The interactions between stratospheric ozone, climate and UV radiation will therefore shift over time; however, the Montreal Protocol will continue to have far-reaching benefits for human well-being and environmental sustainability.

  • 5.
    Broman, Elias
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Brüsin, Martin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Dopson, Mark
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Oxygenation of anoxic sediments triggers hatching of zooplankton eggs2015In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1817, article id 20152025Article in journal (Refereed)
    Abstract [en]

    Many coastal marine systems have extensive areas with anoxic sediments and it is not well known how these conditions affect the benthic-pelagic coupling. Zooplankton lay their eggs in the pelagic zone, and some sink and lie dormant in the sediment, before hatched zooplankton return to the water column. In this study, we investigated how oxygenation of long-term anoxic sediments affects the hatching frequency of dormant zooplankton eggs. Anoxic sediments from the brackish Baltic Sea were sampled and incubated for 26 days with constant aeration whereby, the sediment surface and the overlying water were turned oxic. Newly hatched rotifers and copepod nauplii (juveniles) were observed after 5 and 8 days, respectively. Approximately 1.5 × 105 nauplii per m-2 emerged from sediment turned oxic compared to 0.02 × 105 m-2 from controls maintained anoxic. This study demonstrated that re-oxygenation of anoxic sediments activated a large pool of buried zooplankton eggs, strengthening the benthic-pelagic coupling of the system. Modelling of the studied anoxic zone suggested that a substantial part of the pelagic copepod population can derive from hatching of dormant eggs. We suggest that this process should be included in future studies to understand population dynamics and carbon flows in marine pelagic systems.

  • 6.
    Broman, Elias
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sachpazidou, Varvara
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Dopson, Mark
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Diatoms dominate the eukaryotic metatranscriptome during spring in coastal 'dead zone' sediments2017In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 284, no 1864, article id 20171617Article in journal (Refereed)
    Abstract [en]

    An important characteristic of marine sediments is the oxygen concentration that affects many central metabolic processes. There has been a widespread increase in hypoxia in coastal systems (referred to as 'dead zones') mainly caused by eutrophication. Hence, it is central to understand the metabolism and ecology of eukaryotic life in sediments during changing oxygen conditions. Therefore, we sampled coastal 'dead zone' Baltic Sea sediment during autumn and spring, and analysed the eukaryotic metatranscriptome from field samples and after incubation in the dark under oxic or anoxic conditions. Bacillariophyta (diatoms) dominated the eukaryotic metatranscriptome in spring and were also abundant during autumn. A large fraction of the diatom RNA reads was associated with the photosystems suggesting a constitutive expression in darkness. Microscope observation showed intact diatom cells and these would, if hatched, represent a significant part of the pelagic phytoplankton biomass. Oxygenation did not significantly change the relative proportion of diatoms nor resulted in any major shifts in metabolic 'signatures'. By contrast, diatoms rapidly responded when exposed to light suggesting that light is limiting diatom development in hypoxic sediments. Hence, it is suggested that diatoms in hypoxic sediments are on 'standby' to exploit the environment if they reach suitable habitats.

  • 7.
    Brüsin, Martin
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Svensson, P. Andreas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Individual changes in zooplankton pigmentation in relation to ultraviolet radiation and predator cues2016In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, no 4, p. 1337-1344Article in journal (Refereed)
    Abstract [en]

    Copepods are common crustaceans in aquatic systems and one of the most important producers of carotenoidastaxanthin pigments, which can enhance the animals’ resistance against potentially damaging ultraviolet radiation (UVR), but at the same time, increases the risk of fish predation. Previous studies have demonstrated that copepods have different pigmentation levels matching the current threat level in terms of UVR and fish occurrence. However, these other studies have quantified population-levels changes in pigmentation, making it difficult to disentangle the role of individual phenotypic colour changes from that of selection.We quantified carotenoid-based pigmentation with colorimetric methods, which enabled us to track changes within individual copepods. Two species of copepods, Diaptomus castor and Eudiaptomus gracilis, were exposed to high and low UVR and fish cues in a factorial design. L*a*b* colour values (CIE; CommissionInternational de l’Eclairage) were extracted from digital photographs of each copepod and used as proxies for carotenoid concentration. Our results showed that individual copepods significantly changed their pigmentation in response to both UVR and fish cues within a period of 2 weeks. However, the responses differed between sexes and between adults and juveniles. UVR effects were present in all life-stages whereas fish effects were only detected in juveniles, with largest responses in D. castor. This confirms that carotenoid pigmentation is a phenotypically plastic trait, and highlights that strategies for trading off risks of UVR and predation differ between males and females as well as between life-stages.

  • 8.
    Chi, Xupeng
    et al.
    GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
    Mueller-Navarra, Doerthe C.
    University of Hamburg, Germany.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sommer, Ulrich
    GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
    Javidpour, Jamileh
    GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany ; University of Southern Denmark, Denmark .
    Food quality matters: interplay among food quality, food quantity and temperature affecting life history traits of Aurelia aurita (Cnidaria: Scyphozoa) polyps2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 656, p. 1280-1288Article in journal (Refereed)
    Abstract [en]

    Understanding the interaction between organisms' life history traits and environmental factors is an essential task in ecology. In spite of the increasing appreciation of jellyfish as an important component in marine ecosystem, there are still considerable gaps in understanding how the phase transition from the benthic polyp to the pelagic medusa stage is influenced by multiple environmental factors, including nutrition. To investigate survival, growth, and phase transition of Aurelia aurita polyps, we designed a factorial experiment manipulating food quantity (20μg C, 5μg C and 1.5μg C polyp−1 every other day), food quality (Artemia salina and two dietary manipulated Acartia tonsa), and temperature (13°C, 20°C, and 27°C). Temperature was the key factor determining phase transition of polyps and negatively affecting their survival rate and growth at 27°C, which reflected a summer heatwave scenario. Furthermore, at polyps' optimum tolerance temperature (20°C) in our study, budding reproduction benefits from high food concentrations. Interestingly, polyps fed with food containing high level highly unsaturated fatty acid (HUFA) were able to compensate for physiological stress caused by the extreme temperature, and could enhance budding reproduction at optimum temperature. Moreover, benthic-pelagic coupling (strobilation) was determined by temperature but affected significantly by food conditions. Mild temperature together with optimum food conditions contributes to inducing more polyps, which may potentially bring about great ephyrae recruitments during overwintering. In contrast, heatwave events can potentially regulate plankton community structure accompanied by changes of nutritional conditions of primary and secondary producers and thus, negatively affect the population dynamics of polyps. We suggest a novel polyp tolerance curve, which can help to understand jellyfish population dynamics in different seasons and ecosystems. This sets up a baseline for understanding how anticipated global warming and food conditions may affect the population size of benthic polyps and consequently pelagic medusae.

  • 9.
    Ejsmond, M. J.
    et al.
    Jagiellonian University, Poland.
    Blackburn, N.
    BIORAS, Denmark.
    Fridolfsson, Emil
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Haecky, P.
    BIORAS, Denmark.
    Andersson, A.
    Umeå University, Sweden;Umeå Marine Science Centre, Sweden.
    Casini, M.
    Swedish University of Agricultural Sciences, Sweden.
    Belgrano, A.
    Swedish University of Agricultural Sciences, Sweden;University of Gothenburg, Sweden.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Modeling vitamin B1 transfer to consumers in the aquatic food web2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, p. 1-11, article id 10045Article in journal (Refereed)
    Abstract [en]

    Vitamin B-1 is an essential exogenous micronutrient for animals. Mass death and reproductive failure in top aquatic consumers caused by vitamin B-1 deficiency is an emerging conservation issue in Northern hemisphere aquatic ecosystems. We present for the first time a model that identifies conditions responsible for the constrained flow of vitamin B-1 from unicellular organisms to planktivorous fishes. The flow of vitamin B-1 through the food web is constrained under anthropogenic pressures of increased nutrient input and, driven by climatic change, increased light attenuation by dissolved substances transported to marine coastal systems. Fishing pressure on piscivorous fish, through increased abundance of planktivorous fish that overexploit mesozooplankton, may further constrain vitamin B-1 flow from producers to consumers. We also found that key ecological contributors to the constrained flow of vitamin B-1 are a low mesozooplankton biomass, picoalgae prevailing among primary producers and low fluctuations of population numbers of planktonic organisms.

  • 10.
    Ekvall, Mikael T.
    et al.
    Lund University.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Walles, Tim
    Lund University.
    Yang, Xi
    Lund University.
    Hansson, Lars-Anders
    Lund University.
    Diel vertical migration, size distribution and photoprotection in zooplankton as response to UV-A radiation2015In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 60, no 6, p. 2048-2058Article in journal (Refereed)
    Abstract [en]

    The transparency regulator hypothesis (TRH) proposes that ultraviolet radiation (UVR) is a main driving force behind diel vertical migration (DVM) of zooplankton in clearwater systems. While previous studies have mainly studied DVM in relation to the TRH on a spatial scale across systems we here focus on long-term trends in a single system in order to assess if UVR explains observed patterns in DVM. We show that the strength of DVM in Daphnia is to a large extent explained by UVR and we demonstrate a tipping point at which the UVR intensity drastically affects the strength of DVM in Daphnia. In contrast, the strength of DVM could not be explained by the level of UVR among calanoid copepods. The amount of photoprotective compounds did not differ between zooplankton found at different depths indicating that zooplankton do not change their vertical position in relation to the amount of accumulated photoprotective compounds. In addition, we show that both Daphnia and calanoid copepods display patterns of size structured migration.

  • 11.
    Fridolfsson, Emil
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Bunse, Carina
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. University of Oldenburg, Germany.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lindehoff, Elin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Majaneva, Sanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. The Arctic University of Norway, Norway.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Seasonal variation and species-specific concentrations of the essential vitamin B₁ (thiamin) in zooplankton and seston2019In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 166, no 6, p. 1-13, article id 70Article in journal (Refereed)
    Abstract [en]

    Thiamin (vitamin B1) is mainly produced by bacteria and phytoplankton and then transferred to zooplankton and higher trophic levels but knowledge on the dynamics of these processes in aquatic ecosystems is lacking. Hence, the seasonal variation in thiamin content was assessed in field samples of copepods and in pico-, nano- and micro-plankton of two size classes (0.7–3 µm and > 3 µm) collected monthly in the Baltic Sea during 3 years and in the Skagerrak during 1 year. Copepods exhibited species-specific concentrations of thiamin and Acartia sp. had the highest carbon-specific thiamin content, at both locations. Even members of the same genus, but from different systems contained different levels of thiamin, with higher thiamin content per specimen in copepods from the Skagerrak compared to congeners from the Baltic Sea. Furthermore, our results show that the small plankton (0.7–3 µm) had a higher carbon-specific thiamin content compared to the large (> 3 µm). Additionally, there was a large seasonal variation and thiamin content was highly correlated comparing the two size fractions. Finally, there was an overall positive correlation between thiamin content in copepods and plankton. However, for periods of high thiamin content in the two size fractions, this correlation was negative. This suggests a decoupling between thiamin availability in pico-, nano- and micro-plankton and zooplankton in the Baltic Sea. Knowledge about concentrations of this essential micronutrient in the aquatic food web is limited and this study constitutes a foundation for further understanding the dynamics of thiamin in aquatic environments.

  • 12.
    Fridolfsson, Emil
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lindehoff, Elin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Species-specific content of thiamin (vitamin B1) in phytoplankton and the transfer to copepodsManuscript (preprint) (Other academic)
  • 13.
    Fridolfsson, Emil
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lindehoff, Elin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Thiamin (vitamin B1) content in phytoplankton and zooplankton in the presence of filamentous cyanobacteria2018In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, no 6, p. 2423-2435Article in journal (Refereed)
    Abstract [en]

    Top predators in several aquatic food webs regularly display elevated reproductive failure, caused by thiamin(vitamin B1)deficiency. The reasons for these low-thiamin levels are not understood and information about the transfer of thiamin from the producers (bacteria and phytoplankton) to higher trophic levels is limited. One main concern is whether cyanobacterial blooms could negatively affect thiamin transfer in aquatic systems. Laboratory experiments with Baltic Sea plankton communities and single phytoplankton species were used to study the effect of filamentous cyanobacteria on the transfer of thiamin from phytoplankton to zooplankton. Experiments showed that the thiamin content in copepods was reduced when exposed to elevated levels of cyanobacteria, although filamentous cyanobacteria had higher levels of thiamin than any other analyzed phytoplankton species. Filamentous cyanobacteria also had a negative effect on copepod egg production despite high concentrations of non-cyanobacterial food. Phytoplankton species composition affected overall thiamin concentration with relatively more thiamin available for transfer when the relative abundance of Dinophyceae was higher. Finally, phytoplankton thiamin levels were lower when copepods were abundant, indicating that grazers affect thiamin levels in phytoplankton community, likely by selective feeding. Overall, high levels of thiamin in phytoplankton communities are not reflected in the copepod community. We conclude that presence of filamentous cyanobacteria during summer potentially reduces the transfer of thiamin to higher trophic levels by negatively affecting phytoplankton and copepod thiamin content as well as copepod reproduction, thereby lowering the absolute capacity of the food web to transfer thiamin through copepods to higher trophic levels.

  • 14.
    Hansson, Lars-Anders
    et al.
    Lund University.
    Bianco, Giuseppe
    Lund University.
    Ekvall, Mikael
    Lund University.
    Heuschele, Jan
    Lund University.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Yang, Xi
    Lund University.
    Instantaneous threat escape and differentiated refuge demand among zooplankton taxa2016In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 97, no 2, p. 279-285Article in journal (Refereed)
    Abstract [en]

    Most animals, including aquatic crustacean zooplankton, perform strong avoidance movements when exposed to a threat, such as ultraviolet radiation (UVR). We here show that the genera Daphnia and Bosmina instantly adjust their vertical position in the water in accordance with the present UVR threat, i.e., seek refuge in deeper waters, whereas other taxa show less response to the threat. Moreover, Daphnia repeatedly respond to UVR pulses, suggesting that they spend more energy on movement than more stationary taxa, for example, during days with fluctuating cloud cover, illustrating nonlethal effects in avoiding UVR threat. Accordingly, we also show that the taxa with the most contrasting behavioral responses differ considerably in photoprotection, suggesting different morphological and behavioral strategies in handling the UVR threat. In a broader context, our studies on individual and taxa specific responses to UVR provide insights into observed spatial and temporal distribution in natural ecosystems.

  • 15.
    Hansson, Lars-Anders
    et al.
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Effects of ultraviolet radiation on pigmentation, photoenzymatic repair, behavior, and community ecology of zooplankton2009In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 8, no 9, p. 1266-1275Article in journal (Refereed)
    Abstract [en]

    In this report, we provide a perspective on how zooplankton are able to respond to present and future levels of ultraviolet (UV) radiation, a threat that has been present throughout evolutionary time. To cope with this threat, zooplankton have evolved several adaptations including behavioral responses, repair systems, and accumulation of photoprotective compounds. Common photoprotective compounds include melanins and carotenoids, which are true pigments, but also mycosporine-like amino acids (MAAs) and several other substances, and different taxa use different blends of these compounds. It is not only the level of UV radiation, however, that determines the amount of photoprotective compounds incorporated by the zooplankton, but also other environmental factors, such as predation and supply rate of the compounds. Furthermore, compared to taxa that are less pigmented, those taxa with ample pigmentation are generally less likely to exhibit diel migration. The photoenzymatic repair of UV damages seems to be more efficient at intermediate temperature than at low and high temperatures, suggesting that it is less useful at high and low latitudes, where UV radiation is often extremely high. While predicted future increases in UV radiation are expected to substantially affect many processes, recent studies show that most zooplankton taxa are well adapted to cope with such increases, either by UV avoidance behavior or by incorporation of photoprotective compounds. Hence, we conclude that future increase in UV radiation will have only moderate direct effects on zooplankton biomass and community dynamics.

  • 16.
    Hansson, Lars-Anders
    et al.
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Size-structured risk assessments govern Daphnia migration2009In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 276, no 1655, p. 331-336Article in journal (Refereed)
    Abstract [en]

    One of the more fascinating phenomena in nature is animal mass migrations and in oceans and freshwaters, diel variations in depth distribution of zooplankton are a phenomenon that has intrigued scientists for more than a century. In our study, we show that zooplankton are able to assess the threat level of ultraviolet radiation and adjust their depth distribution to this level at a very fine tuned scale. Moreover, predation risk induces a size-structured depth separation, such that small individuals, which we show are less vulnerable to predation than larger, make a risk assessment and continue feeding in surface waters during day, offering a competitive release from down-migrating larger animals. Hence, we mechanistically show that such simple organisms as invertebrate zooplankton are able to make individual, size-specific decisions regarding how to compromise between threats from both predators and UV radiation, and adjust their diel migratory patterns accordingly.

  • 17.
    Hansson, Lars-Anders
    et al.
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Dartnall, Herbert J. G.
    Lidstrom, Sven
    Svensson, Jan-Erik
    High zooplankton diversity in the extreme environments of the McMurdo Dry Valley lakes, Antarctica2012In: Antarctic Science, ISSN 0954-1020, E-ISSN 1365-2079, Vol. 24, no 2, p. 131-138Article in journal (Refereed)
    Abstract [en]

    The McMurdo Dry Valley lakes of Antarctica constitute some of the harshest and most isolated freshwater environments on Earth which might be expected to limit the biogeographical expansion of many organisms. Despite this, we found that the biodiversity of rotifer zooplankton is the highest ever recorded on the Antarctic mainland. We identified in total nine rotifer taxa, of which six are new to the Antarctic continent, in Lake Hoare, and also the first sub- adult crustacean copepod belonging to the genus Boeckella. A possible explanation for the high biodiversity is that many of the recorded species have arrived in the region in relatively recent times and then established invasive populations, suggesting that their distribution pattern was previously limited only by biogeographical borders. Interestingly, we show that the cosmopolitan rotifer taxa identified are relatively abundant, suggesting that they have established viable populations. Hence, our study suggests that the biogeographical maps have to be redrawn for several species.

  • 18.
    Hansson, Lars-Anders
    et al.
    Lund University.
    Hylander, Samuel
    Lund University.
    Sommaruga, Ruben
    University of Innsbruck.
    Escape from UV threats in zooplankton: A cocktail of behavior and protective pigmentation2007In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 88, no 8, p. 1932-1939Article in journal (Refereed)
    Abstract [en]

    In order to avoid environmental threats, organisms may respond by altering behavior or phenotype. Using experiments performed in high-latitude Siberia and in temperate Sweden, we show for the first time that, among freshwater crustacean zooplankton, the defense against threats from ultraviolet radiation (UV) is a system where phenotypic plasticity and behavioral escape mechanisms function as complementary traits. Freshwater copepods relied mainly on accumulating protective pigments when exposed to UV radiation, but Daphnia showed strong behavioral responses. Pigment levels for both Daphnia and copepods were generally higher at higher latitudes, mirroring different UV threat levels. When released from the UV threat, Daphnia rapidly reduced (within 10 days) their UV protecting pigmentation—by as much as 40%—suggesting a cost in maintaining UV protective pigmentation. The evolutionary advantage of protective pigments is, likely, the ability to utilize the whole water column during daytime; conversely, since the amount of algal food is generally higher in surface waters, unpigmented individuals are restricted to a less preferred feeding habitat in deeper waters. Our main conclusion is that different zooplankton taxa, and similar taxa at different latitudes, use different mixes of behavior and pigments to respond to UV radiation.

  • 19.
    Heuschele, Jan
    et al.
    Technical University of Denmark, Denmark; Lund University, Sweden;University of Oslo, Norway.
    Ekvall, Mikael T.
    Lund University, Sweden.
    Bianco, Giuseppe
    Lund University, Sweden.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Lund University, Sweden.
    Hansson, Lars-Anders
    Lund University, Sweden.
    Context-dependent individual behavioral consistency in Daphnia2017In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 8, no 2, article id e01679Article in journal (Refereed)
    Abstract [en]

    The understanding of consistent individual differences in behavior, often termed “personality,” for adapting and coping with threats and novel environmental conditions has advanced considerably during the last decade. However, advancements are almost exclusively associated with higher-order animals, whereas studies focusing on smaller aquatic organisms are still rare. Here, we show individual differences in the swimming behavior of Daphnia magna, a clonal freshwater invertebrate, before, during, and after being exposed to a lethal threat, ultraviolet radiation (UVR). We show consistency in swimming velocity among both mothers and daughters of D. magna in a neutral environment, whereas this pattern breaks down when exposed to UVR. Our study also, for the first time, illustrates how the ontogenetic development in swimming and refuge-seeking behavior of young individuals eventually approaches that of adults. Overall, we show that aquatic invertebrates are far from being identical robots, but instead they show considerable individual differences in behavior that can be attributed to both ontogenetic development and individual consistency. Our study also demonstrates, for the first time, that behavioral consistency and repeatability, that is, something resembling “personality,” is context and state dependent in this zooplankter taxa.

  • 20.
    Hylander, Samuel
    Länsstyrelsen i Skåne län.
    Biotopkartering av Bivarödsån 2003: Naturvärden och behov av restaureringsåtgärder i ett biflöde till Helge å2005Report (Other academic)
    Abstract [sv]

    Denna rapport beskriver resultaten från en biotopkartering av Bivarödsån. Den karterade vattendragssträckan är en del av Helge ås avrinningsområde och flyter genom Osby och Östra Göinge kommuner. Huvudsyftet med projektet var att ge ett underlag för att kunna bedöma vilka biologiska återställningsåtgärder som är nödvändiga i vattendraget för att återfå den fauna som försvunnit på grund av försurning. Genom kalkning av vattendraget ges möjlighet för utslagna arter att återkomma till området. För att detta ska vara möjligt behöver dock även andra hotfaktorer som förändrad markanvändning, vandringhinder, rensning mm. identifieras och eventuellt åtgärdas. Denna biotopkartering ger en god översikt av Bivarödsån både vad det gäller restaureringsbehov och naturvärden.

    Fältarbetet utfördes september 2003 av Ekologgruppen i Landskrona AB på uppdrag av Länsstyrelsen i Skåne län. Flygbildstolkning har utförts av Marie Eriksson på Länsstyrelsen i Skåne län. Rapportskrivning, beräkningar och kvalitetssäkring av materialet har utförts av Samuel Hylander på Länsstyrelsen i Skåne län. Projektet är bekostat med medel från Naturvårdsverket inom ramen för arbetet med biologisk återställning.

    Biotopkarteringar av vattendrag utgör dessutom viktiga kunskapsunderlag inom arbetet med EU:s ramdirektiv för vatten där utgångspunkten är att ”god ekologisk status” ska upprätthållas i våra sjöar och vattendrag. Resultaten beskriver bl.a. åtgärdsbehov och identifierade nyckelbiotoper och kan därmed användas för att realisera miljökvalitetsmålet ”Levande sjöar och vattendrag”. Rapporten riktar sig främst till handläggare vid kommuner och länsstyrelser men även andra intresserade.

  • 21.
    Hylander, Samuel
    Länsstyrelsen i Skåne län.
    Biotopkartering av Klingstorpabäcken 2003: Naturvärden och behov av restaureringsåtgärder i ett biflöde till Rönne å2005Report (Other academic)
    Abstract [sv]

    Denna rapport beskriver resultaten från biotopkarteringen av Klingstorpabäcken i Klippans kommun, 2003. Vattendraget, som är en del av Rönne ås avrinningsområde, anses vara relativt naturligt och rent och hyser ett bestånd av den sällsynta och fridlysta arten flodpärlmussla (Margaritifera margaritifera). Arten är klassad som sårbar (VU) i ArtDatabankens rödlista.

    Huvudsyftet med biotopkarteringen var att ge ett underlag för att kunna bedöma vilka biologiska återställningsåtgärder som är nödvändiga i Klingstorpabäcken för att återfå ett reproducerande bestånd av flodpärlmussla. Projektet skulle även ge en bild av vilka naturvärden och skyddsvärda biotoper som finns i området samt ge underlag till bedömningen om vattendraget har potential att bli upptaget som nationellt särskilt värdefullt vattendrag.

    Biotopkarteringar av vattendrag utgör viktiga kunskapsunderlag inom arbetet med EU:s ramdirektiv för vatten där utgångspunkten är att ”god ekologisk status” ska upprätthållas i våra sjöar och vattendrag. Resultaten kan även användas för att realisera miljökvalitetsmålet ”Levande sjöar och vattendrag”.

    Fältarbetet utfördes juni-juli 2003 av Samuel Hylander inom ramen för en praktikkurs vid Lunds universitet. Handledare var Marie Eriksson på Länsstyrelsen i Skåne län.

  • 22.
    Hylander, Samuel
    Länsstyrelsen i Skåne län.
    Biotopkartering av Röke å och Humlesjöbäcken 2002: Naturvärden och behov av restaureringsåtgärder i ett biflöde till Almaån/Helge å2005Report (Other academic)
    Abstract [sv]

    Denna rapport beskriver resultaten av en biotopkartering i Röke å och Humlesjöbäcken i Helge ås vattensystem. Huvudsyftet med projektet var att ge ett underlag för att kunna bedöma vilka biologiska återställningsåtgärder som är nödvändiga i vattendragen för att återfå den fauna som försvunnit på grund av försurning. Ett exempel på en sådan försvunnen art är flodpärlmusslan (Margaritifera margaritifera) som finns nedströms i Hörlingeån och som tidigare troligen även har funnits i Röke å. Genom kalkning av vattendraget ges möjlighet för utslagna arter att återkomma till området. För att detta ska vara möjligt behöver dock även andra hotfaktorer som förändrad markanvändning, vandringhinder, rensning mm. identifieras och eventuellt åtgärdas. Denna biotopkartering ger en god översikt av Röke å och Humlesjöbäcken både vad det gäller restaureringsbehov och naturvärden.

    Fältarbetet utfördes under augusti och september 2002 av Ekologgruppen i Landskrona AB, på uppdrag av Länsstyrelsen i Skåne län. Flygbildstolkning och digitalisering av närmiljö och omgivning har utförts av Marie Eriksson på Länsstyrelsen i Skåne län. Övrig digitalisering har utförts av Johan Bendtsen på Länsstyrelsen i Skåne län. Rapportskrivning, GIS-hantering, beräkningar och kvalitetssäkring av materialet har utförts av Samuel Hylander på Länsstyrelsen i Skåne län.

    Projektet är bekostat med medel från Naturvårdsverket inom ramen för arbetet med biologisk återställning.

    Biotopkarteringar av vattendrag utgör dessutom viktiga kunskapsunderlag inom arbetet med EU:s ramdirektiv för vatten där utgångspunkten är att ”god ekologisk status” ska upprätthållas i våra sjöar och vattendrag. Resultaten beskriver bl.a. åtgärdsbehov och identifierade nyckelbiotoper och kan därmed användas för att realisera miljökvalitetsmålet ”Levande sjöar och vattendrag”. Rapporten riktar sig främst till handläggare vid kommuner och länsstyrelser men även andra intresserade.

  • 23.
    Hylander, Samuel
    Lund University, Sweden.
    Flodpärlmusslans känslighet för predation från kräftor: effekt i jämförelse med andra hotfaktorer i ett skånskt vattendrag2004Report (Other academic)
    Abstract [en]

    The freshwater pearl mussel (Margaritifera margaritifera) is today an endangered species. In Sweden it has disappeared from one third of the previously known sites, and its reproduction is not working at 75 % of these sites. Previously the species disappeared because of extensive pearl fishing but today other factors like acidification and eutrophication are more important and there are a number of studies assessing these problems. The aim of this study though was to assess the effects of predation from signal crayfish (Pacifastacus lenisculus) on juvenile mussels since this problem previously has been ignored.

    Since the freshwater pearl mussel is protected another species, Unio tumidus, was used in the experiments. This species looks like the freshwater pearl mussel and has a similar morphology and shell thickness. Also the snail species, Lymnaea stagnalis, was used in some comparing experiments. To put the results in a larger perspective fieldwork was carried out in a steam in Skåne where freshwater pearl mussels are present. The aim of the fieldwork was to understand why the mussel has problems with its reproduction. It included assessment of mussel population, crayfish-fishing, electro-fishing, sampling of sediment and sampling of chemical and physical parameters.

    The experiments showed that crayfish and especially the signal crayfish eat mussels up to a size of about 2 cm. The long times used by the crayfish for eating indicate that they have difficulties to open the mussels. If the crayfish could choose between snails and mussels they preferred to eat snails in all experiments indicating that they choose other food than mussels if possible. Further more the experiments showed that the signal crayfish ate on average more snails than the native noble crayfish (Astacus astacus) did per time unit. This indicates that the signal crayfish has a larger predation impact on the system than the noble crayfish has.

    The fieldwork revealed that there are only adult mussels left in the river (mean length 109 mm). A site with freshwater pearl mussels generally had good shading, high pH and high conductivity. Further more the amount of fine coarse material was quite high in the bottom sediment and this probably is a disadvantage for the mussels. The abundance of crayfish in the stream was generally low indicating that crayfish has a low impact on mussel populations in the stream. The electro-fishing showed that the abundance of trout (Salmo trutta) is relatively good. Infections from glochidia were found but infection rates were comparatively low. The glochidia were concluded to be freshwater pearl mussel with help of DNA-analysis.

    The threats against the freshwater pearl mussel in the stream are many and complex. The biggest treats though are thought to be effects from forestry and gravel-pits in the drainage area.

  • 24. Hylander, Samuel
    Zooplankton responses to threats from UV and predation2009Doctoral thesis, comprehensive summary (Other academic)
  • 25.
    Hylander, Samuel
    et al.
    Lunds universitet.
    Boeing, Wiebke J.
    Graneli, Wilhelm
    Karlsson, Jan
    von Einem, Jessica
    Gutseit, Kelly
    Hansson, Lars-Anders
    Complementary UV protective compounds in zooplankton2009In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 54, no 6, p. 1883-1893Article in journal (Refereed)
    Abstract [en]

    Zooplankton accumulate several groups of photoprotective compounds to shield against damaging ultraviolet radiation (UV). One of these groups, the carotenoids, makes the animals more conspicuous to visually hunting predators, whereas others, such as the mycosporine-like amino acids (MAAs) may not. The blend of photoprotective compounds is therefore important for the UV defense but also for the ability to escape predation through crypsis. Here we assess laboratory and field data from different latitudes to examine how UV, predation threat, and pigment availability ( in food) affects the mixture of UV-protective compounds in copepods. Overall, the blend of MAAs and carotenoids was partly explained by the availability of MAAs in the food, the UV-threat, and the presence of predators. Copepods upregulated their MAA content when UV threat was increasing (i.e., if MAAs were abundant in food), and in field data this accumulation only occurred at high levels of predation threat. If MAAs were scarce, copepods instead compensated with higher carotenoid accumulation. However, when there was a high predation threat this carotenoid compensatory effect was disadvantageous, and low concentrations of both MAAs and carotenoids at high UV-threat resulted in lower reproduction. In all, these results showed that carotenoids and MAAs are complementary substances, i.e., one is high when the other is low, and copepods are, hence, able to adjust their blend of different UV-protective compounds to optimize their defenses to the threats of UV and predation. These defense systems may buffer against direct food-web interactions and help the zooplankton to survive in environments with high UV threat.

  • 26.
    Hylander, Samuel
    et al.
    Tech Univ Denmark.
    Cornelius Grenvald, Julie
    Tech Univ Denmark.
    Kiørboe, Thomas
    Tech Univ Denmark.
    Fitness costs and benefits of ultraviolet radiation exposure in marine pelagic copepods2014In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 28, no 1, p. 149-158Article in journal (Refereed)
    Abstract [en]

    1Life-history theory predicts that organisms should allocate energy throughout their life such that they maximize their fitness. Copepod zooplankton are known to accumulate sunscreens (so-called mycosporine-like amino acids, MAAs) and antioxidant carotenoids to mitigate negative effects of ultraviolet radiation (UVR), but it is not well known how this affects their fitness. We followed cohorts of the marine copepod Acartia tonsa and assessed how fitness was affected by UVR exposure and a diet rich in UVR-protective sunscreens. Several fitness components including somatic growth, egg quality and nauplii production (larvae) were negatively affected by UVR, whereas other components such as size at maturity, survival and length of life were not. Nauplii production through low egg quality was the most influential life-history parameter that changed in response to UVR. There was interaction between fitness costs and food source. If copepods were fed a diet rich in UVR-screening MAAs, they were able to maintain and even increase their fitness even though they were exposed to otherwise detrimental radiation. Levels of UVR-protective carotenoids were low in the studied species and a meta-analysis revealed that marine copepods in general have much lower - by an order of magnitude - levels of carotenoids than freshwater species, while levels of MAAs are similar between the two habitats. We conclude that allocation to different fitness components to some extent is plastic although egg quality is by far the most influential factor, and this is an example of how environmental variability affects overall fitness. Fitness costs associated with UVR exposure in the absence of UVR-screening MAAs were present. Other costs such as costs for accumulating MAAs were not detected, and if present, they were outweighed by a stimulated fitness in combined UVR and MAA treatments challenging the common model that inducible defences (such as accumulation of MAAs) should come with a cost. Low levels of carotenoids in marine systems suggest high predation pressures on pigmented specimens. Accumulation of nonpigmented MAAs could hence be a key adaptation for surface-dwelling marine zooplankton to maintain or even increase their fitness when exposed to detrimental radiation.

  • 27.
    Hylander, Samuel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Ekvall, Mikael T
    Lund University.
    Bianco, Giuseppe
    Lund University.
    Yang, Xi
    Lund University.
    Hansson, Lars-Anders
    Lund University.
    Induced tolerance expressed as relaxed behavioural threat response in millimetre-sized aquatic organisms2014In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 281, no 1788, p. Article ID: 20140364-Article in journal (Refereed)
    Abstract [en]

    Natural selection shapes behaviour in all organisms, but this is difficult to study in small, millimetre-sized, organisms. With novel labelling and tracking techniques, based on nanotechnology, we here show how behaviour in zooplankton (Daphnia magna) is affected by size, morphology and previous exposure to detrimental ultraviolet radiation (UVR). All individuals responded with immediate downward swimming to UVR exposure, but when released from the threat they rapidly returned to the surface. Large individuals swam faster and generally travelled longer distances than small individuals. Interestingly, individuals previously exposed to UVR (during several generations) showed a more relaxed response to UVR and travelled shorter total distances than those that were naive to UVR, suggesting induced tolerance to the threat. In addition, animals previously exposed to UVR also had smaller eyes than the naive ones, whereas UVR-protective melanin pigmentation of the animals was similar between populations. Finally, we show that smaller individuals have lower capacity to avoid UVR which could explain patterns in natural systems of lower migration amplitudes in small individuals. The ability to change behavioural patterns in response to a threat, in this case UVR, adds to our understanding of how organisms navigate in the ‘landscape of fear’, and this has important implications for individual fitness and for interaction strengths in biotic interactions.

  • 28.
    Hylander, Samuel
    et al.
    Länsstyrelsen i Skåne län.
    Eriksson, Marie
    Biotopkartering av Lillån 2002: Naturvärden och behov av restaureringsåtgärder i ett biflöde till Holjeån/Skräbeån2005Report (Other academic)
    Abstract [sv]

    Denna rapport beskriver resultaten av en biotopkartering av Lillån i Skräbeåns vattensystem i Bromölla kommun. Huvudsyftet med projektet var att ge ett underlag för att kunna bedöma vilka biologiska återställningsåtgärder som är nödvändiga i Lillån för att återfå den fauna som försvunnit på grund av markanvändning, vandringshinder och försurning. Projektet skulle även ge en bild av vilka naturvärden som finns i området.

    Fältarbetet utfördes juli 2002 av ALcontrol AB på uppdrag av Länsstyrelsen i Skåne län. Flygbildstolkning, digitalisering och beräkningar har utförts av Marie Eriksson på Länsstyrelsen i Skåne län. En kompletterande inventering av nyckelbiotoper och skyddszoner genomfördes oktober 2004 av Samuel Hylander på Länsstyrelsen i Skåne län som också har kvalitetssäkrat materialet och skrivit rapporten.

    Projektet är bekostat med medel från Naturvårdsverket inom ramen för arbetet med biologisk återställning.

    Biotopkarteringar av vattendrag utgör viktiga kunskapsunderlag inom arbetet med EU:s ramdirektiv för vatten där utgångspunkten är att ”god ekologisk status” ska upprätthållas i våra sjöar och vattendrag. Resultaten beskriver bl.a. åtgärdsbehov och identifierade nyckelbiotoper och kan därmed användas för att realisera miljökvalitetsmålet ”Levande sjöar och vattendrag”. Rapporten riktar sig främst till handläggare vid kommuner och länsstyrelser men även andra intresserade.

  • 29.
    Hylander, Samuel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hansson, Lars-Anders
    Unds universitet.
    Vertical distribution and pigmentation of Antarctic zooplankton determined by a blend of UV radiation, predation and food availability2013In: Aquatic Ecology, ISSN 1386-2588, E-ISSN 1573-5125, Vol. 47, no 4, p. 467-480Article in journal (Refereed)
    Abstract [en]

    Selection pressure induced by simultaneously occurring environmental threats is a major evolutionary driver for organisms in terrestrial, as well as in aquatic ecosystems. For example, protection against ultraviolet radiation (UVR) and predation include both morphological and behavioral components. Here we address those selective pressures on zooplankton by performing a latitudinal monitoring, combined with mechanistic experiments in the Antarctic Southern Ocean, where the UVR-threat is extremely high. We assessed vertical distributions of zooplankton along the Antarctic coast showing that animals were most abundant at 20-80 m and tended to avoid the surface at sites with clear water. UVR-threat disappeared at between 9 and 15 m at sites with low and high water transparency, respectively. Light levels were, however, sufficient for visual fish predation down to approximately 19 and 37 m, respectively. The few zooplankton that were present in surface waters had high levels of non-pigmented UVR-protective compounds (mycosporine-like amino acids) compared to deeper dwelling zooplankton. Overall they had low levels of red pigmented UVR-protective compounds (carotenoids), suggesting high predation on pigmented individuals. In a complementary laboratory study we showed that levels of UVR-protective compounds increased considerably when zooplankton were exposed to UVR in the absence of predator cues. The recently developed transparency-regulator hypothesis predicts that UVR avoidance is an important driver to diel vertical migration in transparent waters, such as in Antarctica. We, however, conclude that copepods resided well below the level where UVR had diminished to very low levels and that predator avoidance or food availability are more likely drivers of zooplankton vertical depth distribution in transparent marine systems.

  • 30.
    Hylander, Samuel
    et al.
    Lunds universitet.
    Hansson, Lars-Anders
    Lunds universitet.
    Vertical migration mitigates UV effects on zooplankton community composition2010In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 32, no 7, p. 971-980Article in journal (Refereed)
    Abstract [en]

    Several zooplankton species are susceptible to ultraviolet radiation (UV), suggesting that UV may shape zooplankton community composition. Little is known, however, about the quantitative effects of long-term UV exposure in relation to biological processes. Therefore, we studied effects of UV on behaviour, population dynamics and reproduction of several zooplankton taxa. We identified different strategies regarding daytime vertical distribution: a strong response to UV threat, illustrated by Daphnia; a weak, albeit significant response, such as in copepods; and lastly, a stationary position in a depth refuge, as in Chydorus and Eurycercus. The relative abundances of the different zooplankton species were similar and only Daphnia and copepod nauplii displayed a slight decrease in relative abundance in response to UV treatment. Daphnia also reacted to the UV threat by increasing resting egg production, whereas long-term population dynamics for all studied species were surprisingly similar between treatments, despite considerable differences in UV exposure for several months. We conclude that zooplankton communities at temperate latitudes are able to survive increased UV levels due to efficient defences, suggesting that future potential increases in UV radiation may result in only moderate impacts on zooplankton population dynamics and community composition.

  • 31.
    Hylander, Samuel
    et al.
    Lunds universitet.
    Jephson, Therese
    Lunds universitet.
    UV protective compounds transferred from a marine dinoflagellate to its copepod predator2010In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 389, no 1-2, p. 38-44Article in journal (Refereed)
    Abstract [en]

    Planktonic organisms living in surface waters can be exposed to harmful levels of ultraviolet radiation (UVR), but few studies have examined accumulation of UV protective compounds in marine zooplankton. Zooplankters are suggested to lack the ability to synthesize these substances and hence must accumulate them from their algal food. Here, we show that both phytoplankton (dinoflagellates) and their zooplankton grazers (copepods) respond strongly to UVR exposure by, respectively, synthesizing and accumulating the natural sunscreens mycosporine-like amino acids (MAAs). In our experiment, the MAAs content increased approximately four times in dinoflagellates exposed to UVR and PAR, as compared to non-UVR controls only receiving PAR (PAR = photosynthetically active radiation). The elevated MAAs level in the dinoflagellates was mirrored in the copepods, which accumulated more MAAs when exposed to UVR as compared to a non-UVR treatment. Overall, copepods accumulated approximately 2-5% of the total MAAs pool. Other UV protective compounds, like carotenoids, were however not accumulated by the copepods. The ability of some species to produce or accumulate photoprotective compounds may lead to increased fitness, and thus these taxa may become more dominant in plankton communities.

  • 32.
    Hylander, Samuel
    et al.
    Lund University.
    Jephson, Therese
    Lund University.
    Lebret, Karen
    Lund University.
    von Einem, Jessica
    Lund University.
    Fagerberg, Tony
    Lund University.
    Balseiro, Esteban
    National University of Comahue, Argentina.
    Modenutti, Beatriz
    National University of Comahue, Argentina.
    Sol Souza, Maria
    National University of Comahue, Argentina.
    Laspoumaderes, Cecilia
    National University of Comahue, Argentina.
    Joensson, Mikael
    Lund University.
    Ljungberg, Peter
    Lund University.
    Nicolle, Alice
    Lund University.
    Nilsson, Per Anders
    Lund University.
    Ranaker, Lynn
    Lund University.
    Hansson, Lars-Anders
    Lund University.
    Climate-induced input of turbid glacial meltwater affects vertical distribution and community composition of phyto- and zooplankton2011In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 33, no 8, p. 1239-1248Article in journal (Refereed)
    Abstract [en]

    Receding glaciers are among the most obvious changes caused by global warming, and glacial meltwater entering lakes generally forms plumes of particles. By taking vertical samples along a horizontal gradient from such a particle source, we found that photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) attenuated 20-25% faster close to the inflow of suspended particles compared with the more transparent part of the gradient. All sampled stations had a deep chlorophyll a (Chl a) maximum at 15-20 m which was more distinct in the transparent part of the horizontal gradient. Picocyanobacteria increased in abundance in more transparent water and their numbers were tightly correlated with the intensity of the deep Chl a maxima. Motile species of phytoplankton had a deeper depth distribution in transparent versus less transparent water. Yet other species, like Chrysochromulina parva, that can withstand high PAR intensities and low nutrient concentrations, increased in abundance as the water became more transparent. Also copepods increased in abundance, indicating that they are more successful in transparent water. We conclude that sediment input into lakes creates horizontal gradients in PAR and UVR attenuation which strongly affect both distribution and behavior of phyto-and zooplankton. The input of glacial flour creates a sub-habitat that can function as a refuge for species that are sensitive to high PAR and UVR exposure. When the glacier has vanished, this habitat may disappear. During the melting period, with heavy sediment input, we predict that competitive species in transparent waters, like Chrysocromulina, picocyanobacteria and copepods, will become less common. The deep Chl a maxima is also likely to become less developed. Hence, glacier melting will probably have profound effects on both species composition and behavior of several planktonic taxa with potential effects on the food web.

  • 33.
    Hylander, Samuel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Kiørboe, Thomas
    Tech Univ Denmark, Denmark.
    Snoeijs, Pauline
    Stockholm University.
    Sommaruga, Ruben
    Univ Innsbruck, Austria.
    Nielsen, Torkel Gissel
    Tech Univ Denmark, Denmark;Greenland Inst Nat Resources, Greenland.
    Concentrations of sunscreens and antioxidant pigments in Arctic Calanus spp. in relation to ice cover, ultraviolet radiation, and the phytoplankton spring bloom2015In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 60, p. 2197-2206Article in journal (Refereed)
    Abstract [en]

    Arctic zooplankton ascend to shallow depths during spring to graze on the yearly occurring phytoplankton bloom. However, in surface waters they are exposed to detrimental ultraviolet radiation (UVR) levels. Here, we quantified concentrations of substances known to have UVR-protective functions, namely mycosporine-like amino acids (MAAs) and the carotenoid astaxanthin, from March to May in Calanus finmarchicus, Calanus glacialis and Calanus hyperboreus. Ice cover was 100% in the beginning of March, started to break up during April and was gone by the end of May. UVR-exposure in the water column was tightly linked to the ice conditions and water UVR-transparency was up to 6 m (depth where 1% radiation remains). Concentrations of MAAs in C. finmarchicus and C. glacialis increased sharply during ice break-up and peaked concurrently with maximum chlorophyll a (Chl a) levels. MAA-concentrations in C. hyperboreus increased later in accordance with its later arrival to the surface. The concentration of astaxanthin increased in all three species over time but there was no synchrony with ice conditions or the phytoplankton bloom. Even though only the upper 6 m of the water column was affected by UV-radiation, MAAs in the copepods were tightly correlated to the UV-threat. Hence, changes in ice cover are projected to have a large impact on the UVR-exposure of zooplankton emphasizing the importance of the timing of zooplankton ascent from deep waters in relation to the phytoplankton bloom and the ice break-up.

  • 34.
    Hylander, Samuel
    et al.
    Lunds universitet.
    Larsson, Niklas
    Lunds universitet.
    Hansson, Lars-Anders
    Lunds universitet.
    Zooplankton vertical migration and plasticity of pigmentation arising from simultaneous UV and predation threats2009In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 54, no 2, p. 483-491Article in journal (Refereed)
    Abstract [en]

    We assessed how zooplankton (copepods) handle the simultaneous threats of predators and ultraviolet (UV) radiation and whether they respond with changes in pigmentation, vertical migration, or both. We found weak vertical migration among copepods in response to UV stress, and this response was not apparently influenced by predation risk. Exposure to high levels of UV radiation caused copepods to retain pigments in the absence of a predation threat. When exposed to predation threat, they reduced their pigmentation regardless of UV level. Thus, they ranked predation as a threat more severe than UV radiation. Reducing the protective pigment level in response to predation in a situation in which UV radiation is high may, however, lead to higher mortality.

  • 35.
    Hylander, Samuel
    et al.
    Lunds universitet.
    Souza, Maria Sol
    Univ Nacl Comahue, Lab Limnol, CONICET, INIBIOMA, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina.
    Balseiro, Esteban
    Univ Nacl Comahue, Lab Limnol, CONICET, INIBIOMA, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina.
    Modenutti, Beatriz
    Univ Nacl Comahue, Lab Limnol, CONICET, INIBIOMA, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina.
    Hansson, Lars-Anders
    Lunds universitet.
    Fish-mediated trait compensation in zooplankton2012In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 26, no 3, p. 608-615Article in journal (Refereed)
    Abstract [en]

    1. Environmental factors fluctuate spatially and temporally, and organisms that can alter phenotype in response to these changes may increase their fitness. Zooplankton are known to be able to induce body pigmentation in response to ultraviolet radiation (UVR) and to reduce the pigmentation when exposed to fish predators. Hence, reduced pigmentation because of the presence of fish could potentially lead to UVR damage, which calls for alternative protective mechanisms. 2. We exposed zooplankton to fish cues and UVR stress to assess whether body pigmentation and cellular antioxidants are flexible predation and UVR defences. 3. Zooplankton exposed to fish predator cues (no direct predation) reduced their pigmentation by c. 30% in 20 days. However, they were able to rapidly counteract negative UVR effects by increasing the activity of antioxidant defences such as glutathione S-transferase (GST). When exposed to UVR, the GST activity increased by c. 100% in zooplankton that had previously reduced their pigmentation because of fish cues. Transparency in the zooplankton did not lead to considerably higher UVR damage, here measured as inhibition of cholinesterase (ChE). 4. We conclude that zooplankton pigmentation and antioxidant enzymes are flexible UVR defence systems, which can be induced when needed. Zooplankton may employ antioxidant defences when pigmentation is reduced to counteract predation risk and thereby rapidly respond to detrimental effects of UVR exposure, that is, they can compensate one trait with another.

  • 36.
    Jonsson, Mikael
    et al.
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Ranaker, L.
    Lunds universitet.
    Nilsson, P. A.
    Lunds universitet.
    Bronmark, C.
    Lunds universitet.
    Foraging success of juvenile pike Esox lucius depends on visual conditions and prey pigmentation2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 79, no 1, p. 290-297Article in journal (Refereed)
    Abstract [en]

    Young-of-the-year pike Esox lucius foraging on copepods experienced different foraging success depending on prey pigmentation in water visually degraded by brown colouration or algae. Both attack rate and prey consumption rate were higher for E. lucius foraging on transparent prey in brown water, whereas the opposite was true in algal turbid water. Pigments in copepod prey may have a cryptic function in brown water instead of a photo-protective function even if prey-size selectivity was stronger than selection based on pigmentation in juvenile E. lucius.

  • 37.
    Jonsson, Mikael
    et al.
    Lunds universitet.
    Ranaker, Lynn
    Lunds universitet.
    Nicolle, Alice
    Lunds universitet.
    Ljungberg, Peter
    Lunds universitet.
    Fagerberg, Tony
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Jephson, Therese
    Lunds universitet.
    Lebret, Karen
    Lunds universitet.
    von Einem, Jessica
    Lunds universitet.
    Hansson, Lars-Anders
    Lunds universitet.
    Nilsson, P. Anders
    Lunds universitet.
    Balseiro, Esteban
    CONICET Univ Nacl Comahue, INIBIOMA, Lab Limnol, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina.
    Modenutti, Beatriz
    CONICET Univ Nacl Comahue, INIBIOMA, Lab Limnol, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina.
    Glacial clay affects foraging performance in a Patagonian fish and cladoceran2011In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 663, no 1, p. 101-108Article in journal (Refereed)
    Abstract [en]

    Climate change is altering temperatures and precipitation patterns all over the world. In Patagonia, Argentina, predicted increase in precipitation together with rapidly melting glaciers increase the surface runoff, and thereby the transport of suspended solids to recipient lakes. Suspended solids affect the visual conditions in the water which in turn restricts visual foraging. The native fish Aplochiton zebra Jenyns, and its filter-feeding cladoceran prey, Daphnia commutata Ekman, were subjected to foraging experiments at three turbidity levels. A. zebra foraging rate was substantially reduced at naturally occurring turbidity levels and the filtering rate of D. commutata was reduced at the highest turbidity level. This indicates that Daphnia may be partly released from predation from A. zebra at the same time as it can maintain relatively high feeding rates as turbidity increases. Lower foraging rates at the same time as the metabolic demand increases, through increased temperatures, may result in larger effects on A. zebra than could be expected from increases in turbidity or temperature alone. Turbidity may, as an indirect effect of climate change, decrease planktivore foraging rates and thereby alter the interaction strength between trophic levels.

  • 38.
    Kiørboe, Thomas
    et al.
    Technical University of Denmark, Denmark.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Plankton beskytter sig med solcreme2013Other (Other (popular science, discussion, etc.))
    Abstract [da]

    Plante- og dyreplankton, der lever nær havoverfladen, udsættes for kraftigt sollys. De bliver solbrændte og akkumulerer solcreme for at beskytte sig mod skadelig UV-stråling. Beskyttelsesmekanismerne har betydning for livet højere i fødekæden.

  • 39.
    Majaneva, Sanna
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. UiT The Arctic University of Norway, Norway;Norwegian University of Science and technology, Norway.
    Fridolfsson, Emil
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Casini, Michele
    Swedish University of Agricultural Sciences, Sweden.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lindehoff, Elin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Margonski, Piotr
    National Marine Fisheries Research Institute, Poland.
    Majaneva, Markus
    NTNU University Museum, Norway.
    Nilsson, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Rubene, Gunta
    Animal Health and Environment BIOR, Latvia.
    Wasmund, Norbert
    Leibniz-Institute for Baltic Sea Research, Germany.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Deficiency syndromes in top predators associated with large-scale changes in the Baltic Sea ecosystemManuscript (preprint) (Other academic)
  • 40.
    Neuheimer, Anna B.
    et al.
    University of Hawaii, USA.
    Hartvig, Martin
    Technical University of Denmark, Denmark.
    Heuschele, Jan
    Technical University of Denmark, Denmark.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Kiorboe, Thomas
    Technical University of Denmark, Denmark.
    Olsson, Karin H.
    Technical University of Denmark, Denmark.
    Sainmont, Julie
    Technical University of Denmark, Denmark.
    Andersen, Kan Haste
    National Institute of Aquatic Resources - DTU Aqua, Denmark.
    Adult and offspring size in the ocean over 17 orders of magnitude follows two life history strategies2015In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 96, no 12, p. 3303-3311Article in journal (Refereed)
    Abstract [en]

    Explaining variability in offspring vs. adult size among groups is a necessary step to determine the evolutionary and environmental constraints shaping variability in life history strategies. This is of particularly interest for life in the ocean where a diversity of offspring development strategies is observed along with variability in physical and biological forcing factors in space and time. We compiled adult and offspring size for 408 pelagic marine species covering >17 orders of magnitude in body mass including Cephalopoda, Cnidaria, Crustaceans, Ctenophora, Elasmobranchii, Mammalia, Sagittoidea, and Teleost. We find marine life following one of two distinct strategies, with offspring size being either proportional to adult size (e.g. Crustaceans, Euratatoria, Elasmobranchii and Mammalia) or invariant with adult size (e.g. Cephalopoda, Cnidaria, Sagittoidea, Teleosts and possibly Ctenophora). We discuss where these two strategies occur and how these patterns (along with the relative size of the offspring) may be shaped by physical and biological constraints in the organism's environment. This adaptive environment along with the evolutionary history of the different groups shape observed life history strategies and possible group-specific responses to changing environmental conditions (e.g. production and distribution).

  • 41.
    Neuheimer, Anna B.
    et al.
    Technical University of Denmark, Denmark ; University of Copenhagen, Denmark ; University of Hawaii at Mānoa, USA.
    Hartvig, Martin
    Technical University of Denmark, Denmark ; University of Copenhagen, Denmark ; University of Göttingen, Germany.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Technical University of Denmark, Denmark.
    Kiorboe, Thomas
    Technical University of Denmark, Denmark.
    Olsson, Karin H.
    Technical University of Denmark, Denmark.
    Saimont, Julie
    Technical University of Denmark, Denmark.
    Andersen, Ken H.
    Technical University of Denmark, Denmark.
    Adult and offspring size in the ocean: a database of size metrics and conversion factors2016Data set
    Abstract [en]

    The purpose of this dataset was to compile adult and offspring size estimates for marine organisms. Adult and offspring size estimates of 408 species were compiled from the literature covering >17 orders of magnitude in body mass and including Cephalopoda (ink fish), Cnidaria (“jelly” fish), Crustaceans, Ctenophora (comb jellies), Elasmobranchii (cartilaginous fish), Mammalia (mammals), Sagittoidea (arrow worms) and Teleost (i.e., Actinopterygii, bony fish). Individual size estimates were converted to standardized size estimates (carbon weight, g) to allow for among-group comparisons. This required a number of size estimates to be converted and a compilation of conversion factors obtained from the literature are also presented.

  • 42.
    Paerl, Ryan W.
    et al.
    University of Copenhagen, Denmark;North Carolina State University, USA.
    Sundh, John
    Stockholm University;Royal Institute of Technology.
    Tan, Demeng
    University of Copenhagen, Denmark.
    Svenningsen, Sine L.
    University of Copenhagen, Denmark.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Pinhassi, Jarone
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Andersson, Anders F.
    Royal Institute of Technology.
    Riemann, Lasse
    University of Copenhagen, Denmark.
    Prevalent reliance of bacterioplankton on exogenous vitamin B1 and precursor availability2018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 115, no 44, p. E10447-E10456Article in journal (Refereed)
    Abstract [en]

    Vitamin B1 (B1 herein) is a vital enzyme cofactor required by virtually all cells, including bacterioplankton, which strongly influence aquatic biogeochemistry and productivity and modulate climate on Earth. Intriguingly, bacterioplankton can be de novo B1 synthesizers or B1 auxotrophs, which cannot synthesize B1 de novo and require exogenous B1 or B1 precursors to survive. Recent isolate-based work suggests select abundant bacterioplankton are B1 auxotrophs, but direct evidence of B1 auxotrophy among natural communities is scant. In addition, it is entirely unknown if bulk bacterioplankton growth is ever B1-limited. We show by surveying for B1-related genes in estuarine, marine, and freshwater metagenomes and metagenome-assembled genomes (MAGs) that most naturally occurring bacterioplankton are B1 auxotrophs. Pyrimidine B1-auxotrophic bacterioplankton numerically dominated metagenomes, but multiple other B1-auxotrophic types and distinct uptake and B1-salvaging strategies were also identified, including dual (pyrimidine and thiazole) and intact B1 auxotrophs that have received little prior consideration. Time-series metagenomes from the Baltic Sea revealed pronounced shifts in the prevalence of multiple B1-auxotrophic types and in the B1-uptake and B1-salvaging strategies over time. Complementarily, we documented B1/precursor limitation of bacterioplankton production in three of five nutrient-amendment experiments at the same time-series station, specifically when intact B1 concentrations were ≤3.7 pM, based on bioassays with a genetically engineered Vibrio anguillarum B1-auxotrophic strain. Collectively, the data presented highlight the prevalent reliance of bacterioplankton on exogenous B1/precursors and on the bioavailability of the micronutrients as an overlooked factor that could influence bacterioplankton growth and succession and thereby the cycling of nutrients and energy in aquatic systems.

  • 43.
    Rodrigo, Gonçalvez
    et al.
    Technical University of Denmark, Denmark.
    Hylander, Samuel
    Technical University of Denmark, Denmark.
    Marine copepods and solar radiation2014In: Copepods: diversity, habitat and behavior / [ed] Laurent Seuront, Nova Science Publishers, Inc., 2014, 1, p. 101-120Chapter in book (Other academic)
    Abstract [en]

    Ultraviolet radiation (UVR) has an overall negative effect on zooplankton. The direct effects (i.e., when the individual is exposed to UVR) include mortality due to DNA damage, and changes in feeding, reproduction and respiration. The effects can also be indirect, for example when UVR affects food quality of phytoplankton. However much of our knowledge comes from freshwater zooplankton (copepods but especially cladocerans), whereas marine studies are comparatively scarce. Here we summarize the current knowledge in marine copepods and try to give an overview of knowledge gaps and interesting areas for further research. The indirect effects of UVR are likely to be more important (and less predictable due to interactions with other factors across trophic levels) than the direct effects.

  • 44.
    Sol Souza, Maria
    et al.
    INIBIOMA CONICET UNComahue, Lab Limnol, San Carlos De Bariloche, Rio Negro, Argentina.
    Hansson, Lars-Anders
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Modenutti, Beatriz
    INIBIOMA CONICET UNComahue, Lab Limnol, San Carlos De Bariloche, Rio Negro, Argentina.
    Balseiro, Esteban
    INIBIOMA CONICET UNComahue, Lab Limnol, San Carlos De Bariloche, Rio Negro, Argentina.
    Rapid Enzymatic Response to Compensate UV Radiation in Copepods2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 2, p. ArticleID: e32046-Article in journal (Refereed)
    Abstract [en]

    Ultraviolet radiation (UVR) causes physical damage to DNA, carboxylation of proteins and peroxidation of lipids in copepod crustaceans, ubiquitous and abundant secondary producers in most aquatic ecosystems. Copepod adaptations for long duration exposures include changes in behaviour, changes in pigmentation and ultimately changes in morphology. Adaptations to short-term exposures are little studied. Here we show that short-duration exposure to UVR causes the freshwater calanoid copepod, Eudiaptomus gracilis, to rapidly activate production of enzymes that prevent widespread collateral peroxidation (glutathione S-transferase, GST), that regulate apoptosis cell death (Caspase-3, Casp-3), and that facilitate neurotransmissions (cholinesterase-ChE). None of these enzyme systems is alone sufficient, but they act in concert to reduce the stress level of the organism. The interplay among enzymatic responses provides useful information on how organisms respond to environmental stressors acting on short time scales.

  • 45.
    Williamson, Craig E.
    et al.
    Miami University, USA.
    Neale, Patrick J.
    Smithsonian Environmental Research Center, USA.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Rose, Kevin C.
    Rensselaer Polytechnic Institute, USA.
    Figueroa, Félix L.
    University of Malaga, Spain.
    Robinson, Sharon A.
    University of Wollongong, Australia.
    Häder, Donat-P.
    Friedrich-Alexander Universität, Germany.
    Wängberg, Sten-Åke
    University of Gothenburg, Sweden.
    Worrest, Robert C.
    Columbia University, USA.
    The interactive effects of stratospheric ozone depletion, UV radiation, and climate change on aquatic ecosystems2019In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, no 3, p. 717-746Article in journal (Refereed)
    Abstract [en]

    This assessment summarises the current state of knowledge on the interactive effects of ozone depletion and climate change on aquatic ecosystems, focusing on how these affect exposures to UV radiation in both inland and oceanic waters. The ways in which stratospheric ozone depletion is directly altering climate in the southern hemisphere and the consequent extensive effects on aquatic ecosystems are also addressed. The primary objective is to synthesise novel findings over the past four years in the context of the existing understanding of ecosystem response to UV radiation and the interactive effects of climate change. If it were not for the Montreal Protocol, stratospheric ozone depletion would have led to high levels of exposure to solar UV radiation with much stronger negative effects on all trophic levels in aquatic ecosystems than currently experienced in both inland and oceanic waters. This “world avoided” scenario that has curtailed ozone depletion, means that climate change and other environmental variables will play the primary role in regulating the exposure of aquatic organisms to solar UV radiation. Reductions in the thickness and duration of snow and ice cover are increasing the levels of exposure of aquatic organisms to UV radiation. Climate change was also expected to increase exposure by causing shallow mixed layers, but new data show deepening in some regions and shoaling in others. In contrast, climate-change related increases in heavy precipitation and melting of glaciers and permafrost are increasing the concentration and colour of UV-absorbing dissolved organic matter (DOM) and particulates. This is leading to the “browning” of many inland and coastal waters, with consequent loss of the valuable ecosystem service in which solar UV radiation disinfects surface waters of parasites and pathogens. Many organisms can reduce damage due to exposure to UV radiation through behavioural avoidance, photoprotection, and photoenzymatic repair, but meta-analyses continue to confirm negative effects of UV radiation across all trophic levels. Modeling studies estimating photoinhibition of primary production in parts of the Pacific Ocean have demonstrated that the UV radiation component of sunlight leads to a 20% decrease in estimates of primary productivity. Exposure to UV radiation can also lead to positive effects on some organisms by damaging less UV-tolerant predators, competitors, and pathogens. UV radiation also contributes to the formation of microplastic pollutants and interacts with artificial sunscreens and other pollutants with adverse effects on aquatic ecosystems. Exposure to UV-B radiation can decrease the toxicity of some pollutants such as methyl mercury (due to its role in demethylation) but increase the toxicity of other pollutants such as some pesticides and polycyclic aromatic hydrocarbons. Feeding on microplastics by zooplankton can lead to bioaccumulation in fish. Microplastics are found in up to 20% of fish marketed for human consumption, potentially threatening food security. Depletion of stratospheric ozone has altered climate in the southern hemisphere in ways that have increased oceanic productivity and consequently the growth, survival and reproduction of many sea birds and mammals. In contrast, warmer sea surface temperatures related to these climate shifts are also correlated with declines in both kelp beds in Tasmania and corals in Brazil. This assessment demonstrates that knowledge of the interactive effects of ozone depletion, UV radiation, and climate change factors on aquatic ecosystems has advanced considerably over the past four years and confirms the importance of considering synergies between environmental factors.

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