| 1. |
- Bondoc, Karen Grace V, et al.
(författare)
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Selective silicate-directed motility in diatoms.
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Diatoms are highly abundant unicellular algae that often dominate pelagic as well as benthic primary production in the oceans and inland waters. Being strictly dependent on silica to build their biomineralized cell walls, marine diatoms precipitate 240 × 10(12) mol Si per year, which makes them the major sink in the global Si cycle. Dissolved silicic acid (dSi) availability frequently limits diatom productivity and influences species composition of communities. We show that benthic diatoms selectively perceive and behaviourally react to gradients of dSi. Cell speed increases under dSi-limited conditions in a chemokinetic response and, if gradients of this resource are present, increased directionality of cell movement promotes chemotaxis. The ability to exploit local and short-lived dSi hotspots using a specific search behaviour likely contributes to micro-scale patch dynamics in biofilm communities. On a global scale this behaviour might affect sediment-water dSi fluxes and biogeochemical cycling.
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| 2. |
- Hansson, Lars Anders, et al.
(författare)
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Instantaneous threat escape and differentiated refuge demand among zooplankton taxa
- 2016
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 97:2, s. 279-285
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Heuschele, Jan, et al.
(författare)
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An increase in pH boosts olfactory communication in sticklebacks
- 2007
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 3:4, s. 411-413
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Tidskriftsartikel (refereegranskat)abstract
- Human-induced eutrophication is a serious environmental problem that constrains visual communication and influences the mate choice process in fishes. Eutrophication also changes the chemical environment and the pH of the water, which could influence the use of olfactory cues in mate choice. Here, we show that an increase in pH enhances the use of male olfactory cues in mate choice in three-spined sticklebacks, Gasterosteus aculeatus. In a laboratory choice experiment, gravid females were more attracted to male olfactory cues when pH was raised. This could compensate for impaired visual communication in eutrophied waters and facilitate adaptive mate choice.
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| 4. |
- Heuschele, Jan, et al.
(författare)
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Context-dependent individual behavioral consistency in Daphnia
- 2017
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Ingår i: Ecosphere. - : John Wiley & Sons. - 2150-8925 .- 2150-8925. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Heuschele, Jan, et al.
(författare)
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Non-consumptive effects of predator presence on copepod reproduction : insights from a mesocosm experiment
- 2014
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Ingår i: Marine Biology. - : Springer. - 0025-3162 .- 1432-1793. ; 161:7, s. 1653-1666
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Tidskriftsartikel (refereegranskat)abstract
- Reproduction in planktonic animals depends on numerous biotic and abiotic factors. One of them is predation pressure, which can have both direct consumptive effects on population density and sex ratio, and non-consumptive effects, for example on mating and migration behaviour. In copepods, predator vulnerability depends on their sex, motility pattern and mating behaviour. Therefore, copepods can be affected at multiple stages during the mating process. We investigated the reproductive dynamics of the estuarine copepod Eurytemora affinis in the presence and absence of its predator the mysid Neomysis integer in a mesocosm experiment. We found that the proportion of ovigerous females decreased in the presence of predators. This shift was not caused by differential predation as the absolute number of females was unaffected by mysid presence. Presence of predators reduced the ratio of males to non-ovigerous females, but not by predation of males. Our combined results suggest that the shift from ovigerous to non-ovigerous females under the presence of predators was caused by either actively delayed egg production or by shedding of egg sacs. Nauplii production was initially suppressed in the predation treatment, but increased towards the end of the experiment. The proportion of fertilized females was similar in both treatments, but constantly fell behind model predictions using a random mating model. Our results highlight the importance of non-consumptive effects of predators on copepod reproduction and hence on population dynamics.
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| 6. |
- Heuschele, Jan, et al.
(författare)
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On the missing link in ecology : Improving communication between modellers and experimentalists
- 2017
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Ingår i: Oikos. - : Wiley. - 0030-1299. ; 126:8, s. 1071-1077
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Tidskriftsartikel (refereegranskat)abstract
- Collaboration between modellers and experimentalists is essential in ecological research, however, different obstacles linking both camps often hinder scientific progress. In this commentary, we discuss several issues of the current state of affairs in this research loop. Backed by an online survey amongst fellow ecologists, modellers and experimentalists alike, we identify two major areas that need to be mended. Firstly, differences in language and jargon lead to a lack of exchange of ideas and to unrealistic mutual expectations. And secondly, constraint data sharing, accessibility and quality limit the usage of empirical data and thereby the impact of ecological studies. We discuss ways to advance collaboration; how to improve communication and the design of experiments; and the sharing of data. We hope to start a much-needed conversation between modellers and experimentalists, to further future research collaboration and to increase the impact of single ecological studies alike.
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| 7. |
- Kiorboe, Thomas, et al.
(författare)
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Havets dufte
- 2013
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Ingår i: Aktuel naturvidenskab. - 1399-2309 .- 1602-3544. ; :3, s. 30-33
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Neuheimer, Anna B., et al.
(författare)
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Adult and offspring size in the ocean : a database of size metrics and conversion factors
- 2016
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Ingår i: Ecology. - : John Wiley & Sons. - 0012-9658 .- 1939-9170. ; 97:4, s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Neuheimer, Anna B., et al.
(författare)
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Adult and offspring size in the ocean over 17 orders of magnitude follows two life history strategies
- 2015
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Ingår i: Ecology. - : John Wiley & Sons. - 0012-9658 .- 1939-9170. ; 96:12, s. 3303-3311
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Tidskriftsartikel (refereegranskat)abstract
- 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).
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| 10. |
- Sainmont, Julie, et al.
(författare)
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Inter- and intra-specific diurnal habitat selection of zooplankton during the spring bloom observed by Video Plankton Recorder
- 2014
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 161:8, s. 1931-1941
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Tidskriftsartikel (refereegranskat)abstract
- Diel vertical migration (DVM) is a common behavior adopted by zooplankton species. DVM is a prominent adaptation for avoiding visual predation during daylight hours and still being able to feed on surface phytoplankton blooms during night. Here, we report on a DVM study using a Video Plankton Recorder (VPR), a tool that allows mapping of vertical zooplankton distributions with a far greater spatial resolution than conventional zooplankton nets. The study took place over a full day-night cycle in Disko Bay, Greenland, during the peak of the phytoplankton spring bloom. The sampling revealed a large abundance of copepods performing DVM (up during night and down during day). Migration behavior was expressed differently among the abundant groups with either a strong DVM (euphausiids), an absence of DVM (i.e., permanently deep; ostracods) or a marked DVM, driven by strong surface avoidance during the day and more variable depth preferences at night (Calanus spp.). The precise individual depth position provided by the VPR allowed us to conclude that the escape from surface waters during daytime reduces feeding opportunities but also lowers the risk of predation (by reducing the light exposure) and thereby is likely to influence both state (hunger, weight and stage) and survival. The results suggest that the copepods select day and night time habitats with similar light levels (similar to 10(-9) mu mol photon s(-1) m(-2)). Furthermore, Calanus spp. displayed state-dependent behavior, with DVM most apparent for smaller individuals, and a deeper residence depth for the larger individuals.
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