2017
 

Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic bloom development

År: 2017

Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic bloom development

Paulsen, M. L., Riisgaard, K., St. John, M., Thingstad, T. F. & Nielsen, T. G. 2017 In : Aquatic Microbial Ecology. 78, p. 161-176

Publication: Research - peer-reviewJournal article – Annual report year: 2017

The subarctic Atlantic phytoplankton spring bloom is one of the largest biological features of the ocean; however, processes initiating the bloom are still not well understood. We hypothesize that the microbial grazing food chain plays an important role in creating a pre-bloom condition with top-down control of small-sized phytoplankton, thus paving the way for a diatomdominated spring bloom. To assess the trophic role of protist grazers during the winter to spring transition, 3 experiments were performed using size-fractionated surface water from the Iceland Basin (March−April 2012). These experiments demonstrated heterotrophic nanoflagellates (HNF) grazing of picophytoplankton to be a key pathway, even though these are rarely considered as important phytoplankton grazers in high-latitude systems. The growth rate of HNF was significantly correlated to the biomass of picophytoplankton and was substantially higher than the growth of the larger microzooplankton (MZP), i.e. ciliates and dinoflagellates. During the first experiment, small phytoplankton dominated and overall protist grazing (HNF + MZP) was low. In the later experiments, MZP grazing on HNF became evident; however, MZP were not able to control the community of larger phytoplankton (>10 μm), which became more abundant. Our experiments thus support the hypothesis that pre-bloom conditions promote a build-up of large phytoplankton, i.e. diatoms. We found that the high growth rates of HNF together with the relaxed MZP grazing pressure allow HNF to respond rapidly to the early primary production by picophytoplankton and maintain a strong top-down control on these. We suggest that this succession may be an important mechanism that allows large diatoms, rather than picophytoplankton, to become the dominant primary producers during the subarctic Atlantic spring bloom
Original languageEnglish
JournalAquatic Microbial Ecology
Volume78
Pages (from-to)161-176
ISSN0948-3055
DOIs
StatePublished - 2017

 

Managing living marine resources in a dynamic environment: the role of seasonal to decadal climate forecasts

År: 2017

Managing living marine resources in a dynamic environment: the role of seasonal to decadal climate forecasts

Tommasi, D., Stock, C. A., Hobday, A. J., Methot, R., Kaplan, I. C., Paige Eveson, J., Holsman, K., Miller, T. J., Gaichas, S., Gehlen, M., Pershing, A., Vecchi, G. A., Msadek, R., Delworth, T., Mark Eakin, C., Haltuch, M. A., Séférian, R., Spillman, C. M., Hartog, J. R., Siedlecki, S., Samhouri, J. F., Muhling, B., Asch, R. G., Pinsky, M. L., Saba, V. S., Kapnick, S. B., Gaitan, C. F., Rykaczewski, R. R., Alexander, M. A., Xue, Y., Pegion, K. V., Lynch, P., Payne, M., Kristiansen, T., Lehodey, P. & Werner, F. E. 2017 In : Progress in Oceanography. 152, p. 15-49

Publication: Research - peer-reviewReview – Annual report year: 2017

Recent developments in global dynamical climate prediction systems have allowed for skillful predictions of climate variables relevant to living marine resources (LMRs) at a scale useful to understanding and managing LMRs. Such predictions present opportunities for improved LMR management and industry operations, as well as new research avenues in fisheries science. LMRs respond to climate variability via changes in physiology and behavior. For species and systems where climate-fisheries links are well established, forecasted LMR responses can lead to anticipatory and more effective decisions, benefitting both managers and stakeholders. Here, we provide an overview of climate prediction systems and advances in seasonal to decadal prediction of marine-resource relevant environmental variables. We then describe a range of climate-sensitive LMR decisions that can be taken at lead-times of months to decades, before highlighting a range of pioneering case studies using climate predictions to inform LMR decisions. The success of these case studies suggests that many additional applications are possible. Progress, however, is limited by observational and modeling challenges. Priority developments include strengthening of the mechanistic linkages between climate and marine resource responses, development of LMR models able to explicitly represent such responses, integration of climate driven LMR dynamics in the multi-driver context within which marine resources exist, and improved prediction of ecosystem-relevant variables at the fine regional scales at which most marine resource decisions are made. While there are fundamental limits to predictability, continued advances in these areas have considerable potential to make LMR managers and industry decision more resilient to climate variability and help sustain valuable resources. Concerted dialog between scientists, LMR managers and industry is essential to realizing this potential
Original languageEnglish
JournalProgress in Oceanography
Volume152
Pages (from-to)15-49
ISSN0079-6611
DOIs
StatePublished - 2017

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A trait database for marine copepods

År: 2017

A trait database for marine copepods

Brun, P. G., Payne, M. & Kiørboe, T. 2017 In : Earth System Science Data. 9, p. 99-113

Publication: Research - peer-reviewJournal article – Annual report year: 2017

The trait-based approach is gaining increasing popularity in marine plankton ecology but the field urgently needs more and easier accessible trait data to advance.We compiled trait information on marine pelagic copepods, a major group of zooplankton, from the published literature and from experts and organized the data into a structured database. We collected 9306 records for 14 functional traits. Particular attention was given to body size, feeding mode, egg size, spawning strategy, respiration rate, and myelination (presence of nerve
sheathing). Most records were reported at the species level, but some phylogenetically conserved traits, such as myelination, were reported at higher taxonomic levels, allowing the entire diversity of around 10 800 recognized
marine copepod species to be covered with a few records. Aside from myelination, data coverage was highest for spawning strategy and body size, while information was more limited for quantitative traits related to reproduction and physiology. The database may be used to investigate relationships between traits, to produce trait biogeographies, or to inform and validate trait-based marine ecosystem models. The data can be downloaded
from PANGAEA, doi:10.1594/PANGAEA.862968
Original languageEnglish
JournalEarth System Science Data
Volume9
Pages (from-to)99-113
ISSN1866-3508
DOIs
StatePublished - 2017

 

How do individuals cope with stress? Behavioural, physiological and neuronal differences between proactive and reactive coping styles in fish

År: 2017

How do individuals cope with stress? Behavioural, physiological and neuronal differences between proactive and reactive coping styles in fish

Vindas, M. A., Gorissen, M., Höglund, E., Flik, G., Tronci, V., Damsgård, B., Thörnqvist, P-O., Nilsen, T. O., Winberg, S., Øverli, Ø. & Ebbesson, L. O. E. 2017 In : Journal of Experimental Biology. jeb.153213

Publication: Research - peer-reviewJournal article – Annual report year: 2017

Despite the use of fish models to study human mental disorders and dysfunctions, knowledge of regional telencephalic responses in non-mammalian vertebrates expressing alternate stress coping styles is poor. Since perception of salient stimuli associated with stress coping in mammals is mainly under forebrain limbic control, we tested region-specific forebrain neural (i.e mRNA abundance and monoamine neurochemistry) and endocrine responses at basal and acute stress conditions for previously characterised proactive and reactive Atlantic salmon. Reactive fish show a higher degree of the neurogenesis marker proliferating cell nuclear antigen (pcna) and dopamine activity under basal conditions in Dl (proposed hippocampus homologue) and higher post-stress plasma cortisol levels. Proactive fish displayed post-stress higher serotonergic signalling (i.e. higher serotonergic activity and expression of the 5-HT1A receptor abundance) in the proposed amygdala homologue (Dm), increased expression of the neuroplasticity marker brain derived neurotropic factor (bdnf) in both Dl and Vv (lateral septum homologue), as well as increased expression of the corticotropin releasing factor 1 (crf1) receptor in the Dl, in line with active coping neuro-profiles reported in the mammalian literature. We present novel evidence of proposed functional equivalences in the fish forebrain with mammalian limbic structures.
Original languageEnglish
Article numberjeb.153213
JournalJournal of Experimental Biology
ISSN0022-0949
DOIs
StateE-pub ahead of print - 2017

 

Vildt, vildere – Villestrup Å

År: 2017

Vildt, vildere – Villestrup Å

Aarestrup, K., Nielsen, J. & Sivebæk, F. 2017 .

Publication: CommunicationInternet publication – Annual report year: 2017

Original languageDanish
Publication date2017
Source/PublisherFiskepleje.dk
StatePublished - 2017