1
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Beckett SJ, Demory D, Coenen AR, Casey JR, Dugenne M, Follett CL, Connell P, Carlson MCG, Hu SK, Wilson ST, Muratore D, Rodriguez-Gonzalez RA, Peng S, Becker KW, Mende DR, Armbrust EV, Caron DA, Lindell D, White AE, Ribalet F, Weitz JS. Disentangling top-down drivers of mortality underlying diel population dynamics of Prochlorococcus in the North Pacific Subtropical Gyre. Nat Commun 2024; 15:2105. [PMID: 38453897 PMCID: PMC10920773 DOI: 10.1038/s41467-024-46165-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 02/16/2024] [Indexed: 03/09/2024] Open
Abstract
Photosynthesis fuels primary production at the base of marine food webs. Yet, in many surface ocean ecosystems, diel-driven primary production is tightly coupled to daily loss. This tight coupling raises the question: which top-down drivers predominate in maintaining persistently stable picocyanobacterial populations over longer time scales? Motivated by high-frequency surface water measurements taken in the North Pacific Subtropical Gyre (NPSG), we developed multitrophic models to investigate bottom-up and top-down mechanisms underlying the balanced control of Prochlorococcus populations. We find that incorporating photosynthetic growth with viral- and predator-induced mortality is sufficient to recapitulate daily oscillations of Prochlorococcus abundances with baseline community abundances. In doing so, we infer that grazers in this environment function as the predominant top-down factor despite high standing viral particle densities. The model-data fits also reveal the ecological relevance of light-dependent viral traits and non-canonical factors to cellular loss. Finally, we leverage sensitivity analyses to demonstrate how variation in life history traits across distinct oceanic contexts, including variation in viral adsorption and grazer clearance rates, can transform the quantitative and even qualitative importance of top-down controls in shaping Prochlorococcus population dynamics.
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Affiliation(s)
- Stephen J Beckett
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Biology, University of Maryland, College Park, MD, USA.
| | - David Demory
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Sorbonne Université, CNRS, USR 3579, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, Banyuls-sur-Mer, France.
| | - Ashley R Coenen
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - John R Casey
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Mathilde Dugenne
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Sorbonne Université, CNRS, UMR 7093, Laboratoire d'Océanographie de Villefranche-sur-Mer (LOV), Villefranche-sur-Mer, France
| | - Christopher L Follett
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Paige Connell
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Biology Department, San Diego Mesa College, San Diego, CA, USA
| | - Michael C G Carlson
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
- Department of Biological Sciences, California State University, Long Beach, CA, USA
| | - Sarah K Hu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Oceanography, Texas A&M University, College Station, TX, USA
| | - Samuel T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Daniel Muratore
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Santa Fe Institute, Santa Fe, NM, USA
| | | | - Shengyun Peng
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Adobe, San Jose, CA, USA
| | - Kevin W Becker
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Daniel R Mende
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Laboratory of Applied Evolutionary Biology, Department of Medical Microbiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | | | - David A Caron
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Debbie Lindell
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Angelicque E White
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - François Ribalet
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Joshua S Weitz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Biology, University of Maryland, College Park, MD, USA.
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA.
- Institut de Biologie, École Normale Supérieure, Paris, France.
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2
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Wang C, Dong Y, Denis M, Wei Y, Li H, Zheng S, Zhang W, Xiao T. Diel variations in planktonic ciliate community structure in the northern South China Sea and tropical Western Pacific. Sci Rep 2023; 13:3843. [PMID: 36890185 PMCID: PMC9995376 DOI: 10.1038/s41598-023-30973-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 03/03/2023] [Indexed: 03/10/2023] Open
Abstract
Though diel variations are geographically widespread phenomena among phytoplankton and zooplankton, knowledge is limited regarding diel variations in planktonic ciliate (microzooplankton) community structure. In this study, we analyzed diel variations in community structure of planktonic ciliates in the northern South China Sea (nSCS) and tropical Western Pacific (tWP). Hydrological characteristics during day and night were slightly different over both the nSCS and tWP, while ciliate average abundance at night was clearly higher than in the day in the upper 200 m. In both the nSCS and tWP, abundance proportions of large size-fraction (> 30 μm) aloricate ciliates at night were higher than in the day. While for tintinnids, abundance proportion of large lorica oral diameter at night were lower than in the day. The relationship between environmental factors and ciliate abundance pointed out that depth and temperature were main factors influencing aloricate ciliate and tintinnid in both day and night. For some dominant tintinnid species, chlorophyll a was another important factor influencing their diel vertical distribution. Our results provide fundamental data for better understanding the mechanisms of planktonic ciliate community diel variation in the tropical Western Pacific Ocean.
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Affiliation(s)
- Chaofeng Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Yi Dong
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Michel Denis
- Aix Marseille Université, Université de Toulon, CNRS/INSU, IRD, Institut Méditerranéen d'Océanologie (MIO), 13288, Marseille Cedex 09, France
| | - Yuanyuan Wei
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China
| | - Haibo Li
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Shan Zheng
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Jiaozhou Bay Marine Ecosystem Research Station, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Wuchang Zhang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. .,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China. .,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Tian Xiao
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
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3
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Laglera LM, Uskaikar H, Klaas C, Naqvi SWA, Wolf-Gladrow DA, Tovar-Sánchez A. Dissolved and particulate iron redox speciation during the LOHAFEX fertilization experiment. MARINE POLLUTION BULLETIN 2022; 184:114161. [PMID: 36179387 DOI: 10.1016/j.marpolbul.2022.114161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/15/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
The redox speciation of iron was determined during the iron fertilization LOHAFEX and for the first time, the chemiluminescence assay of filtered and unfiltered samples was systematically compared. We hypothesize that higher chemiluminescence in unfiltered samples was caused by Fe(II) adsorbed onto biological particles. Dissolved and particulate Fe(II) increased in the mixed layer steadily 6-fold during the first two weeks and decreased back to initial levels by the end of LOHAFEX. Both Fe(II) forms did not show diel cycles downplaying the role of photoreduction. The chemiluminescence of unfiltered samples across the patch boundaries showed strong gradients, correlated significantly to biomass and the photosynthetic efficiency and were higher at night, indicative of a biological control. At 150 m deep, a secondary maximum of dissolved Fe(II) was associated with maxima of nitrite and ammonium despite high oxygen concentrations. We hypothesize that during LOHAFEX, iron redox speciation was mostly regulated by trophic interactions.
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Affiliation(s)
- Luis M Laglera
- FI-TRACE, Departamento de Química, Universidad de las Islas Baleares, Palma, Balearic Islands 07122, Spain; Laboratori Interdisciplinari sobre Canvi Climàtic, Universidad de las Islas Baleares, Palma, Balearic Islands 07122, Spain.
| | - Hema Uskaikar
- National Institute of Oceanography, Dona Paula, Goa, India
| | - Christine Klaas
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | | | - Dieter A Wolf-Gladrow
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Antonio Tovar-Sánchez
- Department of Ecology and Coastal Management, Andalusian Institute for Marine Science, ICMAN (CSIC), Campus Universitario Río San Pedro, Puerto Real, Cádiz, Spain
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4
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Ferreira GD, Figueira J, Marques SC, Hansen PJ, Calbet A. The strengths and weaknesses of Live Fluorescently Labelled Algae (LFLA) to estimate herbivory in protozooplankton and mixoplankton. MARINE ENVIRONMENTAL RESEARCH 2022; 174:105558. [PMID: 34998128 DOI: 10.1016/j.marenvres.2022.105558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 12/21/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
The Live Fluorescently Labelled Algae (LFLA) technique has been used numerous times to estimate microzooplankton herbivory. Yet, it is unknown how mixoplankton (i.e., single-cell organisms that can combine phototrophy and phagotrophy) affect the outcome of this technique. Hence, we conducted a broad-spectrum assessment of the strengths and weaknesses of the LFLA technique, using several mixoplanktonic and protozooplanktonic grazers. Species from different taxonomic groups and different feeding mechanisms were tested in short-term experiments (ca. 5 h) in the laboratory, at different prey concentrations and during light and dark periods of the day. Overall, our findings suggest that the LFLA technique, due to its short-term nature, is an effective tracker of diel ingestion and digestion rates, and can detect new mixoplanktonic predators. We recommend that, irrespective of the prey concentration, incubations to measure grazing rates with this technique should generally be concluded within 1 h (adaptable to the environmental temperature). Nevertheless, our results also call for caution whenever using LFLA in the field: feeding mechanisms other than direct engulfment (like peduncle feeding) may provide severely biased ingestion rates. Furthermore, size and species selectivity are very hard to circumvent. To reduce the effects of selectivity, we propose the combined use of two distinctly coloured fluorochromes (i.e., distinct emission spectra). With this modification, one could either label different size ranges of prey or account for species-specific interactions in the food web.
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Affiliation(s)
- Guilherme Duarte Ferreira
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain; Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Joana Figueira
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Sónia Cotrim Marques
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Per Juel Hansen
- Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Albert Calbet
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain.
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5
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Duarte Ferreira G, Romano F, Medić N, Pitta P, Hansen PJ, Flynn KJ, Mitra A, Calbet A. Mixoplankton interferences in dilution grazing experiments. Sci Rep 2021; 11:23849. [PMID: 34903787 PMCID: PMC8668877 DOI: 10.1038/s41598-021-03176-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 11/29/2021] [Indexed: 11/09/2022] Open
Abstract
It remains unclear as to how mixoplankton (coupled phototrophy and phagotrophy in one cell) affects the estimation of grazing rates obtained from the widely used dilution grazing technique. To address this issue, we prepared laboratory-controlled dilution experiments with known mixtures of phyto-, protozoo-, and mixoplankton, operated under different light regimes and species combinations. Our results evidenced that chlorophyll is an inadequate proxy for phytoplankton when mixoplankton are present. Conversely, species-specific cellular counts could assist (although not fully solve) in the integration of mixoplanktonic activity in a dilution experiment. Moreover, cell counts can expose prey selectivity patterns and intraguild interactions among grazers. Our results also demonstrated that whole community approaches mimic reality better than single-species laboratory experiments. We also confirmed that light is required for protozoo- and mixoplankton to correctly express their feeding activity, and that overall diurnal grazing is higher than nocturnal. Thus, we recommend that a detailed examination of initial and final plankton communities should become routine in dilution experiments, and that incubations should preferably be started at the beginning of both day and night periods. Finally, we hypothesize that in silico approaches may help disentangle the contribution of mixoplankton to the community grazing of a given system.
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Affiliation(s)
- Guilherme Duarte Ferreira
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain. .,Marine Biological Section, University of Copenhagen, 3000, Helsingør, Denmark.
| | - Filomena Romano
- Marine Biological Section, University of Copenhagen, 3000, Helsingør, Denmark.,Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 2214, 71003, Heraklion, Greece
| | - Nikola Medić
- Marine Biological Section, University of Copenhagen, 3000, Helsingør, Denmark
| | - Paraskevi Pitta
- Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 2214, 71003, Heraklion, Greece
| | - Per Juel Hansen
- Marine Biological Section, University of Copenhagen, 3000, Helsingør, Denmark
| | - Kevin J Flynn
- Plymouth Marine Laboratory, Prospect Place, Plymouth, PL1 3DH, UK
| | - Aditee Mitra
- School of Earth and Environmental Sciences, Cardiff University, Park Place, Cardiff, CF10 3AT, UK
| | - Albert Calbet
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain
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6
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Arias A, Selander E, Saiz E, Calbet A. Predator Chemical Cue Effects on the Diel Feeding Behaviour of Marine Protists. MICROBIAL ECOLOGY 2021; 82:356-364. [PMID: 33459836 DOI: 10.1007/s00248-020-01665-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 12/14/2020] [Indexed: 06/12/2023]
Abstract
We have assessed the effect of copepod chemical cues on the diel feeding rhythms of heterotrophic and mixotrophic marine protists. All phagotrophic protists studied exhibited relatively high diurnal feeding rates. The magnitude of the diel feeding rhythm, expressed as the quotient of day and night ingestion rates, was inversely related to the time that phagotrophic protists were maintained in the laboratory in an environment without predators. In the case of the recently isolated ciliate Strombidium arenicola, the rhythm was lost after a few months. When challenged with chemical alarm signals (copepodamides) from the copepod Calanus finmarchicus at realistic concentrations (0.6-6 pM), S. arenicola partially re-established diurnal feeding. Conversely, the amplitude of the diel feeding rhythm for the ciliate Mesodinium rubrum was not affected by copepodamides, although the 24-h integrated food intake increased by approximately 23%. For the dinoflagellates Gyrodinium dominans and Karlodinium armiger, copepodamides significantly reduced the amplitude of their diel feeding rhythms; significant positive effects on total daily ingestion were only observed in G. dominans. Finally, the dinoflagellate Oxyrrhis marina, isolated >20 years ago, showed inconsistent responses to copepodamides, except for an average 6% increase in its total ingestion over 24 h. Our results demonstrate that the predation risk by copepods affects the diel feeding rhythm of marine protists and suggests a species-specific response to predation threats.
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Affiliation(s)
- Anna Arias
- Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona, Spain.
| | - Erik Selander
- Department of Marine Sciences, University of Gothenburg, Box 461, SE-450 30, Göteborg, Sweden
| | - Enric Saiz
- Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona, Spain
| | - Albert Calbet
- Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona, Spain
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7
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Koop S, Oster H. Eat, sleep, repeat - endocrine regulation of behavioural circadian rhythms. FEBS J 2021; 289:6543-6558. [PMID: 34228879 DOI: 10.1111/febs.16109] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/23/2021] [Accepted: 07/05/2021] [Indexed: 02/07/2023]
Abstract
The adaptation of organisms to a rhythmic environment is mediated by an internal timing system termed the circadian clock. In mammals, molecular clocks are found in all tissues and organs. This circadian clock network regulates the release of many hormones, which in turn influence some of the most vital behavioural functions. Sleep-wake cycles are under strict circadian control with strong influence of rhythmic hormones such as melatonin, cortisol and others. Food intake, in contrast, receives circadian modulation through hormones such as leptin, ghrelin, insulin and orexin. A third behavioural output covered in this review is mating and bonding behaviours, regulated through circadian rhythms in steroid hormones and oxytocin. Together, these data emphasize the pervasive influence of the circadian clock system on behavioural outputs and its mediation through endocrine networks.
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Affiliation(s)
- Sarah Koop
- Centre of Brain, Behavior and Metabolism, Institute of Neurobiology, University of Lübeck, Germany
| | - Henrik Oster
- Centre of Brain, Behavior and Metabolism, Institute of Neurobiology, University of Lübeck, Germany
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Traboni C, Calbet A, Saiz E. Effects of prey trophic mode on the gross-growth efficiency of marine copepods: the case of mixoplankton. Sci Rep 2020; 10:12259. [PMID: 32704097 PMCID: PMC7378051 DOI: 10.1038/s41598-020-69174-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/08/2020] [Indexed: 11/11/2022] Open
Abstract
Copepod reproductive success largely depends on food quality, which also reflects the prey trophic mode. As such, modelling simulations postulate a trophic enhancement to higher trophic levels when mixotrophy is accounted in planktonic trophodynamics. Here, we tested whether photo-phagotrophic protists (mixoplankton) could enhance copepod gross-growth efficiency by nutrient upgrading mechanisms compared to obligate autotrophs and heterotrophs. To validate the hypothesis, we compared physiological rates of the copepod Paracartia grani under the three functional nutrition types. Ingestion and egg production rates varied depending on prey size and species, regardless of the diet. The gross-growth efficiency was variable and not significantly different across nutritional treatments, ranging from 3 to 25% in the mixoplanktonic diet compared to autotrophic (11–36%) and heterotrophic (8–38%) nutrition. Egg hatching and egestion rates were generally unaffected by diet. Overall, P. grani physiological rates did not differ under the tested nutrition types due to the large species-specific variation within trophic mode. However, when we focused on a single species, Karlodinium veneficum, tested as prey under contrasting trophic modes, the actively feeding dinoflagellate boosted the egestion rate and decreased the copepod gross-growth efficiency compared to the autotrophic ones, suggesting possible involvement of toxins in modulating trophodynamics other than stoichiometric constraints.
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Affiliation(s)
- Claudia Traboni
- Institut de Ciéncies del Mar (ICM-CSIC), Psg. Marítim Barceloneta 37-49, 08003, Barcelona, Spain. .,Laboratoire d'Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, CP221, Boulevard du Triomphe, 1050, Brussels, Belgium.
| | - Albert Calbet
- Institut de Ciéncies del Mar (ICM-CSIC), Psg. Marítim Barceloneta 37-49, 08003, Barcelona, Spain
| | - Enric Saiz
- Institut de Ciéncies del Mar (ICM-CSIC), Psg. Marítim Barceloneta 37-49, 08003, Barcelona, Spain
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