Towards an Understanding of Diel Feeding Rhythms in Marine Protists: Consequences of Light Manipulation

Arias, Anna; Saiz, Enric; Calbet, Albert

doi:10.1007/s00248-019-01390-y

Cited by 13 publications

(18 citation statements)

References 54 publications

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“…K. armiger is known to graze on a greater extent (ca. 9 R. salina grazer −1 d −1 ) compared to the congeneric K. veneficum 54 , thus, perhaps contributing to enhanced nutrient transfer to the predator in our study.…”

Section: Discussionmentioning

confidence: 59%

Effects of prey trophic mode on the gross-growth efficiency of marine copepods: the case of mixoplankton

Traboni

Calbet

Saiz

2020

Sci Rep

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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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Section: Discussionmentioning

confidence: 59%

Effects of prey trophic mode on the gross-growth efficiency of marine copepods: the case of mixoplankton

Traboni

Calbet

Saiz

2020

Sci Rep

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“…We note that the model predicted dynamics of Prochlorococcus , free virus abundance, heterotrophic nanoflagellate abundance, and the percentage of infected cells do not always recapitulate the magnitude of diel oscillations observed. This gap may point to direct light-mediated modulation of life history traits and behavior [16, 17, 18, 19, 20, 21], and/or unaccounted for feedback mechanisms in the model structure. Like our analysis of ECLIP, we find differences in parameter sets between the best fitting generalist and specialist ECLIPSS models that is then recapitulated via analysis of the full suite of coexisting LHS parameter sets (Supplementary Information, Figure S9 and S12-S15) Hence, rather than conclude that a particular parameter set provides the most explanatory power to observed patterns, we seek to identify mechanisms common to those parameter sets that fit the data nearly equally well.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, oscillations arising in other components reflect a combination of instabilities that can arise in nonlinear population models as well as the cascading impacts of such oscillations on the community. Direct incorporation of diel impacts on grazing [16, 18, 21] or viral traits (e.g., adsorption) [76, 19] may be required to mechanistically understand population dynamics on sub-daily timescales. Second, we have used two focal processes to examine ways that carbon and nutrients in basal picoplankton are transferred, e.g., up through the food chain via grazing or retained in the microbial loop due to viral lysis (aka the viral shunt) [77, 78].…”

Section: Discussionmentioning

confidence: 99%

“…Cyanobacterial population dynamics are influenced by both nutrients and light availability [2, 3, 4, 5, 6, 7, 8] as well as by density- and size-dependent feedback processes with other components of the community [9, 10, 11, 12, 13, 14, 15]. These interactions lead to diel oscillations, including in grazing rates, viral abundances, viral infection rates, and viral activity [16, 17, 18, 19, 20, 21]. The emergence of diel rhythms in abundances and process rates raises the question: how does light-driven growth of photoautotrophs over day-night cycles influence oscillations of other microbial populations and ecosystem processes?…”

Section: Introductionmentioning

confidence: 99%

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Disentangling top-down drivers of mortality underlying diel population dynamics ofProchlorococcusin the North Pacific Subtropical Gyre

Beckett

Demory

et al. 2021

Preprint

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Marine ecosystem models often consider temporal dynamics on the order of months to years, and spatial dynamics over regional and global scales as a means to understand the ecology, evolution, and biogeochemical impacts of marine life. Large-scale dynamics are themselves driven over diel scales as a result of light-driven forcing, feedback, and interactions. Motivated by high-frequency measurements taken by Lagrangian sampling in the North Pacific Subtropical Gyre, we develop a hierarchical set of multitrophic community ecology models to investigate and understand daily ecological dynamics in the near-surface ocean including impacts of light-driven growth, infection, grazing, and phytoplankton size structure. Using these models, we investigate the relative impacts of viral-induced and grazing mortality for Prochlorococcus; and more broadly compare in silico dynamics with in situ observations. Via model-data fitting, we show that a multi-trophic model with size structure can jointly explain diel changes in cyanobacterial abundances, cyanobacterial size structure, viral abundance, viral infection rates, and grazer abundances. In doing so, we find that a significant component (between 5% to 55%) of estimated Prochlorococcus mortality is not attributed to either viral lysis (by T4- or T7-like cyanophage) or grazing by heterotrophic nanoflagellates. Instead, model-data integration suggests a heightened ecological relevance of other mortality mechanisms -- including grazing by other predators, particle aggregation, and stress-induced loss mechanisms. Altogether, linking mechanistic multitrophic models with high-resolution measurements provides a route for understanding of diel origins of large-scale marine microbial community and ecosystem dynamics.

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“…If Prochlorococcus mortality rates peak around midnight, this may be driven by other grazers or by viruses. While mechanisms underlying the diel rhythmicity of phagotrophic activities are not entirely understood (Arias et al 2019), some studies have suggested mixotrophic grazing is positively tied to photosynthetic activities aided by light (Stoecker 1998), such that more nutrients (prey) are required to keep up with the high photosynthesis rates during later times of the day.…”

Section: Discussionmentioning

confidence: 99%

Plasticity in the grazing ecophysiology of Florenciella (Dichtyochophyceae), a mixotrophic nanoflagellate that consumes Prochlorococcus and other bacteria

Edwards

Schvarcz

et al. 2020

Limnology & Oceanography

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Mixotrophic nanoflagellates can account for more than half of the bacterivory in the sunlit ocean, yet very little is known about their ecophysiology. Here, we characterize the grazing ecology of an open-ocean mixotroph in the genus Florenciella (class Dictyochophyceae). Members of this class were indirectly implicated as major consumers of Prochlorococcus and Synechococcus in the oligotrophic North Pacific Subtropical Gyre, but their phagotrophic capabilities have never been investigated. Our studies showed that Florenciella readily consumed Prochlorococcus, Synechococcus, and heterotrophic bacteria, and that the ingested prey relieved nutrient limitations on growth. Florenciella grew faster (3 d −1) in nitrogen-deplete medium given sufficient live Synechococcus, than in nitrogen-replete K medium (2 d −1), but it did not grow in continuous darkness. Grazing rates were substantially higher under nutrient limitation and showed a hint of diel variability, with rates tending to be highest near the end of the light period. An apparent trade-off between the maximum clearance rate (5 nL Florenciella −1 h −1) and the maximum ingestion rate (up to $ 10 prey cells Florenciella −1 h −1) across experiments suggests that grazing behavior may also vary in response to prey concentration. If the observed grazing rates are representative of other open-ocean mixotrophs, their collective activity could account for a significant fraction of the daily cyanobacterial mortality. This study provides essential parameters for understanding the grazing ecology of a common marine mixotroph and the first characterization of mixotrophic nanoflagellate functional responses when feeding on unicellular cyanobacteria, the dominant marine primary producers in the oligotrophic ocean.

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Towards an Understanding of Diel Feeding Rhythms in Marine Protists: Consequences of Light Manipulation

Cited by 13 publications

References 54 publications

Effects of prey trophic mode on the gross-growth efficiency of marine copepods: the case of mixoplankton

Effects of prey trophic mode on the gross-growth efficiency of marine copepods: the case of mixoplankton

Disentangling top-down drivers of mortality underlying diel population dynamics ofProchlorococcusin the North Pacific Subtropical Gyre

Plasticity in the grazing ecophysiology of Florenciella (Dichtyochophyceae), a mixotrophic nanoflagellate that consumes Prochlorococcus and other bacteria

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