Marine planktonic predator-prey interactions occur in microscale seascapes, where diffusing chemicals may act either as chemotactic cues that enhance or arrest predation, or as elemental resources that are complementary to prey ingestion. The phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) and its degradation products dimethylsulfide (DMS) and acrylate are pervasive compounds with high chemotactic potential, but there is a longstanding controversy over whether they act as grazing enhancers or deterrents. Here, we investigated the chemotactic responses of three herbivorous dinoflagellates to point-sourced, microscale gradients of dissolved DMSP, DMS, and acrylate.
View Article and Find Full Text PDFThe study of a species' thermal tolerance and vital rates responses provides useful metrics to characterize its vulnerability to ocean warming. Under prolonged thermal stress, plastic and adaptive processes can adjust the physiology of organisms. Yet it is uncertain whether the species can expand their upper thermal limits to cope with rapid and extreme changes in environmental temperature.
View Article and Find Full Text PDFWe assessed the effects of nutrient imbalanced diets on the feeding, reproduction and gross-growth efficiency of egg production of the copepod Paracartia grani. The cryptophyte Rhodomonas salina, cultivated under balanced (f/2) and imbalanced growth conditions (N and P limitation), served as prey. Copepod C:N and C:P ratios increased in the imbalanced treatments, particularly under P limitation.
View Article and Find Full Text PDFSudden environmental changes like marine heatwaves will become more intense and frequent in the future. Understanding the physiological responses of mixoplankton and protozooplankton, key members of marine food webs, to temperature is crucial. Here, we studied two dinoflagellates (one protozoo- and one mixoplanktonic), two ciliates (one protozoo- and one mixoplanktonic), and two cryptophytes.
View Article and Find Full Text PDFWe studied the phenotypic response to temperature of the marine copepod at the organismal and cellular levels. First, the acute (2 days) survival, feeding and reproductive performances at 6-35°C were determined. Survival was very high up to ca.
View Article and Find Full Text PDFFront Microbiol
March 2022
Proper thermal adaptation is key to understanding how species respond to long-term changes in temperature. However, this is seldom considered in protozooplankton and mixoplankton experiments. In this work, we studied how two heterotrophic dinoflagellates ( and ), one heterotrophic ciliate (), and one mixotrophic dinoflagellate () responded to warming.
View Article and Find Full Text PDFWe 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.
View Article and Find Full Text PDFPredators can induce changes in the diel activity patterns of marine copepods. Besides vertical migration, diel feeding rhythms have been suggested as an antipredator phenotypic response. We conducted experiments to assess the non-lethal direct effects of the predator (northern krill) on the diel feeding patterns of the calanoid copepod .
View Article and Find Full Text PDFCopepod 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.
View Article and Find Full Text PDFPhagotrophic mixotrophs (mixoplankton) are now widely recognised as important members of food webs, but their role in the functioning of food webs is not yet fully understood. This is due to the lack of a well-established technique to estimate mixotrophic grazing. An immediate step in this direction would be the development of a method that separates mixotrophic from heterotrophic grazing that can be routinely incorporated into the common techniques used to measure microplankton herbivory (e.
View Article and Find Full Text PDFTemporal programs synchronised with the daily cycle are of adaptive importance for organisms exposed to periodic fluctuations. This study deepens into several aspects of the exogenous and endogenous nature of microbial grazers. We investigated the diel rhythms of cell division and feeding activity of four marine protists under different light regimes.
View Article and Find Full Text PDFOligotrophic and productive areas of the ocean differ in plankton community composition and biomass transfer efficiency. Here, we describe the plankton community along a latitudinal transect in the tropical and subtropical Atlantic Ocean. Prochlorococcus dominated the autotrophic community at the surface and mixed layer of oligotrophic stations, replaced by phototrophic picoeukaryotes and Synechococcus in productive waters.
View Article and Find Full Text PDFSuspended sediments are a common occurrence in the marine environment. They can be generated by natural causes, including waves and currents, or brought about by anthropogenic activities such as reclamation and dredging. High sediment concentrations are known to have negative consequences on copepods; however, the impact of sediment size has largely been overlooked.
View Article and Find Full Text PDFA correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.
View Article and Find Full Text PDFPlanktonic copepods are a very successful group in marine pelagic environments, with a key role in biogeochemical cycles. Among them, the genus Oithona is one of the more abundant and ubiquitous. We report here on the effects of caloric (food) restriction on the ageing patterns of the copepod Oithona davisae.
View Article and Find Full Text PDFMixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light.
View Article and Find Full Text PDFWe studied the plankton dynamics of two semi-enclosed marine coastal inlets of the north of Jurong Island separated by a causeway (SW Singapore; May 2012-April 2013). The west side of the causeway (west station) has residence times of ca. one year and is markedly eutrophic.
View Article and Find Full Text PDFWe analyzed the concentrations of trace metals/metalloids (TMs) in the water, sediment and plankton of two semi-enclosed marine coastal inlets located north of Jurong Island and separated by a causeway (SW Singapore; May 2012-April 2013). The west side of the causeway (west station) has residence times of approximately one year, and the east side of the causeway (east station) has residence times of one month. The concentrations of most of the TMs in water and sediment were higher in the west than in the east station.
View Article and Find Full Text PDFFunctional ecology is a subdiscipline that aims to enable a mechanistic understanding of patterns and processes from the organismic to the ecosystem level. This paper addresses some main aspects of the process-oriented current knowledge on phagotrophic, i.e.
View Article and Find Full Text PDFArranging organisms into functional groups aids ecological research by grouping organisms (irrespective of phylogenetic origin) that interact with environmental factors in similar ways. Planktonic protists traditionally have been split between photoautotrophic "phytoplankton" and phagotrophic "microzooplankton". However, there is a growing recognition of the importance of mixotrophy in euphotic aquatic systems, where many protists often combine photoautotrophic and phagotrophic modes of nutrition.
View Article and Find Full Text PDFPlanktonic copepods are a key group in the marine pelagic ecosystem, linking primary production with upper trophic levels. Their abundance and population dynamics are constrained by the life history tradeoffs associated with resource availability, reproduction and predation pressure. The tradeoffs associated with the ageing process and its underlying biological mechanisms are, however, poorly known.
View Article and Find Full Text PDFIntensive sampling at the coastal waters of the central Red Sea during a period of thermal stratification, prior to the main seasonal bloom during winter, showed that vertical patches of prokaryotes and microplankton developed and persisted for several days within the apparently density uniform upper layer. These vertical structures were most likely the result of in situ growth and mortality (e.g.
View Article and Find Full Text PDFWe studied the effects of future climate change scenarios on plankton communities of a Norwegian fjord using a mesocosm approach. After the spring bloom, natural plankton were enclosed and treated in duplicates with inorganic nutrients elevated to pre-bloom conditions (N, P, Si; eutrophication), lowering of 0.4 pH units (acidification), and rising 3°C temperature (warming).
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