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The temperature-size rule states that as the temperature increases, the body size of organisms decreases. This rule has been observed in a wide range of organisms, including marine phytoplankton and it is particularly important to model and predict the effects of global warming on the structure and functioning of marine ecosystems. This is so because the size of marine phytoplankton is a critical trait that determines their ecological and biogeochemical roles in marine ecosystems. The size of marine phytoplankton is also affected by resource availability, which relates to growth rates. Here, we compare the effects of a long-term exposure to several temperatures on the cell size of three marine microalgae during their growth curves. The species chosen were the cryptophyte Rhodomonas salina, the dinoflagellate Heterocapsa niei, and the diatom Conticribra (previously Thalassiosira) weissflogii. All algae conformed the temperature-size rule during all the phases of the growth curve. However, the size variations of the microalgae in each of the phases were species-specific. R. salina and H. niei showed higher volumes in the exponential growth phase than during the decline of growth and early stationary phases. Contrarily, the diatom showed smaller volumes during the exponential phase of growth than during the other phases. Overall, the effects of growth rate on cell size exceeded those of temperature for the expected ocean warming by the end of the century. These results also partially support the higher relevance of resource supply than temperature in explaining the variability of phytoplankton size structure in marine ecosystems

Feeding and egg production rates of the copepods Paracartia grani and Centropages typicus feeding on the dinoflagellate Karlodinium veneficum under different nutrient and trophic conditions. See more details in the Excel file

Feeding rates, fecal production rates, egg production rates and gross-growth efficiencies of the copepod Paracartia grani offered a variety of phytoplankton, protozooplankton and mixoplankton in monodiet. See Excel file for details

The classical dichotomy poses strict autotrophic (phytoplankton) and heterotrophic (zooplankton) protists as the only “engines” at the base of marine food webs. This paradigm has been challenged by the existence of unicellular mixoplankton, able to photosynthesize and predate simultaneously. Due to only recently appraisal, our knowledge on the role of mixoplankton in food webs is still very limited. By laboratory and in silico approaches, this Thesis addressed the effect of protistan mixotrophy on copepods, ubiquitous crustacean zooplankton that act as consumers of protists and as prey for larger predators. The ecophysiological response of the calanoid copepod Paracartia grani to several autotrophic, mixotrophic and heterotrophic diets was examined. In most cases no substantial differences in the copepod vital rates emerged on the basis of the nutrition type, as differences were mainly due to species-specific traits of the prey. Nevertheless, when feeding on the dinoflagellate Karlodinium veneficum grown under contrasting trophic modes (auto- vs mixotrophic), copepod egestion rate and gross-growth efficiency varied significantly. This indicates that mixotrophy in certain protists has the potential to influence nutrient transfer, export and recruitment of next copepod generation. As interesting results had emerged from the species K. veneficum, this dinoflagellate was tested as prey for the calanoid copepods P. grani and Centropages typicus with the aim to investigate the effect of inorganic nutrient limitation (N and P) on the food quality of K. veneficum and to ascertain how these abiotic conditions might influence copepod ecophysiological response. Results show that nutrient-limited mixotrophic K. veneficum had more stable stoichiometric ratios in comparison to autotrophs. Both copepod species ingested and reproduced more when fed nutrient-depleted mixotrophic K. veneficum compared to autotrophic counterparts. In the light of this, it can be concluded that this mi, Doctorat en Sciences agronomiques et ingénierie biologique, info:eu-repo/semantics/nonPublished

MitiCap. Así se llama el proyecto que nació en 2018 gracias a la colaboración entre los pescadores de Port de la Selva, Cadaqués y Formentera junto con científicos del ICM-CSIC. Un proyecto que ha durado 5 años cuyo objetivo principal ha sido testar diferentes medidas para mitigar el impacto de la pesca artesanal

[EN] Mixotrophic organisms can obtain nutrition through photosynthesis and also by capturing prey. According to a new study by scientists from the Institut de Ciències del Mar (ICM-CSIC), this mixt strategy can favour the production of marine resources when there is a lack of nutrients or when human activity modifies their availability., [ES] Los organismos mixótrofos combinan dos formas de alimentación: realizando la fotosíntesis y cazando presas. Según un nuevo estudio del Instituto de Ciencias del Mar (ICM-CSIC), esta estrategia puede favorecer la producción de recursos marinos cuando faltan nutrientes o la actividad humana modifica su disponibilidad, [CAT] Els organismes mixòtrofs combinen dues formes d'alimentació: poden fer la fotosíntesi i capturar preses. Segons un nou estudi de l'Institut de Ciències del Mar del CSIC (ICM-CSIC), aquesta estratègia mixta pot afavorir la producció de recursos marins quan falten nutrients o l’activitat humana en modifica la disponibilitat

Inorganic nutrient limitation affects the stoichiometry and nutritional quality of marine phytoplankton. Mixoplankton, able to photosynthesize and feed simultaneously in the one cell, can compensate shortage of nutrients by phagotrophy, theoretically upgrading their nutritional quality for their predators: the zooplankton. Yet, the additional value that phagotrophy in mixoplankton may provide to support zooplankton growth and recruitment has been poorly explored. Therefore, we investigated the feeding and reproductive performances of the copepods Paracartia grani and Centropages typicus on mono-diets of the dinoflagellate Karlodinium veneficum grown as strict autotroph and as mixotroph, both under N and P depletion, and in nutrient-balanced conditions (f/2 medium; only as autotroph). Feeding and reproduction outputs were generally higher in P. grani than in C. typicus. Both copepod species ingested the mixotrophic K. veneficum at similar rates than the autotrophic ones in either nutrient-limited scenario. However, egg production and recruitment rates generally increased when feeding on mixotrophs, in P. grani on both N- and P-limited diets, and in C. typicus under P limitation. In general, P limitation influenced copepod physiology more than N depletion. Our results show that phagotrophy upgrades nutritional quality in nutrient-limited mixotrophs as prey for copepods compared to the strict autotrophic ones. These findings are among the first reported cases of copepod ingestion in the laboratory on actively feeding mixoplankton, and they highlight the importance of considering the trophic mode of the protist and the response by various zooplanktonic predators when attempting to understand the functioning of marine planktonic food webs., SCOPUS: ar.j, info:eu-repo/semantics/published

Inorganic nutrient limitation affects the stoichiometry and nutritional quality of marine phytoplankton. Mixoplankton, able to photosynthesize and feed simultaneously in the one cell, can compensate shortage of nutrients by phagotrophy, theoretically upgrading their nutritional quality for their predators: the zooplankton. Yet, the additional value that phagotrophy in mixoplankton may provide to support zooplankton growth and recruitment has been poorly explored. Therefore, we investigated the feeding and reproductive performances of the copepods Paracartia grani and Centropages typicus on mono-diets of the dinoflagellate Karlodinium veneficum grown as strict autotroph and as mixotroph, both under N and P depletion, and in nutrient-balanced conditions (f/2 medium; only as autotroph). Feeding and reproduction outputs were generally higher in P. grani than in C. typicus. Both copepod species ingested the mixotrophic K. veneficum at similar rates than the autotrophic ones in either nutrient-limited scenario. However, egg production and recruitment rates generally increased when feeding on mixotrophs, in P. grani on both N- and P-limited diets, and in C. typicus under P limitation. In general, P limitation influenced copepod physiology more than N depletion. Our results show that phagotrophy upgrades nutritional quality in nutrient-limited mixotrophs as prey for copepods compared to the strict autotrophic ones. These findings are among the first reported cases of copepod ingestion in the laboratory on actively feeding mixoplankton, and they highlight the importance of considering the trophic mode of the protist and the response by various zooplanktonic predators when attempting to understand the functioning of marine planktonic food webs

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

¿Qué son las gorgonias? ¿Por qué son tan importantes? ¿Cómo podemos protegerlas? Conoce las respuestas en este vídeo que forma parte de los proyectos ResCap y MitiCap (programa PLEAMAR de la Fundación Biodiversidad)

[EN] Claudia Traboni talks about the amazing world of plankton, with a special focus on the organisms that produce oxygen: phytoplankton and mixoplankton, [ES] Claudia Traboni nos introduce en el apasionante mundo del pláncton, con especial enfoque en los organismos productores de oxígeno: el fitoplancton y el mixoplancton, [IT] Claudia Traboni ci proietta nell'appassionante mondo del plancton, mettendo in primo piano gli organismi produttori di ossigeno: il fitoplancton ed il mixoplancton

Many protist plankton are mixotrophs, combining phototrophy and phagotrophy. Their role in freshwater and marine ecology has emerged as a major developing feature of plankton research over recent decades. To better aid discussions, we suggest these organisms are termed “mixoplankton”, as “planktonic protist organisms that express, or have potential to express, phototrophy and phagotrophy”. The term “phytoplankton” then describes phototrophic organisms incapable of phagotrophy. “Protozooplankton” describes phagotrophic protists that do not engage in acquired phototrophy. The complexity of the changes to the conceptual base of the plankton trophic web caused by inclusion of mixoplanktonic activities are such that we suggest that the restructured description is termed the “mixoplankton paradigm”. Implications and opportunities for revision of survey and fieldwork, of laboratory experiments and of simulation modelling are considered. The main challenges are not only with taxonomic and functional identifications, and with measuring rates of potentially competing processes within single cells, but with decades of inertia built around the traditional paradigm that assumes a separation of trophic processes between different organisms. In keeping with the synergistic nature of cooperative photo- and phagotrophy in mixoplankton, a comprehensive multidisciplinary approach will be required to tackle the task ahead., Many protist plankton are mixotrophs, combining phototrophy and phagotrophy. Their role in freshwater and marine ecology has emerged as a major developing feature of plankton research over recent decades. To better aid discussions, we suggest these organisms are termed “mixoplankton”, as “planktonic protist organisms that express, or have potential to express, phototrophy and phagotrophy”. The term “phytoplankton” then describes phototrophic organisms incapable of phagotrophy. “Protozooplankton” describes phagotrophic protists that do not engage in acquired phototrophy. The complexity of the changes to the conceptual base of the plankton trophic web caused by inclusion of mixoplanktonic activities are such that we suggest that the restructured description is termed the “mixoplankton paradigm”. Implications and opportunities for revision of survey and fieldwork, of laboratory experiments and of simulation modelling are considered. The main challenges are not only with taxonomic and functional identifications, and with measuring rates of potentially competing processes within single cells, but with decades of inertia built around the traditional paradigm that assumes a separation of trophic processes between different organisms. In keeping with the synergistic nature of cooperative photo- and phagotrophy in mixoplankton, a comprehensive multidisciplinary approach will be required to tackle the task ahead.

MixITiN is training an innovative team of Early Stage Researchers (ESRs) to develop new methodologies for researching, monitoring and managing our marine environment according to the recently revised paradigm for marine pelagic production. MixITiN brings together world-class European research and training centres from 9 different countries, with skillsets from molecular biology, physiology and computer modelling, to marine and coastal zone management, public and media engagement

Ever since I put my head under water at the age of four I realized that I would have a strong connection with the sea. Today, two decades older, I am pursuing a research career in plankton ecology. My journey started in Naples, my hometown, where I studied marine biology and ecology at the Univer-sity “Federico II”. My first oceanogra-phy lecture was enough to give me a dream to follow. I am profoundly fascinated by diversity of marine systems and intrigued by their complexity. This is the reason that has driven me to start investigating relationships oc-curring within plankton communities through research and has also fuelled my artistic passion about drawing. [...]

Many protist plankton are mixotrophs, combining phototrophy and phagotrophy. Their role in freshwater and marine ecology has emerged as a major developing feature of plankton research over recent decades. To better aid discussions, we suggest these organisms are termed “mixoplankton”, as “planktonic protist organisms that express, or have potential to express, phototrophy and phagotrophy”. The term “phytoplankton” then describes phototrophic organisms incapable of phagotrophy. “Protozooplankton” describes phagotrophic protists that do not engage in acquired phototrophy. The complexity of the changes to the conceptual base of the plankton trophic web caused by inclusion of mixoplanktonic activities are such that we suggest that the restructured description is termed the “mixoplankton paradigm”. Implications and opportunities for revision of survey and fieldwork, of laboratory experiments and of simulation modelling are considered. The main challenges are not only with taxonomic and functional identifications, and with measuring rates of potentially competing processes within single cells, but with decades of inertia built around the traditional paradigm that assumes a separation of trophic processes between different organisms. In keeping with the synergistic nature of cooperative photo- and phagotrophy in mixoplankton, a comprehensive multidisciplinary approach will be required to tackle the task ahead

Many protist plankton are mixotrophs, combining phototrophy and phagotrophy. Their role in freshwater and marine ecology has emerged as a major developing feature of plankton research over recent decades. To better aid discussions, we suggest these organisms are termed “mixoplankton”, as “planktonic protist organisms that express, or have potential to express, phototrophy and phagotrophy”. The term “phytoplankton” then describes phototrophic organisms incapable of phagotrophy. “Protozooplankton” describes phagotrophic protists that do not engage in acquired phototrophy. The complexity of the changes to the conceptual base of the plankton trophic web caused by inclusion of mixoplanktonic activities are such that we suggest that the restructured description is termed the “mixoplankton paradigm”. Implications and opportunities for revision of survey and fieldwork, of laboratory experiments and of simulation modelling are considered. The main challenges are not only with taxonomic and functional identifications, and with measuring rates of potentially competing processes within single cells, but with decades of inertia built around the traditional paradigm that assumes a separation of trophic processes between different organisms. In keeping with the synergistic nature of cooperative photo- and phagotrophy in mixoplankton, a comprehensive multidisciplinary approach will be required to tackle the task ahead., info:eu-repo/semantics/published

A manual for the isolation and maintenance of mixoplankton is provided that offer guidelines to assist students and scientists initiating studies of mixoplankton. The manual contains specific information on: Facilities required, including temperature regulated rooms or cabinets, instruments and consumables Growth media and aseptic precautions General methods and recommendation for isolation of cells from nature and subsequent establishment of cell cultures Specific recommendation for the isolation and culture of different mixoplankton functional groups