Warming and trophic structure tightly control phytoplankton bloom amplitude, composition and succession.

To better identify the responses of phytoplankton blooms to warming conditions as expected in a climate change context, an in situ mesocosm experiment was carried out in a coastal Mediterranean lagoon (Thau Lagoon, South of France) in April 2018. Our objective was to assess both the direct and indirect effects of warming on phytoplankton, particularly those mediated by top-down control. Four treatments were applied: 1) natural planktonic community with ambient water temperature (C); 2) natural planktonic community at +3°C elevated temperature (T); 3) exclusion of larger zooplankton (> 200 µm; mesozooplankton) leaving microzooplankton predominant with ambient water temperature (MicroZ); and 4) exclusion of larger zooplankton (> 200 µm; mesozooplankton) at +3°C elevated temperature (TMicroZ). Warming strongly depressed the amplitude of the phytoplankton bloom as the chlorophyll a concentration was twice lower in the T treatment. This decline under warmer conditions was most likely imputed to increase top-down control by zooplankton. However, removal of mesozooplankton resulted in an opposite trend, with a higher bloom amplitude observed under warmer conditions (MicroZ vs. TMicroZ) pointing at a strong interplay between micro- and mesozooplankton and the effect of warming for the spring phytoplankton blooms. Furthermore, both warming and mesozooplankton exclusion induced shifts in phytoplankton community composition during bloom and post-bloom periods, favoring dinoflagellates and small green algae at the expense of diatoms and prymnesiophytes. Moreover, warming altered phytoplankton succession by promoting an early bloom of small green flagellates, and a late bloom of diatoms. Our findings clearly highlighted the sensitivity of phytoplankton blooms amplitudes, community composition and succession patterns to temperature increases, as well as the key role of initial zooplankton community composition to elicit opposite response in bloom dynamics. It also points out that warmer conditions might favor dinoflagellates and small green algae, irrespective of zooplankton community composition, with potential implications for food web dynamics and energy transfer efficiency under future ocean condition.

Functional and structural responses of plankton communities toward consecutive experimental heatwaves in Mediterranean coastal waters.

The frequency of marine heatwaves (HWs) is projected to increase in the Mediterranean Sea over the next decades. An in situ mesocosm experiment was performed in a Mediterranean lagoon for 33 days. Three mesocosms were used as controls following the natural temperature of the lagoon. In three others, two HWs of + 5 °C compared to the controls were applied from experimental day (d) 1 to d5 (HW1) and from d11 to d15 (HW2). High-frequency data of oxygen, chlorophyll-a (chl-a), temperature, salinity and light from sensors immersed in all mesocosms were used to calculate gross primary production (GPP), respiration (R) and phytoplankton growth (µ) and loss (L) rates. Nutrients and phytoplankton community structure from pigments were also analyzed. HW1 significantly increased GPP, R, chl-a, µ and L by 7 to 38%. HW2 shifted the system toward heterotrophy by only enhancing R. Thus, the effects of the first HW resulted in the attenuation of those of a second HW on phytoplankton processes, but not on community respiration, which was strongly regulated by temperature. In addition, natural phytoplankton succession from diatoms to haptophytes was altered by both HWs as cyanobacteria and chlorophytes were favored at the expense of haptophytes. These results indicate that HWs have pronounced effects on Mediterranean plankton communities.

Metabolic responses of plankton to warming during different productive seasons in coastal Mediterranean waters revealed by in situ mesocosm experiments.

The response of coastal lagoon plankton communities to warming was studied during two in situ mesocosm experiments in spring and fall of 2018 in the Mediterranean. Phytoplankton biomass, gross primary production (GPP), community respiration (R), phytoplankton growth (µ), and loss (l) rates were estimated using high-frequency chlorophyll-a fluorescence and dissolved oxygen sensors, and daily sampling was used to evaluate the nutrient status and phytoplankton pigment functional groups. Warming strongly depressed the dominant phytoplankton functional groups, mainly the prymnesiophytes, diatoms (spring), and green flagellates (fall). It favored minor groups such as the dinoflagellates (spring) and diatoms (fall). In spring, warming depressed GPP and R by half; however, µ (+ 18%) and l (+ 37%) were enhanced. In contrast, both GPP and µ were enhanced by 21% and 28%, respectively, in fall, and no effects were observed for R and l. Warming strongly decreased phytoplankton biomass and oxygen production in spring, and enhanced them, to a lesser extent, in fall. This led to an overall loss of production over both seasons. This study improves understanding of the contrasting effects of warming during two productive seasons, which depend on plankton community composition and interactions between components and environmental conditions.

Co-occurrence networks reveal the central role of temperature in structuring the plankton community of the Thau Lagoon.

To identify the environmental factors that drive plankton community composition and structure in coastal waters, a shallow northwestern Mediterranean lagoon was monitored from winter to spring in two contrasting years. The campaign was based on high-frequency recordings of hydrological and meteorological parameters and weekly samplings of nutrients and the plankton community. The collected data allowed the construction of correlation networks, which revealed that water temperature was the most important factor governing community composition, structure and succession at different trophic levels, suggesting its ubiquitous food web control. Temperature favoured phytoplanktonic flagellates (Cryptophyceae, Chrysophyceae, and Chlorophyceae) and ciliates during winter and early spring. In contrast, it favoured Bacillariophyceae, dinoflagellates, phytoplankton < 6 µm and aloricate Choreotrichida during spring. The secondary factors were light, which influenced phytoplankton, and wind, which may regulate turbidity and the nutrient supply from land or sediment, thus affecting benthic species such as Nitzschia sp. and Uronema sp. or salinity-tolerant species such as Prorocentrum sp. The central role of temperature in structuring the co-occurrence network suggests that future global warming could deeply modify plankton communities in shallow coastal zones, affecting whole-food web functioning.

In situ characterisation of pathogen dynamics during a Pacific oyster mortality syndrome episode.

Significant mortality of Crassostrea gigas juveniles is observed systematically every year worldwide. Pacific Oyster Mortality Syndrome (POMS) is caused by Ostreid Herpesvirus 1 (OsHV-1) infection leading to immune suppression, followed by bacteraemia caused by a consortium of opportunistic bacteria. Using an in-situ approach and pelagic chambers, our aim in this study was to identify pathogen dynamics in oyster flesh and in the water column during the course of a mortality episode in the Mediterranean Thau lagoon (France). OsHV-1 concentrations in oyster flesh increased before the first clinical symptoms of the disease appeared, reached maximum concentrations during the moribund phase and the mortality peak. The structure of the bacterial community associated with oyster flesh changed in favour of bacterial genera previously associated with oyster mortality including Vibrio, Arcobacter, Psychrobium, and Psychrilyobacter. During the oyster mortality episode, releases of OsHV-1 and opportunistic bacteria were observed, in succession, in the water surrounding the oyster lanterns. These releases may favour the spread of disease within oyster farms and potentially impact other marine species, thereby reducing marine biodiversity in shellfish farming areas.

Surface ocean microbiota determine cloud precursors.

One pathway by which the oceans influence climate is via the emission of sea spray that may subsequently influence cloud properties. Sea spray emissions are known to be dependent on atmospheric and oceanic physicochemical parameters, but the potential role of ocean biology on sea spray fluxes remains poorly characterized. Here we show a consistent significant relationship between seawater nanophytoplankton cell abundances and sea-spray derived Cloud Condensation Nuclei (CCN) number fluxes, generated using water from three different oceanic regions. This sensitivity of CCN number fluxes to ocean biology is currently unaccounted for in climate models yet our measurements indicate that it influences fluxes by more than one order of magnitude over the range of phytoplankton investigated.

Understanding barriers and facilitators to participation in colorectal cancer screening: A French qualitative study.

Based on the theory of social representations, this study aims to identify the main determinants to participation in colorectal cancer screening. Six focus groups (N = 29 participants belonging to the general population) were conducted, followed by a theoretical thematic analysis. Screening obstacles are a lack of test's accessibility, a low preoccupation for prevention and the negative image of colorectal cancer. Conversely, screening facilitators are the ease of the new test, being encouraged to get screened and appointment reminder. This study advances understanding of adherence to screening by addressing the beliefs and knowledge surrounding it.

Brief Hospital Supervision of Exercise and Diet During Adjuvant Breast Cancer Therapy Is Not Enough to Relieve Fatigue: A Multicenter Randomized Controlled Trial.

Supervised exercise dietary programs are recommended to relieve cancer-related fatigue and weight increase induced by adjuvant treatment of early breast cancer (EBC). As this recommendation lacks a high level of evidence, we designed a multicenter randomized trial to evaluate the impact of an Adapted Physical Activity Diet (APAD) education program on fatigue. We randomized 360 women with EBC who were receiving adjuvant chemotherapy and radiotherapy to APAD or usual care at eight French cancer institutions. Data were collected at baseline, end of chemotherapy, end of radiotherapy, and 6 months post-treatment. The primary endpoint was the general cancer-related fatigue score using the MFI-20 questionnaire. Fatigue correlated with the level of precariousness, but we found no significant difference between the two groups in terms of general fatigue (p = 0.274). The APAD arm has a smaller proportion of patients with confirmed depression at the end of follow-up (p = 0.052). A transient modification in physical activity levels and dietary intake was reported in the experimental arm. However, a mixed hospital- and home-based APAD education program is not enough to improve fatigue caused by adjuvant treatment of EBC. Cancer care centers should consider integrating more proactive diet-exercise supportive care in this population, focusing on precarious patients.

Water temperature drives phytoplankton blooms in coastal waters.

Phytoplankton blooms are an important, widespread phenomenon in open oceans, coastal waters and freshwaters, supporting food webs and essential ecosystem services. Blooms are even more important in exploited coastal waters for maintaining high resource production. However, the environmental factors driving blooms in shallow productive coastal waters are still unclear, making it difficult to assess how environmental fluctuations influence bloom phenology and productivity. To gain insights into bloom phenology, Chl a fluorescence and meteorological and hydrological parameters were monitored at high-frequency (15 min) and nutrient concentrations and phytoplankton abundance and diversity, were monitored weekly in a typical Mediterranean shallow coastal system (Thau Lagoon). This study was carried out from winter to late spring in two successive years with different climatic conditions: 2014/2015 was typical, but the winter of 2015/2016 was the warmest on record. Rising water temperature was the main driver of phytoplankton blooms. However, blooms were sometimes correlated with winds and sometimes correlated with salinity, suggesting nutrients were supplied by water transport via winds, saltier seawater intake, rain and water flow events. This finding indicates the joint role of these factors in determining the success of phytoplankton blooms. Furthermore, interannual variability showed that winter water temperature was higher in 2016 than in 2015, resulting in lower phytoplankton biomass accumulation in the following spring. Moreover, the phytoplankton abundances and diversity also changed: cyanobacteria (< 1 µm), picoeukaryotes (< 1 µm) and nanoeukaryotes (3-6 µm) increased to the detriment of larger phytoplankton such as diatoms. Water temperature is a key factor affecting phytoplankton bloom dynamics in shallow productive coastal waters and could become crucial with future global warming by modifying bloom phenology and changing phytoplankton community structure, in turn affecting the entire food web and ecosystem services.

Why do women fast during breast cancer chemotherapy? A qualitative study of the patient experience.

BACKGROUND: Why do patients practice fasting? The effects of fasting before treatment with chemotherapy for cancer in humans are currently unknown. However, there is an apparent enthusiasm for fasting among cancer patients. This qualitative study provides data on the motivations to fast and the experience of fasting among a population of women with breast cancer. METHOD: Sixteen semi-structured interviews were conducted, and two researchers independently performed a thematic analysis. To ensure the internal validity of the study, patients had the possibility to rate their agreement with the study results through a satisfaction questionnaire. RESULTS: Six main themes were identified in this study: main reasons to fast, alternative authorities to the oncologist, adapting the fast to social and lifestyle constraints, fasting effects felt during chemotherapy, barriers and facilitators of fasting during chemotherapy, and seeking for a more integrative medicine. Patients' primary motivation to fast was to lower the negative side effects of chemotherapy. Fasting was also reported as a coping strategy to give them a greater sense of control over their treatment and to reduce their anxiety. CLINICAL IMPLICATIONS: Results from the study suggest that, if discouraged from fasting, patients may turn to complementary health care practitioners for support. Medical professionals may thus not know of patients' fasting practice. Health psychologists could play a key role fostering the dialogue between different health professionals and the patient. They could also help to meet patients' needs during cancer treatment to reduce treatment anxiety. Statement of contribution What is already known on this subject? Fasting diet in cancer treatment has become an important topic since Raffaghello et al. published their study on mice in 2008. While the (positive) effects of fasting in humans remain to be proven, there has been a significant enthusiasm for this practice among patients in the last few years. However, patients' motivations to fast remain unclear to the scientific community and clinicians. What does this study add? This study is the first to investigate patients' motivations to fast and patients' experience of fasting in a cancer population. Patients' primary motivation to fast was to lower the side effects of chemotherapy. Fasting acts as an active coping strategy that helps to reduce anxiety. Unsupported patients may turn to complementary health care practitioners.

Fasting and weight-loss restrictive diet practices among 2,700 cancer survivors: results from the NutriNet-Santé cohort.

Nutrition is often used by cancer survivors as a lever to take charge of their own health. However, some dietary behaviors are not currently recommended for patients without medical supervision. Our study aimed at evaluating weight-loss restrictive diets and fasting practices among cancer survivors of the NutriNet-Santé cohort, as well as related socio-demographic and lifestyle factors. In October 2016, 2,741 cancer survivors had completed a specific questionnaire about their practices. Fasting and non-fasting patients (respectively dieting and non-dieting) were compared using logistic regression models. Analyses were weighted according to the age, gender, and cancer location distribution of French cancer cases. 13.8% had already practiced weight-loss restrictive diet as their diagnosis. They were more likely to be women, professionally active, overweight/obese, to use dietary supplements and to have breast cancer (all p < 0.05). 6.0% had already fasted, 3.5% as their diagnosis. They were more likely to be younger, with higher educational level, higher incomes, professionally active, to have a healthy weight, and to use dietary supplements (all p < 0.05). Fasting was associated with the opinion that such practice could improve cancer prognosis (p < 0.0001). Patients who received nutritional information from health care professionals were less likely to practice fasting or weight-loss restrictive diet (0.42[0.27-0.66], p < 0.0001 and 0.49[0.38-0.64], p < 0.0001 respectively). Our study provided original results suggesting that weight-loss restrictive diets are widely practiced by cancer survivors. Fasting was less common in our study though non negligible. Sources of nutritional information received as cancer diagnosis seemed to be a key determinant of these practices.

Determinants of physical activity promotion by smoking cessation advisors.

OBJECTIVE: To investigate the cross-sectional association between personal physical activity (PA) level, Theory of Planned Behavior (TPB) constructs toward PA promotion, and PA promotion behavior among smoking cessation advisors. METHOD: 149 smoking cessation advisors were invited to complete online questionnaires. Hypotheses were tested using Bayesian path analysis. RESULTS: Attitudes and perceived behavioral control (PBC) of smoking cessation advisors were related to PA promotion intentions; intentions were in turn related to PA promotion behaviors. Advisors' personal PA level was indirectly associated with PA promotion behaviors through PBC and PA promotion intentions. CONCLUSION: The TPB is a relevant theoretical framework with which to explore determinants of PA promotion behavior among smoking cessation advisors. The PA level of health care professionals may be linked to PA promotion behavior through some TPB constructs. PRACTICE IMPLICATIONS: Smoking cessation advisor training should include education on attitude development (e.g., PA benefits on smoking cessation), PBC (e.g., modality of PA prescription) and PA promotion intentions (e.g., goal setting). Smoking cessation advisors should also be encouraged to regularly practice PA in order to improve their PA promotion behaviors.

Simulation Method Linking Dense Microalgal Culture Spectral Properties in the 400-750 nm Range to the Physiology of the Cells.

This work describes a method to model the optical properties over the (400-750 nm) spectral range of a dense microalgal culture using the chemical and physical properties of the algal cells. The method was based on a specific program called AlgaSim coupled with the adding-doubling method: at the individual cell scale, AlgaSim simulates the spectral properties of one model, three-layer spherical algal cell from its size and chemical composition. As a second step, the adding-doubling method makes it possible to retrieve the total transmittance of the algal medium from the optical properties of the individual algal cells. The method was tested by comparing the simulated total transmittance spectra for dense marine microalgal cultures of Isochrysis galbana (small flagellates) and Phaeodactylum tricornutum (diatoms) to spectra measured using an experimental spectrophotometric setup. Our study revealed that the total transmittance spectra simulated for the quasi-spherical cells of Isochrysis galbana were in good agreement with the measured spectra over the whole spectral range. For Phaeodactylum tricornutum, large differences between simulated and measured spectra were observed over the blue part of the transmittance spectra, probably due to non-spherical shape of the algal cells. Prediction of the algal cell density, mean size and pigment composition from the total transmittance spectra measured on algal samples was also investigated using the reversal of the method. Mean cell size was successfully predicted for both species. The cell density was also successfully predicted for spherical Isochrysis galbana, with a relative error below 7%, but not for elongated Phaeodactylum tricornutum with a relative error up to 26%. The pigments total quantity and composition, the carotenoids:chlorophyll ratio in particular, were also successfully predicted for Isochrysis galbana with a relative error below 8%. However, the pigment predictions and measurements for Phaeodactylum tricornutum showed large discrepancies, with a relative error up to 88%. These results give strong support for the development of a promising tool providing rapid and accurate estimations of biomass and physiological status of a dense microalgal culture based on only light transmittance properties.

Barriers to, and Facilitators of Physical Activity in Patients Receiving Chemotherapy for Lung Cancer: An exploratory study.

AIM: Physical activity (PA) has a positive effect on the cardiorespiratory fitness, lung cancer symptoms, and quality of life of lung cancer patients. The aim of our study was to identify barriers to, and facilitators of PA in lung cancer patients. METHODS: We collected data from five patients diagnosed with primary, advanced non-small-cell lung cancer (NSCLC) who were receiving chemotherapy. Choosing a qualitative approach, we conducted an exploratory analysis using the thematic analysis technique to process the data. RESULTS: Seven barriers to, and facilitators of PA were identified and grouped into four categories. We found that psychological and social factors affect patients' willingness and ability to engage in PA, while physiological and environmental factors have an impact on the duration, intensity, and regularity of their PA. CONCLUSION: Our study highlighted some of the effects that the barriers to PA have on the practice of it in our patient group. Our findings may be used by professionals to design adapted PA programs.

Significance of plankton community structure and nutrient availability for the control of dinoflagellate blooms by parasites: a modeling approach.

Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole.

DIEL VARIATIONS IN OPTICAL PROPERTIES OF IMANTONIA ROTUNDA (HAPTOPHYCEAE) AND THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) EXPOSED TO DIFFERENT IRRADIANCE LEVELS(1).

Diel variations of cellular optical properties were examined for cultures of the haptophyte Imantonia rotunda N. Reynolds and the diatom Thalassiosira pseudonana (Hust.) Hasle et Heimdal grown under a 14:10 light:dark (L:D) cycle and transferred from 100 µmol photons · m(-2) · s(-1) to higher irradiances of 250 and 500 µmol photons · m(-2) · s(-1) . Cell volume and abundance, phytoplankton absorption coefficients, flow-cytometric light scattering and chl fluorescence, and pigment composition were measured every 2 h over a 24 h period. Results showed that cell division was more synchronous for I. rotunda than for T. pseudonana. Several variables exhibited diel variability with an amplitude >100%, notably mean cell volume for the haptophyte and photoprotective carotenoids for both species, while optical properties such as flow-cytometric scattering and chl a-specific phytoplankton absorption generally showed <50% diel variability. Increased irradiance induced changes in pigments (both species) and mean cell volume (for the diatom) and amplified diel variability for most variables. This increase in amplitude is larger for pigments (factor of 2 or more, notably for cellular photoprotective carotenoid content in I. rotunda and for photosynthetic pigments in T. pseudonana) than for optical properties (a factor of 1.5 for chl a-specific absorption, at 440 nm, in I. rotunda and a factor of 2 for the absorption cross-section and the chl a-specific scattering in T. pseudonana). Consequently, diel changes in optical properties and pigmentation associated with the L:D cycle and amplified by concurrent changes in irradiance likely contribute significantly to the variability in optical properties observed in biooptical field studies.