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Chapter 3 :The early life stages of marine fishes
No full textInternational audienceSuccessful recruitment of marine fish in early life history stages determines the abundance and diversity of fish populations in the ocean and, as such, has critical effects on marine ecosystem function and dynamics. However, early life stages are more vulnerable to environmental variability and perturbations, such as changes in temperature, oceanographic conditions, and prey availability, than their adult counterparts, making this phase in the life of a fish highly uncertain. This chapter explores the key paradigms that shape our understanding of fish’s early life history, recruitment dynamics, and the factors that influence the biology and ecology of vulnerable young fish. The chapter also explores the potential effects of climate and ocean changes on the phenology, distribution, abundance, and recruitment of these key life stages. Understanding the complex interactions between young fish, their recruitment potential, ocean habitat, and climate change is crucial to developing strategic management strategies that increase the likelihood of early life survivorship and recruitment success, inclusive of setting climate-informed harvest limits, designing and siting marine protected areas that steward critical spawning and nursery habitat, and developing targeted conservations measures that protect species with early life stages that particularly vulnerable to climate variability
Global and Regional Marine Ecosystem Models Reveal Key Uncertainties in Climate Change Projections
No full textInternational audienceClimate change is affecting ocean temperature, acidity, currents, and primary production, causing shifts in species distributions, marine ecosystems, and ultimately fisheries. Earth system models simulate climate change impacts on physical and biogeochemical properties of future oceans under varying emissions scenarios. Coupling these simulations with an ensemble of global marine ecosystem models has indicated broad decreases of fish biomass with warming. However, regional details of these impacts remain much more uncertain. Here, we employ CMIP5 and CMIP6 climate change impact projections using two Earth system models coupled with four regional and nine global marine ecosystem models in 10 ocean regions to evaluate model agreement at regional scales. We find that models developed at different scales can lead to stark differences in biomass projections. On average, global models projected greater biomass declines by the end of the 21st century than regional models. For both global and regional models, greater biomass declines were projected using CMIP6 than CMIP5 simulations. Global models projected biomass declines in 86% of CMIP5 simulations for ocean regions compared to 50% for regional models in the same ocean regions. In CMIP6 simulations, all global model simulations projected biomass declines in ocean regions by 2100, while regional models projected biomass declines in 67% of the ocean region simulations. Our analysis suggests that improved understanding of the causes of differences between global and regional marine ecosystem model climate change projections is needed, alongside observational evaluation of modeled responses.Key Points- Global marine ecosystem models projected greater biomass declines with climate change than regional marine ecosystem models for many regions- For both global and regional models, greater biomass declines were projected in CMIP6 than CMIP5 and in IPSL versus GFDL simulations- Projected impacts of climate change on marine ecosystems at regional scales are currently less certain than at global scalePlain Language SummaryClimate change is affecting the world's oceans, marine ecosystems, biodiversity, and the ecosystem services that they support, including fisheries that feed millions of people worldwide. Anticipating the impacts of climate change can help society and managers to prepare for, and adapt to, changes ahead. Present understanding of climate change impacts on the world's oceans based on global models indicates a 5% loss in animal biomass with every 1°C that the planet warms. Here, we compare potential future biomass on regional scales that are most relevant for management decisions about sustainable resource use. We used regional scale ecosystem models tailored to the species and fisheries they represent. We compared climate change projections of ocean biomass changes from these regional models to corresponding areas from global models to see how well they agreed. We found key differences in climate change projections of ocean biomass between global and regional models. In some cases, both global and regional models projected biomass declines, while in others global models suggested a decline and regional models an increase. Our study highlights that we need further exploration and understanding of the differences in ocean biomass change between global and regional marine ecosystem models
Vacuum level for opening the streak canal and measurement of machine-induced changes in teat tissue during milking of dairy camels (Camelus dromedarius)
No full textInternational audienceThis research aims to study some of the teat characteristics involved in milkability of dairy camels, including the relationship between teat anatomy and the vacuum needed to open the teat sphincter (VLOTS). It also investigates short-term machine milking-induced changes in teat tissue thickness and teat anatomical characteristics, as well as their implications for udder health in dairy camels. To study VLOTS, 10 dairy camels in mid-lactation (weight: 516.6 ± 19 kg; age: 13.4 ± 3.8 years; parity: 5 ± 1.8; average milk yield: 7.3 ± 0.8 L/day) were used in Experiment 1. VLOTS was measured 4 h after morning milking for all four teats using an apparatus called a vacuumeter, without a liner or pulsation. Measurements were repeated three times at 2-day intervals and considered as repetition. Teat canal length (TCL), teat wall thickness (TWT), teat cistern separation wall thickness (TSWT), teat cistern diameter (TCD), and teat length were measured using ultrasound. Experiment 2 was performed on six dairy camels in late lactation (weight: 460 ± 55.15 kg; age: 10.2 ± 2.4 years; parity: 3.5 ± 1.0; average milk yield: 3.6 ± 0.7 L/day). External teat measurements (length, barrel, and apex diameters) were recorded with a caliper. Pre-and post-milking teat-end thickness (TET) were evaluated with a cutimeter at 2 cm from the teat end. Ultrasound imaging was performed pre-and post-milking to determine TCL, TWT, TCD, and teat apex diameter (TAD). Milk ejection time and total milking duration were recorded. Residual milk volume was estimated after an injection of 10 IU oxytocin. Milk samples were taken for somatic cell count (SCC). The results showed that only 50 teats out of 120 observations exhibited milk flow at a vacuum up to 70 kPa. Teats were divided into three groups: Group 1 included easy-opening teats that opened at a vacuum level of less than 30 kPa; group 2 included teats that were hard to open, requiring a higher vacuum (31 up to 69 kPa); and group 3 included teats that did not show milk flow at a vacuum higher than 70 kPa. The mean VLOTS for groups 1 and 2 were 19.39 ± 0.66 kPa and 47.13 ± 2.14 kPa, respectively. VLOTS was positively and highly correlated with TCL, TWT, and TSWT (r = 0.71, r = 0.62, and r = 0.51, respectively, p < 0.001) and negatively correlated with teat length and diameter (r = -0.50 and r = -0.30, respectively, p < 0.01). Observation of teats immediately after cluster remova
Accounting for relative age effect in sports performance assessment: Developing age-adjusted performance corridors using mixed models
No full textInternational audienceThis study developed a novel statistical approach to account for relative age effect (RAE) on physical performance in young populations. Data from 1715 elite youth French rugby union players (age: mean yrs, sd ; height: mean cm, sd ; mass: mean kg, sd ) were analysed using their 50 m sprint times. Linear mixed models were employed to characterise the relationship between age and physical performance, incorporating log transformations to address non-linearity and additional parameters to refine model accuracy. Confidence intervals around predictions established performance corridors for each age, while estimated individual effects enabled the calculation of personalised progression curves and corridors. The findings provided novel insights into accounting for RAE and underscored the utility of advanced statistical methods in performance assessment. Specifically, the approach addressed non-linearity in progression with respect to both age and performance level, introduced a new performance indicator - the corridors - that integrates chronological and relative age, and provided a personalised framework for tracking athletes, progression over time
Short‐term effects of food waste composts on physicochemical soil quality and horticultural crop production
No full textInternational audienceAimComposts made from food waste will soon become more widespread on the market thanks to the upcoming enforcement of the legal obligation to sort biowaste. Our experiment aims at improving knowledge on the short-term effects of these composts on soils’ physicochemical properties and vegetable crops.MethodsThree composts with contrasting characteristics were tested: a 100% v/v green waste compost (C1), and two composts composed of 50% v/v food waste and 50% v/v green waste, one prepared directly on the soil (C2) and the other from a competing producer who have the French NFU 44-051 (AFNOR NF U 44-051, 2006) certification for an organic amendment (C3). They were applied at a rate of 100 t ha−1 (dry matter) on two cropped soils with contrasting textures. Soil-and-compost mixes and compost-free soil were planted with lettuce, radish, and potato.ResultsSeventy-four days after planting, composts improved some soil physicochemical properties. The compost-amended soils had better saturated hydraulic conductivity (Ks, 1 10−3–2.5 10−3 cm s−1) than the compost-free soil (0.5 10−3 cm s−1), and water-stable aggregates were higher than the initial value in C3 soil, equal to it in C2 soil, and lower in C1 soil. pH, total nitrogen, and organic carbon increased in all compost-amended soils. Food waste compost stimulated crop production. The yields (dry matter) of all three crops were two to three times higher in the two soils amended with food waste compost compared to unamended soil, whereas they decreased almost two times in the soil amended with green waste compost due to nitrogen immobilization. Trace metals (particularly Pb and Cd) added by the composts, although present in edible parts of the plants, did not exceed the European rules for trace metals.ConclusionThus, food waste composts have positive effects on soils and vegetable crops, and the higher their organic matter content, the higher these positive effects
Apport d'un parcours artistique pour parler des préoccupations sociétales autour de l'élevage porcin auprès des étudiants
No full textInternational audienceThe contribution of an artistic approach to addressing societal concerns about pig farming among studentsThis study explores the impacts of an artistic, specifically theatrical, approach to the training of agricultural engineers at the Institut Agro -Rennes Angers (IARA) in the face of complex societal challenges. In the "Animals, Livestock, and Societies" course unit, offered to 35-40 Master's 1 students at IARA, the educational objective is to enable them to develop a critical and argumentative perspective on the controversies surrounding livestock farming, with the aim of raising awareness and fostering dialogue with society. The educational device, created in collaboration with a stage director, involves students co-writing a play in the form of a mock trial. Highlighting situations related to pig-farming concerns, this 18-hour artistic course includes theatrical techniques and group work. This pedagogical experience is based on strong student involvement. Results show that students develop skills such as "identifying different viewpoints" and "respecting diverse perceptions." However, students experienced the novel artistic activities differently depending on their perceptions. Three-quarters of them found this method engaging, while the others found it questionable or stressful. Such teaching activities encourage them to step out of their comfort zone by testing themselves and changing their viewpoints to embody characters in different positions. Thus, this artistic practice allows future engineers to better understand the complexity societal concerns and to design sustainable and socially acceptable solutions.</p
100 Years of IAHS – Graphic capitalisation and poetic celebration
No full textInternational audienceAbstract. In centenary celebration of IAHS, Converging knowledge, shared in global embrace, Hydrological sciences in captivating displays, A graphic chaptering, and poetic interlace
SalmoGlob – Un nouveau modèle pour l’évaluation des stocks de saumon atlantique à l’échelle de l’Atlantique Nord
No full textInternational audienceÉvaluer l'état des populations de poissons sauvages est essentiel pour guider une gestion efficace dans un contexte de fortes pressions sur la ressource. Dans le cadre du projet SalmoGlob, les chercheurs ont développé un modèle innovant pour évaluer les stocks de saumon atlantique dans l’Atlantique Nord. Ce modèle intègre des données depuis 1971, permettant d’analyser la dynamique des populations à différentes échelles et stades de vie. Adopté par le Conseil international pour l’exploration de la Mer en 2024, il améliore significativement la qualité des évaluations scientifiques et des scénarios de gestion face aux changements globaux
Agricultural R&D and Export Survival in ECOWAS Countries
No full textInternational audienceThis study analyzes the effects of agricultural R&D on the export duration of agricultural products in ECOWAS countries. Research on this subject did not examine the role of R&D. This study aims to fill this gap for ECOWAS countries. We used the PWP-TT model to estimate the effects of upstream and downstream R&D investments on agricultural export survival rates. The main finding is that both upstream and downstream R&D have positive effects on trade duration. However, the results show that these effects vary across countries and that more R&D investments in the agricultural sector are necessary for ECOWAS countries
Reproduction of marine fishes
No full textInternational audienceThe study of fish reproduction has grown in importance as global fish populations decline and aquaculture becomes more prominent, two disciplines for which understanding fish reproduction determinants is critical. Spawners and their reproductive strategy are particularly sensitive to changes in environmental factors such as oceanographic conditions, prey quantity, and pollution. Therefore, comprehending the reproductive performance of fish is essential for evaluating their overall fitness. This chapter offers a comprehensive overview of key concepts related to fish spawning, fecundity, maternal effects, reproductive strategies, and bioenergetics. These concepts are supplemented with case studies and examined from the perspective of climate change and genetic adaptation. Overall, this chapter emphasizes the importance of studying fish species’ reproductive patterns and behaviors in order to estimate population growth rates, identify potential limiting variables, and assess the effects of human activities on populations for the conservation and sustainable exploitation of fish, particularly in the face of climate change