Le parasite isopode, Anilocra physodes, nouvelle source de nourriture pour le poisson lézard Synodus saurus (Synodontidae)

Copyright © 2015 Société Française d'Ichtyologie.During a wide project carried out on the behavior and reproduction of the Atlantic lizardfish Synodus saurus in the Azores (NE Atlantic), specimens of the ectoparasitic isopod Anilocra physodes were discovered in various stomachs contents of these piscivorous predatory fish. This intriguing result allowed us to conclude for the first time that fish species can ingest their own parasites, which becomes doubly beneficial, since it releases them from para- sites but it is also a new food source.RÉSUMÉ: Au cours de différents travaux menés sur le comportement et la reproduction du poisson lézard de l’Atlantique, Synodus saurus, aux Açores (Atlantique NE), des ectoparasites isopodes, Anilocra physodes, ont été découverts dans divers contenus stomacaux de ces prédateurs piscivores. Ce résultat intriguant nous a permis de conclure pour la première fois que des espèces de poissons peuvent ingérer leurs propres parasites, ce qui peut être doublement bénéfi- que pour eux, qui, tout en s’en libérant, disposent d’une nouvelle source de nourriture

Juvenile Sphyraena viridensis, preyed by the lizard fish Synodus saurus. A new predatory association from the Azores

Copyright © 2008 Société Française d’Ichtyologie.Les juvéniles de Sphyraena viridensis, proies de Synodus saurus, une nouvelle association prédateur-proie aux Açores. Au cours d’un travail sur l’écologie (comportement, alimentation et reproduction) du poisson lézard, Synodus saurus, aux Açores (Atlantique NE) nous avons découvert, dans plusieurs contenus stomacaux, des exemplaires postlarvaires et des juvéniles de la bécune à bouche jaune Sphyraena viridensis. Non seulement cette découverte nous a permis d’obtenir, pour la première fois, des postlarves de cette espèce de barracuda mais nous avons réussi à décrire une action de prédation d’un poisson épibenthique envers une espèce pélagique

Cortisol mediates cleaner wrasse switch from cooperation to cheating and tactical deception

Recent empirical research, mostly done on humans, recognizes that individuals' physiological state affects levels of cooperation. An individual's internal state may affect the payoffs of behavioural alternatives, which in turn could influence the decision to either cooperate or to defect. However, little is known about the physiology underlying condition dependent cooperation. Here, we demonstrate that shifts in cortisol levels affect levels of cooperation in wild cleaner wrasse Labroides dimidiatus. These cleaners cooperate by removing ectoparasites from visiting 'client' reef fishes but prefer to eat client mucus, which constitutes cheating. We exogenously administrated one of three different compounds to adults, that is, (a) cortisol, (b) glucocorticoid receptor antagonist mifepristone RU486 or (c) sham (saline), and observed their cleaning behaviour during the following 45. min. The effects of cortisol match an earlier observational study that first described the existence of "cheating" cleaners: such cleaners provide small clients with more tactile stimulation with their pectoral and pelvic fins, a behaviour that attracts larger clients that are then bitten to obtain mucus. Blocking glucocorticoid receptors led to more tactile stimulation to large clients. As energy demands and associated cortisol concentration level shifts affect cleaner wrasse behavioural patterns, cortisol potentially offers a general mechanism for condition dependent cooperation in vertebrates

Preliminary notes on the reproductive biology of the lizardfish, Synodus saurus (Actynopterygii: Synodontidae) in the Azores

Copyright © 2003 Société Française d’Ichtyologie.Between March and November 2000, 307 specimens of the lizardfish Synodus saurus (Linnaeus 1758) were captured on several coastal areas of Terceira Island, Azores. This species is an important coastal epibenthic predator. Although common, its biology, namely its reproduction, is virtually unknown. During the study period, 206 females (155 mm to 460 mm TL) and 101 males (269 mm to 290 mm TL), were captured. Sex ratio was 2:1 with more males in June. Gonados-somatic Index (GSI) for females and males attained its maximum values during Spring and Summer, showing that these are the most intensive reproduction periods. Hepato-somatic Index (HSI) suggests that this species may well recur on body reserves for energy metabolization in gonad development. Nevertheless, more studies are necessary in order to confirm this assumption. Ovarian histology, presenting different oocytarian phases, indicates that this species has an asynchronous posture. The male increment of June, associated to higher GSI values, suggests that this could represent a moment of intense competition for females, within the studied area.RÉSUMÉ: Notes préliminaires sur la reproduction du poisson lézard, Synodus saurus (Actinopterygii : Synodontidae) aux Açores. Entre mars et novembre 2000, 307 poissons lézard, Synodus saurus (Linnaeus, 1758) ont été capturés à divers endroits de la côte de l’île Terceira, aux Açores. Cette espèce est un important prédateur épibenthique. Bien qu’elle soit une espèce assez commune, sa biologie, et surtout sa reproduction, est virtuellement inconnue. Pendant cette étude, 206 femelles (de 155 mm à 460 mm LT) et 101 mâles (de 269 à 290 mm LT) ont été capturés. Le sexe ratio était de 2:1, avec plus de mâles en juin. L’indice gonado-somatique (GSI) pour les femelles et les mâles, a atteint ses valeurs les plus élevées au printemps et en été, ce qui montre que ces mois constituent la période de reproduction la plus intense. L’indice hépato-somatique (HSI), indique que les réserves corporelles sont susceptibles d’être utilisées pour le développement des gonades. Cependant, cette hypothèse doit être confirmée par d’autres études. L’histologie de l’ovaire, qui présente des phases ovocitaires différentes, indique que S. saurus a une ponte asynchrone. L’augmentation du nombre de mâles en juin, associée aux valeurs plus élevées de GSI, suggère l’existence, à cette période, d’une intense compétition pour les femelles

The role of serotonin in the modulation of cooperative behavior

We examined the modulatory role of serotonin in cooperation between unrelated individuals. The identification of the neurohormonal candidates that may modulate levels of cooperation in marine cleaning mutualisms has been a major aim in recent years. Our results provide evidence that serotonin is a driver of cooperative behavioral activities and contribute to the understanding of neural pathways of cooperation, which aim to unravel the basic drive of animal tendencies to cooperate with other

Dopamine disruption increases negotiation for cooperative interactions in a fish

Humans and other animals use previous experiences to make behavioural decisions, balancing the probabilities of receiving rewards or punishments with alternative actions. The dopaminergic system plays a key role in this assessment: for instance, a decrease in dopamine transmission, which is signalled by the failure of an expected reward, may elicit a distinct behavioural response. Here, we tested the effect of exogenously administered dopaminergic compounds on a cooperative vertebrate's decision-making process, in a natural setting. We show, in the Indo-Pacific bluestreak cleaner wrasse Labroides dimidiatus, that blocking dopamine receptors in the wild induces cleaners to initiate more interactions with and to provide greater amounts of physical contact to their client fish partners. This costly form of tactile stimulation using their fins is typically used to prolong interactions and to reconcile with clients after cheating. Interestingly, client jolt rate, a correlate of cheating by cleaners, remained unaffected. Thus, in low effective dopaminergic transmission conditions cleaners may renegotiate the occurrence and duration of the interaction with a costly offer. Our results provide first evidence for a prominent role of the dopaminergic system in decision-making in the context of cooperation in fish.info:eu-repo/semantics/publishedVersio

Preserving the nutritional quality of crop plants under a changing climate: importance and strategies

Background: Global climate is changing more rapidly than ever, threatening plant growth and productivity while exerting considerable direct and indirect effects on the quality and quantity of plant nutrients. Scope: This review focuses on the global impact of climate change on the nutritional value of plant foods. It showcases the existing evidence linking the effects of climate change factors on crop nutrition and the concentration of nutrients in edible plant parts. It focuses on the effect of elevated CO2 (eCO2), elevated temperature (eT), salinity, waterlogging and drought stresses, and what is known regarding their direct and indirect influence on nutrient availability. Furthermore, it provides possible strategies to preserve the nutritional composition of plant foods under changing climates. Conclusions: Climate change has an impact on the accumulation of minerals and protein in crop plants, with eCO2 being the underlying factor of most of the reported changes. The effects are clearly dependent on the type, intensity and duration of the imposed stress, plant genotype and developmental stage. Strong interactions (both positive and negative) can be found between individual climatic factors and soil availability of nitrogen (N), potassium (K), iron (Fe) and phosphorous (P). The development of future interventions to ensure that the world's population has access to plentiful, safe and nutritious food may need to rely on breeding for nutrients under the context of climate change, including legumes in cropping systems, better farm management practices and utilization of microbial inoculants that enhance nutrient availability.info:eu-repo/semantics/publishedVersio

Temperate facultative cleaner wrasses selectively remove ectoparasites from their client-fish in the Azores

Cleaner fishes are key contributors to the health of fish communities. However, much of the information in the literature refers to tropical systems, while fewer studies have examined the activity of cleaner fish inhabiting temperate ecosystems. Facultative cleaner fish are assumed to clean only during their juvenile phase, and have a broader diet than obligatory cleaner fish. Here, we focused on 2 facultative cleaner fish species, Coris julis and Thalassoma pavo, that live along the temperate coasts of the Azorean island of São Miguel. We found that these species focused their cleaning activities on relatively few species of clients, which supports the general idea that facultative cleaner fishes in temperate waters are less dependent on cleaning interactions than obligatory cleaner fishes in tropical waters. Both cleaner species were found to give more bites per host when inspecting larger clients, likely because the latter typically host more parasites. We found that C. julis consumed a greater diversity of food items, which included gnathiid larvae and fewer caligid copepods, compared to T. pavo where no ectoparasites were found. All cleaner fish that we collected after observations of cleaning had eaten gnathiid isopod larvae but not caligid copepods, even though caligid copepods were the most abundant ectoparasite found on the body of 7 selected fish species (including both client and non-client species), suggesting that both species selectively feed on gnathiid isopods. This study is the first to demonstrate that temperate facultative cleaner fish species actively and selectively inspect and remove ectoparasites from their client-fish species.Fundação para a Ciência e Tecnologia (FCT, grant PTDC/MAR/105276/2008. European Regional Development Fund (ERDF) COMPETE - Operational Competitiveness Programme. FCT - Foundation for Science and Techno - project PEst-C/MAR/LA0015/2011.info:eu-repo/semantics/publishedVersio

Machine learning for predicting fracture strain in sheet metal forming

Machine learning models are built to predict the strain values for which edge cracking occurs in hole expansion tests. The samples from this test play the role of sheet metal components to be manufactured, in which edge cracking often occurs associated with a uniaxial tension stress state at the critical edges of components. For the construction of the models, a dataset was obtained experimentally for rolled ferritic carbon steel sheets of different qualities and thicknesses. Two types of tests were performed: tensile and hole expansion tests. In the tensile test, the yield stress, the tensile strength, the strain at maximum load and the elongation after fracture were determined in the rolling and transverse directions. In the hole expansion test, the strain for which edge cracking occurs, was determined. It is intended that the models can predict the strain at fracture in this test, based on the knowledge of the tensile test data. The machine learning algorithms used were Multilayer Perceptron, Gaussian Processes, Support Vector Regression and Random Forest. The traditional polynomial regression that fits a 2nd order polynomial function was also used for comparison. It is shown that machine learning-based predictive models outperform the traditional polynomial regression method; in particular, Gaussian Processes and Support Vector Regression were found to be the best machine learning algorithms that enable the most robust predictive models.publishe