José L P Muñoz

• Ph. D.
• Universidad de Los Lagos

The aquaculture industry in Chile, as in the rest of the world, has rapidly grown, becoming a crucial economic sector. However, diseases pose a major threat, causing significant economic losses and environmental impacts. Various antimicrobials, particularly Oxytetracycline and Florfenicol, are used to combat these diseases, which has boosted produc...

Simple Summary Our results indicate activation of the kynurenine pathway and serotonin activity when stimulated with tryptophan and cortisol supplementation. An amount of 95% of tryptophan is degraded by the kynurenine pathway, indicating the relevance of knowing how this pathway is activated and if stress levels associated with fish culture trigge...

Nutritional immunity regulates the homeostasis of micronutrients such as iron, manganese, and zinc at the systemic and cellular levels, preventing the invading microorganisms from gaining access and thereby limiting their growth. Therefore, the objective of this study was to evaluate the activation of nutritional immunity in specimens of Atlantic s...

Este documento, desarrollado en conjunto por CSIRO Chile Research y la Universidad de Los Lagos, comunica los resultados de trabajo de levantamiento, consolidación y caracterización (no priorización) de aproximadamente seiscientas brechas de sostenibilidad identificadas en las mesas sectoriales llevadas a cabo entre junio y septiembre de 2022 como...

Eleginops maclovinus is a native species with potential for Chilean aquaculture. Understanding the variations between the post-prandial and fasted metabolic responses can contribute to improving the aquaculture of this species. This study aimed to characterize variations in intermediate metabolism during the course of the day in the liver, serum, a...

In teleosts, peripheral serotonin (5-HT) and melatonin (MEL) are synthesised in the gastrointestinal tract (GIT) and regulate secretion and motility processes. Their production is regulated by diet and the passage of food through the GIT. This study aimed to evaluate how intestinal 5-HT, melatonin, and the activity of digestive enzymes varied with...

Fatty acids (FA) have been reported to play a role in the defense against bacterial pathogens. However, studies in fish are limited and no information exists on the modulation of FA of Eleginops maclovinus challenged with the pathogen of aquaculture relevance Francisella noatunensis. We inoculated 144 fish intraperitoneally with 3 doses (low dose [...

It has been suggested that supplementing fish diets with L-tryptophan (L-Trp) and melatonin (MEL) may attenuate stress; however, little clarity exists regarding the physiological effects of both additives and the associated mechanisms in attenuating the stress response. We investigated how MEL and L-Trp in the diet affects the physiology and acute...

Bacterial transmission between cultured and native fish is potentially of great epidemiological significance. We evaluated horizontal transmission of Francisella noatunensis subsp. noatunensis from Salmo salar (Ss) to Eleginops maclovinus (Em) and vice versa by conducting cohabitation experiments. We detected F. noatunensis DNA in infected fish “Tr...

Farmed fish are affected by environmental variability and farming practices, such as farming density, feed composition and feeding regime. We developed four feeding activity indices to assess how environmental variability, ration size and feeding time lags affect the feeding activity of farmed Salmo salar. We used a real-time video monitoring syste...

The brain's immune system is selective and hermetic in most species, including fish, favoring immune responses mediated by soluble immunomodulatory factors such as serotonin and the availability of nutrients against infectious processes. Francisella noatunensis coexist with fish such as Eleginops maclovinus, which raises questions about the suscept...

Chile is the second-largest producer of Atlantic salmon in the world, and the Chilean salmon production accounts for 27% of the world’s production. One important step of the productive cycle in freshwater is the smoltification process that prepares the fish for the marine life stage. This review describes the biological basis of smoltification in A...

Smoltification is a crucial step in the aquaculture of Atlantic salmon. Currently, the Na+/K+ ATPase (NKA) test is used to determine whether fish have adapted to seawater when moved from freshwater. The mortality rate of unadapted fish in Chile is ~10% after smoltification. During this period, BK channel expression decreases in gills after two week...

Eleginops maclovinus is a native species with potential for Chilean aquaculture. However, its optimal stocking density and the impact on its physiology is unknown. The aim of this study is to determine the optimal stocking density range by evaluating parameters of growth, stress, intermediary metabolism, and osmoregulation. For this, 48 immature ma...

Caligus rogercresseyi, a marine ectoparasite, causes notable economic losses for the Chilean salmonid industry. Nevertheless, the immunological responses of infected fish remain poorly understood, including proinflammatory cytokine generation and the respective modulatory effects of various cytokine receptors. This study evaluated mRNA expression o...

The aim of this study was to examine the effects of Flavobacterium psychrophilum, a pathogen that is economically important in the aquaculture sector, on the neuroendocrine response of Oncorhynchus mykiss during a time course experiment with sampling at 0.5, 1, 2, 6, 10, and 30 days post injection (dpi). In the brain, serotonin (5HT) content increa...

Increased levels of tissue monoaminergic neurotransmitters, as well as circulating catecholamines, appear to play a role in the regulation of the physiological responses of teleost fish. Harpagifer antarcticus is a stenothermic, Antarctic notothenioid fish. The aim of this study was to determine the effect of increased seawater temperature and decr...

Eleginops maclovinus is an endemic species of the southern cone with beneficial physiological characteristics for aquaculture. However, this species has a low growth rate under captive conditions, and the optimal feed ration together with the metabolic process is unknown. This study aimed to determine the optimum feed ration during 90 days based on...

The aquaculture industry has many problems associated with bacteria, viruses, and parasites, and the stress caused by these infections can modulate the physiological response in fish. In Chile, the sea lice Caligus rogercresseyi constitutes a major problem affecting the Chilean salmonid industry, having a strong negative effect on salmon production...

Eleginops maclovinus is an endemic fish to Chile that lives in proximity to salmonid culture centers, feeding off of uneaten pellet and salmonid feces. Occurring in the natural environment, this interaction between native and farmed fish could result in the horizontal transmission of pathogens affecting the aquaculture industry. The aim of this stu...

Several studies describe gastrointestinal tract (GIT) melatonin (MEL) synthesis from 5-HT, which itself derives from the essential amino acid L-tryptophan (L-trp) in the intestine. Supplementing L-trp and MEL through diet has shown social-response effects and suppresses neuroendocrine stress in teleosts. In this study, the effects of a MEL and L-tr...

Eleginops maclovinus is a sub-Antarctic fish endemic to the South American coast and is a monotypic species of the Eleginopidae family. A scarce amount of scientific information exists regarding the effects of temperature on E. maclovinus physiology. In this study, E. maclovinus specimens were acclimated for 2 weeks at 10 °C (control), 14, and 18 °...

Although Caligus rogercresseyi negatively impacts Chilean salmon farming, the metabolic effects of infection by this sea louse have never been completely characterized. Therefore, this study analyzed lactate responses in the plasma, as well as the liver/muscle lactate dehydrogenase (LDH) activity and gene expression, in Salmo salar and Oncorhynchus...

The sea lice Caligus rogercresseyi constitute a major problem affecting the Chilean salmonids industry, having a strong negative effect over the production of Atlantic salmon (Salmo salar) and Rainbow trout (Oncorynchus mykiss). Caligidosis has been described affecting Atlantic salmon and rainbow trout more than Coho salmon (Onchorynchus kisutch).T...

Eleginops maclovinus is an endemic, subantarctic Notothenioidei species. This study examined the influence of different environmental salinities (5, 15, and 45 psu; and 32 psu as a control) on energy metabolism in E. maclovinus over a period of 14 days. Metabolite contents and enzymatic activities related to carbohydrate, amino acid, and lipid meta...

Melatonin is synthesized in peripheral locations of vertebrates, including the gastrointestinal tract (GIT). In teleost, information regarding this topic is scarce. Here we studied the presence and synthesis of melatonin at the rainbow trout GIT. Different sections of trout GIT (from esophagus to hindgut) were dissected out and assayed for contents...

Between 2006 and 2009, the Chilean salmon industry suffered a major sanitary crisis caused by outbreaks of infectious salmon anemia virus and Caligus rogercresseyi. Additionally, Piscirickettsia salmonis, the causative agent of piscirickettsiosis, and the parasite C. rogercresseyi continue to impact the salmon industry. This study evaluates the eff...

Salt baths in the production system of salmonids in fresh water, are important for the prevention and control of different diseases such as saprolegnia fungus. This standard procedure generates a rapid depletion of O2 in the water, leading to a significant increase of CO2, affecting blood parameters associated with animal welfare, such as Na⁺, Cl-,...

Most physiological processes, such as feeding behaviour and energy metabolism, exhibit circadian rhythmicity, thus playing a main role in the maintenance of the functional homeostasis. Light-dark and feeding-time cycles are mainly entraining such processes in order to adjust them to the chronological arrangement of the external world. The aim of th...

It has been demonstrated that chemical cues from conspecifics are involved in the alarm response in fish. However, it is still unclear whether an activation of the neuroendocrine stress pathways participate in this reaction in fish. In the present study we evaluated the physiological response of rainbow trout (Oncorhynchus mykiss) to the presence i...

In this study we assessed changes in the osmoregulatory system of juvenile sub-Antarctic Eleginops maclovinus submitted to different environmental salinities (5, 15, 32 and 45 psu) using two different acclimation trials: (1) an end-point experiment (exposure for 14 days) and (2) a time course experiment (specimens were sampled on days 1, 3, 7 and 1...

To assess a possible antistress role of melatonin in fish, we orally administered melatonin to rainbow trout for 10 d and then kept the fish under normal or high stocking density conditions during the last 4 d. Food intake; biochemical parameters in plasma (cortisol, glucose, and lactate concentrations); liver (glucose and glycogen concentrations,...

To assess a possible antistress role of melatonin in fish, we orally administered melatonin to rainbow trout for 10 d and then kept the fish under normal or high stocking density conditions during the last 4 d. Food intake; biochemical parameters in plasma (cortisol, glucose, and lactate concentrations); liver (glucose and glycogen concentrations,...

Intertidal crustaceans have a high degree of physiological plasticity, which allows them to withstand periods of water emersion. In this study we examine the physiological constraints that determine the distribution and abundance of the intertidal porcellanid crabs Petrolisthes laevigatus and Petrolisthes violaceus. This study evaluates the distrib...

Information regarding melatonin production in molluscs is very limited. In this study the presence and daily fluctuations of melatonin levels were investigated in hemolymph, retina and nervous system-related structures in the cephalopod Octopus vulgaris. Adult animals were maintained in captivity under natural photoperiod and killed at different ti...

The colonisation of the terrestrial environment by crustaceans is more apparent in tropical latitudes because of the high diversity of semi-terrestrial and terrestrial crabs. However, in temperate regions there are also great numbers of crustaceans that inhabit ecological niches at the water–air interface. Grapsidae crabs (Decopoda) are especially...

Different hypotheses attempt to explain how different stages of organisms with complex life cycles respond to environmental changes. Most studies have focused at the among-species level showing similar responses to temperature throughout ontogeny. However, there is no agreement about the pattern expected at the intraspecific scale where a strong se...

Variations in environmental temperature have both direct and indirect effects that affect organisms at levels ranging from intra-cellular physiological processes to ecological patterns. These variations are especially important for intertidal marine ectotherms such as littorinids since they alternate between periods of immersion in seawater, and mu...

Question: Developmental time and metabolic rate are correlated at higher levels of organization. Does this allometric relationship scale down to the intraspecific level? Methods: We exposed flies of three species of Drosophila collected at contrasting altitudes and similar latitudes to varying experimental thermal regimes. Metabolic rate was measur...

Several competing hypotheses attempt to explain how environmental conditions affect mass-independent basal metabolic rate (BMR) in mammals. One of the most inclusive and yet debatable hypotheses is the one that associates BMR with food habits, including habitat productivity. These effects have been widely investigated at the interspecific level und...

We studied how food abundance and consumption regulates torpor use and internal organ size in the Chilean mouse-opossum Thylamys elegans (Dielphidae), a small nocturnal marsupial, endemic in southern South America. We predicted that exposure to food rations at or above the minimum energy levels necessary for maintenance would not lead to any signs...

Lizard tail autotomy is considered an efficient anti-predator strategy that allows animals to escape from a predator attack. However, since the tail also is involved in many alternative functions, tailless animals must cope with several costs following autotomy. Here we explicitly evaluate the consequences of tail autotomy for two costs that have b...

The amount of solar radiation absorbed by an organism is a function of the intensity of the radiation and the area of the organism exposed to the source of the radiation. Since the prosobranch gastropod Echinolittorina peruviana is longer than it is wide, its areas of the lateral sides are approximately twice as large as the areas of the frontal an...