Swimming Behavior Research Articles

Vitamin A ameliorates valproic acid-induced autism-like symptoms in developing zebrafish larvae by attenuating oxidative stress and apoptosis

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social deficits and repetitive/stereotyped behaviors. Prenatal exposure to valproic acid (VPA) has been reported to induce ASD-like symptoms in human and rodents. However, the etiology and pathogenesis of ASD have not been well elucidated. This study aimed to explore the mechanisms underlying VPA-induced ASD-like behaviors using zebrafish model and investigated whether vitamin A could prevent VPA-induced neurotoxicity. Here, zebrafish embryos were exposed to 0, 25 and 50 μM VPA from 4 to 96 h post fertilization (hpf) and the neurotoxicity was assessed. Our results showed that VPA affected the normal development of zebrafish larvae and induced ASD-like behaviors, including reduced locomotor activity, decreased distance near conspecifics, impaired social interaction and repetitive swimming behaviors. Exposure to VPA decreased the GFP signal in transgenic HuC:egfp zebrafish according to the negative effect of VPA on the expression of neurodevelopmental genes. In addition, VPA enhanced oxidative stress by promoting the production of reactive oxygen species (ROS) and hydrogen peroxide (H2O2) and inhibiting the activity of superoxide dismutase, then triggered apoptosis by upregulation of apoptotic genes. These adverse outcomes were mitigated by vitamin A, suggesting that vitamin A rescued VPA-induced ASD-like symptoms by inhibiting oxidative stress and apoptosis. Overall, this study identified vitamin A as a promising strategy for future therapeutic regulator of VPA-induced ASD-like behaviors.

Relationships among the fish passage efficiency, fish swimming behavior, and hydraulic properties in a vertical‐slot fishway

AbstractThree‐dimensional hydrodynamic numerical simulation and laboratory fish‐passage experiment with juvenile grass carp (Ctenopharyngodon idella) were used to systematically estimate hydrodynamic parameters, fish passage efficiency, fish swimming behavior, and fish swimming trajectories in a vertical‐slot fishway (VSF) under five different flow discharges. The spatial‐mean time‐averaged velocity magnitude along the slot section determined passage success rate. The absolute value of the time‐averaged Reynolds‐shear‐stress component in the X–Y direction played a decisive role in selecting the swimming path. In addition, fish energy expenditure along the mean‐50% swimming route indicated that higher mainstream velocity did not necessarily signify larger energy consumption, because successfully‐migrating fish selected the relatively lower velocity zone during the migration process. Our findings for fish swimming behavior in response to velocity and turbulence can be used to develop high‐efficiency fishways for grass carps or other species with similar traits.

Study on the hydrodynamics of the helix with non-uniform helical radius in viscoelastic fluid at low Reynolds number

Bacteria exhibit swimming behavior through the rotation of helical flagellar filaments, a common mode of propulsion for artificial micro-swimmers as well. However, most studies have focused on helical filaments with a uniform radius, leaving limited research on filaments with nonuniform radii. This paper presents a simulation of the hydrodynamics of a rotating helical filament with a nonuniform radius. The degree of nonuniformity is characterized by a radius ratio,β. Using the OpenFOAM platform, a simulation module for non-Newtonian Stokes flow was developed and integrated. The kinematics of the filament were predefined by fixing either the pitch or the helical angle, in addition to the helical radius. Thrust acting on the filament were analyzed with regards to the helical radius ratio, rotation speed, and fluid viscoelasticity. Certain modifications were made to apply the resistive force theory (RFT) to filaments with nonuniform helical radii. Results revealed that when the pitch was fixed, the thrust of the helix varied non-monotonically with the radius ratio, with excessive ratios leading to increased resistance. In contrast, helices with fixed helical angles exhibited an increasing thrust with a higher radius ratio. The thrust was greater in Newtonian fluids compared to non-Newtonian fluids, and the propulsion of the helix was influenced by the Deborah number. As the Deborah number approached zero, the thrust of viscoelastic swimming speed approached that of viscous swimming speed. For small, β(,β=1 and 4), the ratio of the thrust in viscoelastic fluid to the thrust in viscous fluid was always less than unity. At, β = 9, elasticity hindered propulsion at low De (De<1.5), while the opposite was observed at high De (De>1.5). A new approach was proposed to evaluate the impact of viscoelasticity on the helix, it was expected that the new calculation method can reduce the computational effort effectively.

Dynamics and phase behavior of metallo-dielectric rod-shaped microswimmers driven by alternating current electric field.

The ability to move and self-organize in response to external stimuli is a fascinating feature of living active matter. Here, the metallo-dielectric rod-shaped microswimmers are shown to have a similar behavior in the presence of an AC electric field. The silica-copper Janus microrods were fabricated using the physical vapor deposition-based glancing angle deposition technique (GLAD). When the aqueous solution of the microrods was under the influence of an external AC electric field, they were found to exhibit different phases such as clustering, swimming, and vertical standing in response to variation of the applied frequency. The swimming behavior (5-90 kHz) of the rods is attributed to the induced-charge electrophoresis (ICEP) phenomenon, whereas the dynamic clustering (<5 kHz) could be explained in terms of the electrohydrodynamic (EHD) interaction. Interestingly, the rods flip to attain the vertically standing position when responding to the applied electric field above 90 kHz. The reorientation and switching of the major axis of the rod along the field direction is attributed to the electro-orientation phenomenon. This is basically due to the dominance of the electric torque above the upper limit of the characteristic frequency, where the strength of slip flows around the microrods is predicted to be poor. The present study not only offers insight into the fundamental aspects of the dynamics and the phase behavior of rod-shaped microswimmers, but also opens an avenue to design reconfigurable active matter systems with features inspired by biological systems.

Effects of water fluoridation on early embryonic development of zebrafish

Fluoride has strong electronegativity and exposes diversely in nature. Water fluoridation is the most pervasive form of occurrence, representing a significant threat to human health. In this study, we investigate the morphometric and physiological alterations triggered by fluoride stimulation during the embryogenesis of zebrafish and reveal its putative effects of stage- and/or dose-dependent. Fluoride exhibits potent biological activity and can be extensively absorbed by the yolk sac, exerting significant effects on the development of multiple organs. This is primarily manifested as restricted nutrient utilization and elevated levels of lipid peroxidation, further leading to the accumulation of superoxide in the yolk sac, liver, and intestines. Moreover, pericardial edema exerts pressure on the brain and eye development, resulting in spinal curvature and reduced body length. Besides, acute fluoride exposure with varying concentrations has led to diverse teratogenic outcomes. A low dose of water fluoridation tends to induce abnormal development of the embryonic yolk sac, while vascular malformation is widely observed in all fluoride-treated groups. The effect of fluoride exposure on blood circulation is universally present, even in zebrafish larvae that do not exhibit obvious deformities. Their swimming behavior is also affected by water fluoridation, resulting in reduced activity and delayed reactions. In conclusion, this study provides valuable insights into the monitoring of environmental quality related to water fluoridation and disease prevention.

Life in a fishbowl: Space and environmental enrichment affect behaviour of Betta splendens.

The public has expressed growing concern for the well-being of fishes, including popular pet species such as the Siamese fighting fish (Betta splendens). In captivity, male Bettas behave aggressively, often causing injuries and death if housed together. As a result, they are typically isolated in small fishbowls, which has been widely criticised as cruel. To investigate the impact of keeping Bettas in these conditions, we recorded the behaviour of individual males in containers of different sizes that were either bare or enriched with gravel, large rocks, and live plants. When male Bettas were housed individually in small bowls (0.5 L) they spent less time swimming than they did when they were kept in larger aquaria (10, 38, and 208 L). Fish that were kept in enriched containers exhibited more instances of swimming. To determine if two male Bettas housed together might coexist peacefully if given enough space and cover from plants and large rocks, we quantified the behaviour of pairs of male Bettas in bare or enriched aquaria of different sizes (10, 38, 208, 378 L). Fish performed fewer approaches and aggressive displays, but not attacks, and more bouts of foraging, when in larger aquaria. This study shows that the small fishbowls typically used in pet stores suppress swimming behaviour in male Bettas and at least a 10-L aquarium is required to ensure full expression of swimming behaviour. Furthermore, even the use of very large aquaria cannot guarantee peaceful cohabitation between two males.

The impact of dietary probiotic supplementation on welfare and growth performance of Nile tilapia (Oreochromis niloticus).

The usage of commercial probiotic products as alternatives to traditional antibiotics in fish culture is initiated to be a potential factor for Nile tilapia fish's welfare and growth. The purpose of the current study is to show the influence of commercial probiotics (Bacillus amyloliquefaciens) dietary supplementation at different levels on Nile tilapia welfare and growth. Apparently healthy fingerlings of Nile Tilapia with a total number of 120 with an average initial weight (26.2 ± 0.3 g) were distributed into four groups (each group had 30 fingerlings). The first group (G1) was given a basal diet without additional probiotics, while other groups [second group (G2), the third group (G3), and the fourth group (G4)] were given basal diets supplemented with different levels of commercial probiotics (1 g, 2 g, and 3 g of probiotics per kilogram of diet), respectively (15 fish in each sub group as replicate), in eight glass aquaria (30 × 40 × 100 cm) for 2 months as an experimental period. The results revealed that the probiotic-treated groups especially G4 (3 g probiotics/kg diet) showed a marked increase in the following behavioral patterns such as feeding and swimming behaviors, while G2 (1 g probiotic/kg diet) had an increase in the foraging behavior compared with G1 control group. While surfacing, body care, and aggressive behaviors with all patterns were the highest in the control group (G1) than all probiotics-treated groups. The crossing test showed that fish rose in the probiotic-treated groups (G3 and G4) were more active and could achieve the highest growth rates. While water quality was better in G4 (3 g probiotic /kg diet) than in other groups. Moreover, G4 (3 g probiotic/kg diet) showed a marked increase in all serum biochemical parameters than the control group (G1). The current study proved that the best level of commercial probiotics (B. amyloliquefaciens) was (3 g probiotic/kg diet) for achieving optimal Nile tilapia fingerlings' growth performance under these experimental conditions. Finally, this work confirms the significance of the addition of probiotics as a feed additive to enhance both growth performance and immunity response, improve water quality, and achieve the welfare of Nile tilapia fingerlings.

The effect of yellow and red illuminations on the swimming behaviour, mortality and growth rates of yellowfin tuna juveniles (Thunnus albacares)

The effect of yellow and red illuminations on the swimming behaviour, mortality and growth rates of yellowfin tuna juveniles (<i>Thunnus albacares</i>)

Fish as a deformable solid: an innovative method to characterise fish swimming behaviour on acoustic videos

Fish as a deformable solid: an innovative method to characterise fish swimming behaviour on acoustic videos

Molecular and cellular basis of life cycle transition provides new insights into ecological adaptation in jellyfish

&lt;p&gt;Jellyfish are renowned for their complex life cycles and important ecological and evolutionary position. The unique transition from the sessile polyp to motile medusa stages is a key process determining a switch in jellyfish behaviour and regulating the formation of jellyfish blooms. Here, we presented a comprehensive cell atlas spanning four successive life cycle stages during the polyp-to-medusa transition in the scyphozoan jellyfish &lt;i&gt;Aurelia&lt;/i&gt; &lt;i&gt;coerulea&lt;/i&gt;. Moreover, we characterised the variation in cell composition and gene expression patterns during the phase transition, especially in the neuromuscular system. We found several previously unreported cell types that potentially underpin the complex swimming behaviour of jellyfish. Furthermore, we discovered the pivotal role of &lt;i&gt;HOX1&lt;/i&gt; in modulating the genesis of striated muscles in &lt;i&gt;A&lt;/i&gt;. &lt;i&gt;coerulea&lt;/i&gt;. Collectively, this study provides valuable insights into the cellular and molecular mechanisms underlying the complex life cycle transition and helps to advance our understanding of ecological adaptation in jellyfish.&lt;/p&gt;

Investigation into Effect of Magnetic Moments to Swimming Behavior and Performance of the Soft Milli-Film Robots

Investigation into Effect of Magnetic Moments to Swimming Behavior and Performance of the Soft Milli-Film Robots

Epigenetic and physiological alterations in zebrafish subjected to hypergravity.

Gravity is one of the most constant environmental factors across Earth's evolution and all organisms are adapted to it. Consequently, spatial exploration has captured the interest in studying the biological changes that physiological alterations are caused by gravity. In the last two decades, epigenetics has explained how environmental cues can alter gene functions in organisms. Although many studies addressed gravity, the underlying biological and molecular mechanisms that occur in altered gravity for those epigenetics-related mechanisms, are mostly inexistent. The present study addressed the effects of hypergravity on development, behavior, gene expression, and most importantly, on the epigenetic changes in a worldwide animal model, the zebrafish (Danio rerio). To perform hypergravity experiments, a custom-centrifuge simulating the large diameter centrifuge (100 rpm ~ 3 g) was designed and zebrafish embryos were exposed during 5 days post fertilization (dpf). Results showed a significant decrease in survival at 2 dpf but no significance in the hatching rate. Physiological and morphological alterations including fish position, movement frequency, and swimming behavior showed significant changes due to hypergravity. Epigenetic studies showed significant hypermethylation of the genome of the zebrafish larvae subjected to 5 days of hypergravity. Downregulation of the gene expression of three epigenetic-related genes (dnmt1, dnmt3, and tet1), although not significant, was further observed. Taken altogether, gravity alterations affected biological responses including epigenetics in fish, providing a valuable roadmap of the putative hazards of living beyond Earth.

Automated Video Analysis of the Specific Effects of the Size and Concentration of Polystyrene Microplastics on the Swimming Behavior of the Crucian Carp (Carassius carassius)

Automated Video Analysis of the Specific Effects of the Size and Concentration of Polystyrene Microplastics on the Swimming Behavior of the Crucian Carp <i>(Carassius carassius)</i>

Aggregation of zooplankton in a Stommel Retention Zone in a laboratory model of Langmuir circulation

AbstractLangmuir circulation is a common form of surface turbulence comprising a series of counterrotating horizontal vortex pairs. Upwellings and downwellings in Langmuir circulation may suspend and trap passive particles or active swimmers like zooplankton in regions known as Stommel Retention Zones. For zooplankton, Stommel Retention Zone formation depends on flow speed and animal swimming speed and direction. Here we explore this biophysical interaction using Daphnia magna in a laboratory model of Langmuir Circulation. The phototactic daphniids were induced to perform different levels of upwards swimming (mimicking diel vertical migration) via constant or intermittent illumination. Some daphniids were additionally exposed to chemically dispersed crude oil, which impaired swimming. We characterized the swimming speed and direction, trajectories, and spatial distribution of daphniids in still water and in response to Langmuir circulation‐like flows of various strengths. In still water, constantly illuminated and oil‐exposed daphniids swam upwards more often than intermittently illuminated animals. Greater levels of upwards swimming in still water corresponded to stronger daphniid aggregations in the downwelling when a Langmuir Circulation‐like flow was present. However, at flow speeds exceeding their swimming abilities, daphniids were generally advected with the flow and uniformly distributed, an effect particularly evident for the weakly‐swimming oil‐exposed daphniids. An individual‐based model was also used to investigate the effects of active swimming vs. passive behavior and of swimming direction on Langmuir circulation‐associated aggregations. Our study of zooplankton Stommel Retention Zones generated in a laboratory facility offers insight into how and when Langmuir circulation‐associated plankton aggregations may occur in the field.

N-nitrosodimethylamine exposure to zebrafish embryos/larvae causes cardiac and spinal developmental toxicity

N-nitrosodimethylamine (NDMA), one of the new nitrogen-containing disinfection by-products, is potentially cytotoxic, genotoxic, and carcinogenic. Its potential toxicological effects have attracted a wide range of attention, but the mechanism is still not sufficiently understood. To better understand the toxicological mechanisms of NDMA, zebrafish embryos were exposed to NDMA from 3 h post-fertilization (hpf) to 120hpf. Mortality and malformation were significantly increased, and hatching rate, heart rate, and swimming behavior were decreased in the exposure groups. The result indicated that NDMA exposure causes cardiac and spinal developmental toxicity. mRNA levels of genes involved in the apoptotic pathway, including p53, bax, and bcl-2 were significantly affected by NDMA exposure. Moreover, the genes associated with spinal and cardiac development (myh6, myh7, nkx2.5, eph, bmp2b, bmp4, bmp9, run2a, and run2b) were significantly downregulated after treatment with NDMA. Wnt and TGF-β signaling pathways, crucial for the development of diverse tissues and organs in the embryo and the establishment of the larval spine, were also significantly disturbed by NDMA treatment. In summary, the disinfection by-product, NDMA, exhibits spinal and cardiac developmental toxicity in zebrafish embryos, providing helpful information for comprehensive analyses and a better understanding the mechanism of its toxicity.

Static magnetic fields reduce swimming activity of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) larvae

Abstract Static magnetic fields (B-fields) are introduced in marine ecosystems by anthropogenic sources such as subsea power cables. Larvae of the gadoids Atlantic haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) disperse over the continental shelf and may encounter B-fields, which could alter their behavior. We tested the behavior of 184 gadoid larvae while they were being exposed to a B-field (22–156 μT), which is in the intensity range of that produced by a high-voltage direct current cable, for a duration of 10 min in a raceway tank. We present a reanalysis of published data on 92 haddock larvae combined with newly collected data on 92 cod larvae tested under the same settings. Exposure did not affect the spatial distribution of the larvae. Both species displayed the same proportion of nonexploratory (78%) and exploratory (22%) individuals. Exposure significantly reduced the average swimming speed of the nonexploratory larvae by 32% and the average acceleration by 30%. Exploratory larvae were not affected. These results indicate that the swimming behavior of a high proportion of gadoid larvae would be reduced by weak static B-fields. Consequences of exposure on dispersal and survival at the population scale awaits further work using biophysical-coupled models.

First report of a Kudoa lutjanus outbreak in farmed Chicken Grunts Parapristipoma trilineatum.

As part of the National Disease Surveillance Program for Taiwanese Aquaculture, we investigated the causative agent of disease outbreaks in farmed Chicken Grunts Parapristipoma trilineatum. In this study, outbreak cases on two separate farms were noticed in coastal Pingtung County, Taiwan. In total, 50 juvenile fish showing clinical signs (such as emaciation and erratic swimming behavior) and broodstock (two females and two males) from both farms were collected to perform gross lesion assessment, histopathological examination, and molecular identification of the pathogen. Clinical symptoms were infected fish exhibited erratic swimming behavior, such as whirling and floating on the surface of the water. In the following months, cumulative mortality had reached 19% and 24%, respectively. The gross lesions in the infected fish included white oval cysts in the muscle, serosa of the internal organs, sclera of the eyes, and cerebral meninges. After conducting a wet mount examination of cysts using a light microscope, we observed a significant quantity of spores with morphological characteristics, suggesting their affiliation with the Myxosporea group. The spores were semiquadrate, with four tiny suture notches at the periphery; the mean spore length was 7.3 μm (SD = 0.5), and the mean spore width was 8.2 μm (SD = 0.6). The mean length and width of the pyriform polar capsules (nematocysts) were 3.6 μm (SD = 0.5) and 2.2 μm (SD = 0.5), respectively. The 18S and 28S ribosomal RNA sequences of these specimens were identical to those of Kudoa lutjanus. As this was the first time an outbreak of K. lutjanus in Chicken Grunts was confirmed, its reappearance with substantial mortality should serve as a warning to the aquaculture industry.

A case of abnormal swimming patterns in juvenile Oblada melanura naturally infected with Philometra obladae (Nematoda: Philometridae) in the Tyrrhenian Sea off Sicily, Italy

The saddled seabream, Oblada melanura (L.), is a common seawater species present in the Mediterranean. Between July and August 2023, during diving activities along the Sicilian coast of Italy, we recorded with a digital camera several specimens of O. melanura showing an abnormal pattern of swimming in the water column. The unusual swimming behaviour was characterized by fast, uncoordinated directional changes and isolation from the remaining fishes in the shoal. Four dead fish were found and collected for necropsy and parasitological evaluation/examination. Upon gross examination, all fish showed an evident coelomic distension; the coelomic cavity of two fish was filled with nematodes that dislocated the coelomic organs, and the other two had degraded nematodes and a conspicuous quantity of fluid in the coelomic cavity. All collected parasites were identified as Philometra obladae (Nematoda: Philometridae) according to morphological criteria. Here, we describe the unusual swimming behaviour of O. melanura naturally infected with Ph. obladae and the results of the examination of dead fish infected with this parasite. Future studies are needed to better evaluate and describe the dynamics and the epidemiology of Ph. obladae infection in wild O. melanura.

Viscous Loading Regulates the Flagellar Energetics of Human and Bull Sperm.

The viscoelastic properties of the female reproductive tract influence sperm swimming behavior, but the exact role of these rheological changes in regulating sperm energetics remains unknown. Using high-speed dark-field microscopy, the flagellar dynamics of free-swimming sperm across a physiologically relevant range of viscosities is resolved. A transition from 3D to 2D slither swimming under an increased viscous loading is revealed, in the absence of any geometrical or chemical stimuli. This transition is species-specific, aligning with viscosity variations within each species' reproductive tract. Despite substantial drag increase, 2D slithering sperm maintain a steady swimming speed across a wide viscosity range (20-250 and 75-1000 mPas for bull and human sperm) by dissipating over sixfold more energy into the fluid without elevating metabolic activity, potentially by altering the mechanisms of dynein motor activity. This energy-efficient motility mode is ideally suited for the viscous environment of the female reproductive tract.

Characteristics and risk assessment of cryptocaryoniasis in large yellow croaker (Larimichthys crocea) at different densities in industrialized aquaculture

With the introduction and advancement of sustainable development in aquaculture, traditional fish farming methods are gradually transitioning to advanced industrial farming models. To explore the occurrence patterns and risks of cryptocaryoniasis in industrialized high-density aquaculture, we used a non-lethal dose of Cryptocaryon irritans theronts (400 theronts/m3) to infect Larimichthys crocea at different rearing densities [low-density group (0.088 kg/m3), medium-density group (0.88 kg/m3), and high-density group (8.80 kg/m3)]. We explored the relationship between L. crocea density and the growth rate of the C. irritans population by observing the differences in growth, feeding, and survival rates of the L.crocea in each group and the changes in water quality and the number of C. irritans tomonts during the rearing process. We also evaluated the risks associated with the occurrence of cryptocaryoniasis in aquaculture. The results showed significant differences in the relative levels of the first round of infection among different density groups of L.crocea, which affected the outbreak speed of cryptocaryoniasis and the maximum relative tomont number (RTN) of L. crocea. Specifically, the outbreak speed of cryptocaryoniasis from fast to slow was as follows: medium-density group>low-density group>high-density group. The RTN when all L.crocea had died in each group was 12.82 (medium-density group), 49.7 (low-density group), and 106.58 (high-density group). The occurrence of cryptocaryoniasis reduced the feeding and growth rates of L.crocea in all groups, and the effect was most pronounced in the second week and the late stages of infection. The occurrence of cryptocaryoniasis caused abnormal swimming behavior in all three density groups. The main manifestations of C. irritans infection in L. crocea included rubbing the snout against the barrel wall, body imbalance, dispersed swimming, and delayed responses. The deterioration of water quality was most pronounced in the high-density group, but the outbreak speed of cryptocaryoniasis was the slowest in the high-density group, suggesting that no significant correlation existed between the deterioration of water quality and the outbreak speed of cryptocaryoniasis. The outbreak speed of cryptocaryoniasis varies depending on the fish-rearing density, and the progression and risk of cryptocaryoniasis are not proportionally correlated with the rearing density of L. crocea.