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1.
J Environ Manage ; 345: 118844, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37604102

RESUMO

Climate change and anthropogenic activities are major influences on the hydrological cycle, further altering river hydrological health. However, the characteristics of the forces in driving the variations of hydrological health at long-short time scales (annual, seasonal, monthly), as well as the potential impacts of these variations on aquatic habitats, remain unclear. In this study, the flow threshold method was introduced to identify the inherent characteristics of river hydrological health degree (RHD) evolution in the upper reaches of the Yangtze River (URYR) through the extreme-point symmetric modal decomposition (ESMD) method and range of variation approach (RVA). The RHD under unregulated conditions was reconstructed to quantify the impacts of anthropogenic activities and climate change. Subsequently, a multifractal model was proposed to establish the relationship between RHD and habitat-weighted usage area (WUA) during the spawning period of the Four Famous Major Carps, aiming to analyze the response mechanisms of habitat conditions to RHD fluctuations. The results showed that the RHD in the URYR exhibited degradation characteristics, experiencing a moderate change with a value of 0.44. Climate change was identified as the dominant factor causing the annual-scale decline in RHD, with an average impact weight of 62.9%. At the annual scale, Anthropogenic activities exacerbate (-3.4), counteract (20.1), and counteract (20.5) the adverse climatic impacts at Yichang, Cuntan, and Zhutuo stations, respectively. Additionally, the effect of human activities during the flood season is slight, with the most favorable and unfavorable impacts occurring in December (50.7) at the Zhutuo station and in October (-27.2) at the Yichang station. Under the influence of driving forces, the multifractal correlation of the RHD-WUA system tended to homogenized as the time window increased, indicating the presence of potential nonlinear dependence, asymmetric fractal characteristics, and positive-to-negative persistence transitions. Therefore, modeling river health considering fish habitat cannot be limited to linear paradigms. The findings provide valuable insights for the management and restoration of aquatic ecosystems.


Assuntos
Ecossistema , Monitoramento Ambiental , Animais , Humanos , Rios , Peixes/fisiologia , Estações do Ano , Hidrologia
2.
Mar Environ Res ; 190: 106123, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37567088

RESUMO

To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The investigation combined biochemical analyses (proteins, carbohydrates, and lipids) with C and N stable isotope analyses (SIA) to simultaneously study phytoplankton, zooplankton, and eight planktivorous fish species (Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Sprattus sprattus, Cepola macrophthalma, Chromis chromis, Boops boops, and Spicara maena). This study is the first to analyze both stable isotope and biochemical compositions in coastal particulate organic matter (POM) size classes (0.7-2.7 µm, 2.7-20 µm, and 20-200 µm), zooplankton size classes (200-300 µm, 300-500 µm, 500-1000 µm, 1000-2000 µm, and >2000 µm), and taxonomic groups. We demonstrated that: (1) POM stable isotope compositions varied based on its spatial origin, the taxonomic composition of its biota, and its biochemical content; (2) δ15N values increased with zooplankton size classes and groups, indicating different trophic levels; (3) Phytoplankton exhibited a lipid-rich composition (∼55%), while zooplankton and fish muscles were protein-rich (∼61% and ∼66%, respectively). Bayesian stable isotope mixing models revealed that, on average: (1) POM from oceanic waters contributed the most to the POM in the bay (>51%), with a dominance of pico-POM (∼43%); (2) The 200-1000 µm zooplankton primarily consumed nano-POM, the 1000-2000 µm zooplankton mostly consumed micro-POM (∼64%), and the >2000 µm zooplankton also mostly consumed micro-POM; (3) Mesozooplankton (200-2000 µm) constituted the main portion (∼42%) of the diet for planktivorous fish species, while macrozooplankton organisms (>2000 µm) were the primary food resource (∼43%) for both B. boops and S. sprattus. Our study underscores the complexity of the pelagic food web and highlights the bottom-up transfer of organic matter from the smallest phytoplankton size fractions to planktivorous fish.


Assuntos
Cadeia Alimentar , Fitoplâncton , Animais , Mar Mediterrâneo , Teorema de Bayes , Isótopos de Carbono/análise , Zooplâncton , Peixes/fisiologia
3.
Nature ; 621(7978): 324-329, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37648851

RESUMO

Marine heatwaves have been linked to negative ecological effects in recent decades1,2. If marine heatwaves regularly induce community reorganization and biomass collapses in fishes, the consequences could be catastrophic for ecosystems, fisheries and human communities3,4. However, the extent to which marine heatwaves have negative impacts on fish biomass or community composition, or even whether their effects can be distinguished from natural and sampling variability, remains unclear. We investigated the effects of 248 sea-bottom heatwaves from 1993 to 2019 on marine fishes by analysing 82,322 hauls (samples) from long-term scientific surveys of continental shelf ecosystems in North America and Europe spanning the subtropics to the Arctic. Here we show that the effects of marine heatwaves on fish biomass were often minimal and could not be distinguished from natural and sampling variability. Furthermore, marine heatwaves were not consistently associated with tropicalization (gain of warm-affiliated species) or deborealization (loss of cold-affiliated species) in these ecosystems. Although steep declines in biomass occasionally occurred after marine heatwaves, these were the exception, not the rule. Against the highly variable backdrop of ocean ecosystems, marine heatwaves have not driven biomass change or community turnover in fish communities that support many of the world's largest and most productive fisheries.


Assuntos
Biomassa , Calor Extremo , Peixes , Animais , Europa (Continente) , Pesqueiros/estatística & dados numéricos , Peixes/classificação , Peixes/fisiologia , Calor Extremo/efeitos adversos , América do Norte , Biodiversidade
4.
Artigo em Inglês | MEDLINE | ID: mdl-37572152

RESUMO

Eyes in low-light environments typically must balance sensitivity and spatial resolution. Vertebrate eyes with large "pixels" (e.g., retinal ganglion cells with inputs from many photoreceptors) will be sensitive but provide coarse vision. Small pixels can render finer detail, but each pixel will gather less light, and thus have poor signal relative-to-noise, leading to lower contrast sensitivity. This balance is particularly critical in oceanic species at mesopelagic depths (200-1000 m) because they experience low light and live in a medium that significantly attenuates contrast. Depending on the spatial frequency and inherent contrast of a pattern being viewed, the viewer's pupil size and temporal resolution, and the ambient light level and water clarity, a visual acuity exists that maximizes the distance at which the pattern can be discerned. We develop a model that predicts this acuity for common conditions in the open ocean, and compare it to visual acuity in marine teleost fishes and elasmobranchs found at various depths in productive and oligotrophic waters. Visual acuity in epipelagic and upper mesopelagic species aligned well with model predictions, but species at lower mesopelagic depths (> 600 m) had far higher measured acuities than predicted. This is consistent with the prediction that animals found at lower mesopelagic depths operate in a visual world consisting primarily of bioluminescent point sources, where high visual acuity helps localize targets of this kind. Overall, the results suggest that visual acuity in oceanic fish and elasmobranchs is under depth-dependent selection for detecting either extended patterns or point sources.


Assuntos
Elasmobrânquios , Visão Ocular , Animais , Acuidade Visual , Células Fotorreceptoras , Peixes/fisiologia , Células Ganglionares da Retina
5.
J Acoust Soc Am ; 154(2): 1041-1047, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37584466

RESUMO

There is increasing awareness of boat sound effects on coral reef assemblages. While behavioral disturbances have been found in fishes, the effects on marine invertebrates remain largely unknown. Here, the behavioral effects of recreational boat sound on thorny oysters at two coral reef habitats within the U.S. Virgin Island National Park were assessed. The "treatment" site was characterized by frequent boat traffic, which increased daytime mean particle acceleration levels (PALrms) by more than 6 dB, while mean PALrms at the "control" site were not contaminated by boat sound. Despite these contrasting soundscapes, all oysters showed the same diurnal cycle, with their valves open at night and partially closed during the day. There was no statistical evidence of behavioral responses in oysters exposed to daytime boat sound. This can be explained by low auditory sensitivity, habituation to a noisy environment due to the pervasiveness of boat sound pollution, or that boat sound may not represent an immediate concern for this species. These findings contrast with laboratory studies that have shown behavioral responses in bivalves exposed to boat sound, highlighting the need for more realistic field-based studies when evaluating potential effects of anthropogenic sounds on this group.


Assuntos
Bivalves , Ostreidae , Animais , Navios , Som , Recifes de Corais , Peixes/fisiologia
6.
Trop Anim Health Prod ; 55(5): 289, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37580646

RESUMO

The pirarucu (Arapaima gigas) is a fast-growing Amazonian species of high commercial value. The present study aimed to determine the dietary crude protein (CP) level to promote maximum zootechnical performance for pirarucu fingerlings and as their resistance to Aeromonas hydrophila, as well as evaluate their hematological parameters. Pirarucu fingerlings (2.4 ± 0.08 g, 6.8 ± 0.52 cm) were distributed in 18 tanks (140 L, 40 fish per tank, n = 3) and fed six experimental diets consisting of increasing levels of CP: 300, 400, 450, 500, 550 and 650 g kg-1 in a completely randomized design. Data were submitted to one-way ANOVA (p < 0.05) and the ideal CP level for weight gain was determined using polynomial regression analysis. The dietary CP levels were evaluated using a quadratic polynomial regression and the level of 595 g kg-1 was determined for the best weight gain. The hematocrit of fish fed 300 g kg-1 was higher than in the other groups. No mortalities were observed after the 15-day bacterial challenge; however, number of pirarucu with bacterial damage on the pirarucu caudal fin was higher in the group that was fed the diet with 300 g kg-1. A dietary protein level of 618 g kg-1 is therefore recommended for providing maximum weight gain and immunological resistance in pirarucu fingerlings weighing 2.4-112.5 g.


Assuntos
Aeromonas hydrophila , Infecções por Bactérias Gram-Negativas , Animais , Aeromonas hydrophila/fisiologia , Ração Animal/análise , Dieta/veterinária , Proteínas na Dieta , Suplementos Nutricionais/análise , Peixes/fisiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Hematócrito/veterinária
7.
J Exp Biol ; 226(14)2023 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-37493068

RESUMO

Work carried out since the late 1970s has provided key insights into the comparative biomechanics, kinematics, behaviour and neurobiology of fish escape responses. An escape response is an ecologically important behaviour used by fishes to evade predation and aggression via rapid swimming movements. With environmental change expected to affect the physiology and biomechanics of aquatic ectotherms, there is a growing interest in understanding how environmental stressors affect the swimming performance and behaviour of fishes during escape responses, particularly in the context of predator-prey interactions. As the study of fish swimming continues to expand, there have been repeated calls to standardise experiments and reporting practices to facilitate integrative and comparative studies. Here, we provide a set of practical guidelines for conducting, analysing and reporting experiments on escape responses in fish, including a reporting checklist to assist authors undertaking these experiments. These resources will facilitate executing and reporting escape response experiments in a rigorous and transparent fashion, helping to advance the study of fish swimming in an era of rapid environmental change.


Assuntos
Peixes , Natação , Animais , Fenômenos Biomecânicos , Peixes/fisiologia , Natação/fisiologia , Comportamento Predatório , Agressão , Reação de Fuga/fisiologia
8.
Philos Trans R Soc Lond B Biol Sci ; 378(1884): 20220139, 2023 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-37427477

RESUMO

Among ray-finned fishes that provide parental care, many spawn in constructed nests, ranging from bowls, burrows and ridges to nests made of algae or bubbles. Because a nest by definition is a construction that enhances the nest-builder's fitness by helping it meet the needs of the developing offspring, nest-building behaviour is naturally selected, as is a preference for spawning with mates that provide well-built nests. However, nest-building behaviour can also be sexually selected, when nest traits increase mating success, protect against sperm competition or nest take-overs by conspecifics. Here, we offer a systematic review, with examples of how competition for sites and location of fish nests relates to sexual selection. We examine direct and indirect benefits of mate choice linked to nest traits, and different types of nests, from a sexual selection perspective. Nest-related behaviours are often under both natural and sexual selection, and we disentangle examples where that is the case, with special attention to females. We highlight some taxa in which nest building is likely to be sexually selected, but lack of research has left them uninvestigated. Some of them are established aquarium species, making them particularly amenable for future research. Finally, we compare with arthropods, amphibians and birds. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'.


Assuntos
Peixes , Comportamento de Nidação , Peixes/classificação , Peixes/crescimento & desenvolvimento , Peixes/fisiologia , Ecossistema , Masculino , Feminino , Animais , Preferência de Acasalamento Animal , Reprodução , Estágios do Ciclo de Vida
9.
J R Soc Interface ; 20(204): 20230212, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37464800

RESUMO

While mathematical models, in particular self-propelled particle models, capture many properties of large fish schools, they do not always capture the interactions of smaller shoals. Nor do these models tend to account for the use of intermittent locomotion, often referred to as burst-and-glide, by many species. In this paper, we propose a model of social burst-and-glide motion by combining a well-studied model of neuronal dynamics, the FitzHugh-Nagumo model, with a model of fish motion. We first show that our model can capture the motion of a single fish swimming down a channel. Extending to a two-fish model, where visual stimulus of a neighbour affects the internal burst or glide state of the fish, we observe a rich set of dynamics found in many species. These include: leader-follower behaviour; periodic changes in leadership; apparently random (i.e. chaotic) leadership change; and tit-for-tat turn taking. Moreover, unlike previous studies where a randomness is required for leadership switching to occur, we show that this can instead be the result of deterministic interactions. We give several empirically testable predictions for how bursting fish interact and discuss our results in light of recently established correlations between fish locomotion and brain activity.


Assuntos
Peixes , Liderança , Animais , Peixes/fisiologia , Comportamento Social , Natação/fisiologia , Locomoção
10.
J Exp Biol ; 226(16)2023 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-37498237

RESUMO

Oxygen is essential for most eukaryotic lifeforms, as it supports mitochondrial oxidative phosphorylation to supply ∼90% of cellular adenosine triphosphate (ATP). Fluctuations in O2 present a major stressor, with hypoxia leading to a cascade of detrimental physiological changes that alter cell operations and ultimately induce death. Nonetheless, some species episodically tolerate near-anoxic environments, and have evolved mechanisms to sustain function even during extended hypoxic periods. While mitochondria are pivotal in central metabolism, their role in hypoxia tolerance remains ill defined. Given the vulnerability of the brain to hypoxia, mitochondrial function was tested in brain homogenates of three closely related triplefin species with varying degrees of hypoxia tolerance (Bellapiscis medius, Forsterygion lapillum and Forsterygion varium). High-resolution respirometry coupled with fluorometric measurements of mitochondrial membrane potential (mtMP) permitted assessment of differences in mitochondrial function and integrity in response to intermittent hypoxia and anoxia. Traditional steady-state measures of respiratory flux and mtMP showed no differences among species. However, in the transition into anoxia, the tolerant species B. medius and F. lapillum maintained mtMP at O2 pressures 7- and 4.4-fold lower, respectively, than that of the hypoxia-sensitive F. varium and exhibited slower rates of membrane depolarisation. The results indicate that dynamic oxic-hypoxic mitochondria transitions underlie hypoxia tolerance in these intertidal fish.


Assuntos
Hipóxia , Oxigênio , Animais , Oxigênio/metabolismo , Potencial da Membrana Mitocondrial , Peixes/fisiologia , Fosforilação Oxidativa , Trifosfato de Adenosina/metabolismo
11.
J Therm Biol ; 114: 103578, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37344032

RESUMO

Heat waves and cold snaps are projected to rise in magnitude, duration, interval, and harshness in the coming years. The current literature examining thermal impacts on the physiology of organisms rarely uses chronic, variable thermal acclimations despite the fact that climate change predictions project a more variable environment. If we are to determine species' susceptibility to climate change, chronic and variable lab acclimations should be prioritized. Here, we acclimated the eurytolerant sheepshead minnow (Cyprinodon variegatus) to two extreme cycling thermal regimes: one warm [resting 27 °C with a spike to 33 °C for 8 h daily], one cold [resting 6.5 °C with a spike to 12 °C for 8 h daily], and three chronically stable conditions (10, 22, and 30 °C) for comparison. We measured enzymatic antioxidants (catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)), total antioxidant capacity, lipid peroxidation (LPO) damage, and citrate synthase (CS) activity in white epaxial muscle. Of particular note, we found significant increases in log CAT activity and SOD concentration in the warm cycling temperatures, and significant increases in GPx activity in the cold cycling temperatures. We found no significant accumulation of LPO damage in any of our thermal acclimation treatments. Thus, sheepshead minnows demonstrate two particularly different mechanisms towards dealing with thermal variation in low and high temperatures. The enzymatic differences between low and high cycling temperatures may define pathways of eurytolerant organisms and how they may survive predicted variability in thermal regimes.


Assuntos
Aclimatação , Temperatura Baixa , Animais , Temperatura , Aclimatação/fisiologia , Peixes/fisiologia , Antioxidantes/metabolismo , Superóxido Dismutase
12.
Mar Pollut Bull ; 192: 115093, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37271077

RESUMO

Understanding the long-term effects of climatic factors on key species' recruitment is crucial to species management and conservation. Here, we analysed the recruitment variability of key species (Dicentrarchus labrax, Platichthys flesus, Solea solea, Pomatoschistus microps and Pomatoschistus minutus) in an estuary between 2003 and 2019, and related it with the prevailing local and large-scale environmental factors. Using a dynamic factor analysis (DFA), juvenile abundance data were grouped into three common trends linked to different habitat uses and life cycle characteristics, with significant effect of temperature-related variables on fish recruitment: Sea surface temperature and the Atlantic Multidecadal Oscillation. In 2010, a regime shift in the North Atlantic coincided with a shift in the common trends, particularly a decline in P. flesus and S. solea trend. This work highlights the thermophilic character of fish recruitment and the necessity to investigate key biological processes in the context of species-specific responses to climate change.


Assuntos
Bass , Linguados , Perciformes , Animais , Temperatura , Peixes/fisiologia , Ecossistema
13.
Physiol Biochem Zool ; 96(3): 233-246, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37278589

RESUMO

AbstractDuring the colonization of freshwater by marine fish, adaptation to hypoosmotic conditions may impact their ability to osmoregulate in seawater. The prickly sculpin (Cottus asper) is a euryhaline fish with marine ancestors that postglacially colonized many freshwater habitats. Previous work on C. asper suggested that isolation in freshwater habitats has resulted in putative adaptations that improve ion regulation in freshwater populations compared with populations with current access to estuaries. To determine whether long-term colonization of freshwater is associated with a reduced ability to ion regulate in seawater, we acclimated C. asper populations from three habitat types that vary in the extent to which they are isolated from marine habitats and compared their seawater osmoregulation. Seawater acclimation revealed that lake populations exhibited a reduced capacity to osmoregulate in seawater compared with coastal river populations with ongoing access to estuaries. In particular, when acclimated to seawater for several weeks, lake populations had lower gill Na+/K+-ATPase activity and lower intestinal H+-ATPase activity than coastal river populations. Lake populations also had a reduced ability to maintain plasma ion concentrations, and they produced lower quantities of intestinal carbonate precipitates in seawater than coastal river populations. Furthermore, there was a positive relationship between the anterior intestinal Na+/K+-ATPase activity and the amount of precipitate produced by the intestine, which suggests that the anterior intestine plays a role in seawater osmoregulation. Our results suggest that the extent of isolation from the sea could, in part, explain the reduced osmoregulation in seawater in postglacial freshwater populations of C. asper.


Assuntos
Osmorregulação , Equilíbrio Hidroeletrolítico , Animais , Equilíbrio Hidroeletrolítico/fisiologia , Aclimatação/fisiologia , Peixes/fisiologia , Água do Mar , Lagos , Ecossistema , Adenosina Trifosfatases/metabolismo , Brânquias/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Salinidade
14.
Sci Rep ; 13(1): 8971, 2023 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-37268732

RESUMO

Present knowledge on spawning seasonality of freshwater fishes in tropical Asia and their relationship with environmental factors remains limited. Three Southeast Asian Cypriniformes fishes, Lobocheilos ovalis, Rasbora argyrotaenia and Tor Tambra, found in rainforest streams in Brunei Darussalam were studied on a monthly basis for a period of 2 years. To assess spawning characteristics, seasonality, gonadosomatic index and reproductive phases were examined from 621 L. ovalis, 507 R. argyrotaenia and 138 T. tambra. This study also examined environmental factors such as rainfall, air temperature, photoperiod and lunar illumination that may influence the timing of spawning of these species. We found that L. ovalis, R. argyrotaenia and T. tambra were reproductively active throughout the year but did not find that spawning in these species were associated with any of the investigated environmental factors. Our study showed that the non-seasonal reproductive ecology found in the tropical cypriniform species is distinctly different from that of temperate cypriniforms, which are known to follow spawning seasonality, suggesting an evolutionary adaptation to ensure their survival in an unstable environment. The reproductive strategy and ecological responses found in the tropical cypriniforms might be shifted in response to climate change scenarios in the future.


Assuntos
Cipriniformes , Animais , Peixes/fisiologia , Reprodução/fisiologia , Fotoperíodo , Água Doce , Sudeste Asiático , Estações do Ano
15.
Ecology ; 104(8): e4119, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37303281

RESUMO

Consumers mediate nutrient cycling through excretion and egestion across most ecosystems. In nutrient-poor tropical waters such as coral reefs, nutrient cycling is critical for maintaining productivity. While the cycling of fish-derived inorganic nutrients via excretion has been extensively investigated, the role of egestion for nutrient cycling has remained poorly explored. We sampled the fecal contents of 570 individual fishes across 40 species, representing six dominant trophic guilds of coral reef fishes in Moorea, French Polynesia. We measured fecal macro- (proteins, carbohydrates, lipids) and micro- (calcium, copper, iron, magnesium, manganese, zinc) nutrients and compared the fecal nutrient quantity and quality across trophic guilds, taxa, and body size. Macro- and micronutrient concentrations in fish feces varied markedly across species. Genera and trophic guild best predicted fecal nutrient concentrations. In addition, nutrient composition in feces was unique among species within both trophic guilds (herbivores and corallivores) and genera (Acanthurus and Chaetodon). Particularly, certain coral reef fishes (e.g., Thalassoma hardwicke, Chromis xanthura, Chaetodon pelewensis and Acanthurus pyroferus) harbored relatively high concentrations of micronutrients (e.g., Mn, Mg, Zn and Fe, respectively) that are known to contribute to ocean productivity and positively impact coral physiological performances. Given the nutrient-rich profiles across reef fish feces, conserving holistic reef fish communities ensures the availability of nutritional pools on coral reefs. We therefore suggest that better integration of consumer egestion dynamics into food web models and ecosystem-scale processes will facilitate an improved understanding of coral reef functioning.


Assuntos
Antozoários , Perciformes , Animais , Recifes de Corais , Ecossistema , Peixes/fisiologia , Nutrientes , Fezes
16.
PLoS One ; 18(6): e0286570, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37379294

RESUMO

Mass coral bleaching events coupled with local stressors have caused regional-scale loss of corals on reefs globally. Following the loss of corals, the structural complexity of these habitats is often reduced. By providing shelter, obscuring visual information, or physically impeding predators, habitat complexity can influence predation risk and the perception of risk by prey. Yet little is known on how habitat complexity and risk assessment interact to influence predator-prey interactions. To better understand how prey's perception of threats may shift in degraded ecosystems, we reared juvenile Pomacentrus chrysurus in environments of various habitat complexity levels and then exposed them to olfactory risk odours before simulating a predator strike. We found that the fast-start escape responses were enhanced when forewarned with olfactory cues of a predator and in environments of increasing complexity. However, no interaction between complexity and olfactory cues was observed in escape responses. To ascertain if the mechanisms used to modify these escape responses were facilitated through hormonal pathways, we conducted whole-body cortisol analysis. Cortisol concentrations interacted with habitat complexity and risk odours, such that P. chrysurus exhibited elevated cortisol levels when forewarned with predator odours, but only when complexity levels were low. Our study suggests that as complexity is lost, prey may more appropriately assess predation risk, likely as a result of receiving additional visual information. Prey's ability to modify their responses depending on the environmental context suggests that they may be able to partly alleviate the risk of increased predator-prey interactions as structural complexity is reduced.


Assuntos
Antozoários , Ecossistema , Animais , Recifes de Corais , Odorantes/análise , Hidrocortisona , Peixes/fisiologia , Comportamento Predatório/fisiologia
17.
Behav Processes ; 210: 104908, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37364624

RESUMO

Fish stock enhancement has been utilised in Taiwan for more than 30 years, yet the impacts of anthropogenic noise on the enhancement programs remain unknown. Anthropogenic noise can induce physiological and behavioural changes in many marine fishes. Therefore, we investigated the effects of acute boat noise (from stock enhancement release sites) and chronic noise (from aquaculture processes) on the anti-predator behaviour in three juvenile reef fishes: Epinephelus coioides, Amphiprion ocellaris and Neoglyphidodon melas. We exposed fish to aquaculture noise, boat noise and a combination of both, followed by a predator scare and documented kinematic variables (response latency, response distance, response speed and response duration). For the grouper E. coioides, their response latency decreased in the presence of acute noise, while their response duration increased in the presence of both chronic and acute noise. Among the anemonefish A. ocellaris, all variables remained unaffected by chronic noise, whereas acute noise increased the response distance and response speed. In the case of the black damselfish N. melas, chronic noise decreased the response speed, while acute noise decreased the response latency and response duration. Our results indicate that acute noise had a stronger influence on anti-predator behaviour than chronic noise. This study suggests that acute noise levels at restocking release sites can impact anti-predator behaviour in fishes, potentially altering fitness and likelihood of survival. Such negative effects and interspecific differences must be considered when restocking fish populations.


Assuntos
Bass , Síndrome MELAS , Perciformes , Animais , Recifes de Corais , Peixes/fisiologia , Ruído , Perciformes/fisiologia
18.
Mar Pollut Bull ; 193: 115183, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37369155

RESUMO

To assess the basal resources supporting food webs impacted by rainfalls, we compared stable isotope ratios (δ13C and δ15N) of fish consumers and organic matter sources between up- and down-sites in an estuary between seasons (June and September) and years (2018 and 2019) that showed different patterns of summer monsoon. Our study showed seasonal differences in the δ13C and δ15N values of basal resources and fish consumers in both years. At the up-site, significant differences of δ13C values of fish consumers were found between years, resulting from changing rainfall period, thereby causing a shift in food availability from terrigenous organic matter to periphyton. In contrast, at the down-site, the consistent isotopic values of fishes were observed in both years, suggesting that rainfall shift has a negligible impact on resources for fishes. Overall, the annual shift in resources for fishes in the estuary may be controlled by contrasting rainfall events.


Assuntos
Peixes , Cadeia Alimentar , Animais , Isótopos de Carbono/análise , Isótopos de Nitrogênio/análise , Peixes/fisiologia , República da Coreia
19.
J Biol Chem ; 299(7): 104899, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37295773

RESUMO

Opsins are universal photosensitive proteins in animals. Vertebrates have a variety of opsin genes for visual and non-visual photoreceptions. Analysis of the gene structures shows that most opsin genes have introns in their coding regions. However, teleosts exceptionally have several intron-less opsin genes that are presumed to have been duplicated by an RNA-based gene duplication mechanism, retroduplication. Among these retrogenes, we focused on the Opn4 (melanopsin) gene responsible for non-image-forming photoreception. Many teleosts have five Opn4 genes including one intron-less gene, which is speculated to have been formed from a parental intron-containing gene in the Actinopterygii. In this study, to reveal the evolutionary history of Opn4 genes, we analyzed them in teleost (zebrafish and medaka) and non-teleost (bichir, sturgeon, and gar) fishes. Our synteny analysis suggests that the intron-less Opn4 gene emerged by retroduplication after the branching of the bichir lineage. In addition, our biochemical and histochemical analyses showed that, in the teleost lineage, the newly acquired intron-less Opn4 gene became abundantly used without substantial changes in the molecular properties of the Opn4 protein. This stepwise evolutionary model of Opn4 genes is quite similar to that of rhodopsin genes in the Actinopterygii. The unique acquisition of rhodopsin and Opn4 retrogenes would have contributed to the diversification of the opsin gene repertoires in the Actinopterygii and the adaptation of teleosts to various aquatic environments.


Assuntos
Evolução Molecular , Peixes , Íntrons , Opsinas , Animais , Peixes/genética , Peixes/fisiologia , Opsinas/genética , Opsinas/metabolismo , Filogenia , Rodopsina/genética , Rodopsina/metabolismo , Peixe-Zebra/genética , Oryzias/genética , Sintenia/genética
20.
J Exp Biol ; 226(13)2023 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-37326209

RESUMO

Ecologists have long been interested in relevant techniques to track the field movement patterns of fish. The elemental composition of otoliths represents a permanent record of the growing habitats experienced by a fish throughout its lifetime and is increasingly used in the literature. The lack of a predictive and mechanistic understanding of the individual kinematics underlying ion incorporation/depletion limits our fine-scale temporal interpretation of the chemical signal recorded in the otolith. In particular, the rate at which elements are incorporated into otoliths is hypothesized to depend on fish physiology. However, to date, time lags have mostly been quantified on a population scale. Here, we report results from controlled experiments (translocation and artificially enriched environment) on individual trace element incorporation/depletion rates in Salmo trutta (Salmonidae). We reported significant lags (i.e. weeks to months) between changes in water chemistry and the subsequent change in otolith composition and highlighted substantial inter-individual variations in the timing and magnitude of Sr/Ca and Ba/Ca responses. These differences are partially linked to the energetic status (i.e. metabolic rate) of the individuals. It therefore appears that individuals with the highest metabolic rate are more likely to record detailed (i.e. brief) temporal changes than individuals having lower metabolic values. The time taken for environmental changes to be reflected in the growing otolith thus can no longer be assumed to remain a constant within populations. Results from the current study are a step towards the fine reconstruction of environmental histories in dynamic environments.


Assuntos
Peixes , Membrana dos Otólitos , Animais , Membrana dos Otólitos/metabolismo , Microquímica , Peixes/fisiologia , Água/metabolismo , Ecossistema
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