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The dispersal of fish into distant and isolated habitats remains a topic of continuous discussion in the field of fish biogeography. This is particularly relevant due to the perceived limitation of fish movement to what is known as active dispersal. Fish migration is often confined to interconnected water bodies, underscoring the significance of dispersal for fish inhabiting isolated aquatic habitats. However, empirical evidence for a natural (i.e. not human‐mediated) mechanism has been limited. Here we explore and provide evidence for waterbird‐mediated endozoochory as a possible dispersal mechanism in various fish species and families. We force‐fed mallardsAnas plathyrynchoswith fertilised eggs of nine bony fish species, covering nine taxonomic families. We recovered viable embryos of five fish taxa in the faeces of mallard, proving the ability of fish eggs to survive the passing of the digestive system of waterbirds. Moreover, the recovered eggs successfully hatched into larvae in two fish species. Taking into the flight speed and numerosity of mallards, as well as the high abundance of fish eggs, our results highlight endozoochory of fish eggs by waterbirds as a possible significant, although likely rare natural dispersal mechanism that can occur across more species than previously known in freshwater fish. [ABSTRACT FROM AUTHOR]

Rotifers are natural initial bait for fish larvae in freshwater. Here, the effects of various concentrations of acidified eggshell powder solutions (0, 20, 40, 80, 160, and 320 mg/L) on the growth and reproduction of the rotifer Brachionus calyciflorus were evaluated in culture experiments (11 days). The population density, catalase (CAT) and superoxide dismutase (SOD) activity, and Na and Mg contents in rotifers were significantly higher in the 20–160 mg/L groups than in the control group. A redundancy analysis showed that the Na, Mg, Cr, K, and Ca contents were positively correlated with the rotifer population density and CAT and SOD activity. Furthermore, the generation time and lifespan of F2 rotifers were significantly higher in the 20–40 mg/L treatment groups (82.0 ± 3.7 hr and 162.0 ± 2.7 hr, respectively) than in the control group (64.0 ± 4.0 hr and 128.0 ± 4.0 hr, respectively). Average egg production in F2 rotifers was significantly higher in the 20–80 mg/L treatment groups (15.2 ± 0.7 individuals) than in the control group (11.7 ± 1.2 individuals). These results indicate that 20 mg/L eggshell powder is optimal for growth and reproduction in B. calyciflorus, providing a theoretical basis for using new mineral sources in high-quality open bait for fish larvae. [ABSTRACT FROM AUTHOR]

Seagrass habitats play a major role in fisheries productivity through nursery functions and feeding grounds for diverse fish species. However, little is known about the seasonal distribution of fish larvae at large spatial scales in coastal East Africa. We investigated drivers of the seasonal fish larvae abundance and composition in seagrass habitats in Kenya and Tanzania. We found a high diversity of fish larvae (54 families) inhabiting seagrass habitats that differed between sites and seasons. Fish larvae abundance were highest in Kenya, particularly during the northeast monsoon season. Overall, total larval abundances per site were low, reaching less than 190 individuals/100 m3 in Kenya and less than 40 individuals/100 m3 in Tanzania, likely related to the low productivity and strong hydrodynamic processes in this region. Our data suggests that most of the fish spawn year-round in these tropical waters as we did not find strong seasonal patterns. All sites had a high relative abundance of larvae from demersal spawning fishes, indicating that many fish species move to coastal sites for spawning. Primary productivity and dissolved oxygen, driven by hydrodynamics conditions are positively related to fish larvae productivity both in Kenya and Tanzania. These findings indicate that the occurrence of both resident and transient fish larvae in seagrass meadows is driven by strong hydrodynamic and tidal processes that transport fish larvae across adjacent habitats. [ABSTRACT FROM AUTHOR]

Amblyomma ticks are vectors of both Rickettsia rickettsii and R. parkeri in the Americas, where capybaras (Hydrochoerus hydrochaeris) are the main hosts in urban areas, thus contributing to the transmission of spotted fever. Herein, we studied: (i) the seasonal dynamics and abundance of ticks in areas where capybaras live, (ii) the effect of environmental variables on tick abundance, and (iii) the presence of Rickettsia-infected ticks. Between September 2021 and September 2022, we sampled ticks using cloth-dragging at 194 sites on the shore of Lake Paranoá in Brasília, Brazil. We measured environmental data (season, vegetation type, canopy density, temperature, humidity, and presence or vestige of capybara) at each site. Nymphs and adults were morphologically identified to the species level, and a selected tick sample including larvae was subjected to genotypic identification. We investigated Rickettsia-infected ticks by PCR (gltA, htrA, ompB, and ompA genes) and associations between tick abundance and environmental variables using Generalized Linear Models. A total of 30,334 ticks (96% larvae) were captured. Ticks were identified as Amblyomma, with A. sculptum comprising 97% of the adult/nymphs. Genotype identification of a larval sample confirmed that 95% belonged to A. dubitatum. Seasonal variables showed significant effects on tick abundance. Most larvae and nymphs were captured during the early dry season, while the adults were more abundant during the wet season. Vegetation variables and the presence of capybaras showed no association with tick abundance. Rickettsia parkeri group and R. bellii were identified in A. dubitatum, while A. sculptum presented R. bellii. We conclude that: (i) Amblyomma ticks are widely distributed in Lake Paranoá throughout the year, especially larvae at the dry season, (ii) the abundance of Amblyomma ticks is explained more by climatic factors than by vegetation or presence of capybaras, and (iii) A. dubitatum ticks are potential vectors of R. parkeri in Brasília. [ABSTRACT FROM AUTHOR]

This study contrasts diet composition patterns of larval fish categorized as strong and weak foragers, identified from quadratic relationships between larval length and the number of prey eaten, for 11 fish species. Two sets of alternative hypotheses test whether strong foragers (1) exhibit precocious behaviour by eating later developmental stages of copepods, and (2) take advantage of random encounters with zooplankton, based on the contrast between the two categories in each 1 mm length-class. Results indicate that strong foragers shift their feeding toward earlier copepod developmental stages, which was most apparent in four flatfish species, and demonstrate stronger overall prey selectivity than weak foragers. Inverse modeling revealed the latter is achieved through increases in apparent prey perception and/or responsiveness to dominant prey types (i.e. nauplii and copepodites) and declines for less frequent prey (e.g. veliger and Cladocera). Foraging strength increased modestly with larger eye diameter and mouth gape. Two possible explanations for prey selection patterns are that strong foragers have inherently different capacity to perceive and attack prey, or that after initially eating sufficient large prey to meet metabolic requirements fuller stomachs depend on the ability of larval fish to take advantage of random encounters. [ABSTRACT FROM AUTHOR]

The role of vegetated habitats such as seagrass and macroalgal beds as nurseries is essential for the survival of larval and juvenile fish, although quantitative evaluation of the contribution of these habitats to nursery function is limited. Moreover, growth–survival relationships of larvae and juveniles associated with vegetated habitats have rarely been examined. To quantitatively and qualitatively evaluate the processes affecting juvenile survival in vegetated habitats, we investigated whether there is a correlation between the degree of selection for bigger and faster‐growing fish and mortality rates for three cohorts by birth date of post‐settlement black rockfish (Sebastes cheni) in a macroalgal bed. We also analyzed relationships between growth rate and experienced temperature by age class to examine the effects of temperature on growth. The latest cohort, which grew under lower vegetation coverage due to a seasonal increase in water temperature, showed higher mortality with evidence of strong selection for survival of bigger and faster‐growing fish. The growth–temperature relationships showed that positive effects of temperature on growth weakened after settlement. Therefore, we suggest that macroalgal coverage has a critical role in controlling the growth–mortality relationship of post‐settlement S. cheni. Furthermore, the negative effects of high temperature on juvenile survival through loss of vegetation may be greater than the positive effects on juvenile growth. These findings would contribute to the management of fisheries resources by increasing the understanding of relationships between survival mechanisms in fish early life stages and vegetation phenology of their habitat under the increasing effects of global warming. [ABSTRACT FROM AUTHOR]

Simple Summary: The increasing world population generates a huge volume of food waste. The use of black soldier fly larvae in the bioconversion of food waste is a new approach and an interesting example of a sustainable, circular economy approach. In this study, different food waste and residues (ranging from a vegetable to a carnivorous diet) were used as rearing substrates for black soldier fly larvae. The effects of different substrates on larvae development, bioconversion efficiency, and variations in surface temperatures were investigated. The results highlighted how an omnivorous diet provides performances comparable to the high-quality substrate diet (commercial chicken feed) and, therefore, can represent an effective strategy for rearing larvae while reducing food waste. Black soldier fly larvae (BSFL) can utilize food by-products or residues for growth, benefiting farm animal's diets' production sustainability. The experiment aimed to assess the effect of different substrate compositions on larval growth, chemical composition, and substrate temperature. BSFL were allocated to one of the four diets (control, vegetable, carnivorous, and omnivorous) for the entire experiment (8 days). The temperature was measured twice daily using a thermal-imaging camera, and the accumulated degree hours (ADH) was calculated. The results showed that the larvae fed the vegetable diet exhibited a significantly reduced growth performance, with a biomass reduction of 26.3% compared to the control diet; furthermore, vegetable-fed larvae showed a lower dry matter content (−30% compared to the average of other diets) due to lower fat content (−65% compared to average of other diets). The nutritional composition of larvae fed an omnivorous diet was similar to larvae fed a high-quality substrate diet (control diet-chicken feed), indicating that the omnivorous diet could be an ideal solution for rearing BSFL larvae; however, the current European legislation prohibits the use of animal meal. The study also revealed that substrate temperatures did not have a discernible influence on larval growth, further emphasizing the importance of diet in BSFL rearing strategies. [ABSTRACT FROM AUTHOR]

The distribution of fish eggs and larvae (ichthyoplankton) reflects spawning and nursery areas as well as dispersal routes. This study's goal is to demonstrate how the identification of ichthyoplankton species and stages and their spatial distribution among natural reefs (NRs) and artificial reefs (ARs) may serve as decision-making tools in conservation and fishery management. Natural reefs exhibited an eight-times higher abundance of eggs, as well as the highest abundance of larvae in the yolk-sac and preflexion phases. In contrast, ARs had the highest abundance of larvae in the flexion and postflexion phases. Natural reefs may serve as breeding grounds for Scaridae, Labridae, and Mugilidae; whereas, ARs may serve as breeding sites for Lutjanidae, Synodontidae, Carangidae, Fistularidae, and Haemulidae. Our study revealed differences between ARs and NRs, which demonstrate the potential of artificial reefs to expand the supply and settlement options of reef fishes and consequently can lead to increased fish production with potential benefits to adjacent fishing areas through connectivity. Thus, ARs as no-take sites can be effective tools for both fishery management and biodiversity conservation. The findings highlight the potential use of ichthyoplankton tools and the importance of considering both types of reefs in marine conservation and management efforts. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) are widely used in many industrial and domestic applications, which has resulted in unintentional human exposures and bioaccumulation in blood and other organs. Perfluorooctane sulfonate (PFOS) is among the most prevalent PFAS in the environment and has been postulated to affect brain functions in exposed organisms. However, the impacts of PFOS in early neural development have not been well described. We used zebrafish larvae to assess the effects of PFOS on two fundamental complex behaviors, prey capture and learning. Zebrafish exposed to PFOS concentrations ranging from 2 to 20 µM for differing 48‐h periods were viable through early larval stages. In addition, PFOS uptake was unaffected by the presence of a chorion. We employed two different experimental paradigms; first we assessed the impacts of increasing organismal PFOS bioaccumulation on prey capture and learning, and second, we probed stage‐specific sensitivity to PFOS by exposing zebrafish at different developmental stages (0–2 vs. 3–5 days post fertilization). Following both assays we measured the amount of PFOS present in each larva and found that PFOS levels varied in larvae from different groups within each experimental paradigm. Significant negative correlations were observed between larval PFOS accumulation and percentage of captured prey, whereas nonsignificant negative correlations were observed between PFOS accumulation and experienced‐induced prey capture learning. These findings suggest that PFOS accumulation negatively affects larval zebrafish's ability to perform complicated multisensory behaviors and highlights the potential risks of PFOS exposure to animals in the wild, with implications for human health. Environ Toxicol Chem 2024;43:847–855. © 2023 SETAC [ABSTRACT FROM AUTHOR]

Objective: Borneol is a widely used Chinese medicine, and borneol extracted from plants or synthesized are the two major types of borneol applied in clinical therapy. In this study, the hepatotoxicity of natural and synthetic borneol in both larval and adult zebrafish was detected. Methods: Adult fish and larval were exposed to borneol. Results: Synthetic borneol induced more obvious developmental toxicity, such as morphological deformity, delay of yolk sac absorption, disappearance of swim bladder, loose hepatic tissue, irregular cells, cell vacuolation and decline in cell count; treatment with synthetic borneol caused more severe oxidative stress, as changes in the activities of CAT and SOD and accumulation of ROS and MDA are more notable; synthetic borneol could disrupt lipid and glycogen metabolism more seriously possibly due to the more notable expression changes of metabolismrelated genes (ide, sirt4, dgat1b, and mgst1); synthetic borneol possibly produced hepatic injury by inducing cell apoptosis. Discussion: Our results suggest synthetic borneol has greater potential to cause hepatotoxicity compare to natural borneol. Conclusions: SB showed higher developmental toxicity than NB in larval zebrafish. Exposure to SB disordered the liver's lipid and glycogen metabolism caused by liver injury in higher concentration groups These findings have implications for understanding the mechanism of the hepatotoxicity caused by borneol, and provide a scientific basis for the drug safety of borneol. [ABSTRACT FROM AUTHOR]

Tonic immobility is an antipredator defence in which the prey animal remains motionless after physical contact with the predator, pretending to be dead. This behaviour has been observed among a variety of taxa but has received only little attention in amphibian larvae. During our field studies with fire salamander larvae, we observed that larvae from different habitats display tonic immobility after handling. In our study site, we find larvae in pond and stream habitats, that differ in several aspects such as their stress response and their risk‐taking behaviour, likely caused by the very different habitat conditions. We measured the time that the tonic immobility behaviour was displayed but found no difference between larvae from the two habitat types. Likewise, we also found no correlation between the size of the larvae and the duration of displaying the behaviour. In conclusion, we found that fire salamander larvae show tonic immobility, but found no evidence that the different habitat conditions influence the tonic immobility behaviour. [ABSTRACT FROM AUTHOR]

Copepods form the bulk of secondary production in marine ecosystems and are a major resource for higher trophic levels. Copepods are highly sensitive to environmental changes as they are ectotherms with a short life span whose metabolism and development depend on abiotic conditions. In turn, changes in their functional structure (i.e. functional trait composition) can have impacts on ecosystems. We examined changes in the copepod functional community in the North Sea over the past five decades, using a trait-based approach. We observed a shift around 1986–1988: the copepod community was initially dominated by larger herbivores, with a long development time, diapause ability, and highest abundances in summer. This community changed abruptly after 1986–1988, to a dominance of smaller carnivore taxa, with shorter development times, less ability to enter diapause, and that display higher abundances in autumn. This rapid reorganization could be driven by higher water temperatures, lower dinoflagellate abundances, and lower nutrient concentrations. These changes could impact adjacent trophic levels, such as phytoplankton on which several species graze or fish larvae, leading to a mismatch situation with consequences for fish recruitment. Our results emphasize the impact that global and regional changes could have on coastal ecosystems through the role played by copepods. [ABSTRACT FROM AUTHOR]

The yellowfin tuna is a very abundant tropical tuna species in the western equatorial Atlantic Ocean and an important fishery resource for the Brazilian tuna fleet. In this study we performed stable isotope analysis to better understand the spatial trophodynamics and dietary changes in yellowfin tuna around two insular marine protected areas in Brazil. A total of 65 yellowfin tuna specimens measuring between 47 and 138 cm LT (total length) were sampled around the archipelagos of Fernando de Noronha (FNA; n = 34) and Saint Peter and Saint Paul (SPSPA; n = 31) between July 2018 and September 2019. Bayesian mixing models and generalized additive models were used to investigate the contributions of four different prey items (zooplankton, cephalopods, fish larvae, and flying fish) to yellowfin tuna diet in each area and their potential changes in relation to predator growth. The four prey items were found to have different overall contributions between the two studied areas, with zooplankton being the most important prey in FNA, whereas flying fish was the most relevant prey to the species' diet in SPSPA. Significant changes in the species diet by size were also found, with fish smaller than 90 cm (TL) having a more generalist diet and larger animals relying more on consuming larger and more nutritious prey (i.e., flying fish). Our results suggest that these two marine protected areas play an important role in ocean dynamics, providing important and different foraging grounds for the development of this predator species. [ABSTRACT FROM AUTHOR]

Iodine is proven to be an effective disinfectant for fish eggs and is commonly used in a hatchery to improve hatching and survival rates. However, tolerance to iodine can vary in different fish species, and it is essential to determine the optimal concentration to ensure successful hatchery production. This study investigated the optimum concentration and exposure time to iodine during incubation to improve rabbitfish larvae's hatching and fertilization rate from 4/2022 -- 8/2022 in Thua Thien Hue, Vietnam. The study consisted of two experiments: Experiment 1 focused on different iodine concentrations: 0 ppm (C1), 50 ppm (C2), 100 ppm (C3), and 150 ppm (C4). Experiment 2 explored three exposure times: 10 minutes (T1), 20 minutes (T2), and 30 minutes (T3) to increase the fertilization, hatching, and survival rates at five days post-hatching. Data were compiled, analyzed, and compared by ANOVA using SPSS ver. 22.0. The results showed that 100 ppm iodine concentration at 20 minutes of exposure resulted in the optimum hatching, fertilization, and survival rates of S. guttatus during artificial reproduction. In the future, integrated solutions in the use of iodine solution for egg treatment and natural food supplementation at the larval stage should be recommended to improve the efficiency in artificial hatchery production of Rabbitfish. [ABSTRACT FROM AUTHOR]

Most likely, the alien snow crab Chionoecetes opilio entered the Kara Sea from the Barents Sea, both due to the migration of adults and with currents at the larval stage. Currently, all bottom stages, including mature individuals and a large number of pelagic larvae, are present in the Kara Sea. However, the origin of larvae has not yet been clarified. The larvae hatched in the Kara Sea should be at an earlier stage of development compared with the larvae arrived here from the Barents Sea due to later development of phytoplankton and, accordingly, later hatching. The larvae of the snow crab Chionoecetes opilio and the spider crab Hyas araneus were collected in the central and southwestern Kara Sea in July–early August 2019 by a Bongo zooplankton net with a diameter of 60 cm. It was established that the larvae were unevenly distributed across the Kara Sea. The most populus region was the border with the Barents Sea in the St. Anna Trough (up to 860 ind./m2), and relatively high concentrations of larvae were recorded in the southwestern part, where their abundance at stations varied from 18 to 302 ind./m2. In the zone of the Ob–Yenisei plume, crab larvae were absent or their abundance was minimal. Using molecular genetic methods, the species identity of 361 larvae (344 C. opilio and 17 H. araneus) was reliably determined, and measurements of a number of morphological structures were made for 401 larvae. Significant differences in size were found at the zoea II stage between C. opilio and H. araneus. In July 2019, in most of the Kara Sea, in zooplankton samples, crab larvae were represented by zoea I of C. opilio with rare specimens of zoea I of H. araneus of the Kara Sea origin. Only in the southwestern part, at the boundary with the Barents Sea, was the presence of zoea II of C. opilio and H. araneus observed in samples with an increased share of the latter species in catches, which probably originated from the Barents Sea. [ABSTRACT FROM AUTHOR]

The Paddlefish (Polyodon spathula) has been extirpated from portions of its native range due to anthropogenic habitat degradation and fragmentation, most notably the impoundment of rivers. To mitigate some of these losses in Oklahoma, Paddlefish have been stocked into reservoirs throughout the state, with variable success in establishing self‐sustaining populations. Two factors thought to contribute to success of Paddlefish stocking are spawning substrate and prey availability, which were quantified in six reservoirs and nine reservoir tributaries. Side‐scan sonar and supervised classification of aerial imagery were used to classify 4517‐ha of river substrate upstream of the river‐reservoir interface in reservoir tributaries. Zooplankton community structure, water clarity, and nutrient availability were also assessed in the same reservoirs and tributaries. One tributary had suitable spawning substrate (>40%), and the rest had minimal (<1.5%), which suggested that availability of suitable spawning substrate was not directly correlated with Paddlefish stocking success. Reservoirs with self‐sustaining Paddlefish populations had higher abundance of large zooplankton (copepods and cladocerans) than reservoirs without a reproducing population. Notably, tributaries associated with Lake Texoma, the one known example of failed restoration, were much more turbid than other rivers. We conclude that abiotic factors such as water clarity may contribute more to variable recruitment than spawning substrate or zooplankton abundance by mediating foraging success of Paddlefish post‐larvae. [ABSTRACT FROM AUTHOR]

Background: Apoptosis is involved (directly and indirectly) in several physiological processes including tissue remodeling during the development, the turnover of immune cells, and a defense against harmful stimuli. The disordered apoptotic process participates in the pathogenesis of various diseases, such as neoplasms, and chronic inflammatory or systemic autoimmune diseases, which are associated with its inadequate regulation. Caspases are vital components of the apoptotic pathway that are involved in developmental and immune processes. However, genome-wide identification and functional analysis of caspase have not been conducted in Mytilus coruscus, which is an economically important bivalve. Results: Here, 47 caspase genes were identified from the genomes of M. coruscus, and the expansion of caspase-2/9 and caspase-3/6/7 genes were observed. Tandem duplication acts as an essential driver of gene expansion. The expanded caspase genes were highly diverse in terms of sequence, domain structure, and spatiotemporal expression profiles, suggesting their functional differentiation. The high expression of the expanded caspase genes at the pediveliger larvae stage and the result of apoptosis location in the velum suggest that the apoptosis mediated by them plays a critical role in the metamorphosis of M. coruscus larvae. In gill, caspase genes respond differently to the challenge of different strains, and most caspase-2/9 and caspase-3/6/7 genes were induced by copper stress, whereas caspase-8/10 genes were suppressed. Additionally, most caspase genes were upregulated in the mantle under ocean acidification which could weaken the biomineralization capacity of the mantle tissue. Conclusions: These results provide a comprehensive overview of the evolution and function of the caspase family and enhanced the understanding of the biological function of caspases in M. coruscus larval development and response to biotic and abiotic challenges. [ABSTRACT FROM AUTHOR]

The tidal occurrence of larval fishes was investigated in the permanently open Kowie Estuary on the warm-temperate coast of South Africa. Larval fishes were sampled in the mouth region using two drifting light traps deployed on the ebb and flood tides every second night for two consecutive 14-day periods, coinciding with the dark moon phase. A total of 553 larval fishes were caught, representing nine families and 26 species, of which Blenniidae and Clupeidae dominated. The prevalence of different estuarine association fish guilds was also tide-specific. Marine and estuarine species, such as Omobranchus woodi, were more dominant during flood tides, while marine straggler species, such as Sardinops sagax, which are not dependent on estuaries, were dominant on the ebb tide. Marine estuarine-dependents were only present during flood tides, potentially indicating ingress and entrainment within the estuary. The results confirm that light trap catches yield a different composition of species compared to towed ichthyoplankton net studies. Additionally, drifting light traps allow for better targeting of species with a phototactic response and reduction of incidental catch. Consequently, a mixture of gear is encouraged for more comprehensive surveys of larval fish occurrence. [ABSTRACT FROM AUTHOR]

We evaluated the potential of the euryhaline copepod Pseudodiaptomus inopinus as a prey to enhance the feeding activity of red sea bream Pagrus major larvae. Pseudodiaptomus inopinus was used to evaluate free amino acid composition and dietary effects on the rearing performance of fish larvae, in comparison to rotifers (control prey). Among free amino acids, alanine, arginine, and glycine were markedly higher in P. inopinus than in rotifers. Larvae were reared for 20 days post-hatching under three feeding treatments: rotifers (control), rotifers supplemented with copepods, and copepods only. Larvae fed copepods alone had a higher growth rate than those in the other treatments. However, the survival rates of these larvae were lower than those under control or copepod supplementation. While equivalent stocking densities of rotifers were employed in the rearing water for both larvae, whether supplemented with copepods or not, the supplemented treatment yielded diminished larval survival and failed to enhance growth rates. According to gut content analysis, larvae receiving supplemented treatment preferentially fed on copepods, and the number of ingested rotifers was reduced. As a result, total ingested mass was lower in the supplemented larvae. This study suggests that copepods containing free amino acid species negatively affect prey acceptance of fish larvae. [ABSTRACT FROM AUTHOR]

We review ichthyoplankton research history in Indonesia, which began when H.C. Delsman conducted studies on fish larvae and eggs in the northern Java region (1921–1938). The Danish 1929 eel expedition net sampling in Indonesian waters discovered an Anguilla bicolor bicolor spawning area off West Sumatra by collecting small leptocephali. After > 45 years of no fish larvae studies in Indonesian waters, the Banda Sea Indonesia-Netherlands Snellius-2 Expedition occurred (1984–1985) before a study on coastal fish larvae at Lombok Island was conducted (1995–1997). Ichthyoplankton research then occurred more frequently in the early 2000s, which started with Indonesia-Japan collaborative Isaacs-Kidd Midwater Trawl (IKMT) surveys for eel larvae (leptocephali), which discovered that some tropical anguillids make short spawning migrations, and that allowed other research, including on marine eel leptocephali. This research was followed by numerous ichthyoplankton surveys in the Indonesian Seas and coastal waters or estuaries. The ichthyoplankton research varied widely in methods, the number of taxa present, and identification levels, with studies being conducted with bongo nets, small beach seines, or push nets. The number of families detected in each region ranged from about 12–90, which included the larvae of several commercially important fish species, and learning about species such as the tunas was an important focus. However, the studies so far are insufficient to guide fisheries management, so we discuss steps to facilitate ichthyoplankton research in Indonesia, which include standardizing survey methodologies, increasing the number of researchers in this field, providing sufficient infrastructure support, and creating data sharing and specimen archiving systems. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of the co-feeding (C) period on the growth and survival of larvae of the yo-yo loach Botia lohachata ornamental species during the weaning period from live food (LF) to inert food (IF). The breeders were subjected to induced spawning using crude pituitary homogenate. A total of 2,400 larvae were used with an average initial weight of 0.39 ± 0.09 mg and an average total length of 4.08 ± 0.21 mm, from a single breeding pair. The live food was newly hatched nauplii of Artemia franciscana, and the inert diet was a commercial ration with 55% crude protein and two particle sizes (142-350 µm and 350-500 µm). As the first food, all larvae received A. franciscana during the first six days, except for the fasting (NC) and inert food (IF) groups. The following co-feeding strategies were employed: C4 = 4 days of co-feeding, C8 = 8 days of co-feeding, C12 = 12 days of co-feeding, and LF = Artemia during the entire experimental period. The longest period with live food promoted better larval growth rates. The specific growth rate of larvae fed live food during the entire period (LF) was higher than that of the other groups, followed by the co-feeding strategies. There was no effect (P > 0.01) on larval survival in the LF, C12, C8, and C4 groups, which ranged from 41% to 53% after 30 days. Treatment R resulted in high mortality and low growth, suggesting that live food should be the first food source for B. lohachata larvae. [ABSTRACT FROM AUTHOR]

Identifying factors that affect larval mortality is critical for understanding the drivers of fish population dynamics. Although larval fish mortality is high, small changes in mortality rates can lead to large changes in recruitment. Recent studies suggest maternal provisioning can dramatically affect the susceptibility of larvae to starvation and predation, the major sources of early‐life mortality. We measured otolith core width‐at‐extrusion and validated that this is a proxy for larval size‐at‐extrusion for eight species of rockfishes (genus Sebastes) to examine the influence of initial larval size on larval growth and survival and to understand how oceanographic conditions experienced by gestating females affect larval size (i.e., quality). Otolith core width‐at‐extrusion was significantly positively related to larval rockfish recent growth rate (5/7 species with sufficient sample size) and survival (all eight species). This suggests that individuals that are larger at extrusion generally grow faster and are more likely to survive early life stages. Otolith core width‐at‐extrusion was positively related to higher presence of Pacific Subarctic Upper Water and was negatively related to warmer, saline waters at the depths gestating mothers inhabited during the months prior to larval collection. In addition, otolith core width was larger further from fishing ports, possibly because these locations were historically less fished, contained more older, larger females, and/or had inherently better habitat quality (higher Pacific Subarctic Upper Water) than sites closer to shore. These results indicate that the environmental conditions female rockfish experience during gestation drive the size of the larvae they produce and impact larval growth and survival. [ABSTRACT FROM AUTHOR]

Winter conditions in the NW Mediterranean cause instability of the water column and non‐geostrophic dynamics, such as vertical mixing and convection are significant. These events involve nutrient supply to the photic zone that can sustain high productivity. In this study, we aim to investigate the role of winter hydrodynamics on the spawning strategies of Sardina pilchardus and Micromesistius poutassou. Data were obtained on two oceanographic cruises (February 2017 and 2018) off the Catalan coast. The occurrence of S. pilchardus eggs very close to the coast indicated a clear preference of the species for spawning in coastal areas. Preflexion and postflexion larvae exhibited a slightly wider distribution showing a clear association with the cold, less saline and more productive coastal waters. Preflexion larvae of M. poutassou were found on the upper slope and over the shelf, being offshore limited by the shelf/slope front present all along the slope. The front would act as a barrier preventing their dispersion towards the open sea. M. poutassou larvae in advanced developmental stages were located close to the coast in the productive shelf waters, with instabilities of the front contributing to larval transport from offshore waters to the coast. The vertical distribution of both species showed high variability, not only related with the daily cycle or developmental stage, but also with the vertical structure of the water column. Overall, the results provide some clues on how the spawning strategies of both species may evolve under future scenarios of higher winter‐stratification, because of the global warming. [ABSTRACT FROM AUTHOR]

To gain a better understanding of the mechanisms underlying spatial heterogeneity in ichthyoplankton communities in the SW Atlantic, we examined for the first time the latitudinal and continental shelf–slope gradients in ichthyoplankton structure and oceanographic features in the Campos Basin during the relaxation phase of coastal upwellings (late autumn to early winter). This region, located on SE Brazil's continental margin, is the most productive offshore oil basin in the country and has ecological relevance owing to the existence of areas that experiences mesoscale (tens to hundreds of kilometers) processes (eddies, filaments, and upwelling) caused by the interaction of continental shelf and slope circulation with deep water masses. The present study collected a total of 3892 fish eggs and 10,030 larvae from 36 sampling stations, averaging 22 eggs per 100 m3 and 56 larvae per 100 m3. A total of 250 taxa (5 for fish eggs and 248 for larvae) were identified, encompassing 80 families and 145 genera. Species distribution exhibited a considerable degree of spatial variability, which was related mostly to hydrological characteristics. In general, greater densities were associated with higher nutrient concentrations areas. Through distance‐based Redundancy Analysis, some discriminating species were found to associate with certain areas of the continental shelf characterized by colder temperatures. The ichthyoplankton distribution patterns suggested a potential influence from mesoscale oceanographic fronts, specifically those that induce upwelling of the cold and nutrient‐rich South Atlantic Central Water. Nonetheless, the methodologies used in this study faced challenges in distinctly identifying these processes. [ABSTRACT FROM AUTHOR]

The distribution of fish larvae in estuaries is crucial for comprehending the functioning of these ecosystems and their role as nursery grounds for marine fish species. Data regarding larval fish assemblages in the coastal waters of Bangladesh are currently scarce. This study examines the spatial and seasonal dynamics of larval fish communities in these waters using a two-year sampling effort with a bongo net. This study investigates the diversity, abundance, and distribution of larval fishes at four sites (Bakkhali River Estuary, Moheshkhalipara, Naf River Estuary, and Rezu Khal Estuary) on the southeastern coast of Bangladesh. A total of 10,387 fish larvae representing 25 families were identified. Clupeidae (42.9%), Engraulidae (35.5%), Ambassidae (10.1%), Myctophidae (2.1%), and Gobiidae (1.9%) were the five most dominant families based on the larval catch composition. Marked seasonal differences in the larval fish abundance were observed. However, these differences were not observed when comparing the four sampled sites. Additionally, the correlation between environmental variables and the larval abundance indicated that salinity negatively influences (p < 0.001) the larval fish abundance. This is the first comprehensive investigation of larval fish assemblages in the coastal waters of Bangladesh. The findings of this study enhance our understanding of the nursery habitat requirements for the early development stages of both migratory and resident species in subtropical coastal waters, providing valuable information for potential applications in management and conservation efforts. [ABSTRACT FROM AUTHOR]

Yellow grub disease, caused by Clinostomum metacercaria, is an endemic zoonotic infection in freshwater fish, responsible for Halzoun syndrome transmitted through the consumption of raw infected fish. This study aimed to conduct a multidisciplinary investigation integrating detailed morphology, oxidative stress, immunology, and histopathology alteration to advance our understanding of Clinostomum infection. In this annual study, 400 Nile tilapia (Oreochromis niloticus) were collected from the Nile River at Al Bahr Al Aazam, Giza Governorate to assess Clinostomum infection prevalence. Of the examined fish, 160 individuals (40.0%) harboured larval Clinostomum infections. Clinostomum metacercariae were observed in various anatomical locations, with 135 fish (33.8%) in buccal cavities, 21 fish (5.25%) in gill chambers, and 4 fish (1.0%) on the skin. Infection intensity ranged from 2 to 12 cysts per fish, averaging 5 cysts, notably with skin infections characterized by a single cyst in each fish. Macroscopic encysted metacercariae were collected from buccal cavities, gills, and skin. Micro-morphology revealed distinct features in C. complanatum, including an elliptical oral sucker with collar-like rings and large sensory papilla-like structures, contrasting with the absence of these features in C. phalacrocoracis. Oxidative stress, assessed through malondialdehyde (MDA) and nitric oxide levels, revealed an elevation in MDA to 35.13 ± 6 nmol/g and nitric oxide to 25.80 ± 3.12 µmol/g in infected fish. In infected fish, MHC-I gene expression increased approximately 13-fold, MHC-II peaked at 19-fold, and IL-1β significantly upregulated by 17-fold, compared to control levels. Histopathology detailed associated lesions, such as cyst encapsulation and eosinophilic infiltration. Clinstomiasis and its impacts on fish hosts offer crucial insights to control this emerging fish-borne zoonotic disease, threatening wildlife, aquaculture, and human health. [ABSTRACT FROM AUTHOR]

Mechanical stimuli arising from fetal movements are critical factors underlying joint growth. Abnormal fetal movements negatively affect joint shape features with important implications for joint health, but the mechanisms by which mechanical forces from fetal movements influence joint growth are still unclear. In this research, we quantify zebrafish jaw joint growth in 3D in free-to-move and immobilised fish larvae between four and five days post fertilisation. We found that the main changes in size and shape in normally moving fish were in the ventrodorsal axis, while growth anisotropy was lost in the immobilised larvae. We next sought to determine the cell level activities underlying mechanoregulated growth anisotropy by tracking individual cells in the presence or absence of jaw movements, finding that the most dramatic changes in growth rates due to jaw immobility were in the ventrodorsal axis. Finally, we implemented mechanobiological simulations of joint growth with which we tested hypotheses relating specific mechanical stimuli to mechanoregulated growth anisotropy. Different types of mechanical stimulation were incorporated into the simulation to provide the mechanoregulated component of growth, in addition to the baseline (non-mechanoregulated) growth which occurs in the immobilised animals. We found that when average tissue stress over the opening and closing cycle of the joint was used as the stimulus for mechanoregulated growth, joint morphogenesis was not accurately predicted. Predictions were improved when using the stress gradients along the rudiment axes (i.e., the variation in magnitude of compression to magnitude of tension between local regions). However, the most accurate predictions were obtained when using the compressive stress gradients (i.e., the variation in compressive stress magnitude) along the rudiment axes. We conclude therefore that the dominant biophysical stimulus contributing to growth anisotropy during early joint development is the gradient of compressive stress experienced along the growth axes under cyclical loading. Author summary: The mechanical forces caused by fetal movements are important for normal development of the skeleton, and in particular for joint shape. Several common developmental musculoskeletal conditions such as developmental dysplasia of the hip and arthrogryposis are associated with reduced or restricted fetal movements. Paediatric joint malformations impair joint function and can be debilitating. To understand the origins of such conditions, it is essential to understand how the mechanical forces arising from movements influence joint growth and shape. In this research, we used a computational model of joint growth applied to the zebrafish jaw joint to study the impact of fetal movements on joint growth. We find that how the amount of compressive loading changes along the rudiment axes and over the loading cycle is critical to the normal growth of the developing joint. Our findings implicate gradients of compressive loading as a promising target when developing therapeutic strategies (such as targeted physiotherapy) for the treatment of musculoskeletal conditions. [ABSTRACT FROM AUTHOR]

Unicellular ciliates like Tetrahymena are best known as free-living bacteriovores, but many species are facultative or obligate parasites. These "histophages" feed on the tissues of hosts ranging from planarian flatworms to commercially important fish and the larvae of imperiled freshwater mussels. Here, we developed a novel bioinformatics pipeline incorporating the nonstandard ciliate genetic code and used it to search for Ciliophora sequences in 34 publicly available Platyhelminthes EST libraries. From 2,615,036 screened ESTs, we identified nearly 6,000 high-confidence ciliate transcripts, supporting parasitism of seven additional flatworm species. We also cultured and identified Tetrahymena from nine terrestrial and freshwater planarians, including invasive earthworm predators from the genus Bipalium and the widely studied regeneration models Dugesia japonica and Schmidtea mediterranea. A co-phylogenetic reconstruction provides strong evidence for the coevolution of histophagous Ciliophora with their Platyhelminthes hosts. We further report the antiprotozoal aminoglycoside paromomycin expels Tetrahymena from S. mediterranea , providing new opportunities to investigate the effects of this relationship on planarian biology. Together, our findings raise the possibility that invasive flatworms constitute a novel dispersal mechanism for Tetrahymena parasites and position the Platyhelminthes as an ideal model phylum for studying the ecology and evolution of histophagous ciliates. [ABSTRACT FROM AUTHOR]

The Wolastoq | Saint John River (W|SJR) in New Brunswick, Canada, is regulated by hydroelectric dams with the largest and furthest downstream being the Mactaquac Generating Station (MQGS). River regulation can disrupt ecosystem connectivity by restricting access to upstream habitat for fishes and parasitic mussel larvae dependent on fishes for dispersal. Following installation of the MQGS, the number of Gaspereau (Alewife, Alosa pseudoharengus [Wilson, 1811]) and Blueback herring, Alosa aestivalis [Mitchill, 1814]) that spawn in that region of theW|SJR has increased dramatically. We assessed ectoparasitic freshwater mussel glochidia on Gaspereau captured at the MQGS and found 100% infested with an average of 43.2 glochidia per fish. Glochidia infested gill rakers, with increasing intensities from the first to fourth gill arch (P < 0.001). At least one million Gaspereau are passed above the MQGS annually, suggesting that millions of glochidia are simultaneously passed upstream each year with their hosts. We sequenced mitochondrial markers (ND1, COI) to ascertain mussel species and confirm both Alewife and Blueback herring as hosts for Alewife Floater (Utterbackiana implicata [Say, 1829]). This study provides critical baseline data on symbiotic interactions tightly interwoven in this river ecosystem and demonstrate that river regulation and fish passage considerations are more complex than most management plans account for currently. [ABSTRACT FROM AUTHOR]

This study investigated how Atlantic sturgeon cells respond to elevated temperatures, shedding light on the potential impacts of climate change on fish. Atlantic sturgeon (Acipenser oxyrinchus), an IUCN (International Union for Conservation of Nature) Red List species and evolutionarily related to paleonisiform species, may have considerable physiological adaptability, suggesting that this species may be able to cope with changing climatic conditions and higher temperatures. To test this hypothesis, the AOXlar7y cell line was examined at 20 °C (control) and at elevated temperatures of 25 °C and 28 °C. Parameters including proliferation, vitality, morphology, and gene expressions related to proliferation, stemness, and stress were evaluated. Additionally, to achieve a comprehensive understanding of cellular changes, mitochondrial and metabolic activities were assessed using Seahorse XF96. AOXlar7y cells adapted to 28 °C exhibited enhanced mitochondrial adaptability, plasticity, heightened cell proliferation, and increased hsp70 expression. Increased baseline respiration indicated elevated ATP demand, which is potentially linked to higher cell proliferation and heat stress defense. Cells at 28 °C also displayed elevated reserve respiration capacity, suggesting adaptation to energy demands. At 25 °C, AOXlar7y cells showed no changes in basal respiration or mitochondrial capacity, suggesting unchanged ATP demand compared to cells cultivated at 20 °C. Proliferation and glycolytic response to energy requirements were diminished, implying a connection between glycolysis inhibition and proliferation suppression. These research results indicate sturgeon cells are capable of withstanding and adapting to an 8 °C temperature increase. This cellular analysis lays a foundation for future studies aimed at a deeper understanding of fish cell physiological adaptations, which will contribute to a better knowledge of environmental threats facing Atlantic sturgeon and fish populations amid climate change. [ABSTRACT FROM AUTHOR]

The medaka fish (Oryzias latipes) is a vertebrate model used in developmental biology and genetics. Here we explore its suitability as a model for investigating the molecular mechanisms of human myopathies caused by mutations in sarcomeric proteins. To this end, the relevant mechanical parameters of the intact skeletal muscle of wild-type medaka are determined using the transparent tail at larval stage 40. Tails were mounted at sarcomere length of 2.1 μm in a thermoregulated trough containing physiological solution. Tetanic contractions were elicited at physiological temperature (10C–30C) by electrical stimulation, and sarcomere length changes were recorded with nanometer-microsecond resolution during both isometric and isotonic contractions with a striation follower. The force output has been normalized for the actual fraction of the cross section of the tail occupied by the myofilament lattice, as established with transmission electron microscopy (TEM), and then for the actual density of myofilaments, as established with X-ray diffraction. Under these conditions, the mechanical performance of the contracting muscle of the wild-type larva can be defined at the level of the half-thick filament, where ~300 myosin motors work in parallel as a collective motor, allowing a detailed comparison with the established performance of the skeletal muscle of different vertebrates. The results of this study point out that the medaka fish larva is a suitable model for the investigation of the genotype/phenotype correlations and therapeutic possibilities in skeletal muscle diseases caused by mutations in sarcomeric proteins. NEW & NOTEWORTHY The suitability of the medaka fish as a model for investigating the molecular mechanisms of human myopathies caused by mutations of sarcomeric proteins is tested by combining structural analysis and sarcomere-level mechanics of the skeletal muscle of the tail of medaka larva. The mechanical performance of the medaka muscle, scaled at the level of the myosin-containing thick filament, together with its reduced genome duplication makes this model unique for investigations of the genotype/phenotype correlations in human myopathies. [ABSTRACT FROM AUTHOR]

A 56-day feeding trial assessed the effects of black soldier fly larvae meal (BSFLM) on the growth performance and hepatopancreas health of juvenile Eriocheir sinensis. Six isoproteic and isolipidic diets with 0% (FM), 10% (BSFLM10), 20% (BSFLM20), 30% (BSFLM30), 40% (BSFLM40), or 50% (BSFLM50) replacement of fish meal by BSFLM were formulated. Compared to FM, replacing 10%–40% of fish meal with BSFLM did not significantly affect the weight gain rate (WGR) or specific growth rate (SGR), while BSFLM50 significantly decreased the WGR and SGR. Crabs fed BSFLM50 had significantly lower T-AOC activity than those fed other diets, and crabs fed BSFLM30, BSFLM40, or BSFLM50 had significantly lower activities of antioxidant enzymes (SOD and GSH-Px) in the hepatopancreas than those fed FM or BSFLM10. Compared to FM, BSFLM10, BSFLM20, and BSFLM30 did not affect the relative expression of genes related to the nonspecific immunity, while BSFLM40 and BSFLM50 upregulated the relative expression of these genes. Furthermore, histological analysis showed that the hepatopancreas was deformed in the BSFLM50 group, with widened lumens and loss of basal membrane integrity. In summary, BSFLM replacing 50% of fish meal reduced growth and structural damage to the hepatopancreas. An immune response was activated when the replacement level was over 30%. Therefore, the replacement level of dietary fish meal by BSFLM is recommended to be not more than 30% of the juvenile E. sinensis feed. [ABSTRACT FROM AUTHOR]

Knowledge of the trophic structure and variability of planktonic communities is a key factor in understanding food-web dynamics and energy transfer from zooplankton to higher trophic levels. In this study, we investigated how stable isotopes of mesozooplankton species varied seasonally (winter, spring, autumn) in relation to environmental factors and plankton size classes in a temperate coastal ecosystem. Our results showed that spring is characterized by the strongest vertical and size-structured plankton food-web, mainly fueled by the phytoplankton bloom. As a result, spring displayed the largest isotopic niche space and trophic divergence among species. On the contrary, both pelagic and benthic-derived carbon influenced low productive seasons (winter and autumn), resulting in more generalist strategies (trophic redundancy). Stable isotope mixing models were used to explore how different seasonal structures influenced the overall food web up to predatory plankton (i.e., mysids, chaetognaths, and fish larvae). Different feeding strategies were found in spring, with predators having either a clear preference for larger prey items (> 1 mm, for herring and dab larvae) or a more generalist diet (sprat and dragonets larvae). During low productive seasons, predators seemed to be more opportunistic, feeding on a wide range of size classes but focusing on smaller prey. Overall, the food-web architecture of plankton displayed different seasonal patterns linked to components at the base of the food web that shaped the main energy fluxes, either from phytoplankton or recycled material. Additionally, these patterns extended to carnivorous plankton, such as fish larvae, emphasizing the importance of bottom-up processes. [ABSTRACT FROM AUTHOR]

A network of marine reserves can enhance yield in depleted fisheries by protecting populations, particularly large, old spawners that supply larvae for interspersed fishing grounds. The ability of marine reserves to enhance sustainable fisheries is much less evident. We report empirical evidence of a marine reserve network improving yield regionally for a sustainable spiny lobster fishery, apparently through the spillover of adult lobsters and behavioral adaptation by the fishing fleet. Results of a Before-After, Control-Impact analysis found catch, effort, and Catch-Per-Unit Effort increased after the establishment of marine reserves in the northern region of the fishery where fishers responded by fishing intensively at reserve borders, but declined in the southern region where they vacated once productive fishing grounds. The adaptation of the northern region of the fishery may have been aided by a history of collaboration between fishers, scientists, and managers, highlighting the value of collaborative research and education programs for preparing fisheries to operate productively within a seascape that includes a large marine reserve network. [ABSTRACT FROM AUTHOR]

Understanding the molecular mechanisms underlying individual responses to environmental changes is crucial for species conservation and management. Pelagic fishes including Atlantic herring (Clupea harengus) are of particular interest because of their key ecological and economic roles and their susceptibility to a changing ocean from global warming. Temperature and photoperiod have been linked with spawning time and location in adult herring, but no study has thus far investigated the role of environmental factors on gene regulation during the vulnerable early developmental stages. Here, we examine DNA methylation patterns of larval herring bred under two temperatures (11°C and 13°C) and photoperiod (6 and 12 h) regimes in a 2 × 2 factorial design. We found consistently high levels of global methylation across all individuals and a decline in global methylation with increased developmental stage that was more pronounced at 13°C (p ≤ 0.007) than at 11°C (p ≥ 0.21). Most of the differentially methylated sites were in exon and promoter regions for genes linked to metabolism and development, some of which were hypermethylated at higher temperature. These results demonstrate the important role of DNA methylation during larval development and suggest that this molecular mechanism might be key in regulating early‐stage responses to environmental stressors in Atlantic herring. [ABSTRACT FROM AUTHOR]

Background: Community diagnosis is an activity to identify problems by collecting data in the community that can locate broad issues and cover various aspects of society. The emergence of health problems is not only caused by individual negligence but can also be caused by community ignorance due to a lack of correct information about a disease. The purpose of this study is to obtain an overview of the health problems in Tegaltandan hamlet, Banguntapan sub-district to determine problem priorities and obtain appropriate alternative solutions to overcome the priority problems that have been resolved. Method: This study used descriptive quantitative analysis by conducting interviews using a community diagnosis questionnaire. The analysis was used to prioritize health problems using the USG method and village community meetings. The sampling technique was purposive sampling with 132 samples obtained. Results: Ten major health problems in the research area that need attention are no organic trash collection center covered in homes, using spray-repellent, not used to wearing a helmet during riding, not sprinkling larvacide powder on the washed water dump as dengue prevention, not applying repellents as dengue prevention not using gloves while chopping ingredients with a knife for cooking, no props when moving heavy objects, not taking care of fish larvae eaters, hypertension and diabetes mellitus. After prioritizing using USG and village community meetings, they all agreed to decide diabetes mellitus as the main health problem in this area. Conclusion: Diabetes mellitus was considered a major problem at the study site that requires further intervention. [ABSTRACT FROM AUTHOR]

The global ornamental fish trade is expanding in response to increased demand for indigenous fish on the global market, while exogenous carotenoids can improve colouration. The 60‐day trial investigated the effect of carotenoid supplementation, via Artemia, on colouration, growth and immunophysiology of Badis badis (dwarf chameleon fish). Carotenoid was enriched at 40 ppm (T1), 80 ppm (T2) and 120 ppm (T3) and compared with controls, C1 (unenriched) and C2 (oil‐enriched). Fish larvae (average weight 0.12 g) were fed enriched–unenriched Artemia in triplicates (5 × 3) in aquarium tanks (15 L). C1 and T2 had better skin colour (lightness and whiteness) in the posterolateral and caudal fins respectively. The value of redness (a*) in the anterolateral region was higher in T2 and T3 (p < 0.05). The anterolateral red index was higher (p < 0.05) in T2 and T3, whereas in the posterolateral and caudal fins, T1 and T2 were higher (p < 0.05). Compared to C1 and C2, the hue angle in carotenoid groups was found to be low (p < 0.05). No significant change in the growth performance was noticed (p > 0.05). Immune scores such as lysozyme and alkaline protease were highest in T3 (p < 0.05), whereas protease activity was highest in T2 (80 ppm). Stress biomarkers, viz., superoxide dismutase, catalase and malondialdehyde were low in groups fed enriched Artemia (p < 0.05). The integrated biomarker response means and star plot area were lower in the enriched groups (T1–T3), while T2 was the lowest. Overall findings reveal that dietary carotenoid improves the colouration and immune status, but fail to promote growth. Furthermore, 80 ppm enrichment dose improves the overall performance. The findings can help fish keepers improve fish colour and health status through carotenoid supplementation. [ABSTRACT FROM AUTHOR]

Designating marine protected areas is widely acknowledged as a highly effective strategy for marine conservation and resource management. In 2019, the Karaburun-Ildır Bay area (the eastern central Aegean Sea, Türkiye) was declared as a Special Environmental Protection Area (SEPA) by the Republic of Türkiye, Ministry of Environment, Urbanization, and Climate Change. In this study, we investigated the ichthyoplankton biodiversity of the Karaburun-Ildır Bay SEPA and its potential as a spawning and nursery ground for marine teleost fishes. Ichthyoplankton samples were collected from ten locations in May 2022, September 2022, and August 2023. Early life stages from 62 species representing 26 families were recorded in the area. A total of 6818 eggs of 28 species and 844 larvae of 50 species were sampled during the study. The early life stages of sparids and mullids were dominant in May while the eggs and larvae of small pelagic fish, especially those of Engraulis encrasicolus and Sardinella aurita, were dominant in August and September. Early life stages of only three non-native fish, Bregmaceros nectabanus, Upeneus moluccensis and Mullidae sp.L1 were found in the study. Our findings indicate that the Karaburun-Ildır Bay SEPA has an important potential for conservation of many commercial fish species as a spawning and nursery area. [ABSTRACT FROM AUTHOR]

Copepods are aquatic invertebrates with a key role at the basis of marine food webs due to their high biomass as well as their elevated fatty acid (FA) content. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are two FA abundant in copepods which have a well demonstrated role in growth and reproduction in marine organisms. While the majority of research has focused on planktonic copepod species, less is known for benthic species despite their high richness, abundance and their role as the main food source for many fish larvae. Temperature is a key driver of organism's fitness as well as ecosystem functioning and sea surface temperature is expected to rise under all CO2 emission scenarios. Thus, understanding how copepods will respond to such changes is crucial given their role in marine food webs. In this study we expose laboratory reared Tachidius discipes, an intertidal benthic copepod to a temperature gradient (12, 15, 18, 21 and 24 °C) including current seasonal variability as well as future scenarios. Survival, FA, growth rates and nauplii production were measured for each temperature. We found decreased survival, increased growth rates and detrimental effects for nauplii production with temperature increase. While relative EPA and DHA decreased with temperature this was not found on absolute levels of these FA. Changes in benthic copepods' biomass as well as their FA composition in response to temperature changes could amplify to higher trophic levels with consequences for food web functioning. [ABSTRACT FROM AUTHOR]

A 10‐year monitoring program was developed to quantify the population dynamics of the long‐snouted seahorse population in the Mar Menor coastal lagoon. Based on 985 underwater visual censuses, we estimated the long‐snouted seahorse (Hippocampus guttulatus Cuvier, 1829) population size in the Mar Menor lagoon and its reduction in size in the last decades, as well as the effect of eutrophication crises in 2016 and 2019 on the species. The annual recruitment for the 2013–2020 period was estimated by comparing the relative abundance of early seahorse life stages in the ichthyoplankton. The density ranged from 0.0458 specimens/m3 at the beginning of the sampling period to 0.0004 at the end, showing a statistically significant difference between the three analyzed periods (Hgl=2 = 14.0, p = 0.001). The long‐snouted seahorse population from the Mar Menor lagoon exemplifies the impact of fishing activities and human pressure, especially euxinic episodes and habitat destruction. As a result of this, the Mar Menor population has decreased from several million specimens to a few thousand, in only three decades. This species showed considerable resilience, the seahorse population began to recover once fishing activity stopped. In contrast, the long‐snouted seahorse showed high vulnerability to habitat loss and an episodic flooding event. Adult seahorses showed preferences for highly complex habitats, especially Caulerpa prolifera–Cymodocea nodosa mixed meadows and habitats of high complexity and anthropogenic origin, such as harbors, jetties, or breakwaters. In contrast, juvenile seahorses preferred monotonous seabeds with low complexity, such as the sandy beds that are characteristic of the Mar Menor lagoon littoral. [ABSTRACT FROM AUTHOR]

Dietary supplementation with Omega-3 fatty acids seems to promote skeletal health. Therefore, their consumption at imbalanced or excessive levels has offered less beneficial or even prejudicial effects. Fish produced in aquaculture regimes are prone to develop abnormal skeletons. Although larval cultures are usually fed with diets supplemented with Omega-3 Long Chain Polyunsaturated fatty acids (LC-PUFAs), the lack of knowledge about the optimal requirements for fatty acids or about their impact on mechanisms that regulate skeletal development has impeded the design of diets that could improve bone formation during larval stages when the majority of skeletal anomalies appear. In this study, Argyrosomus regius larvae were fed different levels of Omega-3s (2.6% and 3.6% DW on diet) compared to a commercial diet. At 28 days after hatching (DAH), their transcriptomes were analyzed to study the modulation exerted in gene expression dynamics during larval development and identify impacted genes that can contribute to skeletal formation. Mainly, both levels of supplementation modulated bone-cell proliferation, the synthesis of bone components such as the extracellular matrix, and molecules involved in the interaction and signaling between bone components or in important cellular processes. The 2.6% level impacted several genes related to cartilage development, denoting a special impact on endochondral ossification, delaying this process. However, the 3.6% level seemed to accelerate this process by enhancing skeletal development. These results offered important insights into the impact of dietary Omega-3 LC-PUFAs on genes involved in the main molecular mechanism and cellular processes involved in skeletal development. [ABSTRACT FROM AUTHOR]

The species diversity and spatial distribution of ichthyoplankton in the coastal and open waters of the northern part of the Black Sea and the southwestern part of the Sea of Azov in June 2020 are presented. The species diversity and abundance of ichthyoplankton changed in accordance with the regional conditions of warming of the upper layer of the sea during the formation of a vertical thermal structure of the summer type. The most favorable conditions for the survival of ichthyoplankton were observed in the open and coastal waters of the Western Sector of research in the initial phase of the summer hydrological season. [ABSTRACT FROM AUTHOR]

Adapted European seabass (Dicentrarchus labrax L.) larvae at 25 days post-hatching (dph) with a primary weight and length of 23 mg and 9.92 mm, start the weaning up to 46 dph using the weaning micro-diet (54% crude protein from fish meal, powder milk, and poultry egg) concurrently with Artemia enriched with fortification emulsions (0.6 g/L) of DHA selco® as a control group (DHAS) or Fish oil + 20% Vitamin C (FOVC), or Fish oil + 20% Vitamin E (FOVE), or Fish oil + 10% Vit. C +10% Vit. E (FOCE), or Fish oil only (FO). At 46 dph, groups of larvae fed enriched Artemia with DHAS and FOVE exhibited the highest final body weight, weight gain, average daily gain, specific growth rate, feed intake, protein efficiency ratio, and survival% as well as the lowest feed conversion ratio. Meanwhile, larvae in FOVC displayed the lowest final body weight, total length, weight gain, average daily gain, specific growth rate, feed intake, protein efficiency ratio, and survival% as well as the highest feed conversion ratio. Gastrointestinal histological assessment exhibited no pathological alteration as well as an improvement in the structure with DHAS, FOVE, FOVC, and FOCE co-additives compared to FO. Glutathione peroxidase enzyme (GPx) recorded the highest rates (P < 0.05) in groups fed Artemia supplemented with DHAS and FOVE followed by FOCE and FOVC. While the lowest record for GPx activity was noted in the FO group. In conclusion, Using augmented Artemia nauplii with fish oil + vitamin E in single or in companion with vitamin C as cheap antioxidants support D. labrax larval growth, survival, and antioxidant efficacy during the critical weaning period. [ABSTRACT FROM AUTHOR]

The intracohort cannibalism present in tropical gar larvae (A. tropicus) generates great problems in its culture, as in other fish species around the world. The addition of tryptophan (Trp) (10, 20, and 30 g/kg) and a control diet (CD) without Trp were evaluated in A. tropicus larvae regarding growth, survival, cannibalism, behavior, digestive enzymatic activity, and genes related to aggressiveness and/or cannibalism in two stages: 0–13 days after hatching (DAH); and only cannibals (14–24 DAH). In the first stage, no differences were observed in growth parameters; cannibalism was lower with the use of Trp, with the lowest percentage being the 10 g/kg Trp treatment (56.75 ± 2.47%) compared to CD (64.75 ± 1.76%). In the second stage, survival was greater in 10 g/kg Trp (75.00 ± 7.07%) than in CD (23.33 ± 5.77%). Thus, cannibalism was lower with 10 g/kg Trp (20.0 ± 10.0%) compared to CD (76.66 ± 5.77%). Cannibal larvae fed with 10 g/kg Trp had a greater enzymatic activity in acid and alkaline proteases and leucine aminopeptidase, as well as the overexpression of avpi1, crh, and htr1a and the subexpression of tph1, th, sstr1, and hdc (p < 0.05). No aggressive behaviors were recorded in the larvae fed with the 10 g/kg Trp treatment, unlike those fed with CD. The use of 10 g/kg Trp improves survival and reduces cannibalism in A. tropicus larvae. [ABSTRACT FROM AUTHOR]

The fluctuations in both time and space of larval fish assemblages in relation to hydrographic characteristics in the waters surrounding Taiwan Bank were studied in October 2021 (autumn) and March 2022 (spring). Throughout the study period, we identified a total of 149 taxa of fish larvae, encompassing 96 genera and 71 families. Engraulis japonicus, Diaphus slender type, unidentified Gobiidae, Apogon sp., unidentified Clupeidae, and Benthosema pterotum were the six dominant taxa and together constituted 47.39% of the total catch. There were no notable temporal variations observed in the abundance of fish larvae, but the species number of fish larvae was greater in spring than in autumn. Significant variations in species composition were observed between the different cruises, and the cluster analysis unveiled a distinct temporal structure of the assemblages of fish larvae. The dynamics of the prevailing currents induced by seasonal monsoons contribute significantly to the transportation of fish larvae. The distribution of fish larvae showed a good association with hydrographic characteristics, where seawater temperature and salinity emerged as the primary explanatory factors influencing the composition of larval fish assemblages in the waters surrounding Taiwan Bank. While the increased influx of nutrients from upwelling ensures abundant food availability, the hydrographic conditions may not be suitable for every fish larva. [ABSTRACT FROM AUTHOR]

Background An ecologically and economically important species in East Asia, the natural resources of pen shell Atrina pectinate have suffered severe population declines due to habitat destruction, pollution, and overfishing. Assessing genetic diversity and population structure is the basis for establishing conservation programs for A. pectinate. Results Our data indicated that high genetic diversity was found in all six populations, with mean allelic richness (Ar) ranging from 8.255 to 9.734, mean observed heterozygosity (Ho) from 0.574 to 0.680, and mean expected heterozygosity (He) from 0.620 to 0.691. The five A. pectinate populations were divided into two clusters. This clustering result was partly consistent with their geographical origin; the RZ population did not cluster with the northern populations (DL, CD), suggesting that there is no genetic divergence and geographical differentiation between the North China Sea (CD, DL, and RZ) and the Southeast China Sea (HK and ST). Conclusion Our results show no significant genetic differentiation between samples from the North China Sea and the Southeast China Sea. High dispersal potential of larvae by passive drift with ocean currents may explain the lack of genetic differentiation between samples. The results suggest a weak level of genetic structure in A. pectinate with a long planktonic larval stage. [ABSTRACT FROM AUTHOR]

Salinity is crucial in fish larval rearing. In longfin batfish (Platax teira), little research has been conducted regarding the specific effects of salinity on growth, survival, deformity, and food utilization efficiency. This study aimed to determine the optimal salinity level for larval rearing of the longfin batfish by testing five different salinity levels (10, 15, 20, 25, and 30°). Larvae of 1.5 cm in length and 0.2 g/fish in weight were stocked in cylindrical fiberglass tanks (300 L) at a density of 1 fish/L. The fish were fed to meet their dietary requirement and divided into four daily feedings. Each treatment was replicated three times over a 28-day period of rearing. The results revealed that salinity significantly influenced the growth (length, weight, biomass), and food utilization efficiency of the longfin batfish larvae. Overall, larvae reared at salinity levels of 15-20° exhibited superior performance compared to those exposed to salinity levels of 10, 25, and 30°. However, salinity did not affect the coefficient of variation, survival, and deformity. From these findings, it is recommended to rear longfin batfish larvae at a salinity of 15-20° to achieve optimal growth and food utilization efficiency. This study provides valuable insights for longfin batfish larval rearing guidance, contributing to the aquaculture development of this economically valuable species. [ABSTRACT FROM AUTHOR]

The development of deformities in farmed fish is largely the result of abiotic, biotic, and xenobiotic factors, information deficiencies in optimizing nutrition, and the genetic background to which the fish are exposed in their early life stages. In general, skeletal anomalies are considered to have significant adverse effects on animal welfare, biological performance of farmed fish, product quality, and production costs. In the data obtained by the meta-analysis method, the presence of negative effects on the formal structures of fish was found, regardless of the region, duration, stage, factor, stock density, and method used to detect deformation. In this regard, in the studies considered within the deformation region/type, 46% of deformities were found in the spine, 37% in the head, and 16% in the total skeleton. In turn, the results of the meta-analysis showed that the percentages of the apparent value were 35.82% in the spine, 33.12% in the skeleton, and 31.06% in the head. The deformation rate had an overall negative effect on the functional characteristics of the fish, regardless of the variables considered. In addition, all statistically significant individual response variables had a negative effect size. In the future, advanced statistical tools such as Bayesian meta-analysis, network meta-analysis, and meta-regression analysis can be used to explore more complex data structures. The rapid development of artificial intelligence techniques will increase the efficiency of data collection and the robustness of results for meta-analysis studies in aquaculture and other fields. [ABSTRACT FROM AUTHOR]