Time Of Hatching Research Articles

Relationship between the timing of embryonic and larval development of pink salmon and downstream migration of its juveniles

Purpose: Determine the relationship between the duration of embryonic and larval development of pink salmon (Oncorhynchus gorbuscha) under different temperature regimes and the timing of downstream migration of their juveniles. Research Material: Multiyear average daily data on water temperature and condition of pink salmon embryos and larvae bred in commercial volumes at the Kurilsky (Iturup Island), Lesnoy and Pugachevsky (Eastern Sakhalin) salmon hatcheries. Methods used: Comparative data analysis, descriptive statistics methods.Results: The known facts about changes in the timing of embryonic development in relation to water temperature were confirmed: The duration of the interval between the dates of hatching of embryos in the first and last batches developed under different thermal conditions was 2.5 times longer than the interval between the dates of fertilization of eggs from these batches. The extension of the embryonic development period in the last batches was accompanied by a shortening of the subsequent development period until the fry were ready to swim, which reduced the difference in the duration of development from egg fertilization to fry swimming at different temperatures. This process is not only associated with different hatching times and slowed development in the winter period. The identified peculiarities in the changes in the duration of intermediate developmental stages under different temperature regimes suggest that fry developing in colder water goes afloat as less developed. Such regulation of the total duration of embryonic and larval development of pink salmon provides mass migration of its juveniles from rivers in the average annual terms of mass development of zooplankton in the coastal sea. Practical Significance: The presented article is a scientific accompaniment of the monitoring of pink salmon juvenile downstream migration in order to forecast changes in the stocks of this species of Pacific salmon.

Pear-Shaped Eggs Evolved to Maximize the Surface Area-to-Volume Ratio, Increase Metabolism, and Shorten Incubation Time in Birds.

Bird eggs can be spherical, ellipsoid, ovoid, or pear-shaped (pyriform), the latter being the most complex. There is however no unambiguous evolutionary/adaptive explanation for this final, exotic shape. We hypothesized that pyriform eggs have a larger surface area-to-volume ratio (S/V) that may be a criterion for increased embryo metabolism. By integrating mathematical approaches, we confirmed this to be the case and developed a model of the egg metabolic rate defined as the ratio of S/V to its maximum possible value, depending on egg length. We found this to be inversely proportional to the egg incubation period and concluded that the complex pyriform shape is most likely due to embryo metabolism increase and, as a result, a reduction in the incubation period and shortened hatching time. As a result of this study, we conclude that some avian eggs are pyriform as this may attain a larger S/V ratio making them grow and hatch quicker.

Salinity does not affect late-stage in-egg embryonic, or immediate post-hatch development in an ecologically important land crab species.

Environmental drivers such as salinity can impact the timing, and duration of developmental events in aquatic early life stages of crustaceans, including terrestrial crabs of the family Gecarcinidae. Low salinity delays larval development in land crabs, but nothing is known about its influence on the crucial late-stage encapsulated embryonic, or immediate post-hatch development. Therefore, we exposed fertilised late-stage embryos of the Christmas Island red crab (Gecarcoidea natalis) to differing salinities (100, 75, 50, or 25 % sea water) for 24 h during their spawning period and measured some key developmental and physiological traits. We found no effect of salinity on time of first heartbeat, time of hatching, first in-egg embryonic and post-hatching heart rate (bpm), or post-hatch activity duration (h). These results highlight the importance of considering all early life stages when fully characterising the effects of environmental drivers on crustacean development, including under climate change.

Impact of late-stage hypoxic stimulation and layer breeder age on embryonic development, hatching and chick quality.

The present study examined the effects of breeder age and oxygen (O₂) concentrations during the late chorioallantoic membrane (CAM) growth stage on embryo development, hatching dynamics, chick quality, bone mineralization and hatchability. A total of 1200 eggs from 33- and 50-week-old ISA layer breeders, weighing 53.85 g and 60.42 g on average respectively, were incubated at 37.7°C and 56 % relative humidity. From embryonic day (ED) 13 to 15, experimental eggs were exposed to hypoxia (15 % or 17 % O₂ for 1 hr/day) while the control was at 21 % O₂. Results showed significant interactions (p = 0.040) between breeder age and oxygen level, with embryos exposed to 15 % and 17 % O₂ exhibiting slower growth by ED 17. However, embryo weight at internal pipping (IP) was unaffected (p > 0.05). At hatch, chick weights were higher in hypoxic groups due to increased yolk sac retention (p = 0.024), while yolk-free weights were influenced only by breeder age (p < 0.001). Hypoxia at 15 % O₂ reduced chick length, toe length, and tibia parameters (p < 0.05), likely due to impaired calcium and phosphorus absorption. Embryos exposed to 15 % O2 had longer internal and external pipping events, delaying hatch time. Embryonic mortality was highest (p < 0.001) at 15 % O₂, contributing to the reduced hatch of fertile eggs. This research demonstrates that controlled hypoxic conditions can slow embryonic development, conserve yolk nutrients, improve organ maturation and chick weight across breeder ages.

Cause‐specific mortality and survival of northern bobwhite chicks

AbstractSurvival of northern bobwhite (Colinus virginianus) chicks is an important parameter influencing population dynamics. We determined cause‐specific mortality and apparent daily survival of bobwhite chicks (n = 170) during 2018 and 2019 at Tall Timbers Research Station, Tallahassee, Florida, USA. We assigned cause‐specific mortality to 58 chicks and unknown fates to 45 chicks. Of those with assigned fates, avian predation comprised the majority (n = 21, 36%) followed by snakes (n = 17, 29%), mammals (n = 16, 28%), and research‐induced mortality (n = 4, 7%). Corn snakes (Pantherophis guttatus) were the primary snake species (13 of 17 snake predations) responsible for predation followed by northern cottonmouths (Agkistrodon piscivorus; n = 3) and 1 eastern diamondback rattlesnake (Crotalus adamanateus). We determined diel timing of mortalities during 2019. All corn snake predations during 2019 (n = 8) occurred during roosting (2100–0700 hrs), whereas the eastern diamondback mortality was a diurnal event; no cottonmouths depredated chicks during 2019. Nine of 11 mammalian events occurred during roosting. Two avian events occurred during 2019, both during daylight hours. Survival was best predicted by the model including the effects of chick age, hatch timing, year, and their interactions. Daily survival of chicks increased with age and reached an asymptote at approximately 70 days; late hatches (after 15 July) survived better than early hatches (βLateHatch×ChickAge = 0.059, 95% CI =−0.003–0.121) and survival for late hatches was marginally lower in 2019 (βLateHatch×ChickAge×Year19 = −0.058, 95% CI = −0.137–0.022). Management focused on increasing survival during the first 2 months of life and early nesting season may substantially benefit bobwhite population abundance. Additionally, roosting appeared to be a vulnerable period for bobwhite chicks.

Natural variation in timing of egg hatching, response to water agitation, and bidirectional selection of early and late hatching strains of the malaria mosquito Anopheles gambiae sensu lato

BackgroundEggs of anopheline mosquitoes hatch within a few days of laying and require high levels of humidity to survive. Assessing natural variation in egg hatching and its environmental and genetic determinants in sibling species of the malaria vector Anopheles gambiae s.l. is important for understanding their adaptation to variable aquatic habitats. Crucially, it can also inform insectary rearing practices toward the optimization of mosquito production for genetic vector control strategies.MethodsHatching rates and timing of egg hatching in long-established and recently colonized strains of An. gambiae s.s, Anopheles arabiensis, and Anopheles coluzzii, were compared under still water conditions (26 ℃) and with cold (4 ℃) and (15 ℃) water agitation regimes. Next, early and late hatching strains of the recently colonized An. coluzzii VK colony were generated through bidirectional selection for 18–23 generations to detect a genetic component for this trait.ResultsHatching rates differed significantly between species and treatments. The older An. arabiensis Senn and An. gambiae s.s. Kisumu strains had the highest proportion of hatching and preferred the nonagitation treatment at 26 °C. In contrast, the more recently colonized An. coluzzii VK and An. arabiensis Rufisque strains had lower overall hatching success but responded strongly to agitation at 4 °C, while the An. coluzzii Mopti strain did not significantly respond to water agitation. In all strains, eggs hatching started at day 2 and continued till day 5 in the older strains, whilst it was more staggered and extended up to day 6 in the younger strains. Bidirectional selection for early and late hatching over many generations resulted in early hatching selected strains with eggs hatching 2–3 days earlier than in late hatching ones indicating a significant heritable component for these traits.ConclusionsWater agitation and temperature and age of colonization are likely important determinants of egg hatching in natural An. gambiae s.l. populations. Current rearing protocols systematically select for fast hatching and result in the progressive loss of staggered egg hatching in older laboratory strains. The selection of novel slow-hatching strains may prove instrumental to enable the mass production, shipping, and release of Anopheles mosquitoes across Africa as part of genetic vector control programs.Graphical

Hatch timing of largemouth bass: implications for recruitment at the Northern edge of their native range

Climate-related shifts in hatch timing could mean that age-0 largemouth bass Micropterus salmoides in north temperate lakes reach larger sizes and experience higher survival, which may contribute to increased prevalence of this species in many lakes. However, information on age-0 largemouth bass life history is lacking for these lakes. We estimated hatch dates, daily growth rates (DGR), and length-based probability of piscivory of age-0 largemouth bass in Wisconsin lakes to: (1) provide baseline data on early life history; (2) compare hatch timing between years with different spring temperature regimes, and (3) project how shifts in hatch timing might influence total length (TL) distributions of age-0 bass if mean DGR remained constant. Most age-0 largemouth bass (>90%) collected from ten Wisconsin lakes (N = 746) hatched between 23 May and 24 June during 2012 and 2013 and did not switch to piscivory during their first summer. Prevalence of positive correlations (16 of 24 lake-year pairings) between TL in and age indicates hatch timing may influence TLs attained by age-0 largemouth bass in August in some lake-years. Mean daily water temperatures in May 2012 were 3.1 °C warmer than in May 2013 for the five of the six lakes where hatch dates were estimated in both years. On average, earliest and median hatch dates for age-0 largemouth bass in these six lakes were 10–11 d earlier in 2012 than in 2013 and hatch duration was approximately 8 d longer in 2012. Despite differences in hatch timing, mean DGR was relatively consistent (range = 0.61–0.74 mm/d) between lakes and years. Simple simulations suggest that earlier hatch dates could result in more age-0 largemouth bass reaching TLs associated with piscivory and overwinter survival by the end of their first summer if growth rates did not change, which could translate to higher recruitment.

Captive Breeding and Early Developmental Dynamics of Cirrhinus mrigala: Implications for Sustainable Seed Production.

Cirrhinus mrigala is an important edible fish with a significant aquaculture contribution in Southeast Asian countries. The current study aims to enhance our understanding of the developmental biology of Cirrhinus mrigala, which is crucial for implementing sustainable fish farming practices. To induce spermiation and ovulation in Cirrhinus mrigala brooders, the synthetic hormone Ovaprim® (GnRH + dopamine inhibitor) was administrated as a single injection dose of 0.2 mL/kg to males and 0.4 mL/kg to females. After induction, the fish spawned, and the eggs produced were fertilized artificially and cell division commenced successfully. The characteristics of each larval developmental stage were closely observed and recorded using a time-lapse imaging technique. The fertilized eggs were spherical, demersal, and non-adhesive throughout their incubation period. The spawned eggs ranged in diameter from 2.1 mm to 2.13 mm and possessed circular yolk sacs. The gastrula stage initiated approximately 4 h after fertilization, with 25% of the yolk sphere covered by blastoderm, reaching 75% coverage at the end of the gastrula stage, approximately 6 h post fertilization. Organogenesis was marked by the formation of notochord and the visibility of rudimentary organs such as the heart, eyes, and gills, followed by tail movement, which was observed at the time of hatching. Compared to other cyprinid fishes, C. mrigala exhibited distinct features at certain stages of embryonic development. Blood circulation was observed to start at the onset of hatching. The lengths of the newly hatched larvae ranged from 2.9 to 3.2 mm, smaller than other reports on induced breeding in carps. The findings of the present study provide a detailed reference for the embryonic development of C. mrigala, which will assist its future research endeavors and large-scale seed production for sustainable aquaculture.

Dose rate dependent genotoxic and metabolic effects predict onset of impaired development and mortality in Atlantic salmon (S. salar) embryos exposed to chronic gamma radiation

Release of radionuclides to the environment from either nuclear weapon and fuel cycles or from naturally occurring radionuclides (NORM) may cause long term contamination of aquatic ecosystems and chronic exposure of living organisms to ionizing radiation, which in turn could lead to adverse effects compromising the sustainability of populations. To address the effects of chronic ionizing radiation on the development of fish, Atlantic salmon embryos were exposed from fertilization until hatching (88 days, 550 day-degree) to dose rates from 1 to 30 mGy·h−1 gamma radiation (60Co). The lowest adopted dose rate was similar to the highest doses measured in some water bodies right after the Chernobyl accident (1 mGy·h−1), however, well above current environmentally realistic scenarios (20 μGy·h−1), or the threshold assumed for significant effects on fish population (40 μGy·h−1). Dose dependent effects were observed on survival, hatching, morbidity, DNA damage, antioxidant defenses, and metabolic status. Histopathological analysis showed dose rate dependent impairment of eye and brain tissues development and establishment of epidermal mucus cell layers accompanied by increased DNA damage at doses ≥1.3 Gy (dose rates ≥1 mGy·h−1).At ≥32.8 Gy (dose rates ≥20 mGy·h−1) deformities and developmental growth defects resulted in respective 46 and 95 % pre-hatch mortality. The 10 mGy·h−1 exposure (≥ 12 Gy total dose) caused significantly increased DNA damage, impaired eye development, and both premature and delayed hatching, while no deformities or effect on survival were observed. We observed a dose rate dependent reduction from dose rate ≥ 20 mGy·h−1 (≥ 27 Gy total dose) on antioxidant SOD, catalase and glutathione reductase enzyme activities. The reduction of antioxidant enzyme activities was in line with observed developmental delay and disturbance to time of hatching. Metabolomic profiles showed a clear shift at dose rates ≥10 mGy·h−1 (≥ 12 Gy total dose) in pathways related to oxidative stress, detoxification, DNA damage and repair. Due to gamma radiation exposure, a switch of central metabolism from glycolysis, citric acid cycle and lactate production towards pentose phosphate pathway indicated a rewiring mechanism for increased production of reductive equivalents to maintain redox homeostasis at the expense of energy output and thus embryonic development.

Research Note: Dynamics of black grouse (Tetrao tetrix) infestation with various Eimeria species

The black grouse (Tetrao tetrix) is an endangered species facing challenges in breeding and reintroduction programs, including parasitic infestations. This study aimed to assess natural infestations by various Eimeria species and infestation dynamics in female, male, and young black grouse kept in a stationary aviary. Faecal samples were collected from adult grouses between April and the time of chicks' hatching and rearing (September). Faecal samples from young birds were collected from the hatching for a period of 1 year. The prevalence of Eimeria spp. was determined by a qualitative method (Fulleborn's flotation) and a quantitative method (McMaster's method with Raynaud's modification). The following Eimeria species were identified: E. lyruri, E. nadsoni and E. nonbrumpti. The average percentages of Eimeria spp. in the cock were 80.52%, 9.27%, and 10.21%, respectively; in the hen, they were 86.19%, 9.28%, and 4.53%, respectively; in the young black grouses they were 84.60%, 9.34% and 6.06%, respectively. The highest E. lyruri infestation was observed in the cock in June (144227 OPG) and July (129365 OPG). In the hen, the infestation intensity increased in May (304302 OPG) and then decreased in June (39583 OPG). Furthermore, an additional increase was observed in July (216533 OPG). Two increases in infestation intensity were also observed in young birds, with peaks in January (91387 OPG) and July (126178 OPG). A positive strong correlation was identified between Eimeria spp. in the cock and the young birds. A statistically significant positive correlation was identified in the hen between E. lyruri and E. nadsoni. No correlation was demonstrated between the infestation intensity and the age of the birds or season of the year in all the grouses under study. Despite some attempts, a comprehensive approach to the issue of coccidiosis in the black grouse as a disease that may affect the success of reintroduction has yet to be established. It seems crucial to monitor the level of Eimeria spp. invasion, and the proposed faecal sampling scheme is an important tool for achieving this goal.

Reproduction of Cernuella virgata (Da Costa, 1778) (Gastropoda: Geomitridae) in its natural environment in Southeast Turkey

ABSTRACT This study aims to investigate the reproductive characteristics of Cernuella virgata (Da Costa, 1778) from Diyarbakır, Southeast Turkey. From October 2023 to February 2024, the reproductive activities of over 300 individuals were monitored in Yeniköy Cemetery in Diyarbakır. The snails were first observed mating on 18 October 2023, after the autumn rains, with the first egg laying observed on 3 November 2023. The last mating observation occurred on 8 January 2024. A total of 225 individuals were noticed mating during this period. The number of eggs per clutch ranged from 36 to 114, with an egg hatching time between 18 and 32 days. Eggs were deposited amidst damp mosses, beneath decomposing vegetation, or on the damp soil surface. The spawning period lasts 12–13 weeks. Egg weights varied from 0.60 to 1.20 mg, and egg diameters ranged from 1.10 to 1.42 mm. Hatchling snails had shells with 1.5–2 whorls (protoconch), weighing between 1.15 and 1.72 mg on. The height of the hatchling’s shells ranged from 0.75 to 0.94 mm, and the width ranged from 1.21 to 1.38 mm. This study offers a detailed insight into the reproductive biology of C. virgata and marks the first record of the species in the region.

Persistent interactive effects of developmental salinity and temperature in Atlantic killifish (Fundulus heteroclitus)

Climate change alters multiple abiotic environmental factors in aquatic environments but relatively little is known about their interacting impacts, particularly in developing organisms where these exposures have the potential to cause long-lasting effects. To explore these issues, we exposed developing killifish embryos (Fundulus heteroclitus) to 26 °C or 20 °C and 20 ppt or 3 ppt salinity in a fully-factorial design. After hatching, fish were transferred to common conditions of 20 °C and 20 ppt to assess the potential for persistent developmental plasticity. Warm temperature increased hatching success and decreased hatch time, whereas low salinity negatively affected hatching success, but this was only significant in fish developed at 20 °C. Temperature, salinity, or their interaction affected mRNA levels of genes typically associated with thermal and hypoxia tolerance (hif1a, hsp90b, hsp90a, hsc70, and hsp70.2) across multiple developmental timepoints. These differences were persistent into the juvenile stage, where the fish that developed at 26 °C had higher expression of hif1a, hsp90b, hsp90a, and hsp70.2 than fish developed at 20 °C, and this was particularly evident for the group developed at both high temperature and salinity. There were also long-lasting effects of developmental treatments on body size after four months of rearing under common conditions. Fish developed at low salinity or temperature were larger than fish developed at high temperature or salinity, but there was no interaction between the two factors. These data highlight the complex nature of the developmental effects of interacting stressors which has important implications for predicting the resilience of fishes in the context of climate change.

Evaluation of d 18 in ovo administration of soursop (Annona muricata) leaf extract into the air space on hatch performance and physiology of Noiler chicks

Efficient poultry production can be accomplished using combined technologies. A combination of in ovo and ethno-veterinary technologies can deliver significant benefits, including reduced labour and production costs. This study evaluated the effect of in ovo administration of soursop leaf extract (SLE) on the hatching performance and physiology of Noiler chicks. A total of 550 eggs were incubated, and 460 fertile eggs were randomly distributed into 4 groups with 3 replicates on the 18th d of incubation. The eggs were then injected with 0.75 µg SLE, 1.5 µg SLE, and saline solution (negative control) at a rate of 0.2 ml in the air space. The noninjected group served as the positive control. At the end of the hatching period, the various groups were evaluated for embryo mortality, hatchability, hatch duration, organ weight, serum biochemistry, and chick quality. The results showed no significant differences (P > 0.05) in embryonic mortality, hatchability, organ weight, total protein, albumin, globulin, aspartate aminotransferase, alanine aminotransferase, and glucose among the treatment groups. However, chick weight, chick quality, and serum triglyceride levels were significantly (P < 0.05) higher in the extract-injected group. Additionally, incubation and hatch times were significantly lower (P < 0.05) in the SLE group compared to the other groups. In ovo administration of soursop leaf extract resulted in reduced incubation duration, hatch time, and embryo mortality. In conclusion, the in ovo injection of SLE improved hatch performance and chick quality.

Climatic variations and Fasciola: a review of impacts across the parasite life cycle.

Fasciolosis, caused by the liver fluke Fasciola spp., is a significant parasitic disease of livestock and humans worldwide. Fasciola transmission and life cycle are highly dependent on climatic conditions, especially temperature and humidity. This dependency has gained significance in the context of ongoing climate change. This literature review examined evidence on the effects of temperature variability on the developmental stages of Fasciola spp. and the snail intermediate hosts. We reviewed free larval stages of Fasciola spp. development, as well as snail intermediate hosts, while investigating the climate-related factors influencing each stage. We found that Fasciola spp. egg hatching and development were inhibited below 10 °C and optimal between 20 and 30 °C, miracidia hatching time decreased with higher temperatures and cercarial shedding by snail hosts accelerated around 27 °C. Further, metacercarial viability declined at higher temperatures but was prolonged by higher humidity. Snail intermediate host growth rates peaked at 25 °C, and their susceptibility to Fasciola infection depends on temperature, underscoring its importance in transmission dynamics. Overall, the Fasciola life cycle and snail host development exhibit stage-specific temperature thresholds, indicating a complex relationship between temperature fluctuations and parasite transmission potential. This research highlights the key role of temperature and humidity on Fasciola spp. and snail development, shedding light on the potential consequences of climate change on their survival, development, and disease transmission. Data limitations, primarily from the scarcity of high-resolution climate-related experiments, should drive future research to enhance predictive models and deepen our understanding of the impact of climate change on this parasitic disease.

Assessing the impact of hatching system and body weight on the growth performance, caecal short-chain fatty acids, and microbiota composition and functionality in broilers

BackgroundVariations in body weight (BW) remain a significant challenge within broiler flocks, despite uniform management practices. Chicken growth traits are influenced by gut microbiota, which are in turn shaped by early-life events like different hatching environments and timing of first feeding. Chicks hatched in hatcheries (HH) experience prolonged feed deprivation, which could adversely impact early microbiota colonization. Conversely, hatching on-farm (HOF) allows early feeding, potentially fostering a more favorable gut environment for beneficial microbial establishment. This study investigates whether BW differences among broilers are linked to the disparities in gut microbiota characteristics and whether hatching systems (HS) impact the initial microbial colonization of broilers differing in BW, which in turn affects their growth patterns. Male Ross-308 chicks, either hatched in a hatchery or on-farm, were categorized into low (LBW) and high (HBW) BW groups on day 7, making a two-factorial design (HS × BW). Production parameters were recorded periodically. On days 7, 14, and 38, cecal volatile fatty acid (VFA) and microbiota composition and function (using 16 S rRNA gene sequencing and PICRUSt2) were examined.ResultsHOF chicks had higher day 1 BW, but HH chicks caught up within first week, with no further HS-related performance differences. The HBW chicks remained heavier attributed to higher feed intake rather than improved feed efficiency. HBW group had higher acetate concentration on day 14, while LBW group exhibited higher isocaproate on day 7 and isobutyrate on days 14 and 38. Microbiota analyses revealed diversity and composition were primarily influenced by BW than by HS, with HS having minimal impact on BW-related microbiota. The HBW group on various growth stages was enriched in VFA-producing bacteria like unclassified Lachnospiraceae, Alistipes and Faecalibacterium, while the LBW group had higher abundances of Lactobacillus, Akkermansia and Escherichia-Shigella. HBW microbiota presented higher predicted functional potential compared to the LBW group, with early colonizers exhibiting greater metabolic activity than late colonizers.ConclusionsDespite differences in hatching conditions, the effects of HS on broiler performance were transient, and barely impacting BW-related microbiota. BW variations among broilers are likely linked to differences in feed intake, VFA profiles, and distinct microbiota compositions and functions.

Research Note: Effects of different light-emitting diode lights during egg incubation on hatching performance and embryo development in White King pigeons

The light provide during incubation can influence hatching characteristics (hatching time, hatchability, etc.) and embryo development in chickens, geese, and turkeys. However, relevant studies on this factor in pigeons are lacking. This study investigated the effects of in ovo photostimulation during embryogenesis on hatching performance, squab quality, and embryo development in pigeons. 400 eggs from paired- bred pigeons were randomly distributed into 4 incubation lighting treatments, with 2 replicates per treatment. The treatments included dark as a control (NL), 12-h light, and 12-h dark photoperiods of white light (WL), red light (RL), and green light (GL) (100 lx at egg level) during the first 15 d of incubation. A total of 1,600 eggs in 4 batches from White King pigeons were used. The results showed that hatching time of the WL group was significantly shorter than that of the dark light group (P < 0.05). The hatchability of fertile eggs in the WL group was significantly higher (P < 0.05), whereas the hatchability of fertile eggs in the RL group was significantly lower (P < 0.05) than that of in the control group. Light stimulation had no effect on time to 90% hatching or average hatching time (P > 0.05). In addition, the hatch window was not extended by light stimulation (P > 0.05). The group incubated under GL showed an increase in embryo weight and relative leg muscle on embryonic d 14 and the hatching day compared to the dark incubation (P < 0.05). Green light stimulated the heart and liver development during the early and middle stages of embryogenesis. It was concluded that white light stimulation during embryogenesis accelerated the hatching process, whereas monochromatic green light had a positive effect on embryo development. Our findings provide important guidance for developing light protocols for pigeon egg incubation.

Histological analysis of Macrobrachium rosenbergii (de Man) eggs incubated in different salinities

Macrobrachium rosenbergii is the freshwater shrimp species of greatest economic interest, and its reproduction has been studied for commercial purposes. This study aimed to evaluate the effect of different salinities (0, 6, and 12 mg L-1) on the embryogenesis of this species. The females were observed daily according to their reproductive behavior. Upon the first sign of spawning, when their eggs were attached to the abdomen, they were collected for egg collection and transferred to the incubators at the respectively tested salinities. The eggs were collected every five days for up to 23 days, separated according to their stage of development, histologically processed, and stained for visualization of structural changes during embryogenesis using an optical microscope. From the egg's histological images at different embryonic development stages, the egg hatching time was evaluated, the changes that occurred in the eggs during embryogenesis, the total area of the eggs, the vacuole area, and the ratio between the vacuole area and the total area of the eggs. Differences were observed in hatching time, egg size, and vacuole area and area ratio. The 6 g L-1 of salinity treatment was statistically different from the other in all parameters analyzed. Therefore, it was concluded that 6 g L-1 of salinity positively influenced embryogenesis, as it presented hatches from the 15th day of embryogenesis, demonstrating that there was a greater speed of migration of vitellogenin for the formation of the embryo, accelerating embryogenesis and hatching of M. rosenbergii.

Developmental morpho-analysis of the caecum in Japanese quail embryos (Coturnix coturnix japonica).

In the current study, we are focusing on the microanatomical structure of quail caecum during the prehatching time to try to understand the function and the role of each cell-built quail caecum reaching how caecum plays an essential role in immunity and absorption. The morpho-developmental features of the quail caecum were described in detail daily from the third incubation day (ID) till hatching time, investigating the gross morphology, microscopic, and ultrastructure using light and scanning electron microscope. The embryonic caecum appeared grossly as two lateral outpocketings with blinded ends, emerging laterally at the junction between the small and large intestine (the ileocaecal junction). The primordia of two caeca, represented by two lateral swellings from the hindgut on the fourth ID, continued growing till the day of hatching, where the caecal wall consisted of three apparent layers: mucosa, musculosa, and serosa. At the time of hatching, the quail caecum was still not fully mature and will continue growing posthatching. The findings in this study can be applied in further studies intended to understand the physiological mechanisms of the caecum during prehatching and posthatching periods. RESEARCH HIGHLIGHTS: Caecum is one of the hindgut derivatives that started as two lateral swellings. The caecal wall consisted of three layers; mucosa, musculosa, and serosa. The caecum plays an essential role in immunity maintenance. Caecum continues to grow posthatching as it is not fully mature at hatching time.

Embryonic and larval development of yellow perch (Perca flavescens) and its sensitivity to incubation temperature.

The ontogenetic development in teleost fish is sensitive to temperature, and the developmental rate has a direct relationship with the environmental temperature within a species' thermal tolerance limit. Temperature determines time to and survival at hatching. Yellow perch is a North American species of ecological and commercial importance, and its phenology is vulnerable to climate change. The embryonic development of yellow perch was comparable to closely related members of the family Percidae. Developmental progression was fastest at 18°C and slowest at 12°C, with medial progression at 15°C. Time to hatch and swim-up, feeding onset, and exogenous feeding phases were different across all incubation temperatures regardless of a gradual post-hatch warming of the 12 and 15°C groups to a common garden temperature of 18°C. Incubation temperature may lower the rate of survival to hatch at 15°C and had complex impacts on developmental abnormalities. Temperature had significant effects on the development rate, time of hatch, survival, and incidence of developmental abnormalities. Early ontogenetic thermal history in ectotherms is an important factor determining phenotypic variation. It will be important to link the thermally induced changes in development described here to the physiological and morphological differences and to link the developmental abnormalities to functional performance.

Climate‐influenced phenology of larval fish transport in a large lake

AbstractElucidating physical transport phenologies in large lakes can aid understanding of larval recruitment dynamics. Here, we integrate a series of climate, hydrodynamic, biogeochemical, and Lagrangian particle dispersion models to: (1) simulate hatch and transport of fish larvae throughout an illustrative large lake, (2) evaluate patterns of historic and potential future climate‐induced larval transport, and (3) consider consequences for overlap with suitable temperatures and prey. Simulations demonstrate that relative offshore transport increases seasonally, with shifts toward offshore transport occurring earlier during relatively warm historic and future simulations. Intra‐ and inter‐annual trends in transport were robust to assumed pelagic larval duration and precise location and timing of hatching. Larvae retained nearshore generally encountered more favorable temperatures and zooplankton densities compared to larvae transported offshore. Larval exploitation of nearshore resources under climate change may depend on a concomitant shift to earlier spawning and hatch times in advance of earlier offshore transport.