Hatching Pattern Research Articles

Resting eggs bank and their hatching pattern in two co-occuring anostracans Phallocryptus spinosus and Branchinectella media (Crustacea) from saline lakes of the Aurès region (Northeastern Algeria)

Resting eggs bank and their hatching pattern in two co-occuring anostracans Phallocryptus spinosus and Branchinectella media (Crustacea) from saline lakes of the Aurès region (Northeastern Algeria)

Long‐term droughts change the hatching patterns of zooplankton resting eggs from permanent and temporary lakes

Abstract Resting eggs are commonly produced by zooplankton inhabiting permanent and temporary lakes. Although resting eggs are acknowledged to survive varying harsh conditions, the effects of desiccation on the viability and hatching patterns of resting eggs are not fully understood and might be context‐dependent. This study simulated one long‐term (1 year) dry‐out episode in wet sediments originating from permanent and temporary lakes and compared hatching patterns through ex situ experiments. The abundance and species richness of hatchlings decreased in dry sediments compared to wet sediments. Hatchling composition differed between wet and dry sediments of each lake category, whereas community variability did not differ between wet and dry sediments of temporary lakes. Overall, there was no difference in the ability of rotifers and crustaceans to cope with desiccation, since all species decreased hatchling numbers after desiccation. Artemia was the only taxon that benefited from drying sediments. Long‐term desiccation may affect the contribution of resting egg banks to future active populations in the water column, even in temporary habitats which presumably select for drought‐resistant resting eggs. The ecological roles played by resting egg banks may be weakening because droughts are becoming more common worldwide, even in former permanent aquatic habitats.

Novel hatching cue in the neotropical damselfly Megaloprepus caerulatus: larval adaptation and maternal constraint

The evolution of sibling cannibalism as a maternal strategy is particularly challenging to explain when nurseries are shared among multiple females. Such is the case for the damselfly, Megaloprepus caerulatus, whose females lay eggs in bark above the water line in large, water-filled tree holes. Asynchronous egg hatching appears to be a maternal bet-hedging strategy to increase the chances that cannibalistic offspring hatch during windows of opportunity, which occur after the remaining large larvae emerge, having eaten all others. We investigated the proximate causes of asynchronous hatching. By monitoring the pattern of egg hatching under ambient temperature in an insectary, we found that egg hatching co-occurred with lower ambient temperatures, which decreased with increasing rainfall. Treating fully developed eggs to a lower temperature for two hours triggered increased hatching relative to controls at ambient temperature. Dissection of control clutches indicated that embryonic development of siblings was asynchronous. Results suggested that the hatching trigger is adaptive. Rainfall assures a recharge of the larval habitat with water and provides wet conditions essential for neonate mobility on bark. Only 40% of neonates in a 4-day drying treatment survived; none survived the 8- and 14-day treatments. This novel hatching trigger should increase the number of neonates entering the nursery after rains, constraining a mother’s control over the timing of egg hatch, while increasing the competition among related and unrelated offspring for limited windows of opportunity in the shared nursery.

Invertebrate richness, diversity and hatching patterns from a semi-arid pool in peninsular India using field sampling and sediment re-hydration

Effective methods for finding the true species richness are necessary for biodiversity research. Such assessments are especially difficult for short-lived freshwater invertebrates found in arid and semi-arid temporary habitats. However, many of these animals produce “resting eggs” that remain viable for a long time and hatch when the habitats refill with water. This aspect can be used to assess the true species richness of these assemblages. We performed a simple, fast, cost-effective, and reliable method of laboratory sediment rehydration along with standard field sampling to understand the richness, diversity and hatching patterns of invertebrates like rotifers, cladocerans, copepods and ostracods and large branchiopods from a temporary pool located in the semi-arid part of peninsular India. Twenty-two rotifers, 5 large branchiopods and 6 micro-crustaceans were found in the study of which 4 species were only found from the rehydrated sediment. Variation in the species composition was higher in the field samples than the lab ones. Field and laboratory species communities were distinct from each other. Species community comparison with a similar habitat nearly 150 km away showed a dissimilarity of 0.70 between the two. Contrasting environmental conditions between the field and lab combined with temporal variation in the hatching patterns of species might explain the dissimilarities seen in the fauna. We propose that the sediment rehydration method along with the field sampling can be used to reveal the true species richness of the local temporary water bodies.

A case study assessing the impact of mating frequency on the reproductive performance of the Hawaiian bobtail squid Euprymna scolopes

BackgroundThe symbiosis between the Hawaiian bobtail squid Euprymna scolopes and bacterium Vibrio fischeri serves as a model for investigating the molecular mechanisms that promote the initial formation of animal-bacterial symbioses. Research with this system frequently depends on freshly hatched E. scolopes, but the husbandry factors that promote hatchling production in a mariculture facility remain underreported. Here we report on the reproductive performance of E. scolopes in response to decreased mating frequency.ResultsOne animal cohort was maintained in a mariculture facility for 107 days, with females assigned to either a control group (mating once every 14 days) or an experimental group (mating once every 21 days). No differences between the groups were observed in survival, the number of egg clutches laid, or hatchling counts. Each group featured multiple females that were hyper-reproductive, i.e., they generated more than 8 egg clutches while in captivity. Examination of the distributions for daily hatchling counts of individual egg clutches revealed significant variation in the hatching patterns among clutches that was independent of mating frequency. Finally, an assessment of hatchling production showed that 93.5% of total hatchlings produced by the cohort were derived from egg clutches laid within the first 70 days.ConclusionsThese results suggest a lower mating frequency does not impede hatchling production. Furthermore, the variation in hatchling production among egg clutches provides new insight into the reproductive performance of E. scolopes as a lab animal for microbiology research.

Diet and Temperature Effects on the Survival of Larval Red Deep-Sea Crabs, Chaceon quinquedens (Smith, 1879), under Laboratory Conditions

Declines in commercial crustacean species (such as lobsters, king crab, etc.) have caused an increased interest in the harvest of the red deep-sea crab Chaceon quinquedens. The red deep-sea crab is a federally managed fishery; however, little is known about the species’ general biology, especially the conditions required for larval survival. We aimed to answer two main questions about the life history of the red deep-sea crab. First, is there a common larval hatching pattern between adult female crabs? Specifically, our inquiries are about the duration of the hatching process, daily peak hatching time, and the relationship between female morphometry and the total larvae hatched. Second, which are the factors affecting the survival and development of larval red deep-sea crabs? In order to answer these research questions, we studied the effects of diet (rotifers, Artemia sp., algae, and unfed), temperature (9 °C, 15 °C, and 20 °C), and aquaculture settings. Ovigerous females were obtained from commercial traps and transported to the NOAA James J. Howard Laboratory, NJ. They were placed in the Females Husbandry and Hatching Collection System (FHCS), where the larvae hatched. Hatching of adult females was monitored and measured by volume. A simple linear regression (SLR) was calculated to predict the number of larvae hatched based on the measured volumes, and it was significant (F = 1196; df = 1, 13; R2 = 0.9892, p = 3.498 × 10−14). Duration of hatching period showed an approximate 30 days for adult females red deep-sea crabs, with a common daily maximum hatching time at 22:00 hrs (hatching time seem to follow the sun cycle and the first hours after sunset, Perez, pers. observation). Linear polynomial quadratic regressions were conducted for both years with an interaction term for the two continuous variables (diet and temperature), and were used to model the proportion of larval survival through time. In both years, a highly significant difference was obtained (F = 56.15; df = 4, 2134; R2 = 0.09353; p = < 2.2 × 10−16). There is an effect of diet and temperature in the survival of red deep-sea crabs, but not a combined effect of them.

Comparative early growth patterns across four dominant fish species in a marine protected area in the East China Sea

Multiple marine protected areas have been established to protect spawning and recruitment fish stocks in the East China Sea. However, inadequate knowledge on early life histories for most species could be the main limiting factor for the effectiveness of these marine protected areas. To address the knowledge gap, the juvenile specimen of four dominant species (Amblychaeturichthys hexanema, Engraulis japonicus, Pampus argenteus and Trachurus japonicus) were collected in the Wentai marine protected area. Comparative analysis was carried out to explore the early growth patterns of these species. Through otolith microstructure analysis, we estimated daily age for 319 individuals and reconstructure the hatching pattern. The result helps more accurately identify hatching time of the four species, and hatching time of P. argenteus was found to shift to an earlier time. Consistent with the differing ecological characteristics, significant differences in growth rate and response pattern to SST were detected among the four species. The revealed early life characteristics and adaptive pattern to experienced thermal conditions could contribute to ecosystem-based fisheries management.

Life finds a way: Hatching dynamics of zooplankton dormant stages in intermittent wetlands from the Brazilian tropical semiarid

Hatching patterns of dormant stages are key to maintain zooplankton populations and to wetland functioning in drylands. However, the hatching dynamics of zooplankton dormant stages may vary across climate zones, and the knowledge of temporal hatching patterns of wetland zooplankton is incipient for tropical drylands in South America. With an ex-situ experiment, we assessed the temporal patterns in community structure of zooplankton hatchlings in the sediment of intermittent wetlands of the Brazilian tropical semiarid. Hatchlings were collected every two days in the laboratory over a 28-day hydration period. Hatchling abundance and richness peaked on the middle-to-late phase (third and fourth weeks), and composition showed a weekly variation over the hydration period. While large Branchiopoda and Moina sp. (Cladocera) predominated in the early phase (until the second week), most taxa of Ostracoda, Rotifera and Cladocera predominated in the middle-to-late phase of the experiment (third and fourth weeks after hydration). We found that the hatching patterns of zooplankton dormant stages in intermittent wetlands from the Brazilian semiarid convey marked short-term dynamics after hydration cues. This is useful to understand the zooplankton egg-bank hatching dynamics in tropical-dryland wetlands, which are expected to be under strong hydric stress in the future.

Differential Hatching, Development, Oviposition, and Longevity Patterns among Colombian Aedes aegypti Populations.

Simple SummaryAedes aegypti is a mosquito that transmits viruses responsible for several diseases in humans, such as dengue, Zika, and chikungunya. It is crucial to study mosquito populations from different countries and regions because control of disease transmission with insecticides can be more effective if adjusted to each population’s characteristics. For this reason, we determined several features of mosquitoes captured in different cities of Colombia: Neiva, Bello, Itagüí, and Riohacha. These included the length of their lifespan, the number of eggs they lay, and the stages in which they die. We found specific patterns for each population. This knowledge will help control programs determine the optimal times to apply insecticides and make surveillance, as well as the type of insecticide used.Dengue, Zika, and chikungunya are arboviral diseases for which there are no effective therapies or vaccines. The only way to avoid their transmission is by controlling the vector Aedes aegypti, but insecticide resistance limits this strategy. To generate relevant information for surveillance and control mechanisms, we determined life cycle parameters, including longevity, fecundity, and mortality, of Colombian Ae. aegypti populations from four different geographical regions: Neiva, Bello, Itagüí, and Riohacha. When reared at 28 °C, Bello had the shortest development time, and Riohacha had the longest. Each mosquito population had its own characteristic fecundity pattern during four gonotrophic cycles. The survival curves of each population were significantly different, with Riohacha having the longest survival in both males and females and Bello the shortest. High mortality was observed in mosquitoes from Neiva in the egg stage and for Bello in the pupae stage. Finally, when mosquitoes from Neiva and Bello were reared at 35 °C, development times and mortality were severely affected. In conclusion, each population has a unique development pattern with an innate trace in their biological characteristics that confers vulnerability in specific stages of development.

Desiccation increases the hatching of resting eggs of a freshwater calanoid copepod

Abstract Many former permanent aquatic habitats now face occasional desiccation due to human activities. Zooplankton might recover from droughts after the hatching of resting eggs, but how desiccation duration affects the viability and hatching patterns of resting eggs is unclear. This study evaluated how desiccation of varying durations (0, 3, 6 and 9 months) affects the hatchling numbers of the freshwater calanoid Notodiaptomus iheringi inhabiting a permanent lake. Hatchlings were observed across all desiccation treatments, and hatchling abundance was higher in longer desiccation treatments. Resting eggs of N. iheringi survive desiccation for up to 9 months even though the tested population originated from sediments of a permanent lake. Desiccation may stimulate hatching by terminating dormancy and by weakening (wet) sediment adversity. Knowledge of the hatching patterns of resting eggs of varying taxa after desiccation can help to understand how zooplankton communities recover after droughts.

Impaired hatching exacerbates the high CO2 sensitivity of embryonic sand lance Ammodytes dubius

Rising oceanic partial pressure of CO2 (pCO2) could affect many traits in fish early life stages, but only few species to date have shown direct CO2-induced survival reductions. This might partly be because species from less CO2-variable, offshore environments in higher latitudes are currently underrepresented in the literature. We conducted new experimental work on northern sand lance Ammodytes dubius, a key forage fish on offshore Northwest Atlantic sand banks, which was recently suggested to be highly CO2-sensitive. In 2 complementary trials, we produced embryos from wild, Gulf of Maine spawners and reared them at several pCO2 levels (~400-2000 µatm) in combination with static (6, 7, 10°C) and dynamic (10→5°C) temperature treatments. Again, we consistently observed large, CO2-induced reductions in hatching success (-23% at 1000 µatm, -61% at ~2000 µatm), and the effects were temperature-independent. To distinguish pCO2 effects during development from potential impacts on hatching itself, some embryos were switched between high and control pCO2 treatments just prior to hatch. This indeed altered hatching patterns, consistent with the CO2-impaired hatching hypothesis. High CO2 also delayed the day of first hatch in one trial and peak hatch in the other, where later-hatched larvae were of similar size but with progressively less endogenous energy reserves. For context, we extracted seasonal pCO2 projections for Stellwagen Bank (Gulf of Maine) from regional ensemble simulations, which indicated a CO2-induced reduction in sand lance hatching success to 71% of contemporary levels by 2100. The species’ unusual CO2 sensitivity has large ecological and scientific ramifications that warrant future in-depth research.

On understanding and manipulating the hatching patterns of Diabrotica virgifera virgifera eggs to improve the design of experiments

AbstractDiabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a well‐studied pest of maize (Zea mays L., Poaceae) in North America and Europe. Many studies on its biology, behaviour, or management rely on individuals reared from either field‐collected insects or laboratory colonies. Naturally, D. v. virgifera eggs require an obligate 8–10‐month diapause, which can cause technical challenges such as a deceleration of research activities. To allow better planning of experimentation, we have investigated the survival and temporal hatching patterns of the pest’s eggs depending on diapause length as well as post‐diapause incubation temperature. Laboratory assays revealed that the highest hatching rates and most synchronized hatching times in a wild diapausing population occurred when eggs were overwintered at the natural diapause length (8–10 months) or shorter (5–7 months) and then incubated at 20–24 °C. Eggs diapaused for only 2 months showed comparably good hatching rates, but hatching patterns appeared more variable. Diapause of <2 or >10 months reduced hatching success, as did low (16 °C) incubation temperatures. For comparison, a well‐studied non‐diapausing laboratory colony was assessed as well. Data matrices on egg overwintering survival, the start, peak, duration, and end of egg hatching, as well as hatching rates are provided for various diapause lengths and three incubation temperatures for both populations. This information will support scientists in choosing a D. v. virgifera colony that fits best their experimental set‐up and study conditions, as well as in optimally planning such studies.

Dormant plasticity of rotifer diapausing eggs in response to predator kairomones.

In freshwater ecosystems, hatching strategy of diapausing eggs (DEs) under predation risk has important ecological implication for zooplankters. Although kairomones released by predators can induce phenotypic responses of prey, hatching patterns of DEs in response to kairomones have received contradictory conclusions in zooplankters. Maternal environment may also affect hatching strategy of DEs during predator-prey interactions. We used classical Brachionus calyciflorus-Asplanchna models to determine the timing and proportion of DE hatching in association with parental and embryonic exposure to kairomones. Results obtained from two Brachionus clones supported the hypothesis that DEs could detect Asplanchna kairomones and adjust hatching patterns. DEs showed early and synchronous hatching patterns in the environment with kairomones. Data also supported the prediction that DEs could gain information about predators from maternal environments and adjusted their hatching pattern in response to the presence of kairomones. Compared with DEs from Brachionus mothers not exposed to kairomones, DEs produced by mothers that were experienced with kairomones attained a higher hatching rate when both of them hatched in the environment either with or without kairomones. Our results suggest that DEs of B. calyciflorus possess dormant plasticity to defend against predation from Asplanchna, which may be regulated by maternal environmental effects during sexual life cycles.

Color2Hatch: conversion of color to hatching for low-cost printing

In this paper, we propose Color2Hatch, a decolorization method for business/presentation graphics. In Color2Hatch, each region represented as a closed path and uniformly colored in scalable vector graphics (SVG) is converted to a region hatched in black and white. From the characteristics of business graphics, the hatching patterns are designed to represent mainly the hue in the region; additionally, lightness and saturation can also be reflected. To discriminate subtle differences between colors, attached short line segments, zigzag lines, and wave lines are used in hatching by analogy to a clock. Compared with the existing decolorization methods, for example, grayscale conversion and texturing, our method is superior in the discrimination of regions, suitable for low-cost black and white printing that meets real-world needs.

Embryo-to-embryo communication facilitates synchronous hatching in grasshoppers

Synchronous hatching within single egg clutches is moderately common in locusts and other insects and can be mediated by vibrational stimuli generated by adjacent embryos. However, in non-locust grasshoppers, there has been little research on the patterns of egg hatching and the mechanisms controlling the time of hatching. In this study, the hatching patterns of six grasshoppers (Atractomorpha lata, Oxya yezoensis, Acrida cinerea, Chorthippus biguttulus, Gastrimargus marmoratus, and Oedaleus infernalis) were observed under various laboratory treatments. Under continuous illumination and a 25/30°C thermocycle, the eggs of these grasshoppers tended to hatch during the first half of the daily warm period. Eggs removed from egg pods and cultured at 30°C tended to hatch significantly earlier and more synchronously when kept in groups vs. singly. In general, eggs hatched earlier when egg group size was increased. Egg hatching was stimulated by hatched nymphs in some species, but not in others. In all species, two eggs separated by several millimeters on sand hatched less synchronously than those kept in contact with one another, but the hatching synchrony of similarly separated eggs was restored if they were connected by a piece of wire, suggesting that a physical signal transmitted through the wire facilitated synchronized hatching. In contrast, hatching times in the Emma field cricket, Teleogryllus emma, which lays single, isolated eggs, were not influenced by artificial clumping in laboratory experiments. These results are discussed and compared with the characteristics of other insects.

Comparison of Mechanical Properties of 3D-Printed Specimens Manufactured Via FDM with Various Inner Geometries

The aim of this study was to investigate the effects of process parameters on tensile strength for PLA specimens produced by fused deposition modeling (FDM). For this purpose, two different density rates (20% and 100%), printing speeds (100 and 130 mm/s), and nozzle temperatures (180 and 220oC) with three different hatching patterns including elliptical and diagonal (Gyroid, Cross 3D ve Grid) were selected. In the study, higher tensile stress was obtained at a rate of 100%, compared to a 20% density rate. When the samples with a 20% density rate are compared among themselves, the highest tensile stress value obtained was measured as 38.76 MPa for the Grid-patterned specimen produced at a nozzle temperature of 2200C and printing speed of 100 mm/s. Statistical analysis was also done for specimens with a 20% density rate. As a result of the variance analysis (ANOVA) method, the confidence level was achieved as 96%. When comparing in terms of specific strength, it was determined that the closest pattern to the full-filled sample with a specific strength of 5,893 MPa/gr was Cross 3D-patterned sample with a value of 5.458 MPa/gr.

Sensing underground activity: diel digging activity pattern during nest escape by sea turtle hatchlings

Synchronous digging activity and emergence from underground nests is important for sea turtle hatchlings, as it reduces predation risk and decreases energy consumption. However, patterns of underground hatching and diel digging activity prior to emergence are invisible and remain largely unknown. In this study, we acoustically monitored the activity of green turtle, Chelonia mydas , hatchlings from hatching to emergence in the field and laboratory. During the hatching period, we did not observe characteristic acoustic events corresponding to pipping and hatching. Hatchlings started digging even though there were still unhatched eggs above them, indicating that green turtles did not hatch as one synchronous group. This observation did not support our hypothesis that synchronized hatching facilitates synchronous emergence. Digging activity tended to increase at night as the hatchlings approached the sand surface and nest emergence became imminent. It is not surprising that there was diel variation in digging activity as the hatchlings approached the surface because diel fluctuations in sand temperature can provide a diel cue. Surprisingly, a diel change in digging activity was also observed when hatchlings were still at a sand depth where temperature remained relatively constant throughout the day (that is, a few days before emergence) and in the laboratory at a constant temperature. This study suggests that the diel activity pattern of hatchling green turtles may occur even in the absence of a diel temperature fluctuation cue. • Green turtle hatchlings did not hatch synchronously. • Digging activity occurred even when some eggs of the nest were unhatched. • Synchronous digging increased at night as the emergence became imminent. • Diel change in activity occurred even under constant conditions. • Acoustic monitoring is useful for investigating underground animal behaviour.

Sibling competition in the broods of Little Egrets Egretta garzetta in a southern Tunisian breeding colony

Asynchronous hatching is a common hatching pattern in the Little Egret Egretta garzetta, however, its role in maintaining dominance relationships and feeding hierarchy among siblings remains poorly studied. In this study, we investigated this issue using data on feeding and aggressive behaviours of Little Egrets nestlings in a southern Tunisian breeding colony. We found that senior nestlings were the first to access the food brought by their parents, and they ingested more food than their younger siblings did. Intermediate nestlings engaged the most frequently in aggression. The youngest nestlings showed a more resigned and less aggressive behaviour, therefore receiving a little less food, but much fewer pecks and injuries than their elders do. These findings stress the importance of hatching order in establishing a feeding hierarchy among Little Egret siblings. Moreover, they suggest that access to food may not be the unique factor that shapes nestlings’ feeding behaviour and competitiveness, as the avoidance of injuries caused by siblings’ attacks may be important. Finally, adult birds appeared to adopt a ‘laissez faire’ strategy, showing no feeding favouritism to counteract or reinforce the effects of hatching asynchrony on their offspring.

Influence of restoration age on egg bank richness and composition: an ex situ experiment

AbstractZooplankton community assembly after flooding in temporary ponds depends mostly on abundance and diversity of the dormant propagule bank. However, our understanding of the hatching patterns of zooplankton is imperfect. We performed an ex situ experiment to study the species composition and temporal sequence of zooplankton emergence from sediments in three ponds that were restored at different times: 1998, 2003 and 2007. The patterns of species hatching observed in our microcosms were compared with the emergent zooplankton community of their equivalent, synchronically inundated ponds. An escalation in species richness and a delay in hatching time were detected with increasing restoration age. In addition, some discrepancies between the egg bank and active populations were observed, especially in the oldest pond. This study illustrates the use of hatching experiments in comparing ponds with different characteristics. Nevertheless, egg bank hatching and water column sampling should complement each other in order to afford a full reflection of past diversity and contribute to a better understanding of the efficiency of restoration practices.

Hatching phase influences thermal preference of broilers throughout rearing

Here we aimed for the first time to analyse whether opposite hatching patterns associated or not to high incubation temperature from day 13 to hatching interferes with the thermal preference and response of broilers to heat stress throughout the rearing period. Fertile eggs from 56-week-old broiler breeders (Cobb-500®) were used in a completely randomized trial with a 2x2 factorial arrangement (Short-Long and Long-Short hatching patterns: short time interval between internal and external pipping followed by long time interval between external pipping and hatching, and long time interval between internal and external pipping followed by short time interval between external pipping and hatching, respectively; and control and high incubation temperatures: 37.5°C and 39°C from the 13rd day, respectively). Thermal manipulation from day 13 was chosen because it is known endocrine axes are already established at this time. At hatching, male chicks were reared in climatical chamber with 16 boxes, maintained at the temperature recommended for this strain, with 4 replicates of 18 chicks per treatment. Broilers with Long-Short hatching pattern and from eggs incubation at 37.5°C preferred the lowest ambient temperature at all analyzed ages, whereas broilers with Short-Long hatching pattern and from eggs incubated at 39°C preferred the highest temperatures from 21 days of age. Heat-exposed broilers showed increased respiratory frequency in all ages analyzed, which should have to contributed to maintainance of their rectal (body) temperature. The hatching patterns did not influence the feed intake, but broilers with Short-Long hatching pattern had better feed conversion, weight gain, and body weight. High incubation temperature reduced the feed consumption, as well as the weight gain and body weight by worsening the feed conversion. The results of this study reveal that hatching patterns associated or not to high incubation temperature influence the broiler thermal preference and heat response throughout the rearing period. Chicks with Long-Short and Short-Long hatching patterns should be reared separately, although this is not practical within a hatcher.