Dormant Eggs Research Articles

To lose is to win: Long‐term co‐occurrence of two asexual populations realized by a dormant strategy of the inferior competitor

Abstract Asexual organisms are ubiquitous. While being members of a single species with the same ecological requirements, multiple asexual genotypes within a species are often found in a single habitat. Niche partitioning in time and space among genotypes has been proposed to explain this phenomenon. However, it is not clear whether these different genotypes co‐occur in the long term. Therefore, we examined the population dynamics of two asexual Daphnia cf. pulex genotypes (JPN1 and JPN2) over 9 years in a small mountain lake. These two genotypes consistently occurred in the same seasons and layers, suggesting that niche partitioning cannot explain their long‐term co‐occurrence. The abundance of JPN1 was typically higher in most years. However, the abundance of dormant eggs in lake sediments was at the same level between the genotypes. Results of a laboratory experiment showed that JPN1 competitively excluded JPN2. However, many JPN2 individuals produced dormant eggs before JPN1 competitively excluded them from the experiment. Furthermore, the competitively inferior JPN2 produced dormant eggs abundantly in the medium containing a crowding cue from JPN1 while no such trend was observed for JPN1. These results showed that a competitively inferior asexual genotype could maintain a population with a competitively superior genotype for a long period of time because it had the ability to detect an increase in competitors and produce dormant eggs each year before being competitively eliminated. Based on these results, we suggest that the variation in genotype‐specific response in dormant egg production to environmental change plays a key role in the long‐term co‐occurrence of different asexual genotypes in single habitats. Read the free Plain Language Summary for this article on the Journal blog.

Development of a technique for determining the viability of dormant organisms in powdered substances

The purposes of pharmaceutical biotechnology and quality control of probiotics containing lyophilized bacterial preparations, as well as the purpose of ensuring biological safety, require methods for rapid determination of the viability of dormant forms. This paper describes an approach to determining the viability of dry powdered substances. Lyophilized powder of Kalanchoe daigermontiana, dry dormant eggs of Artemia salina, and dry powder of Lycopodium sp. spores were proposed as model objects. Suspensions of virus-like particles (VLPs) to SARS-CoV-2 were proposed as a cell-free reference material. The following methods of elemental analysis were used in the study: X-ray fluorescence spectroscopy (XRF) on an energy-dispersive device, atomic absorption spectroscopy with electrothermal atomization, and Zeeman background correction (GZ-AAS). The free water content was determined by NMR spin echo. A new method was also used for recording the kinetics of changes in broadband radio emission in the centimeter and millimeter wavelength ranges, with a measurement duration of up to 20 minutes. Live and inactivated powdered preparations of K. daigermontiana and A. salina were prepared and characterized by elemental composition, water content, and spin-spin relaxation time (T2). For these live and inactivated preparations, it was determined that the flux density of intrinsic thermal radio emission decreases by an order of magnitude with the loss of viability. In the future, the results obtained will allow for a rapid test of the viability of lyophilized therapeutics (from medicinal plants to bacterial mixtures that stabilize the intestinal microflora).
 Keywords: millimeter emission, X-ray fluorescence analysis, NMR spin echo, nanoparticles, powdered substances, medicinal plant raw materials

Turtle-mediated dispersal of anostracan dormant eggs: Evidence for dominance hierarchy effects.

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Study on the quality and symbiotic microbial composition of Artemia nauplii in three main producing areas

Artemia nauplii are high-quality biological feed for aquatic animal breeding, and its quality determines the effectiveness of breeding. The aim of this study was to explore the quality and symbiotic microbial composition of nauplii in different areas. The dormant eggs of Artemia nauplii from Kulundan Lake in Russia, Aibi Lake in Xinjiang, and salt fields in Bohai Bay were selected for incubation, and the relevant indicators of the 29 h incubation period were recorded. A high-throughput sequencing platform was used to analyze the microbial structure of symbiotic bacteria in nauplii between treatments. The PICRUSt2 was used to precalculated the predicted genes and their functions. The hatching rate of Artemia per thousand eggs in Kulundan Lake, Aibi Lake and Bohai Bay was 91.2%, 87.8% and 75.9%, respectively. The Alpha and Beta diversity analysis showed that the richness and evenness of Artemia nauplii in Kulundan Lake were higher than that of in Bohai Bay. At phylum level, Firmicutes, Proteobacteria and Bacteroidota were the dominant symbiotic bacteria of nauplii. But at the genus level, the dominant species of the symbiotic bacteria of nauplii were Bacillus, Pseudomonas and Exiguobacterium. The hatching rate and the abundance of symbiotic bacteria of Artemia nauplii from Kulundan Lake were better than the other two areas. This research might provide a theoretical guidance for the symbiotic bacteria of Artemia nauplii to regulate the feeding health of aquatic animal seedlings, reduce the occurrence of diseases and purify water quality.

Systematic literature review on toxicants impacts dormant eggs in temporary wetlands: an ocean of unknowingness.

Temporary wetlands are recognised biodiversity hotspots. Dormant egg banks, as part of their cryptic biodiversity, are responsible of wetlands resilience. Egg banks are also known to be sensitive indicators of anthropogenic disturbances. This study aims to assess the current state of research of toxicants impact on dormant egg banks in temporary wetlands. The systematic literature review carried out has shown the small number of studies on this topic. This study provides evidence of commonality concerning negative impact effect on the organisms, reducing hatching success, dormant eggs production and emergence, or species richness, among others, which might weaken ecosystem stabilization mechanisms by reducing biodiversity. Our review also revealed a glaring lack of in situ and long-term studies for understanding ecosystem consequences of toxicants on temporary wetlands. These gaps in knowledge hamper our ability to design and implement evidence-based conservation and management programs but opens opportunities for new research lines.

Behavioral Avoidance Response of Daphnia to Fungal Infection Caused by Metschnikowia Species in a Temperate Reservoir.

Simple SummaryThe negative effects of fungal infection on the survival and reproduction of cladocerans, a representative prey community in freshwater, are unexplored. In this study, we hypothesized that the winter migration pattern of Daphnia pulicaria, observed in the Anri Reservoir in South Korea, is the host’s defense response to fungal infection. Daphnia pulicaria was mainly distributed in the central bottom layer of the reservoir before winter (summer to autumn) but migrated to the littoral area during winter as fungal infections in the communities gradually spread in the bottom region. However, when the spread of infection was low, D. pulicaria did not migrate. The migrated individuals with dormant eggs were mostly infected and are believed to have migrated to the littoral area to freeze their dormant eggs. We found that dormant eggs of D. pulicaria obtained from ice crystals had lower hatching and infection rates than dormant eggs obtained adaptively in Daphnia mothers. Such a strategy is an efficient response of D. pulicaria to avoid the spread of fungal infection in communities and to maintain their continuous population growth.Morphological or behavioral defense mechanisms are important evolutionary strategies for the survival of prey. Studies have focused on predation and competition, but infection has been overlooked, despite being a determining factor of distribution and species diversity of prey. We hypothesized that the winter migration of Daphnia pulicaria is a community defense strategy to avoid fungal infection. To test this hypothesis, environmental variables and the Cladocera community, including D. pulicaria, were monitored in three study sections of the Anri Reservoir in the Republic of Korea during September 2010–August 2015. During three winter seasons, the density of infected D. pulicaria increased in all study sections, and they migrated from the central to the littoral area. Most of the infected individuals had dormant eggs in sexually reproducing mothers. However, when the proportion of non-infected individuals was higher than that of infected individuals, winter migration was not observed. Additional microcosm experiments showed that dormant eggs of D. pulicaria obtained from ice crystals in the littoral area had lower hatching and infection rates than those obtained from mothers moving from other zones. Therefore, the migration of D. pulicaria during winter is an active response to avoid intergenerational fungal infection.

From hemolymph to in-vivo: The potential of a 1 mm microlitre flow probe with separate lock chamber for NMR metabolomics in mass limited environmental samples

Metabolomics is one of the leading approaches for understanding the toxic-mode-of-action of environmental contaminants. Nuclear Magnetic Resonance (NMR) spectroscopy has been commonly used in metabolomic studies; however, its main drawback is its relatively low sensitivity, making it challenging to study mass limited but environmentally crucial samples. In this work a 1 mm microlitre probe modified with a separate lock chamber to address this challenge, provided substantial improvements in mass sensitivity relative to conventional 5 mm NMR probes. The 1 mm probe is used to analyze various components of the model organism Daphnia magna, including hemolymph, parthenogenetic eggs, dormant eggs, and neonates. A μL volume flow system is designed for the 1 mm probe to perform an in-vivo exposure of neonates to high salt concentrations. The metabolic investigation of these samples was only achieved due to the minimum sample requirements and high salt tolerance of the probe, demonstrating that the 1 mm microlitre probe modified with a separate lock chamber holds significant potential for future metabolomic studies of mass limited samples.

The new invasive mosquito species Aedes koreicus as vector-borne diseases in the European area, a focus on Italian region: What we know from the scientific literature.

The increased mobility of goods, people, and animals worldwide has caused the spread of several arthropod vectors, leading to an increased risk of animal and human infections. Aedes koreicus is a common species in South Korea, China, Japan, and Russia. Due to its cold-resistant dormant eggs, the adults last from the late summer until the autumn seasons. For these reasons, it seems to be better adapted to colder temperatures, favoring its colonization of hilly and pre-alpine areas. Its first appearance in Europe was in 2008 in Belgium, where it is currently established. The species was subsequently detected in Italy in 2011, European Russia, Germany, the Swiss–Italian border region, Hungary, Slovenia, Crimea, Austria, the Republic of Kazakhstan, and the Netherlands. The role of A. koreicus in the transmission of vector-borne pathogens remains unclear. The available scientific evidence is very old, often not available in English or not indexed in international databases, and therefore difficult to find. According to the literature reviewed, A. koreicus can be considered a new invasive mosquito species in Europe, establishing populations on the European continent. In addition, experimental evidence demonstrated its vector competence for both Dirofilaria immitis and Chikungunya and is relatively low for ZIKA but not for Western Nile Virus. On the other hand, even if the field evidence does not confirm the experimental findings, it is currently not possible to exclude with absolute certainty the potential involvement of this species in the spread, emergence, or re-emergence of these vector-borne disease agents.

Resurrection of dormant zooplankton grazers reveals multiple evolutionary responses to toxic cyanobacteria

AbstractThe cyanobacterial blooms caused by eutrophication exert strong selection on zooplankton grazers. Resurrection ecology, coupled with multivariate reaction norm analysis, can be used to parse the relative contributions of plasticity and evolution to mediating adaptation to environmental changes in natural populations. Here, we tested whether increasing levels of toxic cyanobacteria result in multivariate reaction norm changes in a natural zooplankton population. We resurrected dormant eggs of Ceriodaphnia cornuta (Cladocera) from three sediment layers in Dianshan Lake from 1988 to 2018, a period during which the abundances of cyanobacteria continuously increased, and conducted a common garden experiment to quantify the multivariate reaction norms of nine morphological, life history, and behavioral traits involved in the response to the toxic cyanobacterium Microcystis aeruginosa. The youngest subpopulation coinciding with the high‐eutrophic period was characterized by smaller size at birth and maturity and fewer offspring in their second broods compared with the oldest subpopulation coinciding with the low‐eutrophic period. Patterns of covariance in multivariate trait space provided strong evidence of adaptive evolution in multiple traits over time. The total trait change generated through both constitutive evolution and evolution of plasticity ranged from 1% to 64% depending on the trait and subpopulations being compared. These results suggest that multivariate phenotypic shifts in response to environmental changes in the study population are achieved by integrating plasticity, evolution of trait means, and evolution of plasticity.

Behavior of Aedes albifasciatus (Diptera: Culicidae) larvae from eggs with different dormancy times and its relationship with parasitism by Strelkovimermis spiculatus (Nematoda: Mermithidae).

Aedine mosquitoes go through unfavorable periods as dormant eggs. However, extended dormancy times lead to a depletion of egg reserves, which might be partially compensated by changes in larval-feeding behavior. Changes in larval behavior may also be induced by parasitism by mermithids probably as a strategy to reduce the impact of the parasite on the host. The most abundant floodwater mosquito in southern South America is Aedes albifasciatus (Diptera: Culicidae), a species naturally parasitized by Strelkovimermis spiculatus (Nematoda: Mermithidae). This study aimed to evaluate the behavior of fourth-instar larvae of Ae. albifasciatus from eggs with 2, 4, and 6months of dormancy, parasitized or not by S. spiculatus. To achieve this, eight categories of behavior were defined, and then, each individual was observed for 5min, and its behaviors and their duration were recorded. The behaviors with the highest percentage of observation time were still (50.1%) and wriggle swimming (33.6%), while those with the lowest percentage of observation time were those involving active foraging (less than 8%). A great variability in the behaviors was observed among individuals within the same treatment. The type and duration of each behavior did not vary in relation to egg dormancy time or parasitism, but parasitism affected the level of larval activity. Parasitized larvae performed, on average, fewer behaviors than non-parasitized larvae. This result supports the hypothesis that S. spiculatus parasitism affects the behavior of Ae. albifasciatus larvae by reducing their level of activity.

Refining the evolutionary time machine: An assessment of whole genome amplification using single historical Daphnia eggs.

Whole genome sequencing is instrumental for the study of genome variation in natural populations, delivering important knowledge on genomic modifications and potential targets of natural selection at the population level. Large dormant eggbanks of aquatic invertebrates such as the keystone herbivore Daphnia, a microcrustacean widespread in freshwater ecosystems, provide detailed sedimentary archives to study genomic processes over centuries. To overcome the problem of limited DNA amounts in single Daphnia dormant eggs, we developed an optimized workflow for whole genome amplification (WGA), yielding sufficient amounts of DNA for downstream whole genome sequencing of individual historical eggs, including polyploid lineages. We compare two WGA kits, applied to recently produced Daphnia magna dormant eggs from laboratory cultures, and to historical dormant eggs of Daphnia pulicaria collected from Arctic lake sediment between 10 and 300years old. Resulting genome coverage breadth in most samples was ~70%, including those from >100-year-old isolates. Sequence read distribution was highly correlated among samples amplified with the same kit, but less correlated between kits. Despite this, a high percentage of genomic positions with single nucleotide polymorphisms in one or more samples (maximum of 74% between kits, and 97% within kits) were recovered at a depth required for genotyping. As a by-product of sequencing we obtained 100% coverage of the mitochondrial genomes even from the oldest isolates (~300years). The mitochondrial DNA provides an additional source for evolutionary studies of these populations. We provide an optimized workflow for WGA followed by whole genome sequencing including steps to minimize exogenous DNA.

Using topsoil translocation from natural wetlands to restore rice field systems

Wetlands provide vital habitat for biodiversity and relevant ecosystem services to human population. The rapid transformation of freshwater wetlands to grow food crops became the wetlands strongly threatened by human activities. Restoration efforts related to wetlands have been widely attempted; however, science‐based guidelines are relatively scarce. Here, we analyzed whether different levels of topsoil addition from natural wetlands in the sediment from rice fields influence the zooplankton communities. Our hypothesis was that the richness and abundance of hatchlings would be higher in treatments with high topsoil addition from natural wetlands, followed by treatments with low addition. In the laboratory, eight field sediment samples were incubated for zooplankton hatching in four treatments: rice fields, rice fields added with low (5%) and medium (30%) quantities of sediment from natural wetlands, and natural wetlands. A total of 4,493 hatchlings belonging to 24 taxa were observed in the experiment. While zooplankton richness and abundance did not differ between sediment treatments, significant differences in species composition associated with topsoil addition were observed. SIMPER analysis showed that topsoil addition from natural wetlands enhanced the abundance of cladocerans and larval copepods. Our results showed that sediments from natural wetlands have a bank of zooplankton dormant eggs that can help the recovery of wetlands disturbed by rice fields. The addition of natural wetland sediments in areas disturbed by rice fields modifies the zooplankton composition of the rice fields, aiding the recovery of disturbed natural wetlands for rice production.

Observations of linear aggregation behavior in rotifers (Brachionus calyciflorus).

Linear aggregation is present in some animals, such as the coordinated movement of ants and the migration of caterpillars and spinylobsters, but none has been reported on rotifers. The rotifers were collected and clone cultured in the laboratory at 25 ± 1°C, under natural light (light intensity ~130 lx, L:D = 14:10). The culture medium(pH = 7.3) was formulated as described by Suga et al., and rotifers were fed on the micro algae Scenedesmus obliquus grown in HB-4 medium to the exponential growth stage. When density was high (150 individuals ml-1), the behavior of rotifers was observed using a stereo microscope (Motic ES-18TZLED). In this paper, linear aggregation in Brachionus calyciflorus was found for the first time, and experiments were carried out to verify the correlation between linear aggregation and culture density of B. calyciflorus. With the increase of density, the number of aggregations increase, the number of individuals in the aggregation increased, and the maintenance time of the aggregation was also increased. Therefore, we speculate that the formation of aggregates is related to density and may be a behavioral signal of density increase, which may transmit information between density increase and formation of dormant eggs.

Variation in developmental rates is not linked to environmental unpredictability in annual killifishes.

Comparative evidence suggests that adaptive plasticity may evolve as a response to predictable environmental variation. However, less attention has been placed on unpredictable environmental variation, which is considered to affect evolutionary trajectories by increasing phenotypic variation (or bet hedging). Here, we examine the occurrence of bet hedging in egg developmental rates in seven species of annual killifish that originate from a gradient of variation in precipitation rates, under three treatment incubation temperatures (21, 23, and 25°C). In the wild, these species survive regular and seasonal habitat desiccation, as dormant eggs buried in the soil. At the onset of the rainy season, embryos must be sufficiently developed in order to hatch and complete their life cycle. We found substantial differences among species in both the mean and variation of egg development rates, as well as species‐specific plastic responses to incubation temperature. Yet, there was no clear relationship between variation in egg development time and variation in precipitation rate (environmental predictability). The exact cause of these differences therefore remains enigmatic, possibly depending on differences in other natural environmental conditions in addition to precipitation predictability. Hence, if species‐specific variances are adaptive, the relationship between development and variation in precipitation is complex and does not diverge in accordance with simple linear relationships.

Egg morphology may underpin the successful distribution of large branchiopods in temporary waters

Invertebrate species from temporary aquatic ecosystems produce resistant dormant stages (i.e. eggs) that accumulate in long lived mixed egg banks in the sediment. These dormant eggs not only bridge dry phases but also act as propagules for passive dispersal. Large branchiopod crustaceans (e.g. Notostraca, Anostraca and Spinicaudata) produce dormant eggs of variable shapes, sizes and external ornamentation. While these characteristics are often species-specific and have been used in taxonomy, little is known about their ecological significance, for example, their contribution to colonisation success. Here, we explore the idea that variation in egg morphology may impact vector-mediated dispersal and colonisation success of large branchiopods. We studied egg banks from 98 temporary waters across the Northern Cape, South Africa and assessed whether distribution and densities of eggs carried a morphological signal. Overall, our results imply that both size and external structures may impact dispersal to and successful colonisation of temporary waters by large branchiopods. Specifically, our results show that small propagules ( 400 µm), smooth eggs and medium sized (200–300 µm), polygonal eggs were most widely distributed. Ultimately, our approach provides insight in actual colonisation success of species with different egg types and not only on the propensity of the eggs to be picked up and transported by vectors.

Do temperature and water depth influence microcrustacean hatching responses from floodplain wetland sediments?

Microcrustacea in ephemeral wetlands produce dormant eggs to escape prolonged dry conditions. These eggs can hatch on inundation, although in most cases not all eggs hatch during a single wetting event. Incomplete hatching can reflect bet-hedging strategies, but also the presence or absence of environmental cues that stimulate hatching. This study examines the effects of environmental cues likely to change for wetlands in the future, namely, temperature and water depth. Surface sediments collected from dry anabranches of the Macintyre River floodplain (eastern Australia) were inundated under two temperature regimes (warm and cool) in microcosms of two depths (shallow and deep). Hatched microcrustacea were sampled for 6 weeks. The abundance and assemblage composition of microcrustacea varied by temperature but not by depth. Although the total abundance was greater under warm conditions, the effect of temperature diminished over time. Temperature also had a greater effect on non-ostracods, with 144% more non-ostracods being hatched under warm than under cool conditions. Thus, changes to temperature during inundation periods arising from global climate change or river regulation are likely to influence the abundance and composition of microcrustacean assemblages, especially among non-ostracods, which will influence food availability for larval and juvenile native fish and, hence, recruitment.

Hatching stimulation activity of steroidal glycoalkaloids toward the potato cyst nematode, Globodera rostochiensis.

Cyst nematodes (Globodera spp. and Heterodera spp.) are highly evolved sedentary endoparasites that are considered as harmful pests worldwide. The hatching of the dormant eggs of cyst nematodes occurs in response to hatching factors (HFs), which are compounds that are secreted from the roots of host plants. Solanoeclepin A (SEA), a triterpene compound, has been isolated as HF for potato cyst nematode (PCN) eggs, whereas other compounds, such as steroidal glycoalkaloids (SGAs), are also known to show weak hatching stimulation (HS) activity. However, the structures of both compounds are different and the HF-mediated hatching mechanism is still largely unknown. In the present study, we observed specific hatching of PCN eggs stimulated by the hairy root culture media of potato and tomato, revealing the biosynthesis and secretion of HFs. SGAs, such as α-solanine, α-chaconine, and α-tomatine, showed significant HS activity, despite being remarkably less activities than that of SEA. Then, we evaluated the contribution of SGAs on the HS activities of the hairy root culture media. The estimated SGAs content in the hairy root culture media were low and nonconcordant with the HS activity of those, suggesting that the HS activity of SGAs did not contribute much. The analysis of structure-activity relationship revealed that the structural requirements of the HS activity of SGAs are dependent on the sugar moieties attached at the C3-hydoroxyl group and the alkaloid property of their aglycones. The stereochemistry in the EF rings of their aglycone also affected the strength of the HS activity.

Temperature and photoperiod effects on dormancy status and life cycle parameters in Aedes albopictus and Aedes aegypti from subtropical Argentina.

Aedes albopictus (Diptera: Culicidae) distribution is bounded to a subtropical area in Argentina, while Aedes aegypti (Diptera: Culicidae) covers both temperate and subtropical regions. We assessed thermal and photoperiod conditions on dormancy status, development time and mortality for these species from subtropical Argentina. Short days (8 light:16 dark) significantly increased larval development time for both species, an effect previously linked to diapause incidence. Aedes albopictus showed higher mortality than Ae. aegypti at 16 °C under long day treatments (16 light:8 dark), which could indicate a lower tolerance to a sudden temperature decrease during the summer season. Aedes albopictus showed a slightly higher percentage of dormant eggs from females exposed to a short day, relative to previous research in Brazilian populations. Since we employed more hours of darkness, this could suggest a relationship between day-length and dormancy intensity. Interestingly, local Ae. aegypti presented dormancy similar to Ae. albopictus, in accordance with temperate populations. The minimum dormancy in Ae. albopictus would not be sufficient to extend its bounded distribution. We believe that these findings represent a novel contribution to current knowledge about the ecophysiology of Ae. albopictus and Ae. aegypti, two species with great epidemiological relevance in this subtropical region.

Emergent effects of light and temperature on hatching success of Streptocephalus cafer (Branchiopoda: Anostraca) resting eggs

AbstractResting egg production is considered the most common form of dormancy in aquatic invertebrates. Given that many taxa at least partially terminate resting egg state using environmental cues, knowledge on environmental drivers of hatching success is important, particularly within the context of climate change and environmental degradation. Fairy shrimp (anostracans) are temporary wetland specialists that are reliant on resting egg production for population persistence. Temporary wetlands are common in many arid regions projected to experience increases in temperature, and in areas often compromised by human‐mediated activities. In this study, we assessed the combined effects of light and temperature on the hatching success of Streptocephalus cafer (Anostraca) dormant eggs from temporary wetlands in an arid environment. Both temperature and light altered hatching success, with emergent effects evident. Light caused a significant threefold increase in hatching success overall, while temperature effects were non‐linear, with hatching optimised at 27°C, and especially under light conditions. These results are discussed within the context of shifting climates and disturbances to temporary wetland ecosystems.

Zooplankton hatching from dormant eggs in a large Pampean shallow lake

Dormancy is an essential component of the life cycle for populations that disappear from the plankton during winter. The hatching of resting eggs is the main mechanism for restoring active population components. Here, we analyzed the hatching dynamics of zooplankton from sediments of a shallow lake as affected by temperature. Sediment samples collected every other month were incubated at in situ temperatures and at 20°C. The highest number of individual's hatchings was observed for copepod nauplii, the cladoceran Bosmina sp., and the rotifer Brachionus havanaensis. Temperature showed a positive significant effect on the hatchlings of B. havanaensis. Other zooplankton species were less affected by temperature, and there was no relationship between their emergence from the incubated sediments and occurrence in the water column. We also tested the effect of short-term (6 and 12 weeks) and long-term (a year) storage duration on hatching success. The hatching success of B. havanaensis was not affected by the storage time. In contrast, the hatchlings of Bosmina sp. and nauplii increased after short storage time. The evidence collected here suggests that many zooplankters were not affected by temperature, while for B. havanaensis temperature turned out to be a master variable that links planktonic and passive phases.