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Incidence (%) of females producing diapause cysts among all reproducing females of BRK53 Artemia clone in the main experiment
Source publication
The brine shrimp Artemia exhibits two reproductive modes. 1). oviparity, producing diapause embryos; an. 2). ovoviviparity, producing free-swimming nauplii. Previous studies have suggested the existence of a critical stage that determines the reproductive mode. Physicochemical factors, such as photoperiod, temperature, and salinity, have been sugge...
Contexts in source publication
Context 1
... of the main experiment are shown in Tables 2 and 3. When shifting Artemia from nauplius Tables 2, 4 Reverse experimental stock ...Context 2
... of the main experiment are shown in Tables 2 and 3. When shifting Artemia from nauplius Tables 2, 4 Reverse experimental stock ...Context 3
... direction control Tables 3, 5 Reverse direction experimental Tables 3, 5 production condition to cyst production condition (Table 2), low percentages of oviparity (0.0%-4.5%) in both the fi rst and second broods of the controls showed no signifi cant diff erences among the diff erent stages (post-larva II, post-larva III, post-larva IV, post-larva V, adult I and adult II). For the fi rst brood of treatments, almost all females produced diapause cysts when individuals were shifted at post-larva II stage (98.9%±1.9% of the reproducing females (same below)) and at post-larva III stage (96.7%±3.3%) ...Context 4
... the second brood, this study showed that its reproductive mode could be converted when Artemia were shifted at post-larva IV or earlier stages (Tables 2-5) but could not be converted when shifting performed on post-larva V or later stages (Tables 2, 3). When shifting at post-larva IV, the conversion seemed not complete, especially when shifted from ovoviviparity condition to oviparity condition (oviparity ratio׃ 3.4%±3.3% in control and 30.7%±9.8% in treatment of the main experiment; 4.0%±4.0% in control and 31.9%±7.6% in treatment of the supplementary experiment (Tables 2, 4). ...Context 5
... the second brood, this study showed that its reproductive mode could be converted when Artemia were shifted at post-larva IV or earlier stages (Tables 2-5) but could not be converted when shifting performed on post-larva V or later stages (Tables 2, 3). When shifting at post-larva IV, the conversion seemed not complete, especially when shifted from ovoviviparity condition to oviparity condition (oviparity ratio׃ 3.4%±3.3% in control and 30.7%±9.8% in treatment of the main experiment; 4.0%±4.0% in control and 31.9%±7.6% in treatment of the supplementary experiment (Tables 2, 4). ...Context 6
... of the main experiment are shown in Tables 2 and 3. When shifting Artemia from nauplius Tables 2, 4 Reverse experimental stock ...Context 7
... of the main experiment are shown in Tables 2 and 3. When shifting Artemia from nauplius Tables 2, 4 Reverse experimental stock ...Context 8
... direction control Tables 3, 5 Reverse direction experimental Tables 3, 5 production condition to cyst production condition (Table 2), low percentages of oviparity (0.0%-4.5%) in both the fi rst and second broods of the controls showed no signifi cant diff erences among the diff erent stages (post-larva II, post-larva III, post-larva IV, post-larva V, adult I and adult II). For the fi rst brood of treatments, almost all females produced diapause cysts when individuals were shifted at post-larva II stage (98.9%±1.9% of the reproducing females (same below)) and at post-larva III stage (96.7%±3.3%) ...Context 9
... the second brood, this study showed that its reproductive mode could be converted when Artemia were shifted at post-larva IV or earlier stages (Tables 2-5) but could not be converted when shifting performed on post-larva V or later stages (Tables 2, 3). When shifting at post-larva IV, the conversion seemed not complete, especially when shifted from ovoviviparity condition to oviparity condition (oviparity ratio׃ 3.4%±3.3% in control and 30.7%±9.8% in treatment of the main experiment; 4.0%±4.0% in control and 31.9%±7.6% in treatment of the supplementary experiment (Tables 2, 4). ...Context 10
... the second brood, this study showed that its reproductive mode could be converted when Artemia were shifted at post-larva IV or earlier stages (Tables 2-5) but could not be converted when shifting performed on post-larva V or later stages (Tables 2, 3). When shifting at post-larva IV, the conversion seemed not complete, especially when shifted from ovoviviparity condition to oviparity condition (oviparity ratio׃ 3.4%±3.3% in control and 30.7%±9.8% in treatment of the main experiment; 4.0%±4.0% in control and 31.9%±7.6% in treatment of the supplementary experiment (Tables 2, 4). ...Similar publications
The genus Artemia (Crustacea; Anostraca) is a complex of sibling species and superspecies defined by the criterion of reproductive isolation. Two sexual species are represented in the New World: Artemia persimilis and Artemia franciscana. In Brazil, Artemia franciscana populations are found on a year-round and permanent basis in Rio Grande do Norte...
Citations
... During the oviparous method of reproduction, Artemia females create diapause cysts that can persist up to 28 years without detectable metabolic activity [92][93][94] . When environmental conditions are favorable (temperature and salinity primarily), the cysts resume metabolic activity and are able to hatch [95][96][97] . ...
The development of real-time in-situ monitoring techniques is key to advancing a mechanistic understanding of the impacts of marine pollution, which is challenging to acquire through traditional end-point toxicity testing. We investigated the impacts of different nanopollutants on the hatching process and early-stage development of marine organisms, a vulnerable life stage, by observing oxygen consumption in real-time and morphological changes at regular intervals using a microfluidic platform. Here, two common and distinct nanoparticle (NP) types - polystyrene (PS) nanoplastic and silver (Ag) nanometal, were examined to assess and compare impacts on the hatching process and nauplius stage (first larval stage) of Artemia , a widely used zooplankton model in ecotoxicological studies. The study was conducted over a wide range of doses that are relevant to different environmental conditions, ranging from 0-1 mg/L, over a period of 24 hours. The hatching process of Artemia is comprised of four distinct stages which can be differentiated by metabolism and morphology: hydration, differentiation, emergence, and hatching. During hatching, NP exposure altered the time needed for the resumption of dormant Artemia cysts (hydration duration) at the lowest dose, dramatically prolonged the differentiation stage, and slowed embryo emergence from the cysts. The remaining time for the hatching stage during the experimental timeframe was also shortened. Overall, the presence of NPs led to increased oxygen consumption in multiple stages of the hatching process. Hatchability increased significantly with NP concentration although mortality showed an inverse pattern. This may be attributed to the increased aggregation of NPs in saltwater with increasing concentration which limits bioavailability during hatching but may be more readily consumed post-hatch. Ag NPs had a greater effect on hatching and mortality in comparison to PS NPs. A significant impact of NPs on swimming speed was observed, with a decrease observed in the presence of PS NPs and an increase observed in the presence of Ag NPs.
Graphical abstract
Highlights
Utilization of oxygen sensor integrated microfluidic chip and microscopy for ecotoxicological study.
Bioaccumulation of NPs affected hatching stages and respiration leading to inhibition of hatchability, with greater toxicity of silver NPs.
NPs caused significant mortality and alteration in swimming performance.
... ;https://doi.org/10.1101https://doi.org/10. /2023 (endogenous diapause) (Parra and Yúfera, 2001;Wang et al., 2019). In this dormant stage, cysts may be dehydrated through air drying or osmotic water removal, at which point the cysts are quiescent and can survive up to 28 years (Clegg, 1962). ...
Current studies on abiotic impacts on marine microorganisms often focus on endpoint analysis (e.g., hatching rates, survival). Here, we demonstrate that a mechanistic understanding can be obtained through real-time measurement of respiration and morphology in controlled microenvironments over extended time periods. As a demonstration, temperature and salinity are chosen to represent critical abiotic parameters that are also threatened by climate change and a target species of Artemia , a prominent zooplankton whose reproduction can affect the marine food pyramid. Different temperatures (20, 35, and 30ºC) and salinities (0, 25, 50, and 75 ppt) are shown to significantly alter the duration of hatching stages, metabolic rates, and hatchability. Higher temperatures and moderate salinity boosted metabolic reactivation of latent cysts, while higher temperatures alone sped up the process. Hatchability is inversely related to the duration of the differentiation stage of hatching, which persisted longer at lower temperatures and salinities. Initial oxygen availability affects respiration but not hatchability owing to temperature and salinity interactions.
Graphical abstract
Background
Artemia sinica is a brine shrimp species distributed in hypersaline salt lakes in northern China and Siberia and a successful invasive species in some coastal salterns. Although it is a commercially harvested and cultured species, knowledge of its reproductive characteristics is limited, and existing studies are often contradictory. The combined effects of temperature, salinity, and photoperiod on reproduction characteristics are experimentally studied to better understand its reproductive features.
Methods
There were 36 combinations of three environmental factors (3 × 3 × 4), each with three or four levels, namely temperature (16, 25, 30 °C), photoperiod (6 L:18 D, 12 L:12D, 18 L:6D), and salinity (50, 100, 150, 200 PSU). In each treatment, 48 to 80 pairs of A. sinica from Yuncheng Salt Lake (Shanxi, China) were cultured. Females were observed daily for reproductive mode and the number of offspring produced.
Results
Temperature, photoperiod, salinity, and their interactions significantly affected the lifespan and reproduction of A. sinica. The reproductive period was the longest and accounted for the largest proportion of life span at moderate temperature (25 °C). Total offspring, offspring per brood, and offspring per day increased as salinity decreased, and the number of broods per female was highest at 25 °C. Temperature, photoperiod, and salinity significantly influenced reproductive modes, and interactions among these factors were identified. Artemia sinica primarily reproduces oviparously under low temperature and short daylight conditions, and ovoviviparously under high temperature and long daylight conditions, with the maximum oviparity ratio recorded in treatments of 16 °C, 6L:18D, and 50 or 100 PSU. The maximum ovoviviparity ratio was recorded under 30 °C, 12L:12D, and 100 PSU. Unlike that documented for other Artemia species or populations, the brood size of A. sinica kept increasing throughout the reproductive period. It did not decline even in the last two broods. For the same brood number, the sizes of oviparous and ovoviviparous broods were similar. The length of the oviparous interval was often greater than that of the ovoviviparous interval, suggesting that oviparous offspring might require additional energy and time to construct the multi-layered eggshell. Compared to other species and populations, the A. sinica from Yuncheng Salt Lake has a relatively shorter pre-reproductive development time, a preference for ovoviviparity, and relatively higher fecundity and population growth capacity, making it a suitable culture species for obtaining fresh biomass.
Current studies on abiotic impacts on Artemia, a crustacean which is widely used in aquaculture, and ecotoxicology, often focus on endpoint analysis (e.g., hatching rates, survival). Here, we demonstrate that a mechanistic understanding can be obtained through measurement of oxygen consumption in real-time over an extended time period in a microfluidic platform. The platform enables high level control of the microenvironment and direct observation of morphological changes. As a demonstration, temperature and salinity are chosen to represent critical abiotic parameters that are also threatened by climate change. The hatching process of Artemia consists of four different stages: hydration, differentiation, emergence, and hatching. Different temperatures (20, 35, and 30 °C) and salinities (0, 25, 50, and 75 ppt) are shown to significantly alter the duration of hatching stages, metabolic rates, and hatchability. Specifically, the metabolic resumption of dormant Artemia cysts was significantly enhanced at higher temperatures and moderate salinity, however, the time needed for this resumption was only dependent on higher temperatures. Hatchability was inversely related to the duration of the differentiation stage of hatching, which persisted longer at lower temperatures and salinities. The current approach of investigation of metabolism and corresponding physical changes can be employed to study hatching processes of other aquatic species, even those with low metabolic rate.
The buoyancy of Artemia resting eggs is a feature with both biological and economic importance. Since the buoyancy of resting eggs is dependent on the specific weight of the eggs or salinity of ambient water, we suppose that habitat salinity may exert a selection pressure on resting egg buoyancy, and thereby lower habitat salinity may result in better floating capacity of resting eggs and vice versa. In this study, we compared the floating capacity of resting eggs from 25 Artemia populations. The results showed that the floating capacity of resting eggs varied greatly among different populations. The minimum salinity to float some eggs varied from 0 to 180. The salinity at which all resting eggs floated varied from 80 to 320. The FS50 (salinity with 50% eggs floating) of Zhundong and Yuncheng population was not detectable (over 50% eggs floating in distilled water), that of Kyêbxang Co population was 4.3, while the maximum value found in Dabancheng population was 234.5. In terms of the ‘apparent specific weight’ of resting eggs, 18 populations exhibited a single-peak distribution pattern, while the other 7 populations showed a multiple-peak or non-peak distribution. Negative correlations were found between FS50 and chorion thickness, and between FS50 and the volume percentage of the chorion in eggs, supporting a previous standpoint that shell thickness was a determinative factor for the floating capacity of resting eggs. A positive correlation was determined between FS50 and habitat salinity. The hypothesis that habitat salinity may cause a directional selection on the buoyancy of resting eggs seems to be true.
