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1.
The response of early juveniles of the haarder Liza haematocheila (= Mugil soiuy) to changes of water salinity, and the growth and survival of larvae in water of different levels of salinity were studied. The capacity of adaptation of the larvae of the haarder to fresh water is manifested at early ages. Normally developing six-day-old larvae of the haarder easily endure the transfer from seawater (17–19‰) to brackish water (5‰) and a day later, to fresh water. The resistance of larvae to abrupt decreases in salinity increases with age. Directly transferred to fresh water, all 6–12-day old larvae perish, compared to only 8–30% of 2–3-week old larvae (those retarded in growth). In the course of raising, the larvae have tended to survive better in brackish water (5‰). At decreasing salinity, the growth rate, the content of defatted dry matter, and the content of lipids increase. In fresh water, the stock lipids (triacylglycerols) are accumulated more intensively. With consideration of the original and published data, the problem of formation of the osmoregulatory system in the ontogenesis of mugilids is discussed.  相似文献   

2.
Marine larvae that experience some sub-lethal stresses can show effects from those stresses after metamorphosis, even when they seem to recover from those stresses before metamorphosis. In this study we investigated the short and long-term effects of exposing the larvae of three calyptraeid gastropods (Crepidula fornicata, Crepidula onyx, and Crepipatella fecunda) to temporary reductions in salinity. Larvae of all three species showed slower larval growth rates, longer time to metamorphic competence, and substantial mortality after being stressed in seawater at salinities of 10, 15, and 20 for less than 48 h. Larval tolerance to low salinities varied widely within and among species, but longer stresses at lower salinities were generally more harmful to larvae. However, larvae in nearly all experiments that were able to metamorphose survived and grew normally as juveniles; there were no documented “latent effects.” For all three species, starving larvae in full-strength seawater was not as harmful as exposing larvae to low salinity stress, indicating that detrimental effects on larvae were caused by the salinity stress per se, rather than by an indirect effect of salinity stress on feeding. C. fornicata that were stressed with low salinity as juveniles were more tolerant of the stress than larvae: all stressed juveniles lived and showed reduced growth rates for no more than 3 days. Our data suggest that even though reduced salinity is clearly stressful to the larvae of these 3 gastropod species, metamorphosis seems to generally provide individuals with a fresh start.  相似文献   

3.
In brackish water the variety of marine and freshwater parasite species is considerably reduced. The distribution in brackish water of most marine endoparasites is restricted by the salinity tolerance of their hosts, most of the parasite species are more tolerant than their hosts. The influence of salinity and temperature on nine species has been examined; first stage larvae of Contracaecum aduncum develop in 0-32‰ salinity; Cryptocotyle lingua proved to be infective at salinities down to 4‰. The greatest resistance was found in Anisakis larvae from herring Clupea harengus , which survived for more than half a year. Parasites in the fish intestines appear to be unaffected by changing water salinities, as the osmolarity in the intestines stays nearly constant. Marine ectoparasites ( Acanthochondria depressa, Lepeophtheirus pectoralis ) survive about three times longer than freshwater species ( Piscicola geometra, Argulus foliaceus ) when salinity is 16‰. High temperature increases the effects of adverse salinities on parasites. There is evidence that none of these ecto-parasitic species can develop within the range of 7-20‰ salinity.  相似文献   

4.
During the spawning season of the estuarine prawn Metapenaeus bennettae (Racek & Dall), laboratory and field experiments were conducted to examine the combined effects of temperature and salinity on hatching success of eggs and the survival, growth and development of larvae. Response surface analysis showed that optimal levels of temperature and salinity for maximum hatching success varied depending on conditions during spawning. Similarly, temperature and salinity conditions that produced maximum survival and growth of larvae depended on conditions during rearing prior to experimental temperature/salinity treatments. At the onset of feeding, larvae showed the lowest tolerance to changes in temperature and salinity. Supplementary feeding experiments in the laboratory, and survival rates in field experiments indicated that starvation was a more potent factor than the effects of temperature and salinity in determining survival through the protozoeal larval stages. Late larval stages were relatively indifferent to the effects of temperature and salinity. It is suggested that, during early development, adaptive response to the prevailing physical conditions enhances survival in an estuarine environment.  相似文献   

5.
Newly hatched larvae of the California killifish ( Fundulus parvipinnis ) reared in the laboratory, were tolerant of salinities from fresh water to 70‰. Their salinity tolerance was influenced by incubation salinity; larvae hatched in lower incubation salinities exhibited greater freshwater tolerance than those hatched in higher salinities. In gradual acclimation tests, the upper median lethal salinity for the larvae was 130‰. Freshwater tolerance of the larvae decreased with age; yolk sac larvae were completely tolerant of fresh water while larvae more than 15 days old were least resistant.  相似文献   

6.
The combined effects of temperature (8, 12, 14, 17, 20, 22 and 25°C) and a salinity decrease from 36 to 12‰ on the development of the sea urchin Echinocardium cordatum (Pennant) were studied. Embryonic development proved to be the process most vulnerable to a salinity decrease. It was completed successfully at 8–20°C within a narrow salinity range of 36–28‰ Larvae at the most resistant stage, the blastula, survived at 12–22°C and a salinity of 36–18‰. Larvae at the most sensitive stage, pluteus I with the first pair of arms, died even in a favorable environment, a temperature of 17–20°C and a salinity of 34–28‰. That may be related to qualitative alterations during skeleton formation and to transition to phytoplankton feeding. The resistance of larvae to variations in environmental factors gradually increased in the pluteus II and III stages; however, it significantly decreased before the settling of the larvae. Larvae that were 37 days old survived at a temperature of 14–20°C within a salinity range of 36–22‰ and at 22 and 25°C, they survived at a salinity of 36–24‰; however, all the larvae became abnormal at 25°C. The larvae settled earlier on sand inhabited by adult individuals of E. cordatum than on sand from other locations, and they settled faster at 20–25°C, than at 14 and 17°C. The juveniles, if lacking an opportunity to burrow in the sand, died within 14 days after settling.  相似文献   

7.
Eggs and larvae of the carangid fish, Caranx mate (Cuv. & Valenc.), were incubated at various temperature (17.2 to 33.1 °C) and salinity (10 to 42 ‰) combinations in five experiments. The following rates were directly proportional to temperature: embryonic development, yolk absorption, eye and jaw development, and increase in length. Unfed C. mate larvae attained a maximum size at 25 °C and 20 ‰ Eyes and jaws of larvae were functional by the end of the yolk sac stage at all temperature and salinity levels tested.Hatching success and larval survival at the end of the yolk sac stage were generally greater than 50 % between 22° and 32°C. Hatching success and larval survival at the end of the yolk sac stage were reduced at salinity extremes, especially in low temperature-low salinity and high temperature-high salinity combinations. The frequency of morphological abnormalities was also high at extreme temperatures and salinities.The incipient upper thermal TLm for unfed C. mate larvae acclimated to 23.8°C increased from 31.5°C for newly hatched larvae, to 34.2°C for 72 h larvae, but decreased to 32.0°C for starving larvae after the exhaustion of the yolk supply.  相似文献   

8.
Future climate change is predicted to alter the physical characteristics of oceans and estuaries, including pH, temperature, oxygen, and salinity. Investigating how species react to the influence of such multiple stressors is crucial for assessing how future environmental change will alter marine ecosystems. The timing of multiple stressors can also be important, since in some cases stressors arise simultaneously, while in others they occur in rapid succession. In this study, we investigated the effects of elevated pCO2 on oxygen consumption by larvae of the intertidal porcelain crab Petrolisthes cinctipes when exposed to subsequent salinity stress. Such an exposure mimics how larvae under future acidified conditions will likely experience sudden runoff events such as those that occur seasonally along portions of the west coast of the U.S. and in other temperate systems, or how larvae encounter hypersaline waters when crossing density gradients via directed swimming. We raised larvae in the laboratory under ambient and predicted future pCO2 levels (385 and 1000 µatm) for 10 days, and then moved them to seawater at ambient pCO2 but with decreased, ambient, or elevated salinity, to monitor their respiration. While larvae raised under elevated pCO2 or exposed to stressful salinity conditions alone did not exhibit higher respiration rates than larvae held in ambient conditions, larvae exposed to elevated pCO2 followed by stressful salinity conditions consumed more oxygen. These results show that even when multiple stressors act sequentially rather than simultaneously, they can retain their capacity to detrimentally affect organisms.  相似文献   

9.
The survival, activity and the ability to penetrate the gut wall of the intermediate host were studied for the first stage larvae of Camallanus oxycephalus. Survival was affected by temperature and salinity. The penetration efficiency decreased in a logarithmic relationship with larval age and was more rapid at 25°C than at 20°C. Larval activity rates decreased in a linear relationship with age. Activity was shown to be the most important factor in penetration of the copepod gut wall. These processes were compared with Ancylostoma and Haemonchus larvae. A fundamental difference is believed to exist in the decline of activity rates between Camallanus and Ancylostoma and Haemonchus. This difference is related to the life cycles of the three nematodes.  相似文献   

10.
The effects of temperature on growth, pelagic larval duration (PLD) and maximum swimming speed were compared in the tropical fish marine species Amphiprion melanopus, to determine how temperature change affects these three factors critical to survival in larvae. The effects of rearing temperature (25 and 28 °C) on the length of the larval period and growth were examined in conjunction with the effects of swimming temperature (reared at 25 °C, swum at 25 and 28 °C, reared at 28 °C, swum at 25 and 28 °C) on critical swimming speed (U-crit). Larvae reared at 25 °C had a 25% longer pelagic larval duration (PLD) than larvae reared at 28 °C, 12.3 (±0.3) days compared with 9 (±0.6) days at 25 °C. To offset this effect of reduced developmental rate, growth and U-crit were measured in larvae reared at 28 and 25 °C at the same absolute age (7 days after hatching (dah)) and same developmental age (7 dah at 28 °C cf. 11 dah at 25 °C), corresponding to the day before metamorphosis. Larvae reared at 25 °C were smaller than larvae reared at 28 °C at the same absolute age (7 dah at 25 °C cf. 7 dah at 28 °C), yet larger at similar developmental age (11 dah at 25 °C cf. 7 dah at 28 °C) when weight and standard length were compared. This stage-specific size increase did not result in better performance in larvae at the same developmental age, as there was no difference in U-crit in premetamorphic larvae reared at either temperature (7 dah at 28 °C c.f 11 dah at 25 °C). However, U-crit was considerably slower in 7-day-old larvae reared at 25 °C than larvae of the same absolute age (7 dah) reared at 28 °C. Swimming temperature controls demonstrated that a change in temperature immediately prior to swimming tests did not effect swimming performance for larvae reared at either temperature.A decreased in rearing temperature resulted in longer larval durations, reduced growth rates and slower swimming development in larvae. However, the magnitude of the response of each of these traits varied considerably. As such, larvae reared at the lower temperature were a larger size at metamorphosis but had poorer relative swimming capabilities. This study highlights the importance of measuring a range of ecologically relevant traits in developing larvae to properly characterise their relative condition and performance in response to environmental change.  相似文献   

11.
To understand the ecology and environmental tolerances of newly hatched larvae of the amphidromous fish Sicyopterus japonicus during their downstream migration, the salinity tolerance of eggs, 0-15 day old larvae, and adults, and the temperature tolerance, specific gravity and phototaxis of hatched larvae were examined. Tolerances of adults were measured as survival after a 24 h challenge in freshwater (FW), brackish water (1/3 SW) and seawater (SW). The survival rate of adult S. japonicus was 100% in FW and 1/3 SW, while none survived in SW. Hatching success of eggs (30 eggs each) was significantly higher in FW (mean: 73%) and 1/3 SW (73%) than in SW (19%). Tolerance of newly hatched larvae to salinity and temperature was investigated in different combinations of salinities (FW, 1/3 SW and SW) and temperatures (18, 23 and 28 °C). Larval survival was significantly different in each salinity and temperature. Survival rate was significantly higher in 1/3 SW than in FW and higher in SW than in FW at 23 °C and 28 °C. At the latter part of the experiment, there was no survival in FW and at 28 °C. Survival was higher in lower temperatures, but larval development did not occur in FW. Specific gravity of newly hatched larvae was 1.036 at 28 °C and 1.034 at 23 °C. When exposed to a light source on one side of an aquarium, larval distribution was not affected. Our results indicated larval S. japonicus are more adapted to brackish water and seawater than freshwater, while the adults and eggs are more adapted to freshwater and brackish water than seawater. This is consistent with their amphidromous life history with growth and spawning occurring in freshwater and the larval stage utilizing marine habitats.  相似文献   

12.
The distribution of larval Aspiculuris tetraptera was studied in 4-week-old male and female CFLP mice. Whereas on days 10–12 the larvae were entirely confined to the anterior third of the colon, by day 14 larvae could be found throughout the colon. After day 17 the larvae were again restricted to the anterior colon. This change in distribution was co-incident with a loss of a large proportion of the worm burden, which occurred more consistently in female than in male mice.The degree of acquired immunity stimulated by various immunizing regimens was assessed by the survival of a challenge infection in experimental and control mice. It was found that a high level of immunity was achieved by exposure to a 19-day primary infection, a 36-day low-level infection and also by three 6-day infections, in each of which the larvae were removed by piperazine treatment immediately after the crypt phase.  相似文献   

13.
We developed an age determination method for larval and newly metamorphosed post-larval abalone Haliotis discus hannai in a laboratory experiment and determined the age of field caught individuals. Laboratory experiments showed that competent veliger larvae (4 days after fertilization) had a radula and regularly added rows of radular teeth with age in the absence of metamorphosis. Under environmentally relevant temperatures (17-22 °C), the number of rows of radular teeth increased linearly with age, but slopes of the regression lines were different among temperatures. Rows of radular teeth were added more slowly at lower temperatures. The effect of temperature on the development rate of the radula was quantified by the regression and the temperature coefficient, Q10. The radular development of newly metamorphosed post-larvae, which had not acquired a peristomal shell (adult shell), was comparable with that of veliger larvae, although older post-larvae had a larger number of rows of radula than those of the same age of veliger larvae. From these results, an age determination method of veliger larvae and newly metamorphosed post-larvae was established, using the number of rows of radular teeth. The age of veliger larvae and newly metamorphosed post-larvae was determined by the age determination method for samples collected in August to October of 2003 and 2004 for which the thermal history of the coastal water of Miyagi Prefecture Japan was available. Only 9.1% of veliger larvae (n = 8) captured in the field had formed a radula and these were estimated to be 4-6 days old. The remaining 90.9% of larvae (n = 80) that had not formed a radula were classified as younger than 4 days old. All newly metamorphosed post-larvae (n = 24) that had metamorphosed on substrata were estimated to be 4-6 days old. Results of the field study indicate that these abalone metamorphosed within a few days after the acquisition of competence (4 days after fertilization) at this site, which has suitable crustose algal habitat.  相似文献   

14.
Temperature and salinity tolerances were determined for larval California grunion, Leuresthes tenuis (Ayres), and compared with previous data for Gulf of California grunion, L. sardina (Jenkins & Evermann). Larvae of similar age and acclimation history showed little interspecific difference in thermal tolerance, as measured by half-hour LT50 values for 20–30 day old late postlarvae acclimated at various temperatures, and by upper and lower incipient lethal temperatures for 18°C-acclimated prolarvae. The upper incipient lethal temperature differed by 1 deg.-C (32°C for L. tenuis, 31°C for L. sardina), while the lower incipient lethal temperature for the 18°C acclimated prolarvae of both species was 7.5°C. L. tenuis larvae were much less euryhaline than L. sardina, with incipient lethal salinities of 4.2–41 %. for prolarvae and 8.6–38 %. for 20-day-old postlarvae; comparable values for L. sardina are 4–67.5 %. and 5–57.5 %. Both species show a decrease in temperature and salinity tolerance with age. The larvae of these disjunct congeners show a significant physiological divergence in euryhalinity but not in overall temperature tolerance. These tolerances are discussed in relation to the respective geographic ranges and behavioral responses of the two species.  相似文献   

15.
Effects of reduced salinities on dry weight (DW) and biochemical composition (total lipid and protein contents) of zoea 1 larvae were evaluated in four decapod crustacean species differing in salinity tolerance (Cancer pagurus, Homarus gammarus, Carcinus maenas, Chasmagnathus granulata). The larvae were exposed to two different reduced salinities (15‰ and 25‰ in C. granulata, 20‰ and 25‰ in the other species) for a long (ca. 50% of the zoea 1 moulting cycle) or a short period (16 h, starting at ca. 40% of the moulting cycle), while a control group was continually maintained in seawater (32‰).In general, the increments in dry weight, lipid and protein content were lower at the reduced salinities than in the control groups. In the zoea 1 of H. gammarus (stenohaline) and C. pagurus (most probably also stenohaline), the lipid and protein contents varied greatly among treatments: larvae exposed to low salinities exhibited very low lipid and protein contents at the end of the experiments compared to the controls. In some cases, there were negative growth increments, i.e. the larvae had, after the experimental exposure, lower lipid and protein contents than at the beginning of the experiment. C. maenas (moderately euryhaline) showed a lower variation in protein and lipid content than the above species. The zoea 1 of C. granulata (fairly euryhaline) showed the lowest variability in dry weight, protein and lipid content. Since salinity tolerance (eury- v. stenohalinity) is associated with the osmoregulatory capacity, our results suggest a relationship between the capability for osmoregulation and the degree of change in the biochemical composition of larvae exposed to variable salinities.Besides larval growth of these species should be affected by natural reductions of salinity occurring in coastal areas at different time scales. These effects may be potentially important for population dynamics since they should influence the number and quality of larvae reaching metamorphosis.  相似文献   

16.
To better understand the cascade of molecular reactions leading to delayed development and mortality of early life stages of marine intertidal gastropods, in response to temperature and salinity changes associated with climate change, three biomarkers: total antioxidant capacity, lipid peroxidation and lysosomal stability were investigated on hatched larvae. Encapsulated embryos of three marine gastropod species (Bembicium nanum, Siphonaria denticulata and Dolabrifera brazieri), which have already proven responsive to thermal and osmotic variations, were exposed to six combinations of temperature (22 °C and 30 °C) and salinity (25‰, 35‰ and 45‰) until the larvae hatched. Time to hatching was affected by salinity and temperature in all three species. High salinity (45‰) generally retarded the hatching process although the response was species-specific for temperature. Total antioxidant capacity and lipid peroxidation were also highly species-specific with the general trend showing that these biomarkers were adversely affected by high temperature (30 °C) at salinities of 25‰ and 45‰. Bembicium nanum lysosomal destabilisation increased significantly with an increase in temperature and salinity (30 °C and 45‰) and this was associated with delayed development and increased mortality. Investigations on the additional biomarker, lysosomal stability, gave a clearer picture of the numerous and complex molecular and cellular mechanisms leading to mortality and underdevelopment in response to environmental stress for this species. As few differences were observed in the enzymatic biomarkers total antioxidant capacity and lipid peroxidation between hatched larvae and the previously investigated encapsulated embryo response to thermal and osmotic stress, it is suggested that further studies could be undertaken using embryos encapsulated in egg masses, as it is less time consuming than working on hatched larvae.  相似文献   

17.
Alleviation of salt stress in lemongrass by salicylic acid   总被引:2,自引:0,他引:2  
Idrees M  Naeem M  Khan MN  Aftab T  Khan MM  Moinuddin 《Protoplasma》2012,249(3):709-720
Soil salinity is one of the key factors adversely affecting the growth, yield, and quality of crops. A pot study was conducted to find out whether exogenous application of salicylic acid could ameliorate the adverse effect of salinity in lemongrass (Cymbopogon flexuosus Steud. Wats.). Two Cymbopogon varieties, Krishna and Neema, were used in the study. Three salinity levels, viz, 50, 100, and 150 mM of NaCl, were applied to 30-day-old plants. Salicylic acid (SA) was applied as foliar spray at 10?5 M concentration. Totally, six SA-sprays were carried out at 10-day intervals, following the first spray at 30 days after sowing. The growth parameters were progressively reduced with the increase in salinity level; however, growth inhibition was significantly reduced by the foliar application of SA. With the increase in salt stress, a gradual decrease in the activities of carbonic anhydrase and nitrate reductase was observed in both the varieties. SA-treatment not only ameliorated the adverse effects of NaCl but also showed a significant improvement in the activities of these enzymes compared with the untreated stressed-plants. The plants supplemented with NaCl exhibited a significant increase in electrolyte leakage, proline content, and phosphoenol pyruvate carboxylase activity. Content and yield of essential oil was also significantly decreased in plants that received salinity levels; however, SA overcame the unfavorable effects of salinity stress to a considerable extent. Lemongrass variety Krishna was found to be more adapted to salt stress than Neema, as indicated by the overall performance of the two varieties under salt conditions.  相似文献   

18.
The combined effects of temperature and salinity on larval development and attachment of Balanus trigonus Darwin (Cirripedia, Balanidae) was examined under controlled laboratory conditions. Whilst larval survivorship was not affected (>70%), the duration of larval development was significantly affected by temperature and salinity. The effect of temperature was comparatively stronger than that of salinity. The majority of nauplius II larvae metamorphosed into cypris stage after 4-5 and 10-11 days at 28 °C (22-34‰) and 18 °C (22-34‰), respectively. Temperature, salinity and the duration of assay had a significant effect on cypris attachment with significant interaction among these main effects. Maximum (>80% in 6 days) and minimum percent attachment (0% in 6 days) on polystyrene surfaces were observed at 24 °C (34‰) and 18 °C (22‰), respectively. At high temperature (28 °C) and low salinity (22-26‰), larvae rapidly (4 days) developed into cyprids, but less than 33% attached. These results suggest that low larval attachment rates may lead to the low recruitment of B. trigonus in Hong Kong waters during summer when the water temperature is high (about 28 °C) and salinity is low (<26‰).  相似文献   

19.
Amphioxus Bblhx3 was identified as a LIM-homeobox gene expressed in gastrulae. Structural analysis suggested that it is a member of lhx3 but not of lhx1 gene group. Whole mount in situ hybridization revealed that expression of Bblhx3 was initiated at the early gastrula stage and continued at least until 10-day larvae. Expression of Bblhx3 first appeared in the vegetal and future dorsal area in initial gastrulae and became restricted to the endoderm during gastrulation. In neurulae and early larvae, Bblhx3 was expressed in the developing neural tube, the notochord and preoral pit lineage. In 10-day larvae, Bblhx3 was expressed only in the preoral pit. This expression pattern is apparently distinct from that of vertebrate lhx3 genes that are not expressed during gastrulation.  相似文献   

20.
The metamorphosis of planktonic larvae of the Pacific oyster (Crassostrea gigas) underpins their complex life‐history strategy by switching on the molecular machinery required for sessile life and building calcite shells. Metamorphosis becomes a survival bottleneck, which will be pressured by different anthropogenically induced climate change‐related variables. Therefore, it is important to understand how metamorphosing larvae interact with emerging climate change stressors. To predict how larvae might be affected in a future ocean, we examined changes in the proteome of metamorphosing larvae under multiple stressors: decreased pH (pH 7.4), increased temperature (30 °C), and reduced salinity (15 psu). Quantitative protein expression profiling using iTRAQ‐LC‐MS/MS identified more than 1300 proteins. Decreased pH had a negative effect on metamorphosis by down‐regulating several proteins involved in energy production, metabolism, and protein synthesis. However, warming switched on these down‐regulated pathways at pH 7.4. Under multiple stressors, cell signaling, energy production, growth, and developmental pathways were up‐regulated, although metamorphosis was still reduced. Despite the lack of lethal effects, significant physiological responses to both individual and interacting climate change related stressors were observed at proteome level. The metamorphosing larvae of the C. gigas population in the Yellow Sea appear to have adequate phenotypic plasticity at the proteome level to survive in future coastal oceans, but with developmental and physiological costs.  相似文献   

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