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1.
Photosynthetic activity of Zostera japonica seedlings was measured using a gas volumeter at 0 and 6 days in culture under eight light (0–800 μmol photons/m2/s) and ten water temperature conditions (5–35°C). Seedlings from Ago Bay, Mie Prefecture were cultured in incubators accurately controlled at each test temperature for 1 week. After 1 week, maximum gross photosynthesis (P maxg) appeared at 29°C and most seedlings cultured at 30–35°C bleached and withered. At the same time, the light compensation point (I c) increased only at 30°C during the culture period. As a result, the upper critical water temperature for survival was 29°C in Z. japonica seedlings, which agrees well with that for the southern boundary of Z. japonica around Japanese coast. It is necessary to monitor this species around this boundary as a bio-indicator for seawater warming.  相似文献   

2.
The optimal water temperature in seed germination and the upper critical water temperature in seedling growth were determined for Zostera japonica collected from Ago Bay, Japan. The relationship between the seed germination rates and seed storage period (0, 30, and 60 days) at 0°C was also examined. The optimal water temperature in seed germination was in the range 15–20°C regardless of the storage period, in which germination rates were up to 14%. Seedlings, grown from seeds up to 10 cm in total length, were cultured for 1 week at various water temperatures to measure their relative growth rates. The optimal water temperature in early growth was in the range 20–25°C; relative growth rates ranged from 3.8 to 4.2%. Seedlings could survive up to a water temperature of 29°C, but most seedlings withered at 30 or 35°C. The optimal water temperatures for seed germination and seedling growth were related to the seasonal changes of water temperature in the sampling site. Although seedlings were hardly observed in Ago Bay in summer, Z. japonica might extend its distribution as far as where the summer water temperature is lower than 29°C.  相似文献   

3.
Photosynthesis and respiration rates were measured on 10 cm tall seedlings of Z. japonica at various temperatures and photosynthetic photon flux densities (PPFDs), and the daily compensation points in each season were estimated with a mathematical model based on photosynthetic properties and diurnal changes in solar irradiances. The seedlings were grown from seeds collected at Tategami-ura, Ago Bay, Mie Prefecture, Japan, and cultured for 1 week under the examined temperatures of 10–25°C. The estimated daily compensation points of Z. japonica ranged from 9.3 to 13.6% of the surface irradiance. The total PPFDs in daytime ranged from 3.8 to 5.3 mol photons m−2 day−1. The theoretical depth limits were calculated by the Beer-Lambert law concerning the relative light intensities of the sea surface and the extinction coefficient. The estimated lowest limit of Z. japonica agreed well with the lowest depth (7 m) previously reported. Therefore, the mathematical model in this study can be used to estimate the production and critical growing depth of Z. japonica. Differences in light requirements seem to be one of the reasons for the shallower habitats of Z. japonica in comparison with Z. marina.  相似文献   

4.
Gamma-aminobutyric acid (GABA) at 50 μg/ml and porcine growth hormone (GH) at 0.025 IU/ml were tested to see whether these chemicals would reduce the stress experienced by euryhaline rotifers Brachionus plicatilis species complex (L-, S- and SS-morphotypes) during low temperature (4–12°C) storage. Rotifers cultured at 25°C were transferred to 4–12°C for 10–30 days and transferred back to 25°C for recovery. GABA or GH were added to the rotifers at three different time points: 6 h before transfer from 25°C to low temperature (6h−), on day 7 after preservation at low temperature (7d+) and on the first day of recovery. For L-type rotifers, the GH treatment before the transfer to 4°C for 30 days was effective for better survival, while the GABA treatment was most effective for the S-type preserved at 10°C for 14 days. For the SS-type, the chemical treatments were not effective when the rotifers were preserved at 12°C for 14 days. After low temperature preservation, GABA treatments with the S- and SS-type rotifers just after their transfer to 25°C induced a relatively faster recovery of the rotifer population.  相似文献   

5.
In this study, the energy budget of the Manila clam, Ruditapes philippinarum, was evaluated after one-week acclimation periods at 5, 10, 15, 20, and 25°C. Small clams (151 ± 12 mg DW) and large clams (353 ± 16 mg DW) were fed with the microalgae, Isochrysis galbana. Filtration rate, ingestion rate, assimilation efficiency, oxygen-consumption rate, and ammonia excretion rate were measured. Both filtration rate and ingestion rate of small and large clams were found to be related to temperature. The highest Q 10 values were measured in the range 15–20°C for both small and large clams. Assimilation efficiency of both small and large clams was not significantly influenced by temperature, although the maximum mean values were detected at 20°C. Oxygen consumption rate and ammonia excretion rate of small and large clams were found to be related directly to temperature over the entire range, with a maximum being detected at 25°C. The highest Q 10 value was estimated in the range 10–15°C with regard to oxygen consumption rate, and in the range of 15–20°C with regard to ammonia excretion rate. Scope for growth (SFG) was positive at all temperatures, achieving a maximum value at 20°C in both small and large clams, primarily as a consequence of the enhanced ingestion rate which offset the concomitant elevation in the metabolic rate. In this study we have estimated the thermal optimum for this species at 20°C.  相似文献   

6.
How Zostera marina L. adapts to environmental stresses is of major interest to researchers wanting to obtain a better understanding of how to preserve this ecologically important seagrass. We have examined the structure and chemical properties of the cuticle and epidermal walls of Z. marina cotyledons at the pre-germination stage by microscopy, histochemistry, and chemical analyses. The epidermal cells, which have a smooth plasma membrane and slight wall-ingrowth, are surrounded by thickened outer tangential walls consisting of cellulose and pectic substances. The thick cuticle layer covers the outer surface of the outer tangential walls; the former were observed here to be much thicker than has been reported earlier for the leaves and sheaths of Z. marina. Chemical analysis of the isolated cuticle by attenuated total reflectance–infrared Fourier transform spectrometry and gas chromatography–mass spectrometry detected C16 and C18 fatty acids, ω-hydroxy fatty acids and β-sitosterol as components of the wax and cutin. The outermost cuticle layer was also observed to be covered with a slimy layer consisting of some polysaccharides. These results suggest that the extremely thick cuticle and slimy layer could play a significant role in protecting the cotyledons from environmental stresses at the pre-emergence stage and just after emergence.  相似文献   

7.
Serum thyroid hormone concentrations were measured during the seven stages of metamorphosis (1–7) of the southern hemisphere lamprey, Geotria australis. The respective mean concentrations ± SEM of serum thyroxine (T4) and triiodothyronine (T3) fell from 31.73 ± 4.09 and 5.06 ± 0.70 nM in large ammocoetes sampled in February, at the time when metamorphosis was initiated, to 4.54 ± 0.36 and 1.03 ± 0.12 nM at stage 5. Although there was a small, but significant, recovery of serum T4 concentrations during stages 6 and 7, no such corresponding statistically significant rise occurred in serum T3 concentrations. Serum thyroid hormone concentrations in ammocoetes sampled during the period when metamorphosis was taking place, exhibited a marked seasonal increase between February and May–June (late autumn/early winter); serum T3 and T4 concentrations peaked in May–June and were, respectively, > 2 fold and > 8 fold higher than those recorded for samples in late February (mid summer). By mid-July the serum T4 and T3 levels had declined from the peak values. Ammocoetes taken from streams at 16°C in June and acclimated to aquaria water at 25°C or 6°C had significantly lower serum T3 and T4 concentrations at the higher temperature, and also a lower serum T4, but not T3 concentration, at the lower temperature. Treatment of separate groups of ammocoetes with either propylthiouracil or T3 for 70 days significantly depressed and raised respectively, the serum thyroid hormone and hepatic T3 concentrations and caused significant changes in the body weight, but did not induce the onset of metamorphosis.  相似文献   

8.
The metabolic responses of the juvenile Miichthys miiuy in terms of oxygen consumption and ammonia excretion to changes in temperature (6–25°C) and salinity (16–31 ppt) were investigated. At a constant salinity of 26 ppt, the oxygen consumption rate (OCR) of the fish increased with an increase in temperature and ranged between 133.38 and 594.96 μg O2 h−1 g−1 DW. The effect of temperature on OCR was significant (P < 0.01). Q10 coefficients were 6.80, 1.41, 1.29 and 2.36 at temperatures of 6–10, 10–15, 15–20 and 20–25°C, respectively, suggesting that the juveniles of M. miiuy will be well adapted to the field temperature in the summer, but not in the winter. The ammonium excretion rates (AER) of the fish were also affected significantly by temperature (P < 0.01). The O:N ratio at temperatures of 6, 10, 15 and 20°C ranged from 13.12 to 20.91, which was indicative of a protein-dominated metabolism, whereas the O:N at a temperature of 25°C was 51.37, suggesting that protein-lipids were used as an energy substrate. At a constant temperature of 15°C, the OCRs of the fish ranged between 334.14 (at 31 ppt) and 409.68 (at 16 ppt) μg O2 h−1 g−1 DW. No significant differences were observed in the OCR and AER of the juveniles between salinities of 26 and 31 ppt (P > 0.05). The OCR and AER at 16 ppt were, however, significantly higher than those at 26 and 31 ppt (P < 0.05), indicating salinity lower than 16 ppt is presumably stressful to M. miiuy juveniles.  相似文献   

9.
In the Uranouchi Inlet, which has a commercial fishery of littleneck clam Ruditapes philippinarum, potentially toxigenic species of Dinophysis acuminata showed an annual occurrence except for the summer of 2000–2002. Relatively high abundances of D. acuminata were observed in April 2000 and November 2002. Some samples of D. acuminata cells, which were collected from the inlet in autumn 2002, contained pectenotoxin-2 (0.9–2.8 pg/cell) and okadaic acid (1.9–2.8 pg/cell). Cell length and hypotheca width of D. acuminata found in the Uranouchi Inlet were 33.7–45.0 and 21.0–31.6 μm, respectively. The length-width ratios ranged 1.21–1.71. Sequences of the 5.8S ribosomal RNA gene and flanking internal transcribed spacers, 1 and 2 of cells of D. acuminata from the inlet fell into a D. acuminata complex clade that included, D. acuminata-D. sacculus-D. acuta reported by others. In the inlet, occurrences of D. acuminata were detected within a broad water temperature range between 13.0 and 26.9°C, and those showing more than 25 cells/L were within 16.4–17.3°C for temperature and 27.6 and 34.1 for salinity. This is the first report that cells of Dinophysis acuminata from southern Japanese coastal waters contained okadaic acid and pectenotoxin-2.  相似文献   

10.
To investigate the effect of water temperature on gamete maturation and gamete quality, European grayling (Thymalus thymallus) were held under different temperature regimes prior to spawning. Maturation of males and females and their gamete quality depended strongly on temperature regime. The highest percentages of maturing fish and highest gamete quality were obtained under a creek water temperature regime with natural seasonal fluctuations. In warmed creek water (3–4°C), at a constant temperature of 8–9°C, and under an abruptly increasing temperature, regime maturation rates and gamete quality were reduced. The effect was more pronounced in females than in males. The spawning dates of different wild Austrian grayling populations were also correlated with water temperature data collected during the last 10–15 years. The mean spawning date expressed as the number of days from 21 December until spawning ranged from 98 to 111 days for lower elevation populations, while it was considerably delayed for an alpine population. All populations spawned at water temperatures of 5.5–7.2°C. Regression analysis indicated that spawning date correlated with (1) the overall mean water temperature from 21 December until spawning, (2) the mean water temperature during both the last 10 days and 15 days before spawning, and (3) the difference between mean January temperature and that of the last 15 days before spawning. The regression functions indicate that an increase in water temperature from 21 December to spawning of 1°C advances spawning by 5? days, and an increase of 1°C in the last 10–15 days advances spawning by 3? days.  相似文献   

11.
To investigate the possible direct effect of a stepwise reduction in temperature with increasing size on growth, feeding parameters and muscle growth patterns of juvenile Atlantic halibut (Hippoglossus hippoglossus L.), 804 juvenile halibut (mean initial weight individuals: 14.2 g ± 0.2 SEM) were reared at constant 9, 12 and 15°C or shifted (T-step, i.e. 15–12°C after 36 days) for 99 days. Despite indications of lower optimal temperature for growth with increasing size, equal end weights were obtained between the constant 12°C, constant 15°C and T-step groups. Best overall growth was observed for the group kept at constant 12°C. The limited effect of the T-step group may relate to the size at movement (too big), the temperatures investigated (close to optimum) and the time and size interval investigated (too narrow). Differences in growth were reflected more by alterations in feed intake (C T and F%) than by differences in feed conversion efficiencies (FCE). Differences were found with respect to the density of muscle cells, whereas no differences were found between the average muscle cell diameters. The mean diameter of muscle cells tended to increase only slightly with increasing fish weight, while the mean density of muscle cells tended to decrease. Using an optimum temperature of 12°C, an indication of a possible increased rate of hyperplasia in relation to higher growth was seen.  相似文献   

12.
Standard oxygen consumption rate (MO2) was determined for 19 cownose rays (Rhinoptera bonasus) using flow-through respirometry. Rays ranged in size from 0.4 to 8.25 kg (350–790 mm DW). Respirometry experiments were conducted on seasonally acclimatized rays at temperatures from 19.0 to 28.8 °C. Estimates of mass-dependent MO2 ranged from 55.88 mg O2 kg−1 h−1 for an 8.25 kg ray to 332.75 mg O2 kg−1 h−1 for a 2.2 kg animal at 22–25°C. Multiple regression analysis examining the effect of temperature, salinity, and mass on standard mass-independent MO2 found temperature (P < 0.01), and mass (P < 0.0001) to have a significant effect on oxygen consumption, whereas salinity did not (P > 0.05). Q 10 was calculated as 2.33 (19–28 °C), falling between the estimates determined for two other batoid species, the bull ray (Myliobatos aquila; Q 10 = 1.87) and the bat ray (Myliobatis californica; Q 10 = 3.00). The difference in the Q 10 estimates may be attributed to the use of seasonally acclimatized as opposed to laboratory-acclimated animals.  相似文献   

13.
In this study, flow-through respirometry was used to test the effect of acute temperature change on resting routine metabolic rates of two benthic elasmobranchs, Atlantic stingrays, Dasyatis sabina (n = 7) and whitespotted bamboo sharks, Chiloscyllium plagiosum (n = 7) kept under fluctuating temperature regime of 24–27 and 23–25°C, respectively. Atlantic stingrays and whitespotted bamboo sharks showed a temperature sensitivity (Q10) of 2.10 (21–31°C) and 2.08 (20–28°C), respectively. Not surprisingly, oxygen consumption (MO2) increased in both species as temperature was raised. Acute increases in oxygen uptake may be useful during activities such as foraging, and some elasmobranchs may alter physiological processes by taking advantage of thermal variability in the environment. However, further investigation of different physiological processes is needed to better understand how temperature variation may affect behavioural choices of fishes.  相似文献   

14.
The effects of acute temperature changes (2–17°C) on myocardial contractility with or without adrenergic activation were studied in the isolated spontaneously beating atrium of the Atlantic salmon (Salmo salar) reared at 8°C. The atrial frequency was markedly elevated (from 7 to 46 beats/min) by the rise in temperature from 2–17°C. Both the time to peak tension and to relaxation time were shortened. In contrast, the temperature effect on the maximal tension was modest. Exposure to exogenous adrenaline (1.1 nM–11 μM) resulted in a substantial enhancement of the maximal tension, notably at 2°C, while potentiation of the frequency at 2, 8 and 14°C, was less pronounced. The apparent affinity (pD2) for adrenaline on the chronotropy was higher at 8 and 14°C than at 2°C. For the inotropic responses pD2 was highest at the acclimation temperature (8°C). By comparison with data for the rainbow trout (Oncorhynchus mykiss) obtained by the same experimental design (Ask et al. 1981), species differences were apparent both in temperature dependence of contractile parameters and in their adrenergic activation. The Q10 for the frequency in absence of adrenaline was higher in the salmon than in the trout for the temperature interval 2–17°C. The apparent affinities for adrenaline for the frequency at 8°C and 14°C and for the maximal tension responses at 2°C and 8°C were also highest for the salmon atrium.  相似文献   

15.
An investigation was conducted to evaluate the annual variation in potential predation impact (PPI) on larval and juvenile Pseudopleuronectes yokohamae by Crangon uritai in Hakodate Bay using predator-prey size relationships. Laboratory experiments were designed to estimate the favorable prey size of C. uritai through back-calculation of body length (BL) of P. yokohamae from sagittal otolith diameter observed in the stomachs of C. uritai. The most favorable prey-predator size ratio (BL of P. yokohamae-total length (TL) of C. uritai) class was 0.15–0.19, and ranged from 0.12–0.31. There was a significant positive correlation between the BL increase of P. yokohamae and the bottom water temperature in the field, such that BLs stagnated during the cold year of 1999 from April to June, and increased during the warm year of 2002. In contrast, no significant correlation was found between the TL increase of C. uritai and the bottom water temperature. Moreover, there were no significant differences in the mean TL of C. uritai between months (April–June) or years (1998–2002). Variation of PPI depended on the relationships between the growth rates of P. yokohamae and bottom water temperature. Therefore, the warm year of 2002 resulted in higher potential predation impact (PPI≥20), and it was at least 20 days shorter than that of the cold year of 1999. These results suggest that increased bottom water temperature in the nursery area was one of the most important factors for cumulative predation loss.  相似文献   

16.
Effects of rhythmic temperature change on the growth, body composition and energy budget of hybrid grouper (Epinephelus lanceolatus ♂ × E. fuscoguttatus ♀) were investigated. Nine groups of fish received repeating cycles of low‐temperature manipulation (22°C) for 1, 2 and 4 days followed by recovery temperature (28°C) for (3, 7 and 11 days), (6, 14 and 22 days) and (12, 28 and 44 days) respectively, designated as L1R3, L1R7, L1R11, L2R6, L2R14, L2R22, L4R12, L4R28 and L4R44 respectively. In the control group (C), fish were reared at 28°C throughout the whole experiment. After 96‐day feeding trail, the final weight, relative weight gain rate, specific growth rate, food conversion efficiency and apparent digestibility coefficient of fish in L4R28 were significantly higher than those of control (p < .05). The crude protein contents of fish in L2R14, L2R22, L4R12, L4R28 and L4R44 were significantly higher compared to the control (p < .05). According to energy budget, fish in L4R28 exhibited significantly higher proportion of food energy assimilated into growth and lower proportion consumed for excretion than the control fish (p < .05). These results indicated the occurrence of complete or over growth compensation in hybrid grouper, and the use of repeated cycles of low temperature (22°C) for 4 days followed by recovery temperature (28°C) for 28 days could obtain enhanced growth, that is overcompensation, with improved apparent digestibility coefficient, food conversion efficiency and energetic efficiency into growth. This technique would be more practically applicable in indoor culture for this species.  相似文献   

17.
Pikeperch (Sander lucioperca) fingerlings, trained on dry feed, were kept in pond cages and fed with 2, 4 or 6% of their actual body weight in dry feed. The effect of the daily ration and the temperature of the pond water on the growth, survival, condition factor and feed conversion were observed in an 8-week experiment. The appropriate daily ration at 17–18°C was 2%, while at 24–25°C the 4% ration seemed to be advisable for the practice. The two higher rations led to significantly higher final body weights than the lowest feeding ration. There were no significant differences between the final condition factors or the survivals of the groups. The best feed conversion (FCR) was achieved at the 2% daily ration group and the worst at the 6% group in each week of the experiment.  相似文献   

18.
The kuruma shrimp, Penaeus (Marsupenaeus) japonicus (Bate, 1888), is a valuable aquaculture species in Queensland, Australia. The shrimp is supplied live to the Japanese market and must survive emersed transport for up to 36 h. In-transit mortality after harvest from high water temperatures (> 30 °C) has been reported by the industry, and a knowledge of the effects of high water temperature may provide important information for producers on grow-out management, timing of production and farm location. Experiments were conducted to determine the effect of high water temperature on survival, moulting and food consumption in P. japonicus. Replicated groups of 15.6 ± 0.2 g shrimp were acclimated and exposed to five temperatures, between 28 and 36 °C, for up to 28 days. Mortality was highest at 36 °C and equally lowest between 28 °C and 32 °C. Intermoult period was not significantly different for temperatures between 28 and 32 °C (19.8–15.5 days) but was significantly greater above 32 °C (27.4 days at 34 °C and > 104 days at 36 °C). There was evidence of moulting synchrony at 28 °C. Mean daily food consumption was highest at 32 °C at 2.34% of body weight, but decreased to 1.56% at 28 °C and 1.33% at 36 °C. Over the range of water temperatures examined, survival, moulting rate and food consumption were highest at 32 °C.  相似文献   

19.
The mantle muscles of five cephalopod species, Todarodes pacificus, Photololigo edulis, Sepioteuthis lessoniana, Sepia esculenta, and Sepia longipes, were extracted with 0.1 M NaOH to prepare crude collagen fiber, called ‘residue after alkali extraction’ (RS-AL). Solubility of the collagens in water was examined in the temperature range 20–90°C. The collagens showed a similar tendency in solubility, which gradually increased depending on the treating temperature, and the values at 40–90°C were constantly less than 47.0% for all the species examined. In addition, the collagens were estimated to denature in the approximate temperature range of 37.5–42.5°C. These results suggest that the collagens in RS-AL from these species may have relatively high resistance to hot-water extraction even after their denaturation.  相似文献   

20.
Large yellow croaker, Pseudosciaena crocea, exhibit sexually dimorphic growth, with females growing faster and reaching larger adult sizes than males. Thus, development of techniques for preferentially producing females is necessary to optimize production of these species. We have established a protocol to produce all-female croaker P. crocea through induction of meiotic gynogenesis with homologous sperm. The first set of experiments investigated the ultra-violet (UV) irradiation on sperm motility and duration of sperm activity to determine the optimal UV dosage for genetic inactivation of sperm, yet retaining adequate motility for activation of eggs. Milt from several males was diluted 1:100 with Ringer’s solution and UV irradiated with doses ranging from 0–150 J cm−2. The results indicated that motility and duration of activity generally decreased with increased UV doses. At UV doses greater than 105 J cm−2, after fertilization, motility was <10% and fertilization rates were significantly lower. Highest hatching rate was obtained at 75 J cm−2. A second set of experiments was carried out to determine appropriate conditions of cold shock for retention of the 2nd polar body in P. crocea eggs after fertilization with UV-inactivated sperm by altering the timing, temperature and duration of shock. At 20°C, shock applied at 3 min after fertilization resulted in higher survival rate of larvae at 6 h after hatching. Results of different combinations of three shock temperatures (2°C, 3°C or 4°C) and five shock durations (4 min, 8 min, 12 min, 16 min or 20 min) at 3 min after fertilization demonstrated that shocks of 12 min gave highest production of diploid gynogens. Statistical analysis revealed that maximum production of diploid gynogens (44.55 ± 2.99%) were obtained at 3°C. The results of this study indicate that the use of UV-irradiated homologous sperm for activation of P. crocea eggs and cold shock for polar body retention is an effective method for producing gynogenetic offspring.  相似文献   

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