首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 322 毫秒
1.
Benzo(a)pyrene (BP) in the sediment of Osaka Bay were determined. High concentration was found at two stations near the mouth of Shin-Yodo and off Kobe respectively (0.98g g–1 dry mud basis, 1.1g g–1). The concentration decreases regularly from the mouth of the river further into the bay. The other supplemental determination was carried on the sediment and the seawater of Keihin Canal. Notable BP concentration of 89g g–1 was observed in the sediment beneath the effluent outlet of a gasworks. The BP in the sediment near the ironworks was also considerable, while the BP was relatively less in the sediment beneath the effluent outlet of refineries. These data suggest that coke plants working in gasworks or ironworks may be the larger sources of BP than refineries. The results of Osaka Bay coincide with this hypothesis.Cadmium, lead, copper, zinc, nickel, ignition loss and fine sand content were measured from the same sediment samples of Osaka Bay. Cd, Pb, Cu and ignition loss showed the regular distributions which resemble to BP and accordingly, good correlations with BP. No significant correlations were found between BP and Ni, Zn and fine sand content which showed no regular distributions.  相似文献   

2.
Live-collected shells of the oyster, Crassostrea virginica, contain geochemical records of modern temperature and salinity, so records of prehistoric conditions may be obtained from subfossil shells. Restoration of channelized watersheds in Florida is receiving much attention, and plans for targeted watersheds require information about estuarine conditions before channelization. Lack of historical records necessitates alternative methods to understand pre-disturbance conditions. A 14C-calibrated, amino-acid geochronology based on racemization of glutamic acid yielded ages ranging from 190–1220 AD and from 1270–1860 AD for subfossil oysters from Blackwater River (near-natural watershed) and for Faka-Union Bay (channelized watershed), respectively. δ18O and δ13C values of subfossil shells from Blackwater River indicate salinity and summer temperatures similar to present. Winter temperatures recorded in shells from 190, 590, 720, and 1050 AD appear 1–5 °C colder than present winter temperatures, whereas the shell from 1220 AD records winter temperatures similar to modern winter temperatures. These temperature shifts may indicate change in climate or natural seasonal variation of winter temperature from year to year. Subfossils from Faka-Union Bay may reflect a complicated hydrology, which cannot be evaluated by isotopic compositions alone and demonstrates the need for development of independent elemental proxies for temperature and salinity. Decreases in δ13C from subfossil to modern shells may in part result from CO2 added to the atmosphere from fossil fuel burning (the Suess effect). Subfossil δ13C that is >1‰ more positive than modern shells suggest a change in the dominant carbon sources from terrestrial C4 or aquatic plants to C3 plants (mangroves).  相似文献   

3.
Whole animal respiration rates (R) of myctophid fishes which migrate up to the surface at night were estimated using enzyme activities of the electron-transport-system (ETS). The fish, currently unsusceptible to laboratory experimentation, were caught at sea and stored frozen at –20°C for 14–17 days prior to enzyme assay. Supplemental tests on two tropical marine fishes (gobies and poma-centrids) showed no measurable loss of ETS activity during storage for up to 36 d at –20°C. The ETS/R ratio for gobies and pomacentrids was 1.61. Respiration rates of myctophid fishes estimated using this ETS/R ratio ranged from 17.7 to 453µl O2 individual–1 hr–1 for specimens weighing 26–1101 mg wet weight atin situ temperature of 24–27°C. The relationship between the respiration rate standardized to a temperature of 20°C (R:µl O2 individual–1hr–1) and wet weight (WW: mg) of myctophid fishes was expressed asR=0.790 WW0.84 (r=0.964,n=27). This relationship does not differ appreciably from the respiration rates of other marine fishes calculated from Winberg's equation.  相似文献   

4.
Water quality of Osaka Bay is greatly influenced by freshwater discharge from rivers, to the effect of salinity playing a major role in forming the stratification. The tidal front is expected to appear in such an area even in winter considering the theory of the formation of a tidal front. From the field observation, we recognized a tidal front in winter for the first time in Osaka Bay. The critical value of a parameter log(H/U 3) for generation of a tidal front is obtained as a function of river discharge and cooling effect through sea surface. Differences of nutrients (NH4–N, PO4–P) concentration across the front are not clear, probably because they are utilized by phytoplankton easily. But in (NO2–N)+(NO3–N), DIN, PP and T–P, there is a discontinuity structure across the front, even if the absolute value of concentration difference is small.  相似文献   

5.
Shimada  A.  Nishijima  M.  Maruyama  T. 《Journal of Oceanography》1995,51(3):289-300
Seasonal appearance ofProchlorococcus was studied by flow cytometry in Suruga Bay, Japan in 1992–1993.Prochlorococcus cells were in high concentrations (>1×104 cells ml–1) from July to October 1992 and September 1993, when the water temperature was over 20°C. The 16S rRNA of the isolated cells showed 98.5% sequence homology with that ofP. marinus (Sargasso strain), indicating that they are the same species. The former has a high divinyl-chlorophyll (DV-Chl.)a/b ratio similar to the Mediterranean strain and different from the Sargasso strain. Maximum concentration ofProchlorococcus at the surface water was 2.5×104 cells ml–1 in August 1992 and their DV-Chl.a accounted for 4.0% of the total chlorophylla. A decrease in cell density to less than 5×103 cells ml–1 was observed from December to May with an exceptional rise in January 1993. WhileProchlorococcus showed a maximum concentration of 3.6×104 cells ml–1 at 10 m depth in September 1992, phycoerythrin (PE)-richSynechococcus spp. were dominant with their maximum concentration of 2.2×105 cells ml–1 in the same water body. On the other hand, phycocyanin (PC)-richSynechococcus spp. and the larger phytoplankters showed maximum concentrations in the surface waters in May and June. BothProchlorococcus and PE-richSynechococcus showed their lowest concentrations in April. A significant positive correlation was obtained between cell concentrations of the PE-richSynechococcus andProchlorococcus.  相似文献   

6.
The dynamics of phytoplankton abundance with seasonal variation in physicochemical conditions were investigated monthly at 10 stations around the Chagwi-do off the west coast of Jeju Island, Korea, including inshore, middle shore, and offshore in the marine ranching area from September 2004 to November 2005. Water temperature varied from 12.1 to 28.9°C (average 18.8°C), and salinity from 28.9 to 34.9 psu (average 33.7 psu). The chlorophyll a concentration was 0.02-2.05 μg L1 (average 0.70 μg L1), and the maximum concentration occurred in the bottom layer in April. A total of 294 phytoplankton species belonging to 10 families was identified: 182 Bacillariophyceae, 52 Dinophyceae, 9 Chlorophyceae, 12 Cryptophyceae, 6 Chrysophyceae, 4 Dictyophyceae, 13 Euglenophyceae, 6 Prymnesiophyceae, 5 Prasinophyceae, and 5 Raphidophyceae. The standing crop was 2.21-48.69x104 cells L1 (average 9.23x 104 cells L1), and the maximum occurred in the bottom layer in April. Diatoms were most abundant throughout the year, followed by dinoflagellates and phytoflagellates. A phytoplankton bloom occurred twice: once in spring, peaking in April, and once in autumn, peaking in November. The spring bloom was represented by fourChaetoceros species andSkeletonema costatum; each contributed 10–20% of the total phytoplankton abundance. The autumn bloom comprised dinoflagellates, diatoms, and phytoflagellates, of which dinoflagellates were predominant.Gymnodinium conicum, Prorocentrum micans, andP. triestinum each contributed over 10% of the total phytoplankton abundance.  相似文献   

7.
The abundance and vertical distribution pattern of a mysidMeterythrops microphthalma were investigated in the Japan Sea. Results from vertical hauls from 602–982 m depth to the surface around Yamato Rise in April 1987 indicated that the dominance (by biomass) ofM. microphthalma was third to fifth of major zooplankton taxa. Vertical distribution investigated at a single station in Toyama Bay in June, September and December 1986 showed that the most part of population of this mysid inhabited consistently below 250 m depth. No marked diurnal vertical migration was evident. Data on body composition and oxygen consumption rate ofM. microphthalma are presented. Water content of the body was 75.6–83.8% of wet weight, and ash was 11.4–20.4% of dry weight. Carbon, hydrogen and nitrogen were 37.9–47.5%, 6.2–7.4% and 9.4–10.1%, respectively, of dry weight. Oxygen consumption rates were 2.2–11.0µl O2 individual–1 hr–1 at 0.5°C, and were directly proportional to body mass. From the comparison with the published data on epipelagic and bathypelagic mysids it is revealed that both body nitrogen composition and oxygen consumption rate expressed as adjusted metabolic rate [AMR02,µl O2 (mg body N)–0.85 hr–1] ofM. microphthalma are intermediate between high epipelagic and low bathypelagic levels, indicating typical mesopelagic features.  相似文献   

8.
The mean seasonal cycle and distribution of various life history stages of C. finmarchicus throughout the Georges Bank (GB)-Gulf of Maine (GOM) region were characterized based on 5966 MARMAP zooplankton samples collected during 106 surveys over a 10-year period (autumn 1977–autumn 1987). A high degree of seasonal and spatial variability in C. finmarchicus abundance throughout the region was evident in contoured portrayals of data, grouped into standard stations and 2-month “seasons”.Eight subareas of the Gulf of Maine-Georges Bank region were identified through cluster analysis of standard stations having similar seasonal patterns in mean abundance of C. finmarchicus stages C3, C4, C5 and adults. These were the northern Gulf of Maine (Northern GOM); southern Gulf of Maine (Southern GOM); Scotian Shelf-coastal Gulf of Maine (Scotian-Coastal GOM); Mass Bay; tidally mixed Georges Bank (Mixed GB); tidal front on the Bank separating mixed from seasonally stratified water (Tidal Front GB); seasonally stratified water on the Bank (Stratified GB) and the Continental Slope adjacent to Georges Bank (SLOPE).A distinct seasonal abundance cycle was present in all subareas, but, the magnitude and timing of annual maxima varied greatly among subareas. Peak abundance was reached early (March–April) in Mixed GB, Tidal Front GB and Mass Bay, and late (July–August) in Northern GOM and Scotian-Coastal GOM. Remaining subareas had maxima in May–June. Abundance increased 10-fold from January–February to March–April and decreased sharply from July–August to September–October in all areas except southern GOM and northern GOM. The amplitude of the annual cycle was weakest in northern GOM and southern GOM, where high concentrations of C. finmarchicus persisted year-round, and strongest in the tidally mixed shallow water on GB, where the sparsest densities of C. finmarchicus occurred most of the year. Abundance curves for the various areas converged in March–April, when C. finmarchicus was ubiquitously very abundant (> 104/10 m2), and diverged from September to December.C. finmarchicus stage distribution in the GB-GOM area was highly negatively correlated with mean water column temperature during the stratified season. This seemed more related to the hydrography of the region, which isolates warmer well mixed Georges Bank from the Gulf of Maine and the stratified areas on the Bank, than to temperature, because Calanus abundances decline on the Bank before water temperatures exceed their preferences.A large part of the spatial and seasonal variation in C. finmarchicus abundance and age structure appears to be tightly coupled to major hydrographic regimes and to major circulation patterns in the region. There was a sharp ecotone between well-mixed Georges Bank and the Gulf of Maine as defined by C. finmarchicus abundance patterns and life history distributions. The ecotone is present year-round but is most apparent during the stratified season (May–October), when thermohaline density gradients and the near-surface current jet along the northern flank are generally strongest. The Gulf of Maine had the highest abundances of C. finmarchicus, and lowest spatial and seasonal variation in the region, while tidally mixed Georges Banks displayed the opposite pattern. This indication of stable population centers in the Gulf of Maine would make it a major source of Calanus in the region, particularly during March–April. Distributional patterns also suggest a strong Calanus influence from Scotian Shelf water in northern Gulf of Maine and on the southern flank of Georges Bank.  相似文献   

9.
The accumulation rates of sediment cores in Osaka Bay have been determined by using210Pb dating technique. In the upper 10 cm210Pbex contents show a constant value with depth. The accumulation rates below the homogeneous layer of sediments ranging from 0.12 to 0.61cm y–1 (0.067–0.34 g cm–2 y–1) were obtained. The higher contents of Zn, Cu, Pb and Cr were observed in the upper 10 to 30 cm of sediments. Assuming that the increment of heavy metal content in sediments is due to anthropogenic origin, the amount of anthropogenic input of heavy metals into sediments were estimated to be 1,300–2,700g cm–2 for Zn, 150 – 480 for Cu, 360 – 410 for Pb and 320 – 480 for Cr. The increment appears to start about 100 years ago. In surfical sediments most of heavy metal contents exceeded the background content, and then most part of Osaka Bay is polluted by heavy metals.  相似文献   

10.
The decomposition characteristics of particulate organic matter (POM) sampled with plankton nets in Hiroshima Bay were investigated under aerobic conditions in a laboratory experiment.The POM derived from plankton consisted of both a labile fraction (70–80 % of the whole) and a refractory fraction (20–30%). The labile fraction was completely decomposed within 40 days at 20°C. Although the concentrations of particulate organic carbon (POC) decreased gradually with time, an apparent lag phase was recognized in the decomposition of particulate phosphorus (PP) at an early stage, which might result from a specific uptake of dissolved inorganic phosphorus (DIP) by bacteria. A comparison of the metabolic activity between dissolved organic matter (DOM) and POM by measuring ATP contents showed that the former was one order of magnitude larger than the latter.On the other hand, there was no significant difference among the decomposition rates of POM collected at various depths. The change of the first-order rate constant (k) for the POM decomposition by temperature was expressed ask=0.0329 exp(0.0644T), and the Q10 value was 1.94. There were fairly large variances ink values obtained from the various plankton species. Thek values averaged 0.144 day–1 and ranged from 0.078 to 0.20 day–1 at 20°C.  相似文献   

11.
We report here dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) levels as a function of plankton communities and abiotic factors over a 12-month cycle in the Mediterranean oligotrophic coastal and shallow ecosystem of Niel Bay (N.W. Mediterranean Sea, France). Total particulate DMSP (DMSPp) and DMS concentrations were highly seasonal, peaking during a spring (April) bloom at 8.9 nM and 73.9 nM, respectively. Significant positive correlations were found between total DMSPp concentration and the abundance or biomass of the dinoflagellate Prorocentrum compressum (Spearman's rank correlation test: r = 0.704; p = 0.011). Similarly, DMS concentrations peaked during the development of blooms of P. compressum and Gymnodinium sp. There seemed to be a positive relationship between the chlorophyll a to pheopigment ratio and DMS concentrations, suggesting that DMS was released during phytoplankton growth. High DMS levels recorded in the shallow Niel Bay may also result from the activity of benthic macroalgae, and/or macrophytes such as Posidonia spp., or the resuspension of sulfur species accumulating in sediments. The fractionation of particulate DMSP into three size classes (>90 μm, 5–90 μm and 0.2–5 μm) revealed that 5–90 μm DMSP-containing particles made the greatest contribution to the total DMSPp pool (annual mean contribution = 62%), with a maximal contribution in April (96%). This size class consisted mainly of dinoflagellates (annual mean contribution = 68%), with P. compressum and Gymnodinium sp. the predominant species, together accounting for up to 44% of the phytoplankton present. The positive correlation between DMSP concentration in the 5–90 μm size class and the abundance of P. compressum (Spearman's rank correlation test: r = 0.648; p = 0.023) suggests that this phytoplankton species would be the major DMSP producer in Niel Bay. The DMSP collected in the >90 μm fraction was principally associated with zooplankton organisms, dominated by copepods (nauplii and copepodites). DMSP>90, not due to a specific zooplankton production, resulted from the phytoplankton cells ingested during grazing. The concomitant peaks of DMS concentration and zooplankton abundance suggest that zooplankton may play a role in releasing DMSP and/or DMS through sloppy feeding.  相似文献   

12.
The decomposition of cultured marine phytoplankton (Skeletonema costatum) and natural estuarine seston from Narragansett Bay, RI, was studied at two temperatures (8°C and 18°C) in bottles containing sterile bay-water (30‰) and in bay-water with micro-organisms small enough to pass through a glass fibre filter (nominally < 1μ). About 50% of the particulate organic nitrogen (PON) and particulate phosphorus (PP) was immediately released to the water in dissolved organic forms from both types of organic matter. Comparison of changes in the dissolved organic nitrogen (DON) fraction in the sterile and non-sterile systems indicated that nearly all of the DON initially released was subsequently remineralized. Ammonification proceeded only in non-sterile bay-water. 20–25% of the PP was converted to dissolved inorganic-P (DIP) fraction after only 7 h in both sterile and non-sterile bay-water. Following autolytic releases of DON, DOP and DIP the initial rates of N and P remineralization were temperature dependent: Q10 values for PON and PP decay during first phase of microbially mediated decomposition ranged from 1·3 to 6·4. Rates of remineralization then slowed so that about equal amounts of nutrients were remineralized (45–50% of the N and 57–60% of the P in the phytoplankton and 60–63% of the N and 36–60% of the P in the natural seston) after 30 days storage at either temperature. During 30 days of decomposition in non-sterile seawater the N/P ratios in the dissolved inorganic fractions converged on the ratios of total-N/total-P initially present in the bottles. Kinetic analysis of the decay of total organic-N (TON) and total organic-P (TOP) in the non-sterile systems and analysis of similar sets found in the literature showed that the initial stages of the decomposition of N and P from planktonic POM in vitro could be modelled as the sequential decay, at first-order rates, of two particulate fractions. The first, more labile, fraction comprised about 60% of the particulate N and P. First-order rate constants (−k, base e) for decomposition during the 1st and 2nd phases were 0·02 to 0·2 day−1 and 0·003 to 0·02 day−1, respectively. The decay rates are far too slow to account for the ‘rapid in situ recycling’ of nutrients needed to support phytoplankton production when other means of nutrient resupply (by advection, fixation, rainfall, etc.) are very low.  相似文献   

13.
A method of obtaining the operative sea surface temperature (SST)t using satellite scanner observations in the spectral ranges 3.53–3.94 m and 10.3–11.3 m is realized. The method represents a combination of McClainet al.'s formula (1983) and expressions suggested by the authors which describe the universal angular structures of the radiation temperature fields. The RMS error of reconstructingt at scanning angles of 0–55o is equal to 0.2–0.3°C for atmospheric states corresponding to the SST variation within the limit 6–28°C. An atlas of temperature maps on the grid 0.5×0.5o with temporal averaging from 5 days to 1 month is compiled using the data obtained on board the RVAkademik Vernadsky in the Atlantic Ocean in 1987–1989.Translated by Mikhail M. Trufanov.  相似文献   

14.
Populations of Pleopis polyphemoides were studied in Guanabara Bay, southeastern Brazil, to assess temporal variations in density and population parameters. The abundance of P. polyphemoides varied widely during summer, and collapsed in fall–winter. These variations probably resulted from the combined effects of water temperature and predation pressure. It is assumed that the planktonic population began by hatching from resting eggs, while the collapse of the planktonic population in April seemed to be related to lower temperatures and high densities of predatory chaetognaths.  相似文献   

15.
Some features of jump in water temperature in aSargassum forest   总被引：1，自引：0，他引：1  
To clarify the influence of aSargassum forest on water temperature distributions observations were made inside and outside aSargassum forest off the Nagata Shore on the northern Saiki Bay open to the Bungo Channel on the Pacific side of Kyushu, Japan. About sixty thermistor probes were deployed at 0.5 m depth intervals from the bottom to the sea surface at seven stations spaced at 50–80 m distances along two transects: one inside the forest and the other outside. Water temperature was measured at five minutes intervals from 6 to 9 August 1987 with thermistor probes. The spatial standing crop distribution of theSargassum forest along the transects was investigated. A water temperature jump of about 2°C, recorded during the observation, is probably caused by an intrusion of a warm water mass from the central Bungo Channel to Saiki Bay. The water temperature jump under theSargassum forest on the rough bottom with stones occurred one to two hours behind that outside the forest (sandy bed) although the distance between the transects inside and outside the forest was only 50–80 m. It is suggested that theSargassum forest and the rough bottom would prevent intruding warm water from smoothly replacing cold water due to resistance of theSargassum species and the bottom to a current.  相似文献   

16.
The metal load into sediments and the change in the sedimentary environment of Osaka Bay in the Seto Inland Sea have been studied through geochemical analysis of core sediments, using both Pb-210 dating and a selective chemical leaching technique. Analytical results from a 6-m core of sediment show that copper and zinc pollution started in the late 1800's and the present enrichment ratios of copper and zinc, relative to background levels (20 mg kg–1 for Cu and 94 mg kg–1 for Zn), are 2.8 and 4.1, respectively. The present anthropogenic copper and zinc loads into Osaka Bay sediments, are 47 and 368 ton yr–1, while natural copper and zinc loads are 40 and 186 ton yr–1, respectively. Osaka Bay sediment at the present day is considered to be seriously polluted by zinc, now. The vertical profiles of copper and zinc in four successively separated fractions (10% acetic acid soluble fraction: F-HAC, 0.1M hydrochloric acid-soluble fraction: F-HCl, hydrogen peroxide-soluble fraction: F-H2O2 and hydrofluoric acid-soluble fraction: F-HF) from the core sediments indicate that enrichments of copper and zinc in the upper layer of the sediment are dependent on increases in the metal contents of the F-HAC, F-HCl and F-H2O2 fractions. Copper in F-HAC, and zinc in F-HAC and F-HCl, seem to be of anthropogenic origin.Results of sequential studies of the whole Seto Inland Sea can be summarized as follows: At the present time, the sedimentary loads of copper and zinc over the whole Seto Inland Sea area are 630 and 3,500 ton yr–1, respectively, while the natural and anthropogenic loads are 320 and 310 ton yr–1 for copper and 1,800 and 1,700 ton yr–1 for zinc, respectively.  相似文献   

17.
The vertical distributions of suspended particles in Osaka Bay were measured by using anin situ beam attenuation meter. The concentration of suspended particles near the bottom increases rapidly toward the bottom where size of sediment is in a range of silt. The settling velocity of suspended particles near the bottom was measured with the use of a settling tower in the laboratory. The settling velocity of the suspended particles with diameter from 10 to 100m is 2×10–3cm s–1 to 5×10–2cm s–1. The density of the particles ranges from 2.0 to 1.1 and decreases with increasing particle diameter.  相似文献   

18.
We have studied nitrogen and phosphorus distributions across the thermohaline front in Kii Channel in winter by using engine-cooling sea water of a ferry boat. On Dec. 1986 and Jan. 1987, differences of PO4–P and DIN across the front are recognized. Especially in the latter case, differences of nutrients concentrations across the front are very obvious. But differences of nutrients across the front on Feb. 1986, Feb. and Mar. 1987 are not obvious. Inspite of winter,Akashiwo had happened in Osaka Bay, nutrients mostly have already been utilized by phytoplankton in inner part of Osaka Bay. Consequently, differences of nutrients concentrations across the front are nearly zero.  相似文献   

19.
Egg production, egg viability and fecal pellet production were determined for individual Acartia omorii, which were fed diets of two species of diatoms (Skeletonema costatum and Phaeodactylum tricornutum) and three species of dinoflagellates (Scrippsiella trochoidea, Heterocapsa triquetra and Cochlodinium polykrikoides). Diets were analyzed for fatty acid content as an indicator of food quality. Depending on the diet, egg production of A. omorii varied over time, diminishing with some diets (S. trochoidea, C. polykrikoides, P. tricornutum). This rate of reduction was much more rapid for a diet of C. polykrikoides, which caused egg production to decrease to ca. 2.4 eggs f−1 d−1 in only four days. As for all diets, egg viability was high at the beginning but with the C. polykrikoides and P. tricornutum diets, it rapidly decreased with time. Fecal pellet production also varied with time, depending on the diet. Egg production rate was closely correlated with fecal pellet production. There was no direct relationship between egg viability and egg production rate, but both egg production and viability were affected by the nutritional quality of food. Egg viability was also highly dependent on the composition of fatty acids in the eggs. Egg viability showed positive correlation with the ratio of ω3:ω6 groups among egg fatty acids, and negative correlation with the ratio of 20:5 (n−3) : 22:6 (n−3). While comparing several diets, egg production rate was higher on diets (H. triquetra and S. trochoidea) containing ample amounts of essential fatty acids such as 18:4 (n−3) and 22:6 (n−3). The results suggest that fertility of A. omorii was dependent upon the quality of the food, and dinoflagellate diets, with the exception of C. polykrikoides, were preferable to diatom diets.  相似文献   

20.
Themisto japonica was reared at 1, 5, 8, and 12°C in the laboratory to estimate its intermoult period (IP) and increase in body length (BL) at each moulting (BL).IP was found to be a function of temperature andBL of the specimens, longerIPs being associated with lower temperature and larger specimens.BL was not affected by temperature but increased with growth of the specimens. Observations on consecutive moults indicated that one new segment was added to pleopod rami at each moulting.BLs obtained from the measurement of the segment number of pleopod rami andBL of wild specimens were slightly larger than values obtained from laboratory-raised specimens.IP data obtained from laboratory-reared specimens are combined withBL data from wild specimens to establish a growth model forT. japonica from its release from the marsupium (1.31 mmBL) to the maximum size (17 mmBL) as a function of temperature. This growth model predicts that a total of of 18 moultings is needed forT. japonica to reach the maximum size regardless of temperature, although the time needed to reach the maximum size is highly dependent on temperature. The life cycle, from the newly released larvae (1.31 mmBL) to the spent females (10–17 mmBL), was estimated as 333–593 days at 1°C, 195–347 days at 5°C, 118–210 days at 10°C and 82–146 days at 15°C; the last may be the upper temperature limit forT. japonica. Growth rates ofT. japonica expressed on the basis of body mass are comparable to the rates of euphausiids of equivalent size when the effect of temperature is accounted for. Feeding conditions ofT. japonica in the field are also discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号