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1.
Like many other loliginid squid, Doryteuthis (Loligo) opalescens deposits egg cases on the ocean floor. Depending upon temperature, egg cases may persist for 5–12 weeks before the paralarvae hatch. Because of this relatively long duration and squid’s pelagic life history, egg cases provide a practical life stage to survey. During 2001–2002, squid egg beds in Monterey Bay, Carmel Bay, and around the California Channel Islands were surveyed using a remotely operated vehicle with the goal of delineating the habitat of egg beds that are spawned during active commercial fishing. Egg cases were highly aggregated and densities reached 1338 capsules m−2. Squid eggs were significantly shallower in Central California. Egg cases occurred between 20 and 93 m around the Channel Islands, and in Central California they were between 13 and 61 m. The temperatures in both regions were similar (10–12 °C), with some eggs in Southern California found up to 14.4 °C. Ninety-five percent of eggs were found on sand, suggesting that temperature and substrate are stronger behavioral cues than depth to stimulate spawning. Suitable spawning habitat was defined by three criteria: sandy benthic substrate, temperatures between 10 and 14.4 °C, and depths between 20 and 70 m when the first two criteria hold. Additionally, within this defined area, oxygen concentration is quantified. The greatest commercial landings of market squid occur in both Central and Southern California during a time of year when water temperatures of 10–12 °C are prevalent in the 20–70 m depth range.  相似文献   

2.
Factors affecting the development of the embryos and production of larvae of the spiny lobster Sagmariasus verreauxi were investigated. Mature lobsters were collected from the fishery in New Zealand and held in captivity until they moulted, mated, and extruded eggs. For females, moulting took place in winter (July/August) and mating occurred 58–88 days later in early spring. The ovigerous females were then held at three temperatures and embryo development monitored at approximately weekly intervals. Mean times to hatch were 55, 75, and 130 days at 20°C, 17°C, and 13°C respectively. The total number of larvae that hatched from each female ranged from 0.97 to 1.4 million. The theoretical temperature at which embryo development ceases (a biological zero) for S. verreauxi, of 9.4°C, was calculated from data on the appearance of the median eye, the eyes and the chromatophores, and the time to hatch. An eye index formula was also derived to allow prediction of time to hatch at a range of temperatures using the cumulative difference between the rearing temperature and the biological zero. First instar phyllosomas from embryos reared at 20°C were significantly smaller than those from 17°C and 13°C but there was no significant difference in fitness. This study shows that hatching can be spread over a number of months, without significantly affecting larval quality, simply by manipulating holding temperature.  相似文献   

3.
Larvae of the decapod Crangon uritai were reared in the laboratory in a factorial experiment employing three temperatures (9, 12 and 15 °C) and three salinities (29‰, 32‰ and 35‰) from hatching to the post‐larval stage. The effects of temperature and salinity on survival, intermolt period (IP) and molt increment (MI) were investigated. Larvae from one brood were subdivided into groups of 20 and reared in glass bowls containing filtered sea‐water at a number of temperature–salinity combinations. The reared larvae were transferred daily to the clean bowls prepared with newly hatched Artemianauplii, and number of molts and mortality within each bowl were recorded. The zoeal size (carapace length) was determined from exuvia and dead larvae, and the IP was also recorded. Larvae of C. uritai completed larval development only at 15 °C temperature. The first zoeal stage completed their development at all temperature–salinity combinations and exhibited the highest survival rate. IP at each stage increased with increasing size and greatly decreased with increasing temperature, and intermolt duration (range of days) increased with larval development especially at the lower temperature. Although the MI decreased with increasing size, it was little affected by temperature. This led to a better growth rate with increasing temperature.  相似文献   

4.
To determine the effect of low water temperature on development, walleye pollock (Theragra chalcogramma) eggs from the Bering Sea were reared at −0.6°C, 0.4°C, 2.0°C, and 3.8°C. One group of eggs was reared at 3.9°C under a diel light cycle (14 h light, 10 h dark) to observe the effect of light on development and hatching. Development was normal for all temperatures except −0.6°C; abnormal development of the tail and lack of development of eyes occurred in some embryos. Time to 50% hatch was 820, 620, and 424 h at 0.4°C, 2.0°C, and 3.8°C. Eggs incubated in diel light at 3.9°C developed at the same rate as eggs incubated in constant dark at 3.8°C, but required an additional 72 h to reach 50% hatch. A piece-wise regression model was generated to predict egg age for incubation temperatures of −0.6°C to 3.8°C. For temperatures recorded in the southeastern Bering Sea 1995–1998, the model predicted incubation periods for walleye pollock eggs that varied by 13 days between the warmest and coldest years.Walleye pollock eggs from Shelikof Strait, Alaska, were incubated at 0.2°C, 1.8°C, and 2.8°C. Development was normal for all temperatures. A piece-wise regression model (as above) was generated for incubation temperatures 0.2–2.8°C. When the regression models were compared, Bering Sea eggs (1.4–1.7 mm in diameter), required more time for development prior to hatch than Shelikof Strait eggs (1.2–1.3 mm in diameter) at 1.8°C and 2.8°C. However, for temperatures 0.2–2.0°C, Bering Sea walleye pollock began hatching earlier and at a developmentally younger age than Shelikof Strait walleye pollock.  相似文献   

5.
Eggs from 69 females of spring spawning herring from the German Baltic coast (Travemünde, April 1979) were incubated in clean sea water (20‰ S, temperature 8°C) under standard conditions. Sixty-one trials could be used for the evaluation of hatching success. Viable hatch was taken as a measure to evaluate the effects of chlorinated hydrocarbons accumulated in gonads, liver and muscle of parental fish.PCB levels in running ripe females ranged on a wet weight basis between 19 and 241 ng g?1 (gonad), 20 and 377 ng g?1 (liver) and 11 and 1820 ng g?1 (muscle). Concentrations of other chlorinated hydrocarbons (DDD, DDE, γ-HCH, etc.) were in the same range as reported by other authors for Baltic herring (Huschenbeth, 1973, 1977). Viable hatch was significantly affected at ovary DDE concentrations higher than 18 ng g?1 (wet wt) and PCB concentrations of more than 120 ng g?1 (wet wt).Results are compared with data obtained during earlier investigations with flounder eggs.  相似文献   

6.
Sea-spawned saury eggs collected 20 km off the west coast of the Cape Peninsula were hatched in laboratory tanks and the larvae reared. The larvae were fed initially on nauplii of cultured copepods, Tisbe holothuriae Humes and Pseudodiaptomus hessei (Mrázek). Growth rate during the first 47 days post-hatch averaged 0,62 mm·day?1 (at 18—19°C) and between the 47th and 120th day averaged 0,45 mm·day?1 (at 14,8—15,5°C). Some observations on feeding behaviour are included.  相似文献   

7.
为了解棘颊雀鲷(Premnas biaculeatus)在人工饲养条件下繁殖和仔鱼培养对光照、水温及饵料的要求,采用实验生物学的方法,在严格控制的条件下培养亲鱼、胚胎和仔鱼.结果表明,在(26±1)℃和14L:10D的光暗周期下,2 000 1x和500 1x两种光照强度对亲鱼产卵周期和卵的受精率并没有明显的影响,但是...  相似文献   

8.
The California market squid is ecologically and economically important to the California Current Ecosystem and coastal communities. However, the population undergoes periodic and large-scale fluctuations on the order of magnitudes, largely as a result of warm ocean temperature and reduced ocean productivity related to cycles in El Niño Southern Oscillation. These fluctuations can lead to cascading trophic effects on the ecosystem, market uncertainty, and substantial revenue losses for fishing communities. In order to investigate the role that spawning behavior may play in mitigating the detrimental environmental effects on the population as well as allowing the species to capitalize during favorable ocean conditions, surveys for market squid paralarvae were conducted three times per hatching season from 2012 to 2019. The specific objectives were to (a) assess whether there was a large-scale synchronous peak in paralarval abundance each season, (b) investigate whether market squid paralarvae were found at certain locations in similar abundances throughout the duration of a hatching season, and (c) to understand the influence of oceanographic parameters, such as zooplankton availability, sea surface temperature, and chl-a on paralarvae abundance during each hatching season. Adaptable spawning strategies that varied over time were observed. Market squid displayed large-scale synchronous spawning during cool and productive oceanographic conditions; protracted spawning was observed during warm and oligotrophic conditions. No overall site fidelity was observed across all effort, but during two seasons where habitat compression was possible, market squid consistently spawned in certain areas. Generalized additive models were used to explore the effects of a small set of oceanographic variables on paralarval density on a seasonal basis. Sea surface temperature and geographic variables were generally the most important variables. These findings indicate that market squid spawning behaviors and habitat are adaptable and dependent on oceanography and population density.  相似文献   

9.
Reproduction and early development of the large subarctic copepods Neocalanus cristatus, N. plumchrus and N. flemingeri were investigated in the laboratory. All three species produced eggs at intervals of 5.0 to 14.7 days, depending on species and temperature. The females of N. flemingeri released the fewest clutches of the three species, but with the largest clutch size. Clutch size of N. cristatus was smallest with longest intervals between clutches. Mean±1 S.E. of total fecundities were 386±116 eggs for N. cristatus, 840±214 eggs for N. plumchrus, and 924±346 eggs for N. flemingeri. The egg laying period of a female at 2°C was estimated to be 91 days for N. cristatus, 60 days for N. plumchrus and 47 days for N. flemingeri. The color and outer characteristics of eggs and nauplii of these species were quite different. C : N ratios of the eggs were 9.3–10.5, which were slightly higher than that of females or CV. Egg hatching times for each species were 4.6–5.7 days at 2°C and decreased with increasing temperature at a Q10 of 2.8–3.0. N. cristatus nauplii developed to copepodid stage I (CI) without feeding, and the developmental time in days from hatching to CI was expressed as a Bělehrádek equation, DCI=17068×(T+14.7)−2.05. Reproduction strategies of the three species of Neocalanus are discussed with reference to their life history strategies.  相似文献   

10.
In July 1998, a bottom-mounted Acoustic Doppler Current Profiler was deployed at 36m depth in the centre of the Tsitsikamma National Park on the eastern Agulhas Bank, South Africa. The purpose was to investigate transport of chokka squid Loligo vulgaris reynaudii paralarvae hatched on the inshore spawning grounds (<60m) and ichthyoplankton spawned within the park. Analysis of the first 12 months of data (July 1998–June 1999) shows that surface flow was mainly eastward (alongshore), with a maximum velocity (u-component) of +115cm s?1 and an average of +24cm s?1. Generally, velocity decreased with depth, with a maximum bottom velocity (u-component) of +65cm s?1 and an average of +10cm s?1. Data from a nearby thermistor array show that the water column was usually isothermal during winter (July–September), with bottom flow in the same direction as the surface layer. In summer (December–March), vertical stratification was most intense, and surface and bottom flows differed in velocity and direction. Potential net monthly displacements calculated for three depths (5m, 23m and 31m) indicate that passive, neutrally buoyant biological material (e.g. squid paralarvae, fish eggs and larvae) would likely be transported eastwards in the surface layer for eight of the 12 months, and would generally exceed distances of 220km month–1. Displacement in the bottom layer was more evenly distributed between east and west, with net monthly (potential) transport typically 70–100km, but reaching a maximum of 200km. Wind-driven coastal upwelling, prevalent during the summer, causes the surface layer of the coastal counter-current to flow offshore for several days, resulting in potential displacement distances of 40km from the coast. These results suggest that squid paralarvae hatched on the inshore spawning grounds are not generally transported towards the 'cold ridge', a prominent semi-permanent oceanographic feature of cold, nutrient-rich upwelled water, where food is abundant, and that fish larvae, whether from the surface or bottom layer, are exported beyond the boundaries of the Tsitsikamma National Park.  相似文献   

11.
In the Wellington area (central New Zealand) Forsterygion varium (Forster, in Bloch & Schneider 1801) spawns from early June to late November, Gilloblennius decemdigitatus (Clarke, 1879) from early June to early October, and G. tripennis (Forster, in Bloch & Schneider 1801) from July to October. They deposit their eggs on firm substrates below the low tide level. Egg clusters are attended by an adult fish until hatching, which in the laboratory at 11.5–13.5°C, occurs after 18 days for F. varium and 20 days for G. decemdigitatus. Development to hatching for G. tripennis takes about 21 days at 13–15°c. The egg development of all three species is illustrated. The yolk‐sac larvae (prolarvae) of F. varium, G. decemdigitatus, and G. tripennis at hatching average 5.85, 5.03, and 5.72 mm standard length respectively. Yolk‐sac larvae of F. varium have a single row of 9–17 small, stellate melanophores along the ventral midline of the tail. The yolk‐sac larvae of G. tripennis have up to nine melanophores along the ventral midline of the tail, a medium‐sized melanophore above the optic lobes, and a further two above the medulla. The yolk‐sac larvae of G. decemdigitatus have three large mid‐dorsal melanophores interspersed with five smaller, paler pigment cells, and three large mid‐ventral melanophores interspersed with three of the smaller cells.  相似文献   

12.
The composition and distribution of squid captured between January and March during the 1996 baseline research on oceanography, krill and the environment survey off East Antarctica (80–150°E) was investigated. A total of 195 individuals were captured. The species collected were Galiteuthis glacialis, Mesonychoteuthis hamiltoni, Histioteuthis atlantica, H. eltaninae, Alluroteuthis antarcticus, Batoteuthis skolops and Pholidoteuthis boschmai. Concentrations of squid were low, ranging from 4.4 to 174.7 individuals 100,000−3. The majority of squid captured were G. glacialis (174 individuals, 89.2% of all squid captured), and most of these (n=171) were small paralarvae <25 mm in mantle length. G. glacialis were distributed predominantly west of 120°E in water that was colder, and where the distance from the coastline of the southern boundary of the Antarctic circumpolar current (SB-ACC) was maximal. This water mass had greater concentrations of phytoplankton, was more productive and had maximal sea-ice extent compared to the water mass east of 120°E. G. glacialis was therefore more abundant in water where the majority of krill and krill predators were present compared to warmer oceanic waters of the ACC to the east, where salps dominated.  相似文献   

13.
Acartia bifilosa (Copepoda: Calanoida) is a common species in offing of global waters and it often becomes dominant species in some estuaries. This species develops different strategy according to variation of environment. Despite its ecological role, Acartia bifilosa also has been concerned as live feeds in aquaculture, but study on egg production rate of this species in saturated diet in different temperature and different diet is so far not available. In order to interpret the importance of temperature and diet on natural population variation and also on aquaculture as foods of larval fish, the functional response of reproductive success of Acartia bifilosa was quantified in the laboratory using different temperatures and diets. Acartia bifilosa was captured in Jiaozhou Bay and acclimated to corresponding temperature for 3~4 days. In order to reduce the effect of large extent temperature range on organism, we captured Acartia bifilosa from March to June and acclimated them to temperature which is adjacent to natural temperature. Daily egg production rate (EPR, eggs female-1day-1) was detected for 11~15 days at 5 different temperatures ranged from 8.0 to 23 °C and all the females was feed on saturated diet all through the experiments. EPR on first day was not calculated in the mean EPR to eliminate the effect of different diets. This result showed that Acartia bifilosa spawned continuously during the experiment days and no obvious regulation was found. EPR was positively correlated with temperature from 8.0 to 23 °C. The highest mean EPR was observed at 23 °C (7.3 eggs female-1day-1), and the lowest value was found at 8 °C (3.8 eggs female-1day-1). The effect of diets on EPR was evaluated at two different temperatures (8.0 °C and 12.5 °C). Same trends were found at the two temperatures: mean EPR fed on Chaetoceros sp. was higher than that fed on Skeletonema costatum, and during the 14-day experiments, EPR was higher for females fed on Skeletonema costatum than chaetoceros sp. in the first few days (3~5 days), but it changed reversely in the subsequent days until the end of the experiments. Hatched eggs were observed in the two experiments at temperature 8°C and 12.5 °C and no diapause eggs were found. The hatching success rate was low at 8°C but reached 93.2% at 12.5 °C. According to the results in this paper, we detected the comfortable temperature range for EPR, and evaluated the effect of Skeletonema costatum which often brings out red tide in natural waters. These results are beneficial to ecological research for explaining population variation and population recruitment of this species, These data also can be used in Acartia bifilosa aquaculture.  相似文献   

14.
以自然成熟的亲虾为材料,观察并描述了墨吉明对虾(Fenneropenaeus merguiensis)从受精卵到幼体孵化出膜的胚胎发育过程。结果显示,在水温29°C,盐度28的条件下,墨吉明对虾整个胚胎发育过程需要11h左右。水温和盐度对幼体出膜时间和受精卵的孵化率均有显著的影响(P0.05)。孵化水温从32°C下降到23°C时,幼体出膜时间由555min(9.25h)增加到1108min(18.46h)。胚胎发育的最适水温为26—32°C,在此温度范围内,墨吉明对虾的幼体出膜时间与水温呈负相关。胚胎发育的最适盐度25—35,在此范围内,墨吉明对虾的幼体出膜时间和孵化率均无显著差异(P0.05),说明墨吉明对虾的胚胎发育的盐度范围较广。  相似文献   

15.
Frostfish spawning, as indicated by the presence of planktonic eggs, was observed mainly in north‐eastern, but also in south‐western, New Zealand waters in spring to autumn. Spawning takes place in the afternoon in outer shelf waters 50–200 m deep, with surface temperatures and salinities between 17.5 and 22.0°C and 35.3 and 35.6‰ respectively. Egg and oil droplet diameters ranged from 1.65 to 1.75 mm and 0.40 to 0.43 mm respectively.  相似文献   

16.
Benthic, viable resting eggs of calanoid copepods were found for the first time in the Seine estuary (France) during July 2008. Vertical distribution of the resting eggs in the sediment was determined up to 10 cm depth. Hatching success of the eggs extracted from different 1-cm thick sediment layers was experimentally tested immediately after extraction and after a long refractory phase (i.e. 11 months) of storage at low temperature (4–5 °C). The hatching success of resting eggs obtained immediately after sediment incubation was lower (0.72%) than the value observed after 11 months (4.50%) with an overall hatching success of 2.37%. The marine, calanoid copepod Temora longicornis was the primary species to hatch from the eggs; however, the estuarine calanoid copepod Eurytemora affinis also hatched from resting eggs. The mean abundance of eggs found in sediment (1.42 × 106 eggs m−2) was comparable to that reported for other marine and estuarine calanoid copepods. The Seine estuary sediment had a high variability of egg abundance (between 0.14 and 8.10 × 107 eggs m−3) suggesting that the hydrodynamics of this macrotidal estuary are likely responsible for this variability. Significant sediment resuspension occurs in the Seine estuary during flood periods and spring tides leading to resting eggs to contribute along the year to the nauplii recruitment of calanoid copepods. On average, around 400,000 nauplii m−3 month−1 of the main calanoid copepods can emerge from the surface layer sediment in the Seine estuary, suggesting that resting eggs could play an important role in the population dynamics of key calanoid copepods in the Seine estuary.  相似文献   

17.
The activity of NaCl in artificial seawater was measured potentiometrically with Na+- and Cl? -sensitive electrodes. The salinity of the solutions, examined at 25°C, ranged from 10–40‰ salinity. The change in the activity from 5–25°C was measured at 35‰ salinity.The molal mean activity coefficient of NaCl in 35‰ seawater at 25°C is 0.667. The relative partial molal enthalpy of NaCl in 35‰ seawater is ?130 ±50 cal mol?1. This value is in good agreement with the value measured in pure 0.72 M NaCl.The results were compared with activity coefficients predicted by a specific interaction model and by an ion association model. Good agreement was found in both cases.  相似文献   

18.
Six early, post-cleavage embryonic stages for chokka squid Loligo vulgaris reynaudii eggs that were developed in an aquarium are identified and described, expanding the embryonic stages for this species from 14 to 20. The influence of water temperature on embryonic development is described. At temperatures <12 and >15°C, high percentages of morphological abnormalities were observed in embryonic development. Gross forms are described and illustrated.  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.
Kim  Kyung-Su  Shim  Jeong Hee  Kim  Suam 《Ocean Science Journal》2015,50(2):381-388

It widely thought that ocean acidification processes that caused by atmospheric CO2 increase and accordingly lower seawater pH conditions might cause serious harm to marine food webs in certain ecosystems in the near future. Little is known about how marine fishes respond to reduced pH conditions. We investigated the effects of CO2 conditions on the growth of olive flounder (Paralichthys olivaceus) larvae. Newly hatched larvae were reared at three different levels of pCO2 (574, 988 and 1297 µatm) in temperature-controlled (21 ± 0.5°C) water tanks for four weeks until metamorphosis. The experiment was repeated three times in May, June, and July 2011, and body lengths and weights were measured at the completion of each experiment. The results indicated that the body length and weight of flounder larvae significantly increased with increasing CO2 concentrations (P < 0.05). A higher daily growth rate during the early larval stage (hatching to 14 days) was found among the larvae reared in low pCO2 conditions, while a significantly lower growth rate was found among larvae in higher pCO2 water conditions. On the other hand, in the late larval stage (18 days after hatching to metamorphosis), the daily growth rate of larvae was much higher in high CO2 water. Bone density of larvae, however, decreased with increasing CO2 concentration in the water

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