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1.
Field-collected tetrasporophytes of Palmaria palmata were tumbled in 300-L outdoor tanks from January to August at ambient daylength or in a constant short-day (SD) regime (8 h light per day), both at 10 or 15 °C. Tetrasporangia were massively induced after 2.5 months under SD conditions at 10 °C and completely lacking at 15 °C, both under SD or ambient daylength conditions, with a few tetrasporangia present at 10 °C and ambient daylength. Elongation rates of tagged tetrasporophytic thalli peaked from March to April in all four conditions, when the biomass densities in the outdoor tanks were close to 2.5 kg fresh weight m− 2. Under all four conditions, juvenile proliferations started to appear in June from the margins of the old fronds, and attained approximately 1 cm in length by the end of July.Approximately 80% of the tetraspores were released during the first three dark phases in a light/dark regime, and the remaining 20% during the light phases. A minimum of 10 min darkness was observed to trigger spore release. White light inhibited tetraspore release, while a similar number of spores were released in continuous red light or in the light/dark regime, although with no significant differences of spore release during subjective days and nights.Sporelings were successfully derived from the released tetraspores for mass propagation of the male gametophyte in 2000-L outdoor tanks in a greenhouse. Mass production of male gametophytic sporelings of P. palmata was completed two times by SD induction of tetrasporangia at 10 °C, release of spores in darkness and culturing the sporelings until they were ready to be propagated vegetatively in greenhouse tanks. One experiment lasted from January to October 2001, with spore release in June, and the second from September to April 2003, with spore release in January. These results may support the development of sustainable, year-round Palmaria farming.  相似文献   

2.
To investigate the illuminance requirements for the culture of red algae in finfish effluent, both Chondrus crispus and Palmaria palmata were assessed simultaneously at three irradiances. Apical tips, 3.5 cm length, were stocked at 2 g L?1 in 1-L glass flasks with enriched seawater in two 24-day experiments, at 10 and 14 °C, respectively. Palmaria grew up to 70 % better and up took more nutrients than Chondrus under five of the six experimental conditions, except at 14 °C and low irradiance (daily photon dose of 3.4 mol photon m?2 day?1). Specific growth rate of both species at high irradiance, 13.1 and 17.2 mol photon m?2 day?1, at each trial, 10 and 14 °C, respectively, was 40 and 20 % better than at medium irradiance, but nutrient uptake was similar at both medium and high irradiance. Chondrus growth rate was higher during Experiment 2 (14 °C and 17.2 mol photon m?2 day?1) than during Experiment 1 (10 °C and 13.1 mol photon m?2 day?1), while Palmaria growth rate was similar in both trials, but always significantly higher than Chondrus. In the range 10–14 °C, Palmaria is the best candidate for integration with Atlantic halibut juveniles (Hippoglossus hippoglossus).  相似文献   

3.
Culturing small propagules of coral has the potential for high yield with low environmental impact, provided that mortality is low. This study investigated the size-specific mortality and growth of minute fragments (as small as 5 polyps) of two of the most abundant reef-building corals in Hawaii (Porites lobata and P. compressa). Two ex situ nursery systems differing in cost, design complexity, and labor intensity were compared. The first nursery experiment lasted for four months in a large tank with high water motion/surge and extensive manual cleaning to remove competitive algae. The corals were then transferred to a simple low-flow tank containing sea urchins (Tripneustes gratilla) and reduced cleaning, where they were grown for six more months (Nursery II). ‘Nursery I’ resulted in 92% of P. lobata and 73% of P. compressa fragments surviving and nearly doubling in area, in spite of a brief infestation by a nudibranch (Phestilla sibogae) that primarily fed on larger P. compressa fragments. There was a significant positive relationship between fragment size and growth rate, and survivorship was significantly different between donor colonies (genets), but there was no evidence of size-specific mortality. ‘Nursery II’ on the other hand had clear size-specific mortality and higher urchin damage for smaller fragments, resulting in moderate survivorship (78% for P. lobata and 76% for P. compressa), and only a slight increase in the total area covered by coral tissue. Fragments larger than 3 cm2 were undamaged and had the highest survival and growth rates. This study illustrates how size-specific mortality can be reduced by ex situ nursery conditions.  相似文献   

4.
Two species of macroscopic marine algae (Rhodophyceae) were grown and harvested continuously during 1974 in Fort Pierce, Florida. The seaweeds Gracilaria sp. and Hypnea musciformis were grown in both 600-l and 350-l tanks in the third stage of a nutrient removalaquaculture process that included microscopic marine algae and oysters in the first two stages. Mixtures of secondary-treated waste water and sea water constituted the initial nutrient source, with the seaweeds utilizing nutrients not assimilated by the microscopic algae and/or generated by the oysters. Standing crops of up to 7 900 g wet weight of Hypnea and 9 000 g Gracilaria were maintained. The Hypnea cultures could not be maintained in summer when tank temperatures reached 30°C, but Gracilaria grew during the entire year. On the basis of periodic harvesting, yields were consistently between 12 and 17 g dry weight per m2 per day for both species. These yields are as high as those achieved by mass cultures of microscopic marine algae, or by fast growing commercial crops such as sugar and rice.  相似文献   

5.
Light-emitting diode (LED) technology offers potential energy-efficient light sources for algal aquaculture. In this study, the growth rate and ulvan yield of Ulva pertusa used for broad commercial applications were enhanced in vitro. To investigate the response of Ulva to LEDs, algae were grown under white fluorescent, pure primary color LED, and mixed LED lights for 28 days. Ulva sp. under blue LED and white fluorescent light showed higher specific growth rate (SGR, 12% day?1) than other light sources, while the growth under mixed red-blue LED light was lower than that under white fluorescent lighting. Despite the differences in alga growth under LEDs and white fluorescent light, few differences are observed in N and P content among algae grown under any light source. U. pertusa showed tissue nitrogen and ulvan contents in the ranges of 4.4–6.7% and 20.4–25.1%, respectively, under all LED light treatments. The ulvan extracted from algae under blue LED showed high levels of antioxidant activity measured with 2,2-diphenylpicrylhydrazyl (DPPH) radical and hydrogen peroxide. Moreover, the ulvan obtained under different lights showed different monosaccharide compositions. Based on these results, LEDs should be considered as the main light sources for indoor seaweed cultivation.  相似文献   

6.
The potential use of non-arable land in the al-Wusta region of the Sultanate of Oman for the production of algae biomass was examined. Brackish cleaned production water from oil production supplemented with commercial fertilizer was used as growth medium. The indigenous isolate Cyanobacterium aponinum WP7(1) was grown in open ponds using batch or semi-continuous cultivation. Biomass production rates of 15–24 g/m2/day were achieved. The change of salinity due to evaporation, which was thought to be a major challenge, did not exceed 35 ppt. All cultures showed contaminations with weed algae. Contaminations with green algae or diatoms were detectable using fluorescence pattern excited by four different wavelengths using a pulse-amplitude-modulation chlorophyll fluorometer (PAM). It is possible to estimate the health level and the mayor groups of which a culture is composed using the PAM method. Therefore, the fluorescence of the photosynthetically inactive sample is compared with the fluorescence after all copies of photosystem II were closed by exposing the sample to a high-intensity light beam. A detection limit of one weed algae cell in a hundred cells was achieved.  相似文献   

7.
The aim of this work was to assess the potential use of different dried macroalgae as food in the rearing of Paracentrotus lividus. Growth, consumption and food conversions were compared in adult sea urchins fed with fresh or dried thalli of four macroalgae species. Six experimental diets were tested: (a) fresh Palmaria palmata; (b) fresh Saccharina latissima; (c) dry P. palmata; (d) dry S. latissima; (e) dry Laminaria digitata and (f) dry Grateloupia turuturu. Linear growth rates were similar for all treatments. Specific growth rate was higher in sea urchins fed with fresh P. palmata, but no difference was found between animals fed with fresh S. latissima and those fed with dried diets. Regarding daily food consumption (DFC), sea urchins consumed the same amount of dried macroalgae as fresh but exhibited a higher food conversion efficiency (FCE) when fed with fresh P. palmata. However, this FCE was only significantly higher when compared to sea urchins fed with dry L. digitata. Dried G. turuturu is not a suitable diet due to its rapid degradation after rehydration. The results suggest that P. lividus adults can be reared on dried macroalgae thalli without detriment to their somatic growth, especially over short periods. The low cost of feeding sea urchins with this diet could help small shellfish farmers to diversify their production into echinoculture.  相似文献   

8.
The use of recirculating aquaculture systems (RAS) permits the production of fish with a small amount of water and they are an alternative to the scarcity and pollution of water resources. The implementation of an annular settler made by concentric cylinder in an RAS tank allowed the optimal growth conditions of the fish and improves the removal of solids naturally with the presence of low water velocities in the sedimentation zone. The hydrodynamic analysis conducted in this study using computational fluid dynamics allowed the evaluation of different parameters for the geometric design of the settler and its effect on the velocity flow fields that directly affect the particle sedimentation process. Through the evaluation of different geometric configurations of the settler, the use of gratings in the perimeter of the settler with maximum height hr = 1/6h, width and separation of 0.5hr, for tank diameter (D) to water depth (h) ratios (D/h) less than 6 was established. These conditions produced velocities between 15−25 cm/s into the cultivation zone, optimal for fish growth. In addition, with the perimetral gratings, velocities less than 2 cm/s are generated inside the settler, situation that benefits the settling of particles and self-cleaning of the tank.  相似文献   

9.
Nile tilapia Oreochromis niloticus (L.) held in timed‐pulse feeding chambers, were provided with algal‐rich water dominated by either green algae (Scenedesmus, Ankistrodesmus, Chlorella and Tetraedron) or cyanobacteria (Microcystis) to determine the effect of temperature and phytoplankton concentration on filtration rates. Green algae and cyanobacteria filtration rates were measured as suspended particulate organic carbon (POC) kg?1 wet fish weight h?1. Ivlev's filter‐feeding model described the relationships between filtration rates and suspended POC concentration of green algae and cyanobacteria. Filtration rates of both green algae and cyanobacteria increased linearly as water temperature increased from 17 °C to 32 °C and were significantly higher in the warm‐water regime (26–32 °C) than in the cool‐water regime (17–23 °C). Filtration rates at 95% saturation POC (FR95) in green algal and cyanobacterial waters were 700 mg C kg?1 h?1 and 851 mg C kg?1 h?1 in the warm‐water regime and 369 mg C kg?1 h?1 and 439 mg C kg?1 h?1 in the cool‐water regime respectively. The FR95 in warm water were achieved at lower POC concentrations than in cool water.  相似文献   

10.
The aim of this study was to evaluate the use of synthetic fibre as a biological support for the adhesion of nitrifying bacteria in an aquaculture recirculation system (RAS). It was developed from three assays over 120 days. In the first assay, the synthetic fibres used as biological support were introduced in tanks of biological filtration of the system for posterior respirometry analysis and scanning electron microscopy (SEM). Respirometry and SEM were performed 10 days after inoculation with nitrifying microorganisms. Water quality parameters were monitored daily, and the respirometry showed that the bacteria in this assay were consuming the following amounts of ammonium: concentrations [C1]35.369 mg NH3/L, R2 = 0.9912; [C2]51.628 mg NH3/L, R2 = 0.9883; [C3]79.494 mg NH3/L, R2 = 0.986; and [C4]215.225 mg NH3L, R2 = 0.9934. In the second assay, a 1920-L tank was stocked with 120 Nile tilapia, Oreochromis niloticus, with an initial weight 32.11 ± 7.6 g and a biomass of 3.8 kg. After 60 days, the tank and its contents were assessed to evaluate zootechnical parameters and physical–chemical parameters of water quality. From these results, a third assay was developed in which the biomass of fish was increased to challenge the recirculation system. The tank was stocked with 480 jundiá Rhamdia quelen (initial weight 11.34 ± 2.4 g and biomass 5.4 kg) for 60 days. In both the tilapia and jundiá assays, the fish were fed four times per day with a commercial diet of 35% crude protein and 42% crude protein, respectively, at 5% of each individual fish’s body weight. At the end of the zootechnical assays, the synthetic fibres used showed efficient biological support for bacterial growth, as confirmed by scanning electron microscopy. The fibres also demonstrated maintenance of the water quality, which allowed good fish growth in the recirculating aquaculture system, and the maintenance of up to 11.19 kg/m³ of biomass of fish.  相似文献   

11.
A technique for the intensive rearing of Artemia salina larvae (Branchiopoda) of 1 – 4 mm using the blue-green algae, Spirulina maxima (Cyanophycea) in dry powder form is described. Experimentation was carried out in a small volume (20 l) and techniques were simplified whenever possible to enable minimal handling (i.e. water is not renewed). The system is therefore easily applicable to medium and large volumes. The production requirements of Artemia salina for larval aquaculture at Centre Océanologique de Bretagne have been fulfilled by this technique since 1974 in 450-l volumes. Growth and survival rates have been satisfactory to date.Up to a certain threshold and within a given age group, the amount of food introduced influences mean population size. Under optimal conditions it is possible to rear larvae of 1 mm in 2 days, 2 mm in 4 days and 3.75 mm in 6 days. The minimal food supplies required to obtain these figures are respectively 600 mg, 1 800 mg and 4 300 mg of Spirulina powder for 10 000 larvae at the ages of 2, 4 and 6 days. These rapid growth rates are achieved by overfeeding the larvae, which results in a reduction in the size of the installations and in time demanded for culture maintenance. The use of an optimal feeding regime gives a growth rate very close to the maximum and diminishes production costs only slightly.Consequently, an optimal larval concentration per unit volume is the most economically feasible choice for a production unit. The maximum larval concentration which gave good growth and survival rates was established for an average food quantity (3 200 mg/10 000 larvae). Larval densities may reach 13 to 14 2-day-old larvae (1 mm), five 4-day-old larvae (2 mm) and two 6-day-old larvae (3.75 mm) per ml of water. To regulate the concentration of Artemia, fixed volumes of the culture are removed regularly, thus considerably increasing the production of a given tank. The weekly production of a 450-l tank is approximately 75 g of dry matter.  相似文献   

12.
Ceramic clay has been increasingly used to improve contrast and prey detection in tanks for rearing of fish larvae. In contrast to live microalgae or algae pastes, clay increases turbidity without contributing to the organic matter load. In addition, clay may aggregate and sediment organic matter and bacteria, facilitating its removal. Marine larvae are sensitive to infections by opportunistic bacteria. Fish, algae, and live feed increase the microbial carrying capacity of the rearing water which allow exponential growth of bacteria and favor fast-growing opportunists. Reducing substrate levels by replacing microalgae with clay may reduce bacteria proliferation and benefit larvae. We compared the effects of three rearing regimes including live Isochrysis galbana, Nannochloropsis oculata paste, and ceramic clay on the bacterial community, concentration of organic matter, and growth and survival of Atlantic cod larvae (Gadus morhua L.). The application of clay resulted in reduced substrate levels for bacteria in the rearing water compared to the addition of live algae or algae paste. To some extent, clay aggregated and transported organic matter to the bottom of the larval fish tanks, where it could be effectively removed. Fish tanks receiving clay showed a lower abundance of bacteria in the water than tanks added algae paste or live algae. Fish tanks with algae paste showed a higher abundance of bacteria and a higher share of cultivable bacteria and TCBS counts than the other two treatments. Tanks with live algae showed low relative abundances of opportunistic bacteria and TCBS counts in both water and rotifers. Cod larvae in tanks with clay or live algae initiated exponential growth earlier than larvae in tanks with algae paste. Larvae in tanks receiving clay had significantly higher dry weight than larvae in tanks receiving algae paste at day 5 and 20 post hatching. The survival of larvae in the tanks added clay was variable. Two of the three tanks with clay had significantly higher larval survival than the tanks with live algae or algae paste. However, one tank with clay underwent 100% mortality. It is not possible to conclude whether this was related to the use of clay or an incidental development of a harmful microbial community in this tank. The effects of clay addition on larval performance should be studied further. Clay addition appears to be an easy way to reduce bacterial load during early first feeding of marine larvae without compromising the beneficial effects of turbidity.  相似文献   

13.
The growth and gross growth efficiency of small Japanese little-neck clams, Tapes japonica, were investigated under two sets of experimental conditions. Over a 21-day period, growth of the clams, measured as an increase in dry weight and meat protein-N, was found to be correlated with the quantity of algal protein-N available and the amount of algal protein-N actually consumed by animals maintained at three different phytoplankton levels. With an increase in the quantity of phytoplankton presented there was a proportional increase in the quantity consumed and an increase in growth. The gross growth efficiency, based on the protein-N content of the algae consumed and the dry meat gain in protein-N, was highest at the lowest phytoplankton level (48%). At the two other phytoplankton levels there was little difference in growth efficiency, and it averaged 37.6%. Two tank designs were used in the study, one in which the fecal matter settled out of suspension and one in which the fecal material was continuously resuspended. There was little difference in the growth achieved using either tank design.  相似文献   

14.
As their natural prey, copepods are considered the ideal diets for hatchery culture of fish larvae. However, intensive cultivation of copepods has proven difficult and low culture productivity is the norm, which severely limits their use in aquaculture. This study investigated the effects of algal diets on a range of productivity‐related parameters, including egg production, hatching success, naupliar and copepodite survival, post‐embryonic development time, population growth and sex ratio of a small‐sized tropical copepod, Parvocalanus crassirostris, which has been identified as a high potential species for aquaculture. The diets tested included three live algal diets: Isochrysis sp. (T‐Iso), Pavlova 50 (Pav) and the diatom Chaetoceros muelleri (Cht); two algal paste diets: Isochrysis sp. (P‐Iso) and Thalassiosira weissflogii (P‐TW), as well as four mixed algae treatments composed of three binary algae diets (T‐Iso + Pav, T‐Iso + Cht and Pav + Cht) and a tri‐algal diet (T‐Iso + Pav + Cht). All parameters examined except sex ratio were significantly affected by the diets. The binary algal diet T‐Iso + Cht produced significant higher total egg production over female lifespan (121.0 ± 5.9 eggs) than all other treatments (P < 0.05). Survival during naupliar and copepodite stage was significantly superior when P. crassirostris were fed either the mixed diet of T‐Iso + Cht or the monoalgal diets of Cht or T‐Iso (P < 0.05) than other diets. These three treatments also had the fastest time of development to adults (ranging from 6.2 to 6.7 days). With an initial 100 adults, the T‐Iso + Cht treatment produced the highest population growth over a 15‐day cultivation period, which was significantly higher than other treatments (P < 0.001). In contrast, the algal paste treatments, including (P‐Iso) produced overall the worst results for various parameters examined. However, the sex ratio of P. crassirostris was not significantly affected by diets and was always heavily skewed towards females (>84% were females) across all treatments. Based on the results of this study, T‐Iso + Cht is recommended for intensive cultivation of P. crassirostris.  相似文献   

15.
This paper describes experiments in which nine species of prawns were compared for their suitability for intensive culture in closed systems. The species tested were: Macrobrachium rosenbergii, Penaeus aztecus, P. indicus, P. japonicus, P. monodon, P. occidentalis, P. orientalis, P. schmitti and P. setiferus. Tanks with a bottom area of 0.6 m2 and water depth 20 cm were stocked with juvenile prawns (0.2–0.5 g mean live-weight) of each species at two stocking densities, equivalent to 25 and 166 prawns/m2. Water conditions were maintained at 28±2°C and 28–30‰ (M. rosenbergii was reared in fresh water), and growth and survival were monitored during 16 weeks.Fastest growth was recorded for P. monodon and P. orientalis, which reached mean live-weights of 25.43 g and 22.80 g respectively at the low stocking density and 12.95 g and 14.63 g at the high stocking density. Best survival was recorded for P. monodon, which was considerably better than any of the other species. It was concluded that P. monodon and P. orientalis merit further consideration as candidates for intensive culture.  相似文献   

16.
Three potentially valuable red seaweeds, Chondrus crispus Stackhouse, Gracilaria bursa pastoris (S.G. Gmelin) P.C. Silva and Palmaria palmata (L.) O. Kuntze, collected in northern Portugal, were cultivated using the nutrient-rich effluents from a local turbot (Scophthalmus maximus Linnaeus) and sea bass (Dicentrarchus labrax Linnaeus) farm. The algae were cultivated in a two level cascade system. Several arrangements of the cascade system, stocking densities (3, 5, 7 and 8 kg m− 2) and water fluxes (140 and 325 l h− 1) were tested to optimize biomass yield and nitrogen uptake rate and efficiency. The yield and the total ammonium nitrogen (TAN) uptake of the three species were highly seasonal. Palmaria could not survive culture conditions during the summer when water temperature was above 21 °C. In the spring, Palmaria had an average yield of 40.2 (± 12.80) g DW m− 2 day− 1 and a nitrogen uptake efficiency (NUE) of 41.0% (± 17.26%). NUE expresses, in percentage, the average reduction in TAN concentration between the inflows and the outflows of the tanks. Chondrus performed better in summer with an average yield of 37.0 (± 11.10) g DW m− 2 day− 1 and removing 41.3% (± 17.32%) of nitrogen. Gracilaria grew year round, but also performed better during spring/summer, producing an average of 29.1 (± 2.90) g DW m− 2 day− 1, and only 7.3 (± 5.08) g DW m− 2 day− 1 during autumn. Yield of C. crispus did not differ significantly when grown at two different stocking densities (5 kg m− 2 and 8 kg m− 2). On the other hand, Gracilaria had significantly higher yields at 5 than at 7 kg m− 2. Better NUE, on average 76.7% (± 22.13%), was also obtained with 5 kg m− 2 stocking density and only 63.8% (± 24.62%) with 7 kg m− 2. The yield of Gracilaria increased significantly with the increase of water flux from 140 to 325 l h− 1 and more nitrogen was removed from the water. However, NUE decreased from 48.4% to 33.4% at 140 and 325 l h− 1, respectively. Biofiltration was highly improved by a cascade system with a NUE as high as 83.5%.  相似文献   

17.
The cold-water subtidal brown alga Laminaria japonica has been commercially farmed in the Far East and has been on top of all marine-farmed species in terms of farming area and annual output worldwide. The successful trials of transplantation of young sporophytes from the north to the south in winter along the Chinese coast in the 1950s led to the spreading of cultivation activities down to a latitude of 25–26°N. Up to today, nearly 50% of the annual output of this farmed alga, as a cold-water species, comes from the sub-tropical south in China. The demand to have high-temperature-tolerant strains/ecotypes in farming area calls for a practical method to judge and select the desired parental plants for breeding programs and for seedling production. In this paper, we report our results on using chlorophyll fluorescence measurement and short-term growth performance in tank culture to estimate the temperature tolerance of offspring from two populations, Fujian Farmed Population (FFP) sampled from Fujian province (latitude: 25–26°N) in subtropical area and Qingdao Wild Population (QWP) sampled from Qingdao (latitude: 36°N). Contrary to what has been usually thought, the results revealed that offspring from Qingdao wild population in the north showed better performance both in short-term growth and survival rates and in optimal quantum efficiency (Fv / Fm) when exposed to higher temperature (20–25 °C). This result was further confirmed by fluorescence quenching analysis. QWP distributed along the southern distribution limit at a latitude of 36°N in the Pacific west coast is thus taken as a more ideal one than the farmed population in subtropical region as a source of parental plants for breeding high-temperature-tolerant varieties.  相似文献   

18.
The experiment was conducted to assess the growth of juvenile greenlip abalone Haliotis laevigata fed a range of Ulva rigida diets with different nitrogen contents and an artificial pelleted diet. The minimal nutrient concentration resulting in significant enrichment of U. rigida was 2.25 mg N l?1. The maximum nitrogen content obtained by U. rigida in this study was 6.099%, which resulted from an inorganic nutrient concentration of 7 mg N l?1. However, no further significant increase in enrichment occurred from nutrient concentrations of 10 and 15 mg N l?1. Abalone specific growth rate in shell length (SGRL) and wet weight (SGRW) and foot muscle yield were significantly higher for abalone fed the artificial diet compared to those fed any U. rigida diet. Abalone fed U. rigida enriched in less than 15 mg N l?1 had similar growth rates compared to abalone fed unenriched U. rigida. Abalone fed the artificial diet contributed a higher percentage of weight gain into the valuable foot muscle. The foot muscle moisture content of abalone fed the artificial diet was significantly lower than that of abalone fed any U. rigida diet. The conclusions reached by this study should assist Australian abalone producers in assessing the potential benefits of using U. rigida as an effluent biofilter and subsequent food source for the commercially important juvenile greenlip abalone.  相似文献   

19.
A dual column photobioreactor (PBR) (2 × 47 L) with mixed CO2/air bubbling was tested for cultivation of the microalga Rhodomonas salina as food for live feed copepods. In the continuous growth phase, the cell density was relatively stable at 2.40 ± 0.13 × 106 cells/ml at an average dilution rate of 0.46 ± 0.02 per day throughout the 30‐day experiment. The produced algae had a high content of both total fatty acids (TFA) and free amino acids (FAA). Especially, the harvested algae contained a high proportion of poly‐unsaturated fatty acids that made up 80% of the TFA and of essential amino acids (35% of all FAA), implicating desirable components as feed for copepods. The current PBR was sufficient to feed a culture of the calanoid copepod Acartia tonsa at a density of 2,500 adult/L in ca. 500 L culture with a daily yield of approximately 17 × 106 eggs. To be able to sustain the integrated copepods production, the suggested volume of the algae cultures should be ca. 20% of the copepod culture volume.  相似文献   

20.
The possible roles of algae (i.e. “green water”) in facilitating Macrobrachium rosenbergii larviculture have been investigated.Larvae were incubated with 14C uniformly labeled Tetraselmis sp. and Phaeodactylum sp. No counts were incorporated by the larvae indicating that negligible quantities of algal cell material are ingested directly. In contrast, Artemia nauplii assimilated and digested appreciable quantities of algae under similar conditions.The algae rapidly removed ammonia that had been added to the larviculture medium even starting at levels toxic to the larvae (0.6 ppm). However, very high densities of Artemia (20/ml) caused ammonia accumulation even in the presence of the algae due to their own increased metabolic rate when fed upon algae and due to the reduced number of assimilating algae. Removal of the Artemia under these conditions was followed by rapid disappearance of the ammonia.The beneficial effects of Tilapia as a larviculture associate, reported elsewhere, was observed only in the presence of algae. Larval mortality actually increased in water that had supported the growth of Tilapia if algae were not present.It is concluded that algae facilitate the growth of Macrobrachium larvae only indirectly by removing toxic material, notably ammonia, from the medium. Under conditions where the Artemia are grown before contact with the Macrobrachium larvae and where other means of ammonia removal are employed, larval growth and development are not affected by the presence of algae and the latter can be dispensed with.  相似文献   

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