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Nauplii
Kinds of Nauplii Selected AbstractsSpatial distribution and feeding habits of Pacific cod (Gadus macrocephalus) larvae in Mutsu Bay, JapanFISHERIES OCEANOGRAPHY, Issue 2 2002Tetsuya Takatsu The spatial distributions and feeding habits of Pacific cod (Gadus macrocephalus) larvae, and the spatial distributions of copepod nauplii and copepodites, their main prey, were examined in Mutsu Bay from February to March during 1989,92. Yolk-sac larvae were caught at 30,45 m depth at the bay mouth. Larvae without yolk were collected at 8,45 m depth at the bay mouth and the inner part of the bay, and large larvae were chiefly found in the bay. This geographical pattern in larval size may have been because of transport to the inner part of Mutsu Bay by the Tsugaru Warm Current. The dominant taxa of copepod nauplii and copepodites in the diet and the environment changed each year. Larvae fed mainly on abundant taxa in the environment, suggesting that larvae are opportunistic feeders. Nauplii and copepodites were abundant in the bay, especially in 1992. Copepodites were slightly more abundant in the diet of cod larvae in 1992 than in 1991, but this difference was smaller than in the environment. In addition, larvae with empty digestive tracts were scarce in 1991 and 1992. Prey concentrations in the bay in 1991 and 1992 seem to have been high enough to sustain most Pacific cod larvae. [source] Survival and development of five species of cyclopoid copepods in relation to food supply: experiments with algal food in a flow-through systemFRESHWATER BIOLOGY, Issue 9 2005ULRICH HOPP Summary 1. Cyclops spp. generally develop and grow during favourable food conditions in spring and undergo a diapause in summer, while Acanthocyclops robustus, Mesocyclops leuckarti and Thermocyclops crassus develop and grow in summer when they face poorer food conditions and more competition from Cladocera. Since nauplii are the bottleneck in copepod development, we tested the hypothesis that Cyclops abyssorum and C. vicinus nauplii have higher food requirements for survival and development than the nauplii of A. robustus, M. leuckarti and T. crassus. We also tested survivorship and development from hatching to adulthood. 2. Survivorship and development of the copepods was studied in a flow-through system using five concentrations of the phytoflagellate Chlamydomonas reinhardtii in the range from 1 × 104 to 4.5 × 105 cells mL,1 (approximately 0.5,22.5 mg C L,1). 3. Nauplii of both species of Cyclops died at intermediate to low (C. abyssorum) and low (C. vicinus) food concentrations, while nauplii of A. robustus, M. leuckarti and T. crassus survived at all concentrations. 4. The negative effects of low food concentration were also reflected in development. In C. abyssorum and C. vicinus, development duration increased at low food concentration while development was much less affected in A. robustus and T. crassus. Mesocyclops leuckarti was intermediate between Cyclops spp. and A. robustus/T. crassus, with an increase in development duration at the lowest food concentration. 5. Our results support the hypothesis that summer diapause in Cyclops spp. has developed as a strategy to avoid a food bottleneck for nauplii. [source] Use of the oligochaete, Lumbriculus variegatus, as a prey organism for toxicant exposure of fish through the dietENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2006David R. Mount Abstract The oligochaete, Lumbriculus variegatus, has several characteristics that make it desirable as a prey organism for conducting dietary exposure studies with fish. We conducted 21- and 30-d experiments with young fathead minnows (Pimephales promelas) and rainbow trout (Oncorhynchus mykiss), respectively, to determine whether a diet consisting solely of L. variegatus would support normal growth and to compare performance with standard diets (Artemia nauplii, frozen brine shrimp, or trout chow). All diets were readily accepted, and fish survived and grew well. Food conversion in both fathead minnows and rainbow trout was as high as or higher for the oligochaete diet compared with others, although this comparison is influenced by differences in ration, ingestion rate, or both. The oligochaete diet had gross nutritional analysis similar to the other diets, and meets fish nutrition guidelines for protein and essential amino acids. Methodologies and practical considerations for successfully using oligochaetes as an experimental diet are discussed. Considering their ready acceptance by fish, their apparent nutritional sufficiency, the ease of culturing large numbers, and the ease with which they can be loaded with exogenous chemicals, we believe that L. variegatus represents an excellent choice of exposure vector for exposing fish to toxicants via the diet. [source] A short-term sublethal in situ toxicity assay with hediste diversicolor (polychaeta) for estuarine sediments based on postexposure feedingENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2005Susana Maria Moreira Abstract This study evaluated a short-term sublethal endpoint for in situ toxicity assays for estuarine sediments, based on postexposure feeding of the polychaete Hediste (Nereis) diversicolor Müller. A method for precisely quantifying postexposure feeding rates of H. diversicolor was established under laboratory conditions using Artemia franciscana Kellog nauplii. The sensitivity of the postexposure feeding response to copper was investigated by comparing postexposure feeding rates to growth and lethality. The 48-h and 96-h median lethal concentration (LC50) of copper were 241 and 125 ,g/L, respectively, whereas the 48-h median inhibitory concentration (IC50) for postexposure feeding and the 20-d IC50 for growth were 52 and 25 ,g/L of copper, respectively. The influence of different exposure conditions (substrate, temperature, salinity, food availability, and light) on H. diversicolor postexposure feeding was assessed; temperature and salinity were found to influence significantly postexposure feeding. The effectiveness of the proposed in situ assay was investigated by deploying it at two reference and six contaminated Portuguese estuaries. A 48-h exposure period was followed by a 1-h postexposure feeding period. High organism recoveries (89,100%) were obtained. Postexposure feeding was depressed significantly (17,90%) at all contaminated sites relatively to reference sites. The proposed in situ assay with H. diversicolor was shown to be a potential useful tool for estuarine sediment toxicity testing. [source] Estrogenic compounds affect development of harpacticoid copepod Tigriopus japonicusENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2003Helen S. Marcial Abstract The aim of this investigation was to evaluate the impact of estrogenic compounds onthe harpacticoid copepod Tigriopus japonicus after continuous exposure to environmentally relevant concentrations. Natural estrogen (17,-estradiol), three known estrogenic compounds in vertebrates (bisphenol A, 4-nonylphenol, p - t -octylphenol), and an invertebrate molting hormone (20-hydroxyecdysone) were tested for their effects on development and reproductive characters in two successive generations of T. japonicus. Less than 24-h-old nauplii (parentals) were exposed to four sublethal concentrations of these compounds for 21 d at 25°C. The first brood of nauplii (F1) produced was monitored further under the same culture conditions and exposures to test compounds. Results showed that all estrogenic compounds affected development (both in number of days to reach copepodid stage and sexual maturity) in the parental generation. Similar effects were apparent in the F1; however, fecundity, sex ratio, and survival were not significantly affected, even at concentrations as high as 10 ,g/L (nominal concentration). The invertebrate molting hormone 20-hyroxyecdysone had no detectable effect on any of the endpoints tested but gave the lowest 48-h 50% lethal concentration (LC50) value. The results suggest that endocrine disruption could occur in copepods following exposure to environmentally relevant concentrations of estrogenic compounds, especially if they are exposed starting from embryonic development. [source] Spatial distribution and feeding habits of Pacific cod (Gadus macrocephalus) larvae in Mutsu Bay, JapanFISHERIES OCEANOGRAPHY, Issue 2 2002Tetsuya Takatsu The spatial distributions and feeding habits of Pacific cod (Gadus macrocephalus) larvae, and the spatial distributions of copepod nauplii and copepodites, their main prey, were examined in Mutsu Bay from February to March during 1989,92. Yolk-sac larvae were caught at 30,45 m depth at the bay mouth. Larvae without yolk were collected at 8,45 m depth at the bay mouth and the inner part of the bay, and large larvae were chiefly found in the bay. This geographical pattern in larval size may have been because of transport to the inner part of Mutsu Bay by the Tsugaru Warm Current. The dominant taxa of copepod nauplii and copepodites in the diet and the environment changed each year. Larvae fed mainly on abundant taxa in the environment, suggesting that larvae are opportunistic feeders. Nauplii and copepodites were abundant in the bay, especially in 1992. Copepodites were slightly more abundant in the diet of cod larvae in 1992 than in 1991, but this difference was smaller than in the environment. In addition, larvae with empty digestive tracts were scarce in 1991 and 1992. Prey concentrations in the bay in 1991 and 1992 seem to have been high enough to sustain most Pacific cod larvae. [source] Seasonal trophic dynamics affect zooplankton community variabilityFRESHWATER BIOLOGY, Issue 11 2009BEATRIX E. BEISNER Summary 1. The degree to which communities are variable may be affected by the ecological conditions to which they are exposed and can affect their propensity to form alternative states. We examined the influence of two common ecological factors, predation and seasonal successional stage, on the variability in community composition of herbivorous pond plankton. In a highly replicated, two factor, mesocosm experiment we determined whether beta diversity was affected by seasonal successional stage of the community (two levels), by fish predation (presence/absence) or by their interaction. 2. Several significant changes were found in the composition of the rotifer, cladoceran and copepod assemblages. Most cladoceran abundances showed sharp declines in the presence of fish, while some rotifers, as well as their assemblage species richness, responded favourably to fish. The copepod assemblage was composed of omnivorous and carnivorous species, which added invertebrate predation to the experiment and which intensified as the season progressed. Copepods showed responses to fish predation that depended on seasonal successional stage of the initial community, because of changes in their stage structure and edibility as they grew from nauplii to adults. 3. Community variability was consistently high at the end of each month-long experimental period for both cladoceran and rotifer assemblages, except under two conditions. In the early season treatments, the rotifer assemblages were more consistent (lower beta diversity) in the presence of fish. This was attributed to high population growth rates for rotifers under these ecological conditions because of reduced copepod predation on them through a trophic cascade from fish. Low community variability was also observed in the late season for rotifers when fish were excluded and, as a result, they were exposed to high invertebrate predation from cyclopoid copepods. 4. Results from the early season support theoretical predictions that when community size increases, variability in composition should decline because of an increase in competitive processes over stochastic ones. Late season results suggest that a second mechanism, specialist predation, can also reduce prey community variability. Our study demonstrates that plankton communities may be more predictable under certain trophic web configurations and challenges ecologists to find ways to incorporate such inherent variability into experiments and community theory. [source] Habitat selection and diel distribution of the crustacean zooplankton from a shallow Mediterranean lake during the turbid and clear water phasesFRESHWATER BIOLOGY, Issue 3 2007BRUNO B. CASTRO Summary 1. The fish fauna of many shallow Mediterranean Lakes is dominated by small-bodied exotic omnivores, with potential implications for fish,zooplankton interactions still largely unknown. Here we studied diel variation in the vertical and horizontal distribution of the crustacean plankton in Lake Vela, a shallow polymictic and eutrophic lake. Diel sampling was carried out on three consecutive days along a horizontal transect, including an open-water station and a macrophyte (Nymphaea alba) bed. Since transparency is a key determinant of the predation risk posed by fish, the zooplankton sampling campaigns were conducted in both the turbid (autumn) and clear water (spring) phases. 2. In the turbid phase, most taxa were homogeneously distributed along the vertical and horizontal axes in the three consecutive days. The only exception was for copepod nauplii, which showed vertical heterogeneity, possibly as a response to invertebrate predators. 3. In the clear water phase, most zooplankton taxa displayed habitat selection. Vertically, the general response consisted of a daily vertical migration (DVM), despite the limited depth (1.6 m). Horizontally, zooplankters showed an overall preference for the pelagic zone, independent of the time of the day. Such evidence is contrary to the postulated role of macrophytes as an anti-predator refuge for the zooplankton. 4. These vertical (DVM) and horizontal (macrophyte-avoidance) patterns were particularly conspicuous for large Daphnia, suggesting that predation risk from size-selective predators (fish) was the main factor behind the spatial heterogeneity of zooplankton in the spring. Thus, the difference in the zooplankton spatial distribution pattern and habitat selection among seasons (turbid and clear water phases) seems to be mediated the predation risk from fish, which is directly related to water transparency. 5. The zooplankton in Lake Vela have anti-predator behaviour that minimises predation from fish. We hypothesise that, due to the distinct fish community of shallow Mediterranean lakes, aquatic macrophytes may not provide adequate refuge to zooplankters, as seen in northern temperate lakes. [source] Survival and development of five species of cyclopoid copepods in relation to food supply: experiments with algal food in a flow-through systemFRESHWATER BIOLOGY, Issue 9 2005ULRICH HOPP Summary 1. Cyclops spp. generally develop and grow during favourable food conditions in spring and undergo a diapause in summer, while Acanthocyclops robustus, Mesocyclops leuckarti and Thermocyclops crassus develop and grow in summer when they face poorer food conditions and more competition from Cladocera. Since nauplii are the bottleneck in copepod development, we tested the hypothesis that Cyclops abyssorum and C. vicinus nauplii have higher food requirements for survival and development than the nauplii of A. robustus, M. leuckarti and T. crassus. We also tested survivorship and development from hatching to adulthood. 2. Survivorship and development of the copepods was studied in a flow-through system using five concentrations of the phytoflagellate Chlamydomonas reinhardtii in the range from 1 × 104 to 4.5 × 105 cells mL,1 (approximately 0.5,22.5 mg C L,1). 3. Nauplii of both species of Cyclops died at intermediate to low (C. abyssorum) and low (C. vicinus) food concentrations, while nauplii of A. robustus, M. leuckarti and T. crassus survived at all concentrations. 4. The negative effects of low food concentration were also reflected in development. In C. abyssorum and C. vicinus, development duration increased at low food concentration while development was much less affected in A. robustus and T. crassus. Mesocyclops leuckarti was intermediate between Cyclops spp. and A. robustus/T. crassus, with an increase in development duration at the lowest food concentration. 5. Our results support the hypothesis that summer diapause in Cyclops spp. has developed as a strategy to avoid a food bottleneck for nauplii. [source] Preparation, antimicrobial activity, and toxicity of 2-amino-4-arylthiazole derivativesHETEROATOM CHEMISTRY, Issue 4 2006Pedro Morales-Bonilla Seven 2-amino-4-aryl-1,3-thiazoles (1a,g) and their corresponding 2-aminoacetyl (2a,g) and 2-aminoacetyl-5-bromo (3a,g) derivatives were synthesized and tested in vitro against 11 reference strains, three Gram-positive and four Gram-negative bacteria, two yeasts, and two moulds. Toxicity of the compounds was also evaluated using the brine shrimp test. Compounds 1a, 1b, 1e,g, and 3b showed moderate antimicrobial activity at different concentrations. The results indicated that acetylation of the amino group and bromination at position 5 of the thiazole moiety cause lost of activity. Compounds 1a, 1e, and 1f showed toxicity to brine shrimp nauplii below 10 ppm. Most other compounds showed moderate toxicity, LD50 above 100 ppm. Structures of all compounds were confirmed by NMR and MS data. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:254,260, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20182 [source] Impacts of a Small Dam on Riverine ZooplanktonINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2008Shuchan Zhou Abstract In order to explore the temporal impacts of a small dam on riverine zooplankton, monthly samples were conducted from November 2005 to June 2006 in a reach of Xiangxi River, China, which is affected by a small hydropower plant. A total of 56 taxa of zooplankton were recorded during the study and rotifers were the most abundant group, accounting for 97% of total taxa, while the others were copepod nauplii and copepod adults. This study indicated that: (1) the small dam in the Xiangxi River study area created distinct physical and ecological conditions relative to free-flowing lotic reaches despite the constrained channel and small size of the dam; (2) the existence of the plant's small dam had a significant effect on the zooplankton community. In long periods of drought or dry seasons the effect of the dam on potamoplankton was more pronounced (e.g., November, February, March, and May). But the downfall or the connectivity of channel appeared to decrease the effect of small hydropower plants on riverine zooplankton (e.g., April). The present observation underscores the need for additional studies that provide more basic data on riverine zooplankton communities and quantify ecological responses to dam construction over longer time spans. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Habitat Characteristics of Eurytemora lacustris(Poppe, 1887) (Copepoda, Calanoida): The Role of Lake Depth, Temperature,Oxygen Concentration and Light IntensityINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2005Peter Kasprzak Abstract Field observations, laboratory experiments and a literature survey were conducted to evaluate the habitat characteristics of Eurytemoralacustris (Poppe 1887), a freshwater calanoid copepod species. Combined effects of temperature and oxygen concentration in the deep water of thermally stratifying lakes seem to be the ultimate factors governing the occurrence of the species throughout its home-territory. E. lacustris is largely restricted to relatively deep lakes (>30 m) providing a hypolimnetic refuge characterised by low temperatures (<,10 °C) and oxygenated water during summer. Therefore, although the species is spread over much of Europe it was only found in a small number of lakes. Long-term records in different lakes revealed E. lacustris to be perennial with relatively high biomasses occurring from May to September. During thermal stratification on average 87% of the nauplii and 72% of the copepodite biomass was found in hypolimnetic waters colder than 10 °C. Diurnal vertical migration was observed for the copepodid stages, but the migration amplitude clearly decreased from May to September. The migration amplitude was significantly related to light intensity. According to its special habitat requirements, E. lacustris might be considered a glacial relict sensitive to temperature increase and oxygen depletion. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Telotroch formation, survival, and attachment in the epibiotic peritrich Zoothamnium intermedium (Ciliophora, Oligohymenophorea)INVERTEBRATE BIOLOGY, Issue 3 2008Laura R.P. Utz Abstract. Aspects of the life cycle of the peritrich ciliate Zoothamnium intermedium, an epibiont on calanoid copepods in the Chesapeake Bay, were investigated using host and epibiont cultures. Experiments were designed to characterize the formation, survival, and attachment of free-swimming stages (telotrochs) and to assess whether telotrochs preferentially attach to primary (Acartia tonsa and Eurytemora affinis) or alternate hosts from the zooplankton community (the rotifer Brachionus plicatilis, barnacle nauplii, polychaete larvae, and a harpacticoid copepod). The results showed that telotroch formation started 2 h after the death of the host, with >90% of the zooids leaving the host carapace within 7 h. Formation of telotrochs was triggered only by the death of the host, failing to occur when the host was injured or unable to swim. Telotrochs failed to attach to non-living substrates and survived for only 14 h in the absence of host organisms, suggesting that members of Z. intermedium are obligate epibionts. Attachment success decreased with telotroch age, indicating that colonization success in nature may strongly depend on the ability to find a suitable host in a short period of time. Individuals exhibited no preferences in colonizing juvenile or adult stages of A. tonsa or E. affinis. While telotrochs were able to colonize barnacle nauplii and the harpacticoid copepod in the absence of individuals of A. tonsa or E. affinis, they did not attach to the rotifers or polychaete larvae. Telotrochs preferentially colonized individuals of A. tonsa when in the presence of other non-calanoid host species. [source] Larval rearing of chub, Leuciscus cephalus (L.), using decapsulated Artemia as direct foodJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2003A. Shiri Harzevili Summary Little is known about the larviculture of the chub, Leuciscus cephalus (L.), an endangered cyprinid species endemic to European flowing waters. The use of decapsulated Artemia cysts as food for chub larviculture was investigated. After 3-day feeding with the rotifer Brachionus calyciflorus, the larvae were fed on different diets: (i) dried decapsulated Artemia cysts, (ii) Artemia nauplii, (iii) rotifers for seven more days and then Daphnia collected from a pond, and (iv) an artificial diet. After a 24-day rearing period, the highest survival rate was obtained with the larvae receiving decapsulated Artemia cysts. Feeding of the larvae with an artificial diet resulted in a significantly lower survival rate compared with the other groups. At the end of the experiment, the larvae fed on Artemia nauplii yielded a significantly higher mean length compared with the other groups. Feeding an artificial diet resulted in a significantly lower average weight and mean length gain compared with the other groups. [source] Growth and survival of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed isocaloric diets with different protein levels during weaningJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2000R. V. Eguia Summary The growth of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed four isocaloric diets (4200 kcal kg,1) with different protein levels during weaning was determined. Diets containing 45, 50, 55, and 60% protein were formulated by linear programming using amino acid profiles based on that of 2-day-old river catfish larvae. Artificial diets were fed to the larvae beginning at day 5 after being initially fed Artemia nauplii for 4 days. The larvae thrived solely on artificial diets from day 8 to day 16. On the other hand, the control larvae were fed Artemia nauplii from day 1 to day 16. Results of the feeding trial showed that growth and survival of M. nemurus larvae given the diet containing 60% protein were high and comparable to those of the larvae given only live food (control). Larvae fed the 55% protein diet had significantly lower growth and survival than the larvae on the control and 60% diets but significantly higher growth and survival rates than did larvae fed with 45 and 50% protein diets. Carcass moisture and total lipids after 16 days of feeding did not differ significantly (P > 0.05), but body protein increased with increasing dietary protein. Body protein of the control larvae was similar to that of larvae given the 60% protein diet. [source] Further evidence and characterization of Artemia franciscana (Kellogg, 1906) populations in ArgentinaJOURNAL OF BIOGEOGRAPHY, Issue 11 2004Francisco Amat Abstract Aim, This paper reports the presence of Artemia franciscana (Kellogg, 1906) in Mar Chiquita (CHI) salt lake and in Las Tunas (TUN) lagoon, as well as at a shallow lake in Salinas Grandes (Province of Córdoba) in Argentina. To date, this species has been considered absent from Argentina. This study also provides further data on the characterization of the A. franciscana populations from this area. Location, Province of Córdoba (Argentina). Methods, The cyst samples collected at the three hypersaline environments were measured to assess its mean diameter with a dissecting microscope. The length of the nauplii hatched from the cysts was also determined with the microscope. The adults raised from these nauplii under strictly controlled conditions were analysed for 12 morphological parameters and compared through multivariate discriminant analysis with other American populations. Fatty acids from the total lipids were analysed by gas chromatography. Reproductive compatibility was evaluated from single-pair intraspecific and interspecific crosses of adult specimens. Results, The results endorse the morphometric assimilation of the Artemia populations of this area to other American populations of the A. franciscana,super-species', together with its morphometric differentiation from the species A. persimilis (Piccinelli & Prosdocimi, 1968). The more conspicuous population from CHI shows cross-fertility with A. franciscana original from San Francisco Bay (California, USA). Both populations from CHI and TUN show cross-fertility between them and reproductive isolation with A. persimilis from Hidalgo (Province of La Pampa), which to date is considered to be endemic or exclusive of hypersaline ecosystems in Argentina. The reproductive characteristics displayed by the population from TUN lagoon suggest the existence of an occasional hybridization between A. franciscana and A. persimilis (Papeschi et al., 2000). Artemia cysts from CHI and TUN show a fatty acid profile rich in eicosapentaenoic acid differing markedly from the fatty acid profiles found in A. persimilis cysts. Main conclusions:,Artemia franciscana is present in Argentina at 36° S and north of this latitude. Artemia persimilis is confined to the south of latitude 37°10, S. There are different pieces of evidence that point to a certain level of hybridization of the two species taking place in the land belt between these parallels. [source] Sibling cannibalism in dorada under experimental conditions.JOURNAL OF FISH BIOLOGY, Issue 4 2000II. Effect of initial size heterogeneity, light regime on early cannibalism Cannibalism among embryos and larvae of Brycon moorei (Characidae) occurs during daytime and night-time, and persists under permanent darkness. Embryos and larvae of dorada-provisioned with formulated feed over the first week of exogenous feeding did not survive, except for those exerting cannibalism. When offered alternative fish prey [embryos of Prochilodus magdalenae (0·5,0·8 mg) and Oreochromis niloticus (9,10 mg)], 1-day-old embryos of dorada preferred preying on these, thereby reducing early cannibalism. However, this promoted depensatory growth and more intense cannibalism later in the larval stage. Dorada provisioned with Artemia nauplii in excess showed more homogeneous growth and higher survival, most cannibalistic acts being restricted to the first 24 h of exogenous feeding, just after oral teeth were fully developed (21 h after hatching). Provisioning dorada with Artemia nauplii a few hours before their oral teeth were fully developed reduced early cannibalism from 41 to 15%. High proportions of deformed fish caused higher mortality, both directly and indirectly, as they promoted early cannibalism, depensatory growth and more intense cannibalism among larvae. The initial sorting of embryos, based on their occupation of the water column improved survival significantly during the first week of exogenous feeding, up to 52% in progenies containing <10% of deformed fish. Size-grading of larvae and young juveniles over the next 2 weeks reduced cannibalism to 2·6 and 1·9% day,, in the first and second weeks, respectively. These results indicate that cannibalism in dorada can be mitigated efficiently through appropriate rearing procedures, and open promising perspectives for the intensive culture of this fast-growing tropical species. [source] Experimental vertical transmission of Macrobrachium rosenbergii nodavirus (MrNV) and extra small virus (XSV) from brooders to progeny in Macrobrachium rosenbergii and ArtemiaJOURNAL OF FISH DISEASES, Issue 1 2007R Sudhakaran Abstract White tail disease (WTD) is a serious problem in hatcheries and nursery ponds of Macrobrachium rosenbergii in India. Experiments were carried out to determine the possibility of vertical transmission of M. rosenbergii nodavirus (MrNV) and extra small virus (XSV) in M. rosenbergii and Artemia. Prawn broodstock inoculated with MrNV and XSV by oral or immersion challenge survived without any clinical signs of WTD. The brooders spawned 5,7 days after inoculation and the eggs hatched. The survival rate of larvae gradually decreased, and 100% mortality was observed at the post-larvae (PL) stage. Whitish muscle, the typical sign of WTD, was seen in advanced larval developmental stages. The ovarian tissue and fertilized eggs were found to be positive for MrNV/XSV by reverse transcriptase-polymerase chain reaction (RT-PCR) whereas the larval stages showed positive by RT nested PCR (nRT-PCR). In Artemia, reproductive cysts and nauplii derived from challenged brooders were normal and survival rates were within the expected range for normal rearing conditions. The reproductive cysts were found to be positive for MrNV/XSV by RT-PCR whereas the nauplii showed MrNV/XSV-positive by nRT-PCR. The PL of M. rosenbergii fed nauplii derived from challenged Artemia brooders died at 9 days post-inoculum with clinical signs of WTD. [source] Bacterial enteritis and the development of the larval digestive tract in olive flounder, Paralichthys olivaceus (Temminck & Schlegel)JOURNAL OF FISH DISEASES, Issue 9 2004D-H Kim Abstract Three bacterial isolates obtained from diseased olive flounder larvae, Paralichthys olivaceus, were identified as Vibrio ichthyoenteri based on the results of phenotypic characterization and 16S rRNA gene sequencing studies. Bacterial enteritis was reproduced in 16 and 22 days post-hatch (dph) larvae by administering brine shrimp nauplii, Artemia salina, dosed with the environmental isolates and reference strains of V. ichthyoenteri. To investigate the effect of the disease on development of the stomach, a pepsin activity assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis of the expression of the pepsinogen gene were performed. Expression of olive flounder pepsinogen was detected from 30-dph larvae and the increased level of pepsin activity coincided with reduced susceptibility to the disease. Growth rates of V. ichthyoenteri, V. anguillarum and Edwardsiella tarda were tested in artificial stomach conditions using HCl and porcine pepsin. All the strains of V. ichthyoenteri were inhibited by low pH conditions which corresponded with an increase in pepsin levels. This suggests that differentiation of the stomach in olive flounder larvae and juveniles, an essential physiological development, also provides the host with a non-immunological defence mechanism. [source] Development of a sensitive diagnostic assay for fish nervous necrosis virus based on RT-PCR plus nested PCRJOURNAL OF FISH DISEASES, Issue 5 2000L Dalla Valle A polymerase chain reaction (PCR)-based assay to detect nervous necrosis virus (NNV) in fish was developed by using two sets of primers designed on a highly conserved region of the coat protein gene encoded by RNA2 of NNV. The first pair of primers amplified a fragment of 605 bp by one-step reverse-transcription (RT)-PCR, while the second pair amplified an internal segment of 255 bp by nested PCR. Addition of nested PCR increased the assay sensitivity 100-fold when carried out in a separate tube (two-step assay) and 10-fold when performed in the same tube (one-step assay). The sensitivity of the two-step assay was 104 times higher than that of virus cultivation. Nested PCR served also to confirm the specificity of the first amplification, as verified also by Southern hybridization analysis and direct sequencing. In species known to be susceptible to infection, such as European sea bass, Dicentrarchus labrax, and gilthead seabream, Sparus aurata, NNV was often detectable in brain tissue by RT-PCR alone but only by the two-step assay in blood, sperm, ovarian tissue or larvae. The same was true for sperm and ovarian tissue of shi drum, Umbrina cirrosa. NNV was also detected in the brains of Japanese red seabream, Pagrus major and brown meagre, Sciaena umbra, suggesting that these species can also be infected. No NNV was detected in samples of Artemia salina nauplii and rotifers obtained from a fish farm with an NNV outbreak. The inclusion of nested PCR in the assay appears to be necessary to screen out NNV-positive broodfish by blood sampling and testing of their larval progeny. [source] Relating the ontogeny of functional morphology and prey selection with larval mortality in Amphiprion frenatusJOURNAL OF MORPHOLOGY, Issue 6 2010Justin Anto Abstract Survival during the pelagic larval phase of marine fish is highly variable and is subject to numerous factors. A sharp decline in the number of surviving larvae usually occurs during the transition from endogenous to exogenous feeding known as the first feeding stage in fish larvae. The present study was designed to evaluate the link between functional morphology and prey selection in an attempt to understand how the relationship influences mortality of a marine fish larva, Amphiprion frenatus, through ontogeny. Larvae were reared from hatch to 14 days post hatch (DPH) with one of four diets [rotifers and newly hatched Artemia sp. nauplii (RA); rotifers and wild plankton (RP); rotifers, wild plankton, and newly hatched Artemia nauplii (RPA); wild plankton and newly hatched Artemia nauplii (PA)]. Survival did not differ among diets. Larvae from all diets experienced mass mortality from 1 to 5 DPH followed by decreased mortality from 6 to 14 DPH; individuals fed RA were the exception, exhibiting continuous mortality from 6 to 14 DPH. Larvae consumed progressively larger prey with growth and age, likely due to age related increase in gape. During the mass mortality event, larvae selected small prey items and exhibited few ossified elements. Cessation of mass mortality coincided with consumption of large prey and ossification of key elements of the feeding apparatus. Mass mortality did not appear to be solely influenced by inability to establish first feeding. We hypothesize the interaction of reduced feeding capacities (i.e., complexity of the feeding apparatus) and larval physiology such as digestion or absorption efficiency contributed to the mortality event during the first feeding period. J. Morphol., 2010. © 2010 Wiley-Liss, Inc. [source] Use of Cyclopoid Copepod Apocyclops dengizicus as Live Feed for Penaeus monodon PostlarvaeJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2009Omidvar Farhadian In this study, the suitability of cyclopoid copepod Apocyclops dengizicus as a live food for black tiger shrimp, Penaeus monodon, postlarvae was investigated. After 14 d, P. monodon postlarvae (PL1) had survival rates of 41.7 ± 2.9% (mean ± SE), 28.7 ± 1.2%, 56.3 ± 3.7%, 4.4 ± 1.9%, and 2.8 ± 1.0% when fed A. dengizicus (CC), Artemia nauplii (AN), mixture of A. dengizicus and Artemia nauplii (CC + AN), artificial shrimp feed (SF), and microalga Tetraselmis tetrathele (TT), respectively. Specific growth rates (SGRs) of P. monodon were maximum (14.2 ± 0.6%/d) in CC + AN, followed by CC (11.0 ± 0.4%/d), AN (9.3 ± 0.7%/d), SF (6.1 ± 0.2%/d), and TT (6.0 ± 0.5%/d). The total n-3 fatty acids of postlarvae increased from 20.6 to 25.8% when fed with CC, 28.8% with AN, and 29.0% with CC + AN. Better survival and SGRs of P. monodon postlarvae could be attributed to docosahexaenoic acid : eicosapentaenoic acid : arachidonic acid ratio of CC (10.2:3.2:1) diet. The results of this study showed that A. dengizicus has a potential to be used as a substitute live feed for P. monodon postlarvae because of better survival, growth, and high polyunsaturated fatty acids. [source] Growth, Maturation, Induced Spawning, and Production of the First Generation of South American Catfish, Pseudoplatystoma sp., in North AmericaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2008Konrad Dabrowski Growth, plasma steroids, and the appearance of gonads (histology and gonadosomatic index) were followed in South American catfish (surubim, Pseudoplatystoma sp.) raised in captivity in the aquaculture facility at The Ohio State University, Columbus, Ohio, USA, from 2003 until 2006. Broodstock growth showed a great individual variation and it did not seem sex dependent. The levels of 11-ketotestosterone were high in males during the reproductive season. Three out of six females spawned after receiving two doses of carp pituitary extract (0.5 and 5 mg/kg) at 11-h intervals. Fertilization was performed in only one female in February 2006. Egg size was 0.73 ± 0.06 mm in diameter at stripping. Two males released sperm, and it was used for fertilization. Sperm concentrations were 24 × 109 and 15.5 × 109 spermatozoa/mL in Male 1 and Male 2, respectively, and viability was confirmed after activation in 0.3% NaCl. Embryo survival at 9 h after fertilization was 44 and 23% for Male 1 and Male 2, respectively. Embryos hatched 15 h after fertilization. Larvae were 3.53 ± 0.09 mm in length at hatching and were successfully raised (72% survival after 2 wks) using live brine shrimp nauplii. [source] Effects of Larval Stocking Density on Laboratory-Scale and Commercial-Scale Production of Summer Flounder Paraliehthys dentatusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2000Nicholas J. King Experiments 1 and 2 at commercial scale tested the densities of 10 and 60 larvae/L, and 10, 20, and 30/L, respectively. The laboratory scale experiment tested the densities of 10, 20, 30, and 40 larvae/L. Experiments were carried out in two separate filtered, flow-through seawater systems at URI Narragansett Bay Campus (laboratory-scale), and at GreatBay Aquafarms, Inc. (commercial-scale). At both locations, the larvae were raised in a "greenwater" culture environment, and fed rotifers and brine shrimp nauplii according to feeding regimes established for each location. Water temperature was maintained at 21C (± 2) and 19C (± 1) for the duration of laboratory and commercial experiments, respectively. Experiments 1 and 2 at the commercial location were terminated at 42 and 37 d post hatch (dph), respectively, and the laboratory experiment lasted 34 DPH. Larvae initially stocked at 10/L grew to an average length of 14.3 and 14.4 mm, and were significantly larger (P < 0.05) than those stocked at 30/L (13.1 mm) and 60/L (11.7 mm) in commercial scale experiments I and 2, respectively. At laboratory scale, no significant differences in length were detected, although mean total length tended to decrease with increasing stocking density (average length of 14.2, 13.3, 12.7, and 12.7 mm for treatments of 10, 20, 30, and 40/L, respectively). Final survival percentage was not affected by stocking density in either commercial experiment, and was 61 and 40% for treatments of 10 and 60/L in Experiment 1, respectively, and 62, 59, and 56% for Experiment 2, respectively. Similarly, there was no significant difference in final survival percentage among treatments in the laboratory experiment, which averaged 59, 55, 56, and 37% for treatments of 10, 20, 30, and 40L. respectively. Since larval length was not different between the intermediate densities (20 and 30 Iarvae/L), and because high-density rearing can produce a much greater numerical yield per tank, we recommend a density of 30 larvaen as an optimal stocking density for the hatchery production of summer flounder. [source] Effects of chlorpyrifos in freshwater model ecosystems: the influence of experimental conditions on ecotoxicological thresholdsPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 10 2005René PA van Wijngaarden Abstract Three experiments were conducted to determine the impact of the insecticide chlorpyrifos (single applications of 0.01 to 10 µg AI litre,1) in plankton-dominated nutrient-rich microcosms. The microcosms (water volume approximately 14 litres) were established in the laboratory under temperature, light regimes and nutrient levels that simulated cool ,temperate' and warm ,Mediterranean' environmental conditions. The fate of chlorpyrifos in the water column was monitored and the effects on zooplankton, phytoplankton and community metabolism were followed for 4 or 5 weeks. The mean half-life (t1/2) of chlorpyrifos in the water of the test systems was 45 h under ,temperate' conditions and about 30 h under ,Mediterranean' environmental conditions. Microcrustaceans (cladocerans and copepod nauplii) were amongst the most sensitive organisms. All three experiments yielded community NOEC (no observed effect concentrations) of 0.1 µg AI litre,1, similar to those derived from more complex outdoor studies. Above this threshold level, responses and effect chains, and time spans for recovery, differed between the experiments. For example, algal blooms as an indirect effect from the impact of exposure on grazing organisms were only observed under the ,Mediterranean' experimental conditions. The relatively simple indoor test system seems to be sufficient to provide estimates of safe threshold levels for the acute insecticidal effects of low-persistence compounds such as chlorpyrifos. The robustness of the community NOEC indicates that this threshold level is likely to be representative for many freshwater systems. Copyright © 2005 Society of Chemical Industry [source] Effects of the commercial probiotic Lactobacillus casei on the growth, protein content of skin mucus and stress resistance of juveniles of the Porthole livebearer Poecilopsis gracilis (Poecilidae)AQUACULTURE NUTRITION, Issue 4 2010L.H.H. HERNANDEZ Abstract A 11-week feeding trial was carried out to determine the effects of the probiotic bacteria Lactobacillus casei from the commercial product Yakult® on the growth performance, proximal composition, protein content of skin mucus and stress resistance of juvenile Porthole livebearer Poeciliopsis gracilis. Triplicate groups of 15 juveniles per tank with an initial weight of 47 ± 9 mg (mean ± standard deviation) were fed with Artemia nauplii enriched with the probiotic, by using the bacteria cells plus the fermented milk (group ProN) and the other (group ProC) by using only the bacterial cells, eliminating the fermented milk by centrifugation. A control of fish was set up, by feeding non-enriched Artemia nauplii. Growth performance and survival rates did not show significantly differences among the treatments and control group, but a slightly tendency of higher values for body weight, weight gain and specific growth rate was observed in the juveniles of ProC treatment. Whole body proximate composition did not show significant differences among the groups, but higher values of protein and lipid contents were observed in the groups fed with the probiotic. Content of protein in the skin mucus were significantly higher in the ProC treatment than control group. Recovery rates after an air-dive test were significantly higher on the fish fed with the probiotic cells than the control group. These results show that L. casei might be used as a probiotic for fish and would help during the culture of juvenile of the Porthole livebearer P. gracilis. [source] Assessment of dietary lecithin and cholesterol requirements of mud crab, Scylla serrata, megalopa using semi-purified microbound dietsAQUACULTURE NUTRITION, Issue 6 2007M.-H. HOLME Abstract The effects of varying dietary lecithin and cholesterol levels on growth, development and survival of mud crab, Scylla serrata, megalopa were evaluated using six semi-purified, microbound diets formulated to be iso-energetic and containing three levels of supplemental lecithin (0, 20 and 40 g kg,1 diet dry weight) and two levels of supplemental cholesterol (0 and 7 g kg,1 diet dry weight). Fifteen megalopa were reared individually in each treatment and the nutritional value of diets was assessed on basis of mean dry weight and mean carapace width of newly settled first crab stage, as well as development time to the first crab stage and overall survival. A significant interaction between supplemental dietary lecithin and supplemental dietary cholesterol was found for final mean dry weight of newly settled crabs, and highest survival (60%) was recorded for megalopa fed diets containing the highest levels of dietary lecithin (39.7,44.1 g kg,1) (diet 5 and 6) regardless of whether diets were supplemented with cholesterol; this rate of survival was identical to that of megalopa fed live Artemia nauplii. The results indicate that supplemental dietary cholesterol may not be essential for mud crab megalopa when fed diets containing sufficient levels of supplemental dietary phospholipids. [source] Use of Cyclop-eeze as a substitute for Artemia nauplii in larval rearing of giant freshwater prawn Macrobrachium rosenbergii (De Man 1879)AQUACULTURE NUTRITION, Issue 2 2007C. MOHANAKUMARAN NAIR Abstract Four feeding experiments, replacing 25% (T1), 50% (T2), 75% (T3) and 100% (T4), by dry weight, of the live feed Artemia nauplii for Cyclop-eeze, a new larval feed that was claimed to contain the highest known levels of astaxanthin and omega-3 polyunsaturated fatty acids, were compared against a control that was fed with Artemia and egg custard alone, to the larvae of giant freshwater prawn Macrobrachium rosenbergii (De Man 1879). Analysis of different production characteristics of the larvae revealed that the highest survival up to postlarvae (PL) stage was obtained for T2 in which 50% of the Artemia nauplii were replaced by Cyclop-eeze [freeze-dried (FD) deep frozen (DF)], and the highest astaxanthin content of the larval tissue obtained in T4 in which the larvae were fed 100% Cyclop-eeze, although the survival rate was the lowest in this treatment. The costs of different treatments were also compared. The Artemia consumption million,1 larvae was the highest in control (11490 g), followed by T1 (8240 g), T2 (4990 g), T3 (3730 g) and T4, which completely replaced Artemia from stage 5 onwards (1830 g). The highest consumption of Cyclop-eeze million,1 larvae was in T4 (1670 and 10 880 g), followed by T3 (850 and 5560 g), T2 (410 and 2690 g) and T1 (230 and 1490 g) of FD and DF, respectively. The astaxanthin contents of the late-stage larvae fed under the four treatments were 24.90, 27.40, 28.60 and 35.60 ,g g,1 tissue for T1, T2, T3 and T4, respectively, while that of the control was 23.70 ,g g,1. The lowest cost of live feeds million,1 PL was obtained for T2 (US$ 428.60), followed by T1 (US$ 490.46), control (US$ 529.07) and T3 (US$ 583.26), while it was the highest for T4 (US$ 890.93). The results indicated that Cyclop-eeze could economically replace Artemia nauplii at 50% level that could significantly improve the survival and carotenoid composition of the larvae of M. rosenbergii. [source] Complete and partial replacement of Artemia nauplii by Moina micrura during early postlarval culture of white shrimp (Litopenaeus schmitti)AQUACULTURE NUTRITION, Issue 2 2006L. MARTÍN Abstract Growth rate, soluble protein content, osmotic stress and digestive enzyme activity were studied in early Litopenaeus schmitti postlarvae under different feeding regimens, by partially or completely replacing Artemia nauplii with Moina micrura. Growth was significantly higher in the postlarvae fed with a mixture of M. micrura, Artemia nauplii and algae (0.030 mg dry weight (dw) larva,1 day,1, 17.4 ± 2.1% day,1), together with the postlarvae fed on Artemia nauplii and algae (0.027 mg dw larva,1 day,1, 18.3 ± 1.9% day,1). Complete replacement of Artemia nauplii by M. micrura produced the lowest growth rate (0.018 mg dw larva,1 day,1, 14.3 ± 1.6% day,1) and induced the highest protease and , -amylase activities and lower soluble protein contents. No significant difference among the treatments could be detected in postlarval resistance to osmotic stress. Based on the growth results, soluble protein content, enzymatic activity and osmotic stress resistance, we determined that the partial replacement of Artemia nauplii by M. micrura did not affect the growth, the soluble protein content and the nutritional state in the postlarvae of L. schmitti. To our knowledge, this is the first reported use of M.micrura as feed for early postlarvae of L. schmitti. [source] The use of squid protein hydrolysate as a protein source in microdiets for gilthead seabream Sparus aurata larvaeAQUACULTURE NUTRITION, Issue 1 2000Kolkovski In the present study, the use of predigested proteins as an ingredient of microdiets offered to gilthead seabream larvae was tested. The protein source (freeze-dried squid powder) was hydrolysed with protease (trypsin and pancreatin). Different levels of raw squid protein and hydrolysate (100% protein, 50% protein/50% hydrolysate, 100% hydrolysate) were added to the microdiets to produce a dietary protein level of 65%. For comparison, cofeeding of Artemia nauplii and microdiet as well as microdiet supplemented with pancreatin were also offered to the larvae. The final average dry weights of 32-day-old larvae were 1.65 ± 0.04 mg, 1.38 ± 0.06 mg and 1.13 ± 0.1 mg, respectively, for larvae cofed 0%, 50% and 100% hydrolysate microdiets and Artemia nauplii. Survival of larvae was not affected by protein source. The survival of larvae cofed Artemia nauplii and microdiet was significantly higher than that of larvae fed exclusively on microdiet (68% and 80%, respectively). These results suggest that the use of hydrolysate (at 50% greater) as a protein source in diets for seabream larvae is not to be recommended. [source] | ||||||||||||||||